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1937 Homochitto River Project Revisited
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Prud'homme B.

In 1937, the US Army Corps of Engineers began a flood control project on the lower end of the Homochitto River, an east tributary to the Mississippi River south of Natchez. Upon completion, the lower serpentine 20 mile reach was shortened to a straight channel only 10 miles long. The steepened river gradient and increased flow velocity stimulated immediate headward erosion resulting in continuous geomorphic channel adjustments of every tributary along the adjusting river channel, including every tributary stream on the Homochitto National Forest. Riparian habitat along the river has all but completely disappeared and aquatic habitat diversity has been dramatically homogenized. Transportation systems and other infrastructure have suffered extensive damage, valuable property has been lost, and untold millions of cubic yards and tons of sediment have gone downstream into the Mississippi River. Potential may exist for the geomorphic trend of the river and tributaries to cease and reverse.

A Geospatial Methodology for Mapping Land Parcels with Individual On-Site Wastewater Disposal Systems
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Cartwright J., Grala K., Collini R.

Individual on-site wastewater disposal systems (IOWDS) or septic systems are an ever-increasing source of non-point source pollution along the coast of Mississippi. Inventories of these systems are not always complete or simply non-existent. This project utilized geospatial technologies, specifically geographic information systems (GIS), to identify land parcels that are potentially using an IOWSD. The approach used existing service utility provider records, land parcels, and improvement values to identify properties that are likely to have on-site waste disposal for a specific service area. The methodology was developed around geocoding techniques coupled with multi-criteria selection for property identification. The project area had a total of 83,863 parcels and 22,976 were identified as non-serviced parcels. Using a threshold improvement value of $7,500 resulted in 9,550 parcels that potentially have an IOWDS. These identified parcels were assessed for vulnerabilities based on groundwater depth, high-tide flooding for current and future sea level rise, and current and future storm surge under future sea level rise scenarios. 6,232 (65%) of these were found to be at some level of risk over the next several decades due to changes in groundwater, high tide, and/or storm surge as seas rise. Additional spatial analyses were performed and identified 1,621 parcels were near existing infrastructure to help prioritize transitioning from on-site disposal to a service utility.

A more efficient way of integrating Watershed Boundary Dataset (WBD) into web-based Agricultural Integrated Management System (AIMS)
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Sahin A.N., Ozeren Y.

Agricultural Integrated Management System (AIMS) is a web-based tool developed by The National Center for Computational Hydroscience and Engineering (NCCHE) University of Mississippi, and USDA-ARS National Sedimentation Laboratory, for watershed conservation management planning. AIMS is intended to provide a user-friendly environment for data analysis and watershed modeling with automated input data preparation capabilities from seamless geospatial data for any watershed in the United States. Watershed Boundary Dataset (WBD) is used to define the simulation boundaries of AIMS models including the topographic landscape analysis tool TopAGNPS. One of the advancements of the new AIMS environment is GeoJSON data format to represent geospatial features, which required conversion of WBD hydrologic unit boundaries into GeoJSON data format, and re-establishment of the hydrologic unit hierarchy. The conversion enables inter-operation between backend Python and Java modules, and the watershed simulation models running under AIMS, including TopAGNPS, for locally transferring remote or saved structured data independently from the map servers. This allows importing the geospatial data as an object with its hierarchy for backend operations without requiring additional parsing or server-side operations (authentication, data transfer, etc.). This method also increases the stability, security, and speed of the system and decreases its dependency of it on external resources. The key features of the new AIMS platform including the updated WBD will be presented.

Advances in Groundwater Modeling for the Mississippi Delta from the Mississippi Alluvial Plain (MAP) Project
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Duncan L.L., Haugh C.J.

The goal of the regional groundwater availability study of the Mississippi Alluvial Plain (MAP) is to improve estimates of water availability, both past and present, and to determine how groundwater resources will respond to current and future stresses. Groundwater withdrawals from the Mississippi River Valley alluvial aquifer within the Mississippi Delta have been vital for agricultural production. Despite the apparent stabilization of groundwater levels in some places across the Mississippi Delta following several recent years with above-average rainfall, long term sustainability of the aquifer remains a concern due to the large groundwater-level declines over the last century, increasing demand for irrigation from groundwater, and uncertainty about future climate.

The MAP study builds upon the previously developed Mississippi Embayment Regional Aquifer Study (MERAS). The Mississippi Delta inset groundwater flow model offers several enhancements over older versions of the regional groundwater flow model, including higher spatial, vertical, and temporal resolutions. The inset model uses the newer MODFLOW 6 and PEST++-IES modeling and parameter estimation technology, providing more robust calibration. The inset model incorporates information from airborne electromagnetic surveys through a new surficial aquifer base, updated confining unit thickness, and zoned parameterization of aquifer properties. The inset model also uses Soil-Water-Balance model estimates for recharge and runoff estimates, agricultural water use estimates partially derived from the Mississippi Department of Environmental Quality voluntary metering program, and a denser streamflow routing network.

Accurate assessments of water availability in the Delta are critical to informing management decisions, establishing best practices for water use, and contending with projected changes to the regional water cycle. The groundwater response to different combinations of water management practices and anticipated changes in water budget components is examined using the groundwater model. This study is intended to provide improved estimates of historical, current, and future groundwater availability and to aid water resource managers in making decisions that can help sustain agricultural and industrial practices in the MAP region using a numerical groundwater model.

Analysis of Long-term Trend and Change points in Maximum Air Temperature within Mississippi River Valley Alluvial Aquifer
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Raju M., Ramirez Avila J.J.

In this study, an attempt is made to investigate long-term trends in maximum temperature within Lower Mississippi River Basin (LMRB) in order to understand the temperature patterns within Mississippi River Valley Alluvial Aquifer (MRVAA) at annual time scale. Daily air temperature data of Global Historical Climatology Network (GHCN) was used to obtain daily maximum air temperature for seventy-six (76) stations within LMRB. Non-parametric statistical tests, Modified Mann Kendall (MMK) and Pettitt were used at 0.05 significance level to assess the trend and change point analysis in temperature variable. Results of MMK trend tests indicated significant increasing and decreasing trends. However, increasing trends outnumbered decreasing trends. Magnitude of annual maximum temperature showed an increase by 0.0005 - 0.0012 ℃ per year over the period 1969 to 2019. Change point analysis results at 0.05 significance level, indicated that increasing shifts occurred since 1985, with decreasing shifts in the year 1988. The results of this study will help in understanding the behavior of temperature patterns in an agriculturally intensive region. Further, the study needs to be extended to explore the trends and changepoints in other temperature variables like mean, minimum to understand the overall pattern of temperature variables within MRVAA to plan and manage the irrigation and crop production.

Aquatic vegetation management to enhance multiple-user benefits of southeastern wetlands
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Ervin G.N., Turnage G., Lazaro-Lobo A.

Resource managers of public lands, such as national wildlife refuges, are tasked with meeting multiple use needs of the fish and wildlife that reside on these lands, as well as the people who utilize those lands for recreational activities such as fishing, boating, and wildlife watching. Biologists at the Sam D. Hamilton Noxubee National Wildlife Refuge (NNWR) have identified the dominance of certain problematic aquatic plants as a key obstacle to achieving these multiple use needs in lakes and associated wetlands on this and other southeastern wildlife refuges. Few methods are currently known that allow the control of some of the problematic aquatic plant species that they encounter, while simultaneously enhancing the diversity of desirable species, maintaining water quality, and providing diverse aquatic habitats that are needed for many species of wildlife and for human users of these facilities.

This project was aimed at determining optimally effective methods of managing invasive and problematic aquatic plants to enhance wetland plant diversity in a way that improves the quality of wetlands as wildlife habitat and sources of recreational use, while also minimizing potential negative impacts on water quality and desirable native plant species. We tested a variety of chemical control measures (herbicides) to reduce the abundance of key nuisance plant species, while attempting to minimize negative impacts on key water quality parameters (e.g., dissolved oxygen, nitrogen, and phosphorus). We found that all three herbicides tested gave long-term reduction of white water lily and water shield, but a timing mismatch in the phenology of these species and American lotus resulted in failure to control the latter species. None of the water quality parameters that were monitored indicated substantial negative impacts of the herbicide treatments.

Assessing background trends in monitoring wells at the groundwater transfer and injection pilot project located in Shellmound, Mississippi
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Purdom K., O'Reilly A., Wren D.

The Groundwater Transfer and Injection Pilot project (GTIP) is focused on testing the effectiveness of direct injection of groundwater into the Mississippi River Valley Alluvial Aquifer (MRVAA). The project is in Shellmound, MS approximately 8 miles northwest of Greenwood, MS and west of the Tallahatchie River. The MRVAA is the primary source of irrigation water for the local farming industry, and water levels in the MRVAA have gradually declined for decades. Prior to beginning the pumping phase of the project, the monitoring wells in the surrounding area had their water levels continuously recorded for a year. The data included represents a full growing and irrigation season, as well as the off season in the winter. Having data from all seasons allowed for extensive understanding of how the local groundwater levels were impacted by irrigation, weather patterns, and Tallahatchie River stage. Groundwater levels during the summer 2020 growing season prior to injection show frequent drawdown events contributing to decreases of 1-4 ft in water level; over the following fall-spring off season water levels recovered 1-3 ft. Trends in groundwater levels prior to injection indicate that water levels near the injection site exhibit at least one month of lag time relative to the levels near the extraction site and Tallahatchie River. We will present water level trends in the GTIP project area from the year prior to the pumping phase of the project and identify important trends resulting from climate and farming practices.

Assessment of embankment damage due to wave impact in an on-farm reservoir
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Ozeren Y., Wren D., Rossell W.

On-farm reservoirs and tailwater recovery systems are commonly used conservation practices in the Mississippi Delta region to provide additional irrigation water and reduce demand on groundwater resources. Built above ground by using locally available soils, on-farm reservoirs are filled to capacity with spring rainfall and runoff and kept at full capacity as much as possible until growing season. Strong winds combined with high water levels during winter and spring months generate damaging waves which rapidly erode the earthen embankments, leading to additional maintenance costs for producers. The goal of this study was to assess embankment impairment due to wind generated waves in an on-farm reservoir near Shelby, MS. A wind station and two 2 m long self-logging wave staffs were installed to measure wind speed, wind direction and water level continuously during spring and summer months of 2021. The embankment geometry was monitored via land-based RTK surveys that were carried out during the same period. An attempt was made to quantify the rate of embankment impairment for the measured wind and wave characteristics. Key findings of the field study and comparison of field measurements with previous laboratory and field measurements will be presented.

Assessment of flood inundation mapping of the Catalpa Creek Watershed in Mississippi by 2-d hydraulic modelling
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Poudel S., Roldan M., Ramirez Avila J.J., Czarnecki J., Schauwecker T., Achury S.O.

The Catalpa Creek Watershed in Mississippi is very susceptible to flooding events especially flash floods. The watershed is characterized by very mild slopes and alluvium clay rich soils which make the basin highly vulnerable to flooding. Although floods cannot be controlled completely, the flood risk hazards can be minimized by having an advance information of extreme flood prone zones of the watershed. By predicting the water level of the adjoining streams in different rainfall scenarios, the flood inundation extent of a location within the watershed can be identified. To assess the flood inundation, hydrologic simulations are carried out and a 2-D hydraulic model of the watershed is developed. The Hydrologic Modeling System (HEC-HMS) is used for the hydrologic modeling work, whereas the River Analysis System (HEC-RAS) model is used to develop the hydraulic model and flood inundation map. The flood depth, water surface elevation and velocity distribution are simulated to determine the extent of flooding. The developed hydraulic model is calibrated based on the Manning's roughness coefficient by comparing with the downstream rating curve. The results obtained from the model are maximum water depth and maximum flood velocity at the time of peak runoff for several flood prone zones within the watershed.

Bamboo-char supported nano zero-valent iron (BC-nZVI) for water remediation
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Karunaratne T.

The use of nano zero-valent iron (nZVI) on water remediation applications have not been fully explored because of its agglomeration and rapid passivation. Biochar has been widely used to provide the stability to nZVI by preventing its agglomeration. Herein, a series of bamboo-char supported nZVI composites (BC-nZVI) are synthesized via a carbothermal reduction of iron salts using bamboo-char as a reduction source. BC-nZVI consists of nZVI particles with diameters ranging from 20 to 200 nm that are evenly distributed on the bamboo-char matrix. The effects of iron salt type (i.e., Fe(NO3)3, FeSO4, FeCl2, and FeCl3), carbothermal reduction temperature (600-1000 &8451;C), iron loading (5-40%) on the synthesized structure, morphology, and heavy metal (Cu2+ and Pb2+) removal performance of BC-nZVI are evaluated. At the optimum condition (i.e., FeCl2, 15% iron loading, and 1000 &8451;C), the as-synthesized BC-nZVI exhibits high Langmuir adsorption capacities of 100.4, and 63.9 mg/g for Cu(II), and Pb(II) respectively. This study suggests that carbothermal reduction could be a promising route and a green alternative path of borohydride reduction for the production of BC-nZVI for water remediation.

Bankfull discharge: Contrasting regional curves and frequency curves
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Ramirez Avila J.J., Achury S.O., Raju M., Chaux L.C.

Regional Curves are stream restoration practitioners' tools that relate measured stream morphology, discharge, and drainage area. These are valuable tools for geomorphic assessment to analyze departure from equilibrium conditions in disturbed ecosystems and for restoration planning to determine approximate channel dimensions and discharge. The relationship between the drainage area and the magnitude of the flow observed at bankfull stage in reference stable reaches is a fundamental key to achieve a baseline restoration design. Research on bankfull discharge in the US has resulted in general agreement that the annual series bankfull discharge recurrence intervals are approximately equal to a 1.5-year event. A study is performed to evaluate if the 1.5-year bankfull discharge recurrence interval assumption represents the flow observed at bankfull stage in reference sites assessed to estimate the Regional Curves. Datasets used to develop Regional Curves in different physiographic regions of the US have been collected and used to generate stream flow and watershed characteristics reports by using the web application USGS StreamStats. Field measured bankfull flow discharges for each individual location are correlated with the peak flow discharge frequency curves reported by StreamStats to identify a corresponding return period. Preliminary results indicate that the peak flow discharge observed at a return period of 1.5 years overestimate the magnitude of the flow observed at bankfull stage. Similarly, the determination of a return period that better represents the magnitude of the flow at bankfull stage for different locations varies among physiographic regions and more importantly, to the level of urban development of the drainage area.

Bayous to Beaches: Connecting inland behaviors to the health of the Gulf of Mexico
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Dalessandri S., Blackmon L.

The University of Southern Mississippi's Marine Education Center, with support from the EPA, has developed a Meaningful Watershed Educational Experience (MWEE) curriculum which can be easily implemented into the classroom. Target audience are grades 7-12, however with a bit of modification younger students can also participate. The program focuses on connecting behaviors on land and upriver to water quality along the Gulf Coast. The curriculum comes in the form of brief educational videos designed for classroom viewing, each addressing an aspect of watershed health. Suggested activities accompany each video engage students by promoting hands on engagement and critical thinking. Over the past 3 years, teachers from the Gulf Coast region and as far away as the central Midwest have participated in this project through teacher professional development workshops and student field experiences at our coast Mississippi outdoor education center. Each group brought new perspective and the last few years carried with it many challenges. These challenges inspired us to extend our reach by creating a standalone curriculum which can be delivered virtually and be taken into the field at the discretion of the implementing teacher. The resulting curriculum aims to reinforce the connection and shared stewardship responsibility among all who live within important watersheds.

Biogeochemical Impacts of Altered Freshwater Flow to the Mississippi Sound
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Dillon K.S., Milroy S.P., Shiller A.M., Gilbert M.

The Bonnet Carrè Spillway (BCS) is a flood control structure on the lower Mississippi River that is periodically opened at peak flow to prevent flooding in New Orleans and other municipalities. Since its construction in 1931, the spillway has only been opened fourteen times. However, in recent years, spillway openings have become more common with four openings since 2016. In 2019, the BCS was opened twice for a combined total of 123 days, sending large amounts of Mississippi River water into the Mississippi Sound resulting in large reductions in salinity, extensive algal blooms and nearly 100% mortality of oyster reefs. Weekly water quality assessments were conducted from June thru August 2019 to measure nutrients, dissolved organic carbon and nitrogen, chlorophyll a, and particulate organic matter as well as the stable isotopic composition of water (δ18O and δD) for water source tracking. River water had high nitrate concentrations (92 μM) and low ammonium and soluble reactive phosphate (SRP) concentrations (<2 μM). Water isotope results show that water from some regions of the Sound was composed of nearly 50% Mississippi River water. Dissolved inorganic nitrogen (DIN) and chlorophyll concentrations increased by an order of magnitude compared to historical measurements and bottom water hypoxia was measured across large portions of the Sound when bottom water salinity was greater than 12 psu. Bottom water ammonium and phosphate concentrations were elevated at when DO was low (< 4 mg/L) due to anaerobic mineralization of organic matter, dissimilatory nitrate reduction to ammonium or a combination of the two processes however diffusion of these nutrients from sediments cannot be ruled out with the available data. After the BCS closure in late July, nutrient concentrations throughout the Sound returned to low background concentrations within several weeks.

C.C. Lynch Sponsor Presentation
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Lynch M.

Water quality conditions in many regions are evolving over time and so, too, are the technologies that are used to measure these changes. Continuous water quality monitoring allows for an expanded temporal view of conditions at a particular site of interest. Multiparameter platforms have sensors available for the measurement of algae and some of the parameters of interest that drive or are affected by blooms. Algae-specific sensor technologies include fluorescence-based sensors designed to monitor chlorophyll-a, phycocyanin, and phycoerythrin. By using these sensor technologies connected to a data telemetry device and then to a cloud-based data hosting platform, real-time data-driven decisions can be made intelligently and in a cost-effective manner.

Calibration and Validation of flow and water quality parameters using SWAT-CUP and LOADEST
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Nepal D., Parajuli P.B.

For the management of watersheds, hydrological models play an important role. To improve the accuracy of a hydrological model, calibration is performed. Validation helps to evaluate the improved accuracy of the calibrated model. However, sometimes, calibration is challenged by limited data availability. Measurement of water quality samples is done less frequently than flow because of high cost and limited resources availability. Therefore, it is necessary to estimate their loads/ concentrations during the periods of no measurements. The present study aims to 1) test regression model performances in predicting water quality loads 2) Soil and Water Assessment Tool (SWAT) calibration and validation of flow, total suspended solids (TSS), total nitrogen (TN) and total phosphorous (TP) at three monitoring stations at Big Sunflower River Watershed (BSRW). In this study we used Load Estimator (LOADEST) which has different regression models to predict water quality loads (during the period when flow data are available) to increase the number of data availability for calibration and to convert concentrations of TSS, TN and TP into loads since SWAT outputs TN and TP loads. Model evaluation was performed using R2, Nash-Sutcliff Efficiency (NSE) and Partial Load Ratio (PLR). The performance of LOADEST was found generally good in load prediction with a tendency towards overestimation in most of the cases (R2: 0.90-0.96, NSE: 0.50-0.95 and PLR: 0.84-1.17). The Sequential Uncertainty Fitting SUFI-2 algorithm inside SWAT-CUP was used for calibration and validation. The uncertainty analysis showed acceptable values of P and R factors for streamflow (p-factor: 0.72-0.87 and r-factor: 0.74-1.27) and TSS (p-factor: 0.56-0.89 and r-factor: 0.43-2.83). Model performance evaluation was performed using R2 and NSE. Model performed well for stream flow during both calibration and validation (R2: 0.60-0.86, NSE: 0.60-0.86). Similarly, performance evaluation for TSS indicated acceptable values (R2: 0.60-0.91, NSE: 0.38-0.91). The model evaluation statistics for TN and TP will be obtained further. The calibrated and validated model will then be used to simulate different Best Management Practice (BMP) scenarios. This study is believed to offer recommendations for successful multi-site and multi-variable calibration and validation to SWAT modelers under limited data availability.

Can short rotation woody bioenergy crops improve shallow groundwater quality in the Lower Mississippi Alluvial Valley?
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Kyaw T.Y., Siegert C., Renninger H.

In the Lower Mississippi Alluvial Valley (LMAV), agricultural runoff is a critical environmental problem because it degrades the water quality. Although the LMAV is a pivotal region for agricultural production, there are also areas of marginalized land where row crop production is less profitable due to experiencing seasonal waterlogging and high water tables. Consequently, these marginal lands are usually left unmanaged. However, establishing short rotations woody crops (SRWCs) on these floodplains can be beneficial to land owners because the climatic, agricultural, and infrastructural systems of the LMAV have the potential for developing a biomass-based economy. Furthermore, SRWCs possibly improve water quality due to their capacity to take up dissolved nutrients coming from agricultural fertilizations. Therefore, this study evaluated the nutrient mitigation potential of flood-tolerant SRWCs established as a bioenergy plantation. In 2018, we established a riparian bioenergy plantation in Sidon, MS in the LMAV. Our plantation had two planted blocks, each containing 75 individuals of black willow (Salix nigra), eastern cottonwood (Populus deltoides), and American sycamore (Platanus occidentalis), and two unplanted blocks (control). To collect shallow groundwater samples, we installed 16 groundwater wells (2 m depth) along the elevational gradient of the plantation. We collected groundwater samples monthly in 2018, 2019, and 2021, and biweekly in 2020 when the plantation was not flooded. We analyzed dissolved organic carbon (DOC) and nutrient concentrations in the samples, such as nitrate, ammonia, orthophosphate, and total phosphorus. To test the hypothesis that our plantations could mitigate nutrient runoff, we used a linear mixed effects model by considering locations where water samples were collected as fixed effects, and blocks and date of data collection as random effects. Our preliminary results showed that with an average nitrate concentration of 1.77 mg/L from adjacent agriculture, our plantation was successful at mitigating 90% of nitrate in 2019 in planted blocks, while there was no significant mitigation of nitrate in unplanted blocks. In both planted and unplanted blocks, there was a significant increase of DOC concentrations in 2020. However, before its discharge into the river, the average DOC concentration detected in the unplanted blocks (27.35 mg/L) was about 3 times higher than that of planted blocks. No significant mitigation of ammonia and orthophosphate has been observed yet. Our results suggested that SRWCs could mitigate nitrate runoff. Therefore, planting flood-tolerant SRWCs for bioenergy along the marginal floodplains potentially improves the water quality of the LMAV.

Characterization of plastic Lay-flat irrigation tubing material properties and outlet flow performance as impacted by mil thickness and internal tubing pressure
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Caey D.

Lay-flat irrigation tubing, or poly-pipe, has become a low-cost solution for flood irrigation on leveled-to-grade farmland through the Mid-South. Poly-pipe is available in a range of diameters and material thicknesses in lengths of up to one-quarter mile, providing the flexibility to be adapted to meet variable field conditions and flow requirements. System challenges include management of even flow distribution across the length of installed poly-pipe sections and poly-pipe failures from over-pressurization. Computerized hole selection (CHS) prescriptively determines the optimum outlet hole size for each furrow, providing the desired water output to maximize water use efficiency. Poly-pipe failures are common and are believed to result from improperly selected poly-pipe diameter and thickness and can also be influenced by incorrectly sized outlet holes at the furrows, creating elevated internal tubing pressures that result in material deformation. Theses failures can be identified as catastrophic, such as in a complete failure, or rupture, of the poly-pipe. However, over-pressurization can also result in stretching/elongation of outlet holes before complete material failure occurs, altering hole geometry and significantly affecting the flow dynamics of the hole. However, little research exists to quantify these factors and their relationships as causal agents for failure. The objectives of this study were to characterize poly-pipe performance by: 1) quantification of material properties of available poly-pipe mil. thicknesses, 2) evaluation of the interaction of poly-pipe thickness and internal pressure on failures. Virgin poly-pipe samples were analyzed in static conditions utilizing ASTM D882-18 "Standard Test Method for Tensile Properties of Thin Plastic Sheeting" in an MTI 2K Bench-Top Universal Testing System to capture the material properties in tension (modulus of elasticity, burst strength, and tensile strength) for each mil. thickness. Each thickness of poly-pipe was found to be significantly different (p<0.0001) across the assessed material properties analyzed. Further analysis was conducted in dynamic conditions simulating hole flow/pressure relationships to evaluate hole reaction to pressure changes. Single holes were punched in 44-inch sections of 7, 9, and 10 mil poly-pipe, and subjected to increasing pressures of up to 150% of yield tensile strength. Flow rates were captured at four pressures up to 100% of calculated yield tensile strength, at 150% of yield tensile strength, and the subsequent four pressures post 150%. Significant differences (p<0.0001) were observed between pre and post over-pressurization for all mil thicknesses, with differences being more pronounced in the 7 mil poly-pipe. No significant differences were observed between poly-pipe diameters of the same mil thicknesses. Further analysis is ongoing to assess the effects of over-pressurization in multi-hole poly-pipe configurations to assess if the effects are consistent across all holes.

Characterization of water quality, biology, and habitat of the Pearl River and selected tributaries contiguous to and within Tribal lands of the Pearl River community of the Mississippi Band of Choctaw Indians, 2017–18
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Driver L.J., Hicks M.B., Gill A.C.

The Mississippi Band of Choctaw Indians (MBCI) is a federally recognized tribe with territories in Mississippi and Tennessee. MBCI has sovereign authority over its natural resources and is responsible for protecting the quality of waters within the Tribal lands and restoring impaired waters. The U.S. Geological Survey (USGS), in cooperation with MBCI, collected physical habitat, water-quality, and biological community data at 8 selected stream sites within and contiguous to the MBCI Pearl River community in central Mississippi in 2017 and 2018. Data from MBCI waters were evaluated to establish baseline conditions and to provide a general context of current condition of water quality and biological communities among sites.

Generally, water-quality concentrations were within natural ranges and were not considered to be chronically stressful for aquatic life, with a few exceptions. Concentrations of total nitrogen and total phosphorus often where slightly elevated at seven of the eight sampled stream sites, indicating nutrient enrichment as a possible stressor and nutrients were frequently highest in Wolf Creek downstream of the wastewater treatment plant that services the Pearl River community. Organic wastewater compounds, including compounds with endocrine-disrupting potential, were detected at low concentrations in water samples from most sites, but were often below the laboratory reporting limit. Likewise, concentrations of most trace elements and PAHs in bed sediment were very low among sites.

Overall, periphyton, macroinvertebrate, and fish communities appeared to be typical of central Mississippi streams. However, the diversity, composition, and abundance of taxa sampled from Wolf Creek were generally distinctive as compared to other sites. Particularly, the Wolf Creek site downstream of the wastewater treatment plant had the lowest Mississippi-Benthic Index of Stream Quality (M-BISQ) score, indicating a substantially altered macroinvertebrate community compared to the other sample sites and data from a local least disturbed stream. This Wolf Creek site also had relatively lower diversity and higher abundance of some diatom indicator taxa and higher abundance of tubificid worms, indicating possible ecological responses to nutrient enrichment.

Data and results from this study can be directly used by the MBCI as a baseline from which to compare future data collection efforts and a guide for directing intensive data collection and assessments efforts and for targeting areas for implementation of best management practices.

Characterizing Inundation Regimes of a Lowland, Bottomland Hardwood Forest
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Perera N., Shockey M., Jones N.

In bottomland hardwood forests, such as those surrounding the Sipsey River in Western Alabama, the magnitude, frequency, duration, and spatial extent of flooding drive the structure and function of the floodplain ecosystem. Hydrogeomorphic features (i.e., sloughs) impact both local scale inundation dynamics and downstream flooding. In this study, we quantify dynamic water storage in a lowland floodplain using a two-dimensional hydrodynamic model built with the U.S. Army Corps of Engineers' Hydrologic Engineering Center River Analysis System (HEC-RAS). Traditionally, hydrodynamic models are used to analyze the extent and duration of flooding. However, we will use the results of our model to quantify changes in water storage in floodplain sloughs along an 18 km reach. The floodplain was modeled using Digital Elevation Model (DEM) data from USGS, and then validated using 77 years of flow data collected from USGS Gage 02446500. The results from this model will be used to predict how inundation regimes impact the structure and function of bottomland hardwood forest ecosystems.

Computing the Effectiveness of BMP implementation on water quality and hydrology in Yazoo River Basin by modelling approach
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Venishetty V., Parajuli P.B.

Deterioration of water quality due to non-point source (NPS) pollution is prominent across the world. Agriculture is the major source of NPS pollutants that is mainly induced by runoff. Yazoo River Basin (YRB) is the largest watershed in the state of Mississippi, of which about 47% of land use is large scale agriculture and the remainder is Forest (50%), wetlands, water and urban (3%). Major Crop in the region are Corn, Soybean and Cotton. Continuous and Crop rotation practices are applied in the region. To minimize and mitigate pollution from agricultural lands, numerous Best Management Practices (BMP) were being implemented in the state and country. By using Soil and Water Assessment Tool (SWAT), impact associated due to BMP implementation is quantified. SWAT model efficiency has been tested using Nash-Sutcliffe Efficiency index (NSE) and Coefficient of Determination (R2). Calibration and validation of various Hydrologic (Streamflow) and water quality parameters (Total Suspended Sediment (TSS), Total Nitrogen (TN), and Total Phosphorus (TP)) is done for various USGS gage stations spread across the watershed. Model performance is Good for streamflow, Satisfactory for TSS, TN and TP. Management practices such as Vegetative Filter Strips (VFS), Tail Water recovery Ponds (TWP), and Cover Crops were preferred for analysis in this study. Simulations from VFS implementation show significant reductions in sediment, and nutrient concentrations in water, and similar results are expected to be found from TWP and Cover crop practices as well. Hence it is essential to understand and quantify the impact of BMP on water quality.

Cover Crops and Irrigation Impacts on Soybean Production in the Mississippi Delta
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Kaur G., Russell D., Singh G., Quintana N.

Excessive groundwater pumping for irrigation has declined water levels in the Mississippi River Valley Alluvial Aquifer. Potential solutions to groundwater conservation can be adopting management practices such as irrigation scheduling using sensors and planting cover crops. A study was conducted from 2019 to 2021 at the National Center for Alluvial Aquifer Research, Leland, MS to determine the impact of cover crops and sensor thresholds for irrigation scheduling on soybean production, water productivity, and irrigation water use efficiency (IWUE). The cover crops included in the study were: cereal rye (Secale cereale L.), hairy vetch (Vicia villosa R.), wheat (Triticum aestivum L.) + radish (Raphanus sativus L.) + turnip (Brassica rapa L.) mix, and no cover crop control. Irrigation treatments included: no irrigation/rainfed, -40 kPa, and -90 kPa sensor threshold for irrigation initiation. The experimental design was a randomized complete block with four replications. The highest soybean yield was obtained in hairy vetch treatments under the -40 kPa irrigation threshold in 2020. No significant differences were found for soybean yield in 2021. Water productivity was at least 10% lower in all treatments under the -40 kPa irrigation threshold compared to all other treatments in 2020. The water productivity was highest in -90 kPa followed by no irrigation and -40 kPa sensor threshold treatments in 2021. The IWUE was higher in cereal rye treatment than the other cover crop treatments in 2021. When data was averaged over two years, net returns above total specified expenses were highest in no cover crop treatments under the -40 kPa irrigation threshold.

Detangling Tanglewood: Characterizing vertical, horizontal, and longitudinal hydrologic connectivity in a Coastal Plain headwater stream
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Peterson D.M., Jones C.N., Shogren A.J., Plattner A., Godsey S.E., Atkinson C.L., Benstead J.P.

Upstream hydrologic processes affect the chemical, physical, and biological function of downstream aquatic ecosystems. However, there are systematic gaps in our understanding of watershed storage and connectivity dynamics that limit our ability to effectively manage downstream waters—particularly in Coastal Plain landscapes. We are working to bridge this gap by characterizing drivers of vertical, horizontal, and longitudinal hydrologic connectivity in a 90-ha headwater stream in the Upper Coastal Plain of western Alabama. We first identified three distinct hydrogeomorphic features based on varying degrees of stream incision. We then installed a network of nested shallow groundwater wells across these features and performed seasonal stream network surveys to capture variable scales and dimensions of water movement. Additionally, we used an Electrical Resistivity Tomography (ERT) survey to characterize subsurface structure. Results suggested that vertical connectivity is constrained by discontinuous clay layers based on observed water table perching and evidence of preferential flow through the clay confining units. Horizontal connectivity (i.e. both hillslope storage and connectivity) was driven by the degree of incision; the incised reach consistently received water from the hillslope, whereas the depositional reaches were consistent sources of water to the hillslope. Finally, longitudinal connectivity was a function of both stream incision and season, as stream drying was variable across seasons, but stream width distributions followed unique seasonal patterns that were variable across stream hydrogeomorphology types. Our results provide an initial characterization of how upstream processes impact downstream water quality in low-gradient, Coastal Plain watersheds.

Development of a preliminary metric-based indicator of functional recovery for tidal marshes
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Dybiec J.M., Ledford T., Rinehart S., Tatariw C., Mortazavi B., Cherry J.

Despite their known importance, an estimated 25-50% of tidal marshes have been lost worldwide over the past 50 years due to anthropogenic pressures, such as coastal development and pollution, and those that remain are at increased risk of loss due to climate change. While tidal marsh restoration and creation efforts are used to offset these losses, post restoration/creation monitoring typically focuses primarily on the recovery of plant communities. As a result, the recovery of important functions like carbon storage and nitrogen removal capacity, both of which are of great ecological and societal importance, is often not assessed. Therefore, an accessible method for estimating functional recovery in restored and created tidal marshes would be of great benefit to coastal sustainability efforts. Metric-based indicators have previously been used to assess ecosystem functions through simple and inexpensive biotic/abiotic measures, and therefore, may provide a useful method to assess restoration in a time-effective and budget-friendly manner.

Using data collected from 12 restored/created and 4 natural tidal marshes across the Mississippi-Alabama Gulf Coast during Summer 2021, we calculated percent recovery of certain functions at restored/created marshes by pairing them with reference natural marshes. We then used backwards model selection to determine what combination of simple site characteristics (e.g., soil bulk density, percent plant cover, site age) could explain the recovery of more complex functions (e.g., soil organic matter accumulation, above/belowground biomass). For example, we found that soil organic matter recovery could be estimated through site age and bulk density, while plant biomass recovery could be estimated by site age and percent plant cover. From these relationships, we generated metrics capable of "scoring" functional recovery in tidal marshes based on these easier-to-measure factors. Further data collection in Summer 2022 will allow us to assess the validity of this indicator of functional recovery. While preliminary in nature, this model represents a unique and accessible method for improving post-restoration/creation monitoring efforts.

Development of a Vadose-Zone-Sensitive model by means of a radio spectrum recycling
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Boyd D.R., Kurum M.

A longstanding research focus within hydrology is the remote sensing of soil moisture across the entire depth of the vadose zone at sufficient spatial and temporal resolutions to address human needs for crop growth, water management, drought prediction, and many other research areas. While many forms of remote sensing can provide insight into vegetation health and surface water availability, microwave remote sensing is perhaps the most mature method for detecting water content within Earth land structure's due to its penetrative capabilities. While active microwave remote sensing is capable of performing such remote sensing measurements at desirable resolutions, such systems cannot be easily proposed due to the cost of building such a network in addition to the competing frequency space between commercial and public ventures.

The signals of opportunity (SoOp) method is a form of radio spectrum recycling that allows for the reuse of active microwave signals from systems designed for navigation and communication to science application systems. The SoOp method allows for high spatiotemporal resolution microwave measurements while maintaining a low size, weight, power, and cost for individual receiver systems. Such systems have shown success in recent years for estimating surface soil moisture in recent years through machine learning, and future SoOp missions and experiments dedicated for surface and root-zone soil moisture are expected. The development of models which are capable of recreating these bistatic scenarios over land structures is an area of ongoing research within the remote sensing community.

This research showcases the development of a vadose-zone-capable model for estimating changes in soil moisture by means of a generalized, SoOp modeling suite developed at Mississippi State University. This model is an upgraded variant of the SoOp Coherent Bistatic scattering model (SCoBi) which allows for simulation of bistatic scattering within multilayered soil moisture profiles and vegetation structures across land surfaces. Added features to the model will enable the simulation of varying land structures across Earth structures with sensitivity to features such as topography, land cover classification, and surface roughness. This model is anticipated to help explore the sensitivity of multifrequency SoOp systems to variations in soil moisture profiles over multiple land surfaces. Sample simulations will be presented at the conference.

Development of the CCHE1D Looped Channel Network Model
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Zhang Y., Chao X., Al-Hamdan M., Bingner R., Vieira D.

The CCHE1D model, developed by National Center for Computational Hydroscience and Engineering (NCCHE), is designed for dendritic 1D channel networks to efficiently simulate unsteady flows with non-equilibrium and non-uniform sediment transport and channel morphological change, general pollutant transport and fate, nutrient dynamics and water temperatures. However, the dendritic channel network allows only one outlet and junctions of flow confluence, which is not applicable for more general and realistic cases that can be described only by looped channel networks with multiple outlets and junctions of both flow confluences and divergences, such as agricultural irrigations, natural river networks and urban floods. To expand its capabilities in handling looped channel networks, CCHE1D model needs new developments on the numerical solver and the generation tools for looped channel networks.

In this study, the junction-point water stage prediction and correction (JPWSPC) method proposed by Zhu et al. (2011) will be integrated into CCHE1D model to resolve the general 1D channel networks, either looped or dendritic. In JPWSPC, each branch is computed independently, which guarantees the simplicity, efficiency, and robustness of the numerical model. In addition to the digitization tool, the CCHE1D model plans to modify a delineation tool of dendritic channel network based on the watershed-merging algorithm (Zhang and Jia, 2020) for looped channel network generation. The observation that the loops only exit between junctions would make it possible to enable the watershed-merging algorithm for looped channel network generation.

This paper will present some preliminary results from selected test cases of looped channel networks to demonstrate the developments at the current stage for the CCHE1D looped channel network model. More results will be reported in the future.

Does improving soil health benefits water quality in the Mississippi Delta?
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Sarmiento-Rodriguez L.A., Ramirez Avila J.J., Locke M., Singh G., Achury S.O.

Research has shown that enhancing soil health improves crops productivity and benefits water quality. A study was established to determine whether differences in soil health, associated with different soil management practices, could have a positive effect on runoff water quality from agricultural fields in the Mississippi Delta. The soil quality/health indices for plots/fields with different management scenarios in two different locations of the Mississippi Delta, are to be correlated with runoff water quality concentrations and loads. The soil health/quality index for the study fields/plots was determined using the Soil Management Assessment Framework (SMAF). Study fields/plots were planted with irrigated soybean and corn under different cover crop residue scenarios in 2021. Six indicators were selected to contrast the potential impact of management practices: aggregate stability, soil organic carbon, pH, soil test phosphorus, bulk density and soil test potassium. Irrigation runoff samples were collected from corn and soybean plots to determine concentrations and loads of total phosphorus, nitrate—nitrogen (NO3-N), total Kjeldhal nitrogen, total nitrogen, total suspended solids, salinity, pH, and turbidity. This presentation will show preliminary results of the study as well as further steps towards the completion of a sensitivity analysis of the SMAF tool.

Downscaling GRACE Equivalent Water Thickness Data for Mississippi Using Neural Nets
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Awawdeh A.R., Yasarer H., Pulla S., Kumar M.

The importance of having high-resolution and effective hydrological data has increased with the recent climate change and continuous relying on underground water. Having such data has been made possible after launching the Gravity Recovery and Climate Experiment (GRACE) in 2002. GRACE enabled researchers to extract data about terrestrial water storage, ice loss, and sea-level change in a temporal resolution of one month. Although this was a great achievement, it is still can't be relied on for small regions because the GRACE data grids are very coarse, i.e. 25 km by 25 km. The goal of this paper is to address the efficiency of using Feedforward Artificial Neural Networks (ANNs) with backpropagation error algorithm to scale down GRACE precipitation data for the State of Mississippi to smaller grids to be used on smaller regions. Both Climate Hazards group Infrared Precipitation with Stations (CHIRPS) and TerraClimate will play an important role in the downscaling process. CHIRPS provides a high-resolution rainfall dataset while TerraClimate provides a dataset of monthly climate and climatic water balance for global terrestrial surfaces. A script in Python programming language and executed via Jupyter Notebook was developed to download all the needed data as well as for the ANN model development. Preliminary results showed that the ANN approach performed well with a significant accuracy and the developed models can be utilized to predict Equivalent Water Thickness with a high accuracy in the Mississippi region.

Economic Assessment of Pluvial and Irrigation Runoff Recycling to Stop Aquifer Depletion in the Mississippi Delta
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Quintana N.

We explore the economic merits of on-farm water storage with tail-water recovery systems to reduce aquifer depletion in Sunflower County, MS—a region with expanding irrigated acreage and substantial off-season precipitation. Optimal management gain potential is substantial on a broad scale and long planning horizon, including more than $4 billion in producer surplus, 5 million acre-feet of conserved groundwater, and land capitalization of $24 per acre. Sensitivity analyses provide insights with respect to the impact of discount rates, rainfed returns, return flows, and aquifer recharge rates. The main contrast between our framework and previous analyses of On-Farm Storage economics is that we assess its merits over the net present value of the stream of profits over the life of the aquifer while previous studies employ a seasonal profit maximization framework over no more than 30 years of planning horizons. The insight of a long planning horizon is that it exploits the high recovery value at the end of the infrastructure useful life (the more cycles the relatively cheaper it is to maintain). The optimization over the life of the aquifer rather than over each period brings to account the merits of conservation: a reduction in groundwater used today results in cheaper pumping costs in the future, an effect that is lost in myopic optimization. Results can inform stakeholders about the optimal allocation of funds directed at agricultural practice adoption and agricultural water investments.

Effects of Microcystin-LR on channel catfish susceptibility to microbial pathogens
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Marchant A., Ford L., Petrie-Hanson L., Peterman B., Hanson L.

Cyanobacterial blooms have become increasingly common in natural water bodies and aquaculture systems. These blooms can release several toxins that are health risks for many species including humans, domesticated animals, wildlife, and fish. The most studied environmentally stable toxin produced by cyanobacteria is the hepatotoxin, Microcystin (MC-LR). Channel catfish (Ictalurus punctatus) ponds often have blooms that express MC-LR, but losses due to the toxin are rare. However, we believe that the toxin may be a predisposing factor of losses in catfish to summer pathogens due to the effects that MC-LR has on the liver. In our studies, we investigated the effects of a known dosage of MC-LR on the channel catfish liver, and its effects on channel catfish susceptibility to the summer bacterial pathogens Edwardsiella piscicida and Aeromonas hydrophila. In the first trial, treatment fish were intracoelomically injected with a 500 ng/g bw dose and were sampled along with control fish over a 6-day period. The MC-LR treated fish were not visibly affected but completely stopped eating, when sampled all treated fish through day 4 had no ingesta and had full gall bladders, most control fish demonstrated ingest a in the gut and lighter colored typical gall bladders. Serum aspartate aminotransferase and alanine aminotransferase levels were significantly elevated from 6 hours through 96 hours post-exposure indicating hepatotoxicity. Alkaline phosphatase and bilirubin levels were not substantially affected. Histology confirmed substantial hepatic injury among the treated fish. Later trials that contained both MC-LR and the bacterial pathogens resulted in significantly greater mortality in the treatment group containing both MC-LR and the bacteria in comparison to bacteria only treatments, and no losses within only MC-LR. Our study demonstrated exposure to subclinical doses of MC-LR, can compromise the function of the liver and digestive system and these are critical organs of the innate immune defenses which may have resulted in the increased mortality when encountering bacterial pathogens.

Effects of select herbicides for management of American frogbit grown in mesocosms
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Turnage G., Lazaro-Lobo A., Blassingame B., Robinson O., Calhoun K., Ervin G.N.

Limnobium spongia (frogbit) is a free-floating aquatic plant that can produce extensive floating mats that cause negative ecological, social, and economic impacts, which can have negative effects on aquatic fauna (i.e., dissolved oxygen depletion) and restrict waterbody access, navigation, and recreational usage by humans. Literature describing effective control measures for frogbit is minimal. Control efficacy of high and low doses of seven foliar applied herbicides (2,4-D, florpyrauxifen-benzyl, flumioxazin, glyphosate, imazamox, imazapyr, and triclopyr) were evaluated in a mesocosm setting in the summers of 2018, 2020, and 2021. Both emergent and submersed frogbit biomass were reduced 99 to 100% by imazamox (0.56 and 1.11 kg a.i. ha-1) and imazapyr (0.42 and 0.84 kg a.i. ha-1) 8 weeks after treatment (WAT) compared to non-treated reference plants. Triclopyr (6.71 kg a.i. ha-1) reduced frogbit biomass 92% and flumioxazin (0.42 kg a.i. ha-1) reduced biomass 87 to 93% compared to reference plants. 2,4-D (2.12 and 4.24 kg a.i. ha-1), glyphosate (2.83 and 5.67 kg a.i. ha-1), triclopyr (3.36 kg a.i. ha-1), florpyrauxifen-benzyl (0.02 and 0.05 kg a.i. ha-1), and flumioxazin (0.21 kg a.i. ha-1) did not reduce frogbit biomass 8 WAT compared to reference plants. Future research should consider the efficacy of different herbicide combinations to control frogbit, as well as the role of diluent volume per unit area, especially with imazamox and imazapyr. Field studies also will be useful in determining whether the results observed in this study will translate to management of frogbit in natural settings.

Engaging partners and empowering communities: establishing a well water network in Alabama
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Curl J.N.

Cooperative Extension Services serve as a repository of information to a wide breadth of clients nationwide in search of reliable, science-based materials. In Alabama, there were limited resources for private well owners prior to development of the Alabama Private Well Program (APWP) in 2020. Administration and Extension field staff indicated the need for a program to assist county offices in addressing the needs of a client base previously overlooked.

APWP follows the precedent of established Extension led well water programs. The APWP's purpose is to build capacity to County based Extension professionals through trainings and resources to address frequent questions and concerns from well owners.

As the pilot stage of the program continues, entities from across Alabama continue to express interest in well water educational materials. This is evident in the diverse audience that attended the well water webinar series, initially intended for Extension personnel. Professionals from regulatory agencies, non-profit organizations, power utilities, and financial institutions were strongly supportive of the program and aided in the development of a multi-agency and Extension network.

Approaching its third year, the APWP will begin hosting workshops throughout the state for private well owners. The APWP workshops will give an opportunity to well owners to have their water tested, while simultaneously creating a database of demographic information and well characteristics to be used to plan subsequent workshops and determine where bacterial contamination is most present in the state. APWP directly benefits homeowners who rely on private wells for drinking water while addressing a statewide need for well water resources beyond homeowners. This presentation will explore the approach to collecting well characteristics and the impact of a multi-agency partnership on building a new Extension program.

Establishing a model system to investigate eutrophication and invasion of southeastern US floodplain wetlands
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Sample A., Ervin G., Turnage G.

Increased nutrient inputs into the Mississippi River resulting from extensive agricultural activity and loss of wetlands in the Lower Mississippi Alluvial Valley (LMAV) can be mitigated via wetland restoration initiatives. The goal of this study was to establish a model system for studying the effects of species invasion and eutrophication on floodplain wetlands in the southeastern US. A multi-year mesocosm study was developed in which two regionally non-weedy emergent macrophyte species—Juncus effusus (Common Rush) and Schoenoplectus tabernaemontani (Softstem Bulrush)—and two common weedy emergent macrophyte species—Typha latifolia (Broadleaf Cattail) and Phragmites australis (Common Reed)—were chosen as model species. The first year of the mesocosm study was aimed at determining baseline growth and nutrient removal from the water column for each species, grown in a monoculture setting, under a standardized flooding and nutrient availability regimen based on water quality studies and flood duration data from the LMAV. Results from the first year showed clear differences in growth patterns between the weedy and non-weedy species. As expected, the weedy species exhibited faster radial spread and reached taller maximum heights than the non-weedy species. The non-weedy species also showed relatively consistent growth rates through the growing season, whereas the weedy species displayed relatively short bursts of rapid growth prior to flowering. Despite those differences in growth, we saw no differences in nutrient removal from the water column based on species or species designation (weedy or non-weedy), with over 50% removal of total nitrogen by all species. This work will be followed by simulated scenarios of species invasion in the second year (monoculture and mixed species mesocosms) and eutrophication (mixed species mesocosms with baseline and increased nitrogen concentrations) in the third year. The results of this work should be useful for wetland managers regarding species selection for project design and in planning adaptive management strategies considering these two major wetland management challenges.

Evaluating the response of invasive flowering rush (Butomus umbellatus) cytotypes to chemical control measures
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Hockensmith J., Turnage G., Shoemaker C.

Establishment and spread of invasive species has affected ecosystems across the globe. These intruders compete with native species for resources, which often leads to reduced biodiversity as well as other environmental issues. Flowering Rush (Butomus umbellatus) is one such species that has invaded the northern United States and Canada. Flowing Rush is a perennial, aquatic species that can be found growing along the shoreline of lakes and other waterbodies. In North America, two distinct cytotype populations occur: diploid and triploid. These cytotypes differ in key anatomical and physiological properties. Despite these differences, current best management practices of chemical control are based solely off research conducted on triploid populations, which account for only 29% of flowering rush populations in North America. In this study, we assessed the effect of two commonly used chemical control measures for aquatic plants, Diquat and Endothall, on diploid and triploid cytotypes. After establishment and subsequent herbicide application, plants were followed to eight weeks post treatment. At this time the plants were harvested to assess the efficacy of the treatments on above- and belowground biomass accumulation, in addition to belowground asexual rhizomatous bud production. We observed that when treated with herbicides, bud production in diploid plants increased, while bud production in triploid plants was unaffected. Additionally, in diploid Flowering Rush, higher concentrations of Diquat and Endothall increased bud production compared to control and low concentration treatments. Both Diquat and Endothall reduced the overall above- and belowground biomass. Our results suggest that diploid and triploid populations display different reactions to chemical controls and that further research is needed to elucidate these differences.

Evaluation of automated sampling protocols for edge-of-field water quality monitoring
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Hill M., Ramirez Avila J.J., Baker B., Evans K.O.

Recent efforts to document the efficacy of suites of conservation practice impacts on water quality have utilized automated edge-of-field water sampling units. Automated sampling procedures involve the collection of composite samples to estimate event mean concentrations which are multiplied by measured discharge to ascertain stream nutrient loading from agricultural landscapes. However, a central and critical step in sample collection procedures is the programmed automated trigger to engage sampling of a runoff event which is designed to represent nutrient concentrations across a runoff hydrograph. However, given the variability in intensity and duration of runoff events, program conditions could have an impact on measured nutrient concentrations and thus estimations of nutrient transport. This study aims to understand the tradeoffs related to sampling protocol by examining differences in nutrient concentrations collected with three different sampling regimes: time-series, flow-weighted by volume, and flow-weighted by change in flow rate. Samplers were installed side-by-side to test the sampling protocols during individual runoff events, the side-by-side trials were replicated in three row-crop agricultural fields in the Mississippi Alluvial Valley from May 2021 through May 2022. Water samples were analyzed for non-point source pollutants of concern: Total Nitrogen, Nitrite-Nitrate -N, Total Kjeldahl Nitrogen, Total Inorganic Phosphorus, Turbidity, and Total Suspended Solids. A multivariate approach is used to parse the influence sampling protocol, season, farm and sensor configuration are having on water quality indicators. Results will help us understand the relative accuracy of nutrient transport estimations in studies that utilize edge-of-field monitoring to examine conservation practice efficacy in agricultural landscapes. Further, results may indicate which sampling protocol is most effective in the widest range of magnitudes of runoff events, providing practical guidance for monitoring efforts.

Evaluation of process parameters impacting energy-efficiency and emerging contaminant removal in membrane reactors
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Mark-Ige J., Gude V.G.

It is well known that activated sludge process is robust but energy intensive and offers only limited removal of micro pollutants and soluble microbial products. Advanced wastewater treatment processes such as membrane bioreactors are being increasingly adopted in wastewater treatment plants to address the discharge quality and environmental pollution issues. Aerobic (AeMBR) and Anaerobic Membrane Bioreactors (AnMBR) are an essential part of the advanced wastewater treatment options, which offer advantages in terms of lower effluent discharge and smaller footprints over the traditional wastewater treatment plants. The key driver for anaerobic membrane bioreactors (AnMBRs) for municipal treatment is enabling the transition to energy neutral wastewater treatment (Wang et al., 2018). However, membrane fouling is a major drawback to utilization of MBRs. This study examines data reported in literature and analyzes correlations between wastewater characteristics and various operational parameters such as Mixed Liquor Suspended Solids (MLSS), Hydraulic Retention Time (HRT), Solid Retention Time (SRT), Temperature (T), Biogas production, Transmembrane Pressure (TMP), and Chemical Oxygen Demand (COD) against Methane production (CH4), Membrane Fouling, Soluble Microbial Products (SMP), and Extracellular Polymeric Substrate (EPS). These external and internal are the major factors attributed to fouling of the MBRs. Preliminary data analysis indicates that the strength of the influent COD has a major influence on methane production. This presentation will include a detailed analysis of influencing factors and recommendations for improving the membrane reactor performance to accomplish energy-neutral or energy-positive and superior wastewater treatment.

Evaluation of the utility and performance of an autonomous surface vehicle for mobile monitoring of waterborne biochemical agents
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Wolfe J.S., Chesser Jr. G.D., Lowe W., Moorhead J., Turnage G., Dash P., Moorhead R.

The need for real-time monitoring and management of water quality in inland and coastal marine environments is increasingly significant due to increases in land utilization which can negatively impact aquatic ecosystems from surface water runoff. Conventional water quality monitoring methodologies are laborious and expensive, requiring in situ monitoring stations and/or specialized manned vessel sampling missions at fixed locations and resultant laboratory analysis of water samples. These conventional methods are limited in their ability to gather high resolution spatio-temporal data. Multi-purpose autonomous surface vehicles (ASVs) provide a powered platform for sensors/instrumentation and serve as mobile sampling stations that enhance spatial and temporal data gathering capabilities. Solar powered ASVs provide long endurance continuous operations capabilities. However, commercially available solar powered ASVs are limited, and ASV autopilot navigational accuracy is affected by environmental forces (wind, current, and waves) that can alter trajectories and negatively affect spatio-temporal resolution of water quality data. The goal of this research was to evaluate the utility and navigational performance of a commercially available solar powered ASV (SeaTrac SP-48) equipped with a multi-sensor payload to operate autonomously under varying conditions of environmental forces. The specific objective was to evaluate the ability of the ASV to accurately and repeatedly maintain established A-B line transects under varying environmental conditions, where lateral deviation from a planned linear route was measured and expressed as cross-track error (XTE). Three testing scenarios by location (inland reservoir, riverine, and coastal) were considered to comprehensively evaluate the vessel under varying environmental conditions of wind, waves and current that could potentially alter trajectory and/or position. Results indicated mean XTE for A-B line transects tested across all scenarios of environmental conditions did not exceed 2.39 m. This work serves to provide a conceptual framework for development of spatial and temporal resolution limitations of ASVs for real-time monitoring campaigns and future development of station keeping and adaptive sampling technologies.

Evaluation of water quantity and quality of coastal watersheds of Mississippi
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Bhattarai S., Parajuli P., To F.

The unique interface of coastal waters lying between ocean and terrestrial land serves as a critical habitat to many shellfish species and it supports a wide range of human activities. This study evaluates the quantity and water quality of water runoff from the coastal watersheds in Southeastern Mississippi into the Bay of Saint Louis. A process-based river-basin scale Soil and Water Assessment Tool (SWAT) model is applied to integrate current scenarios of different management practices implemented into the upland watersheds which are predominated by forests. Two adjacent watersheds namely, Wolf River Watershed and Jourdan River Watershed are studied independently, the developed model is calibrated and validated for the flow, sediment, and nutrient yield using data collected from USGS 02481510 and USGS 02481660 stations for each watershed. Statistical analysis of the developed SWAT model includes coefficient of determination (R2) and Nash-Sutcliffe Efficiency (NSE), and the model's prediction was evaluated. Quantifying the amount of sediment yield and nutrient loss from small coastal watersheds flowing into St. Louis Bay will be insightful in assessing the impacts of water pollution in the bay ecosystem.

Evolution of Water Disinfection Practices
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Hutcherson D.

In 1900, diarrhea and enteritis, was a significant cause of death in the US. It was through drinking water disinfection and treatment that we have been able to almost eradicate these diseases—one of the greatest public health achievements of the 20th century.

We look back in history at how water has been treated (or not) to make it safe. We will look at factors affecting water sanitation; from source to tap.

  • What is the best source of water?
  • Can the source be protected from contamination?
  • Is treatment feasible for the contaminants present?
  • Is reintroduction of contaminants possible?
We'll look at this and more concerning water treatment.

Examination of rainfall variability in the Bahamas using data from a volunteer rain gauge network
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Fuhrmann C., Wells J., Rodgers J.

Water resources in the Bahamas are currently under increasing stress from several factors. Rainfall in the region has been declining in recent decades and the latest suite of climate models from the Intergovernmental Panel on Climate Change suggest that this trend will continue in the future. Moreover, many Bahamian islands are experiencing population growth and an expansion of tourism, both of which lead to greater demands for potable water. Small islands like those in the Bahamas are especially prone to the combined effects of climate change and increasing population because of their limited land area and because rising sea levels are negatively impacting the freshwater lens. Despite these concerns, there is a dearth of basic water resource information in the Bahamas, including measurements of rainfall. As freshwater consumption continues to deplete much of the groundwater storage, it becomes increasingly necessary to explore surface-based storage options such as catchment systems, which are strongly influenced by rainfall patterns. In 2017, we received funding through the 100K Strong in the Americas Program to collect rainfall data on the Bahamian island of San Salvador as part of the Community Collaborative Rain, Hail, and Snow network (CoCoRaHS). This is a volunteer network whereby local residents record rainfall once a day from manual rain gauges. Through the grant, we were able to install several gauges and recruit and train volunteers to record rainfall on San Salvador. Many of these gauges now have over four years of daily data. In this presentation, we provide a summary of the spatial and temporal patterns of rainfall across San Salvador during the period 2018-2021. In addition, we explore the different synoptic-scale weather types associated with rainfall on the island using surface weather maps, which provide insight into the processes that help generate rainfall. CoCoRaHS gauges have also been installed on other Bahamian islands, allowing us to better understand the important variation in rainfall and associated weather patterns across a larger portion of the Bahamian archipelago. In doing so, we hope to promote sustainable water resource management in the Bahamas that accounts for both short-term weather variability and long-term climate change.

Exploring circular economy concept of repurposing spent bioelectrochemical system materials for reuse in agricultural applications
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Sauers J., Band D., Ghimire U., Reddy K.R., Magbanua B., Gude V.G.

Circular economy concept (CEC) has been introduced to promote sustainability of current resource utilization and waste management practices. The concept can be loosely defined as an economic system that aims to accomplish sustainable development and economic prosperity by moving away from the "end-of-life" concept. CEC looks to repurpose, recover, reduce, and recycle materials in production and consumption processes. An interesting investigation using CEC is crushing expended bioelectrochemical treatment systems (BES) made from natural materials of bentonite, terracotta, and biochar, that were treated with synthetic municipal wastewater (SWW) and synthetic dairy wastewater (DWW) to create soil amendments to promote plant growth. The BES were constructed for nutrient capture from the SWW and DWW. Soil amendments benefit plant growth by providing more nutrients to the soil. This investigation follows how well 60 corn plants can grow in four different soil amendments. The four-soil amendment were biochar amended soil (BS), terracotta amended soil (TS), terracotta - biochar from SWW-BES amended soil (SWWS) and terracotta - biochar from DWW-BES amended soil (DWWS). Each soil amendments accounted for 10% of the growing medium. The corn was treated with three different nutrient treatments (100% Hoagland nutrition solution, 50% Hoagland nutrition solution, and 0% Hoagland nutrition solution). A control soil consisting of no amendments was used as the reference condition. Each soil amendment and control soil had a total of 12 plants, each of which was subdivided into the three nutrient treatments (4 plants per nutrient treatment). The investigation took place over 38 days at the Soil-Plant-Atmosphere Research Unit at Mississippi State University. The plants were harvested on day 38 and were analyzed for plant height, leaf number, leaf area, leaf dry weight, stem dry weight, root dry weight, shoot dry weight, total dry weight, root/shoot ratio, root length, root surface area, root volume, chlorophyll, flavonoids, nitrogen balance index, stomata conductance, transpiration, and plant tissue. The soil was tested for texture and nutrient analysis. Further, plant tissue was also analyzed. The results and some preliminary conclusions of this on-going investigation will be discussed in this research presentation.

First-Year Cover Crops, Strip-Till, and No-Till Affected Cotton Yield and Runoff Water Quality
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Roberts C., Gholson D., Locke M., Spencer D., Steinriede R.W., Krutz L.J., Pieralisi B., Crow W.

Conservation cropping systems have many benefits; most of these are associated with water use, infiltration, and water runoff quality. Despite these potential benefits, research and development of effective conservation cropping methods for cotton producers in the Mid-South are limited. A study is being conducted in Stoneville, MS, from 2021 to 2023 to determine how cotton yield, water use efficiency (WUE), and nutrient and soil in water runoff are influenced by conservation tillage and cover cropping systems. Study treatments were established in the fall of 2020 and included reduced tillage, subsoil, winter fallow (RT), strip till, winter fallow (ST), strip till, cover crop (ST, CC), strip till, subsoil, cover crop (ST, SS, CC), no till, winter fallow (NT), no till, cover crop (NT, CC), no till, and minimal surface disturbance subsoil, cover crop (NT, SS, CC) In the first year of full study implementation (2021), lint yield was decreased in no-till (NT) treatments by up to 16% (1382 kg ha-1) compared to conventional reduced tillage (RT; 1647 kg ha-1). Strip-tillage coupled with cover crops did not have an impact on yield compared to RT. Tailwater runoff from a rainfall event in late August did not differ between treatments. Preliminary observations indicate that glyphosate concentration in runoff water is greater following a burndown application of glyphosate in NT,CC and NT,SS,CC treatments (907 μg L-1) than in RT treatments (482 μg L-1). Few conclusions can be made regarding irrigation WUE since irrigation only occurred in a single RT plot due to exceptional rainfall. Since this is the first complete year of treatment implementation, treatment effects are expected to become more apparent as this long-term study continues.

Furrow Infiltration Estimation in a Surface Sealing Loam Soil
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Rix J.P., Lo T.H., Gholson D.M., Singh G., Rudnick D.R.

Seven different soil management treatments categorized as biological, chemical, and mechanical are being tested as possible remedies for reoccurring surface sealing on Mississippi Delta loam soils. The treatments include conventional tillage, medium-term no-till, new no-till with gypsum, cereal rye, subsoiling, polyacrylamide (PAM), and furrow diking. In 2021, field-satiated hydraulic conductivity was measured by single ring infiltrometer tests for two treatments, medium-term no-till and conventional tillage, in June and October. Analysis of variance suggested no significant difference between the two treatments in terms of mean natural logarithm of field-satiated hydraulic conductivity. 2021 rainfed corn grain yield results were subjected to Fisher's Least Significant Difference test. Furrow diking and PAM were found to be higher and statistically different than no-till with respect to mean yield. Future work will include single ring infiltrometer tests on four treatments: cereal rye, PAM, subsoiling, and conventional tillage.

Graphene Sand Composites and Their Applications in Water Treatment
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Nusair A., Alkhateb H., D'Alessio M.

Water scarcity and the occurrence of chemicals of emerging concern (CECs) are making the world in need of safe and renewable water resources. Slow sand filtration (SSF) represents an affordable but effective method to filter water. However, SSF has a few weaknesses such as clogging and the inability to effectively remove CECs. The goal of this study was to investigate the ability of graphene-coated sand to overcompensate these limitation. Three types of sand, Ottawa, concrete, and masonry, were used. Graphine-coated sand was obtained using a reduction method to transform a coating of sugar into elemental carbon in N2 atmosphere at temperatures reaching 750℃ followed by activation with sulfuric acid. Vertical flow-through columns were used to evaluate the ability of the different materials to remove turbidity and bacteria. Due to the additional expense related to the activation process, columns packed with graphene-coated sands were tested alongside the non-activated ones as well as columns containing the raw sands. A digital microscope as well as Raman spectroscopy, scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy were implemented to verify the effectiveness of the coating process.

The digital microscope revealed that rounded (Ottawa sand) particles were coated less efficiently than sub-angular and angular particles (concrete and masonry sand). The Raman spectroscopy revealed the formation of G and D bands in all three graphitized sands suggesting complete graphitization of the sugar and the presence of defect site necessary for the adsorption of contaminants. Furthermore, the peak intensity was 30% higher in concrete and masonry graphitized sands compared to Ottawa graphitized sand. SEM revealed the formation of carbon sheets 10 nm thick and EDS results backed up the geological identification of the sands with quantification of the elements. In the presence of high turbidity (average: 250 NTU), graphene-coated Ottawa sand, not only achieved higher turbidity removal than the raw Ottawa sand but also experienced less severe clogging. Higher bacterial removal was achieved with graphene-coated sands, in particular Ottawa and masonry, compared to the corresponding non-coated sands.

Hydrologic Performance and Life-Cycle Cost Analyses of Green Stormwater Infrastructure
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Abera L.E., Surbeck C.Q., Alexander K.

Urbanization increases impermeable land cover by diminishing other permeable land covers such as grass and forests. This change affects the hydrology of urban areas and results in excess stormwater runoff or flooding events. A sustainable way to reduce the amount of impermeable surfaces and allow stormwater to infiltrate into the ground is to use green stormwater infrastructure (GSI). In this study, computer simulations were performed to assess the hydrologic performance of GSI in runoff reduction. Life-cycle cost analyses (LCCA) of stormwater infrastructure were also performed to determine the cost-effectiveness of GSI practices, considering capital and operation and maintenance (O&M) costs.

This presentation will show the economic and hydrologic analyses results of green stormwater infrastructure for a proposed development site in Oxford, Mississippi. The HydroCAD stormwater modeling tool was used to perform hydrologic modeling for three types of GSI: permeable pavement, rain garden, and grassy ditch. The site was modeled using the curve number reduction method, which reduced the weighted average curve number of the site when GSI was implemented. The peak flow and volume of stormwater runoff were estimated for multiple scenarios based on the city's design storms. Depending on the type and size of the GSI and the storm intensity, the simulation results showed that applying GSI reduced the volume of excess runoff by 12% on average. Of the three GSI scenarios, the rain garden resulted in the highest reduction in the volume of stormwater runoff. A life-cycle cost analysis was performed using the Water Environment Research Foundation (WERF) Low Impact Development Cost Analysis Tools. Based on the LCCA results, the net present cost of GSI scenarios is higher than for traditional stormwater infrastructure. However, the LCCA does not include other external factors, such as environmental and health benefits. A co-benefit analysis was conducted using the Community-enabled Life-cycle Analysis of Stormwater Infrastructure Costs (CLASIC) tool to quantify these benefits.

Impact of Bonnet Carrè Spillway openings on coastal wetland plant productivity utilizing remote sensing imagery
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Feldpausch K., Wu W.

Wetlands are highly productive ecosystems that provide important ecosystem services. However,they have been threatened by extreme hydrological events, such as diversions of freshwater, droughts, and accelerated sea-level rise through change of inundation and salinity regimes. This study evaluated how diversions of freshwater, particularly Bonnet Carrè Spillway openings in 2019, affected vegetation productivity in salt marshes on the Mississippi Gulf Coast, US. The Bonnet Carrè Spillway was built to prevent and mitigate flooding in New Orleans. The frequency of its opening has increased over the last two decades, and 2019 was marked the first time in history that this spillway was opened in two consecutive years and twice in one year.

We first developed a model to link vegetation green biomass to spectral information of Landsat and Sentinel satellite images, and then applied the model to hindcast vegetation green biomass based on the historical images before and after the openings of the Bonnet Carrè Spillway to assess the openings' impact on vegetation. My study area is two estuarine systems that differ in their proximity to the Bonnet Carrè Spillway, elevation, salinity, nutrient levels, including Hancock County Marshes on the west, and Grand Bay National Estuarine Research Reserve on the east in Mississippi. We found marginal short-term impact. Future studies should focus on long-term impact of these extreme events on salt marshes. This study improves our understanding of vegetation and blue carbon dynamics in highly productive salt marsh ecosystems. It also informs the unexpected consequences of anthropogenic activities on valuable ecosystems.

Impact of freshwater diversions on vegetation in coastal wetlands based on remote sensing derived vegetation index
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Wu W., Grimes E., Suir G.

To improve understanding on the efficacy of large-scale freshwater and sediment diversion projects in restoring coastal wetlands, we aim to evaluate the long-term changes in wetland vegetation in diversion outfall areas.

We selected two diversion outfall areas (Caernarvon and Davis Pond, LA, U.S.) as the study sites and compared them to the reference wetlands nearby with similar pre-diversion vegetation compositions. We implemented multi-level Bayesian models to evaluate 1) how peak-season Landsat-derived Normalized Difference Vegetation Index (NDVI) changed over time in reference to the initiations of the freshwater diversions, and 2) how peak-season NDVI responded to mean and variability of inundation and salinity, key abiotic factors that would be affected by freshwater diversions.

Analysis showed differences in temporal trends of NDVI for the Caernarvon project, and differences in how inundation and salinity impacted NDVI between the reference and diversion sites, indicating that diversions played a key role in affecting vegetation. For the Caernarvon diversion project, variability of water level (inundation) and salinity and mean salinity were important to affect NDVI, while mean water level and mean salinity were important for the Davis Pond diversion project. The variability has not been traditionally accounted for in quantitative models but can be more important to consider than the mean levels.

The study provides a modeling framework that can comprehensively evaluate freshwater diversions with uncertainties accounted for. It will inform future use of freshwater diversions for wetland restoration.

Impacts of Furrow Irrigation Spacings in Sharkey Clay Soils Under Corn Production
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Freeland T.B., Gholson D., Kaur G., Singh G.

More than 40% of the land in the Mississippi Delta is classified as clayey soils. In MS, the majority of corn is produced on either sandy loam or silt loam soils. Clayey soils are now being brought into the list of soils growers produce corn on due to it's economic return. The risks associated with these soils, like frequent flooding and waterlogging, are a hurdle for farmers. Corn can lose 5-30% yield with each day of soils being flooding depending on the stage of corn. The objective of this research is to find out if altering furrow irrigation spacings can reduce or eliminate the waterlogging of corn in these soils and boost corn yield. A field experiment was conducted at NCAAR in 2021 using a complete randomized block design with four replications. Furrow irrigation spacings replications include every row irrigation (ER), 1-meter skip row irrigation (1R), 3-meter skip row irrigation (3R-I and 3R-NI), and 7-meter skip row irrigation (7R-I and 7R-NI). Data on irrigation water applied, volumetric water content, plant population, plant heights, crop water stress index, multispectral imagery, corn yield, and grain quality was collected from this study. No significant differences were found between ER and 3R-NI treatments for corn yield. The 7R-NI had 9.21% lower yield than all other treatments except 3R-I and 1R. The 3-meter skip row irrigation treatment showed 1.29% higher volumetric water content than all other treatments. The 3-meter skip row treatment held the highest volumetric water content across all seven middles, showing that the water moved laterally through the treatment. Results from the first year of this study indicate that there was ample subsurface later movement of water in the 3-meter skip row irrigation treatment to meet crop water demands.

Impacts of livestock management areas on stream water quality in the Catalpa Creek
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Chaux L.C., Ramirez Avila J.J., Achury S.O., Czarnecki J., Schauwecker T.

Livestock production is a predominant economic activity in the United States (US). However, it is also considered one of the agricultural activities that contributes to pollution of the nation's waters. It's currently estimated that around 55% of the assessed US streams have been impaired by sediments and nutrients coming from non-point sources via overland flow. A study was established to assess the spatiotemporal variation in water quality under baseflow conditions in the mainstream flowing through the MSU Joey Bearden Dairy Research Center. Water quality monitoring consisted of biweekly grab sampling and in-situ testing (dissolved oxygen, pH, turbidity, specific conductivity, total dissolved solids) from July 2019 to March 2020. Laboratory analysis of water samples included assessment of total suspended solids (TSS), total phosphorus (TP), total nitrogen (TN) and coliforms concentration. Water quality parameters were contrasted with state and national recommended water quality criteria. Results suggest the study reach is unable to meet the nutrient requirements for the assigned designated use. Mean concentrations of TP were 10 and 6 times higher than the nutrient criteria during the summer and winter months, respectively, while TN concentrations were 4 and 2 times higher. Overall, colony forming units of Escherichia coli exceeded in up to 19 times the corresponding criteria. In addition to the impairment on water quality, field observations have evidenced the unrestricted access of animals to the stream has negatively affected stream hydrology (i.e. higher runoff due to compacted soils) and geomorphology (i.e. streambank erosion). Monitoring efforts after implementing a 30-ft riparian zone buffer will be contrasted to evaluate the BMP effectiveness.

In-situ conversion biomass to biochar-supported graphene-shelled zero-valent iron nanoparticles for heavy metals removal from water
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Zhang X., Karunaratne T., Zhang J.

Owe to the high reactivity and uptake capacity, zero-valent iron nanoparticles (nZVI) are a type of widely used engineering nanomaterial for heavy metal removal. However, nZVI suffers severe agglomeration and rapid passivation issues that impede its practical application for water remediation. Biochar, produced from biomass thermal conversion, has been recognized as a good carrier for nZVI to alleviate its aggregation issues. Herein, we report the in-situ synthesis of biochar supported graphene-shelled nZVI (BC-G@Fe0) through the carbonization of iron salt impregnated biomass. Biochar was served as the support material to prevent nZVI from aggregation, and graphene shell was served as the protecting agent to protect nZVI from rapid passivation. The structure and morphology of BC-G@Fe0 are characterized by X-ray spectroscopies and electron microscopies. The performance of BC-G@Fe0 for heavy metal removal was evaluated through batch adsorption experiments. The effects of carbonization condition and iron loading ratio on the formation of BC-G@Fe0, as well as heavy metal uptake capacities, were investigated. This study demonstrated a new type of nZVI sorbent, BC-G@Fe0, with enhanced dispersibility and stability for water remediation.

Incorporating Cover Crops into Successful Corn Production Systems
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Mullican N., Larson E., McCoy J., Lemus R., Krutz J., Bond J., Maples W.

Growing cover crops may restrict planting opportunities and corn productivity, particularly in high rainfall environments common in the Midsouth region of the U.S. This study was conducted to identify factors and management practices needed to successfully integrate cover crops into Midsouth corn production systems without sacrificing economic returns or increasing production risks. Field studies were conducted to evaluate effects of cover cropping cultural practices and species on corn growth and productivity in Mississippi in 2021. Various seeding methods affecting cover crop distribution, including strip tillage, had little influence on corn production systems. However, the presence of living cover crops at planting stunted corn growth and development when they were not terminated by herbicides applied at least two weeks prior to planting. This interference reduced corn grain yield compared to where no cover crops were grown, or cover crops which were terminated at least four weeks in advance of planting. These preliminary findings indicate that growing cover crops can hinder our ability to produce corn and implement early planting systems. Abundant vegetation produced by cover crops will shade the soil, restricting solar warming, which hinders corn seedling establishment and growth. Thus, growers seeking to gain benefits associated with growing cover crops must use herbicides to terminate cover crops at least a couple weeks in advance of planting in order to maintain corn productivity associated with early planting systems tailored for high rainfall, southern climates.

Invasive alligator weed (Alternanthera philoxeroides) in the southeastern United States: a future research plan
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Schmid S.A., Ervin G.N., Turnage G.

Invasive aquatic plants have the capacity to fundamentally alter the structure and function of the systems they inhabit. Alternanthera philoxeroides (alligator weed) is an emergent aquatic amaranth that is native to South America and invasive in many regions globally. Historically, invasion (and management as a result) has been most intense in the southeastern United States, however, there are substantial invasive ranges in Australia, New Zealand, and East Asia. In invaded sites, alligator weed can alter system structure by forming dense mats of shoots at the water's surface. These mats can displace native plants that are important food and habitat for aquatic fauna. In the United States, biocontrol of alligator has primarily focused on the insect vector Agasicles hygrophila (Alligatorweed flea beetle). The success of alligator weed biocontrol in geographic locations with climate conducive to the survival of the flea beetle led to global adoption of this strategy in areas of similar climate. This allowed aquatic plant managers in these areas to shift their focus and resources to other target species. However, alligator weed continues to colonize newer and more environmentally diverse ecosystems with climate not suitable for the survival of the flea beetle. This poses new problems for alligator weed management. This presentation 1) summarizes the historic research and management paradigms for alligator weed, 2) contextualizes the literature with the current status of alligator weed, 3) discusses the future of alligator weed biocontrol in the southeastern United States, and 4) exhibits preliminary research efforts at Mississippi State University including alligatorweed phenology and integrated management utilizing herbicides and a second insect vector, Amynothrips andersoni (Alligatorweed thrips).

Inventory of on-farm water storage systems for irrigation in two Mississippi agricultural regions
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Tagert M.L., Brock M.L., Paz J.O., Lo T.H., Krutz L.J.

Surface water is being increasingly used for irrigation in two agricultural regions of Mississippi—the Mississippi Delta region and northeast Mississippi. Producers in both areas rely on supplemental irrigation to meet crop water demands and reduce risk during the summer growing season. In the Mississippi Delta, groundwater from the Mississippi River Valley Alluvial Aquifer (MRVAA), a shallow subsurface aquifer, serves as the main source of water for irrigation. The MRVAA experiences the second highest daily pumping rate in the United States at 45,803 million liters per day. Over 60% of cropland in the Mississippi Delta is irrigated with groundwater from the MRVAA, and the continual increase in irrigation over the past few decades has resulted in declining MRVAA groundwater levels in the central Delta. It is difficult and expensive to access groundwater in northeast Mississippi, so surface water is the main source of water for irrigation here. In both regions of the state, surface water is obtained from both nearby rivers and streams and by capturing runoff from precipitation and irrigation in on-farm water storage (OFWS) ponds. Although there are differences in how OFWS systems are constructed in the Mississippi Delta and the northeast region of the state, systems in both regions provide the dual benefit of providing water for irrigation and reducing nutrients flowing off-site and into other water bodies in the watershed. Thus, there is a need to quantify the use of these systems to better measure their benefits on a watershed scale. From 2007 to 2020, a geospatial inventory showed that 794.5 hectares of land have been converted to surface water storage in OFWS systems in the Big Sunflower River Watershed (HUC 08030207) in the Mississippi Delta. The inventory was conducted using aerial imagery from the National Agricultural Imagery Program (NAIP), which was acquired from the Mississippi Automated Resource Information System (MARIS) and the United States Department of Agriculture (USDA)—Natural Resources Conservation Service (NRCS) Geospatial Data Gateway. A similar geospatial inventory is in progress for northeast Mississippi.

Investigating the contribution of modified P-enriched biochar on acid soil's pH buffering capacity
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Carter K.S., Beatrice A., Varco J.J., Dygert A., Brown S., Pittman Jr. C.U., Mlsna T.

Biochar can directly hold cations in soil because of the negative charge that exists on its surfaces. Besides, improving soil cation exchange capacity, the negative charges on biochar surfaces can buffer acid soil by protonation and deprotonation mechanisms. Moreover, biochar can ameliorate soil acidity due to the presence of oxide, carbonate and hydroxide of its basic cations (Ca, Na, K, and Mg). Both biochar surface functional groups and basic cations concentrations can be altered by modification with chemical agents (Chemerys, 2017; Godwin et al., 2019), which could affect its soil pH buffering capacity. However, information concerning the impact of modified biochar application on soil pH buffering capacity is still scanty. This study investigated the pH buffering capacity of acid soil amended with three P-enriched modified Douglas fir biochars and compared this to amendment with untreated Douglas fir biochar. These three P-enriched biochars, designated CCPP, CAPP and MSPP, were prepared by treating Douglas fir biochar respectively, with: 1) anhydrous calcium chloride (CaCl2) and potassium phosphate monobasic (KH2PO4), 2) calcium carbonate (CaCO3) and diammonium phosphate {(NH4)2HPO4} and 3) aqueous solution of magnesium sulfate (MgSO4), potassium hydroxide (KOH) and potassium phosphate monobasic (KH2PO4). The acid soil was then treated with biochar samples in biochar: soil ratios of 0%, 10%, 30%, and 50% (w/w), followed incubation for 30 days at room temperature with soil moisture levels maintained at 80% field capacity. The soil-biochar mixtures were titrated with 0.1 M aqueous HCl solutions and the resultant pH values determined. The amount of H+ added to soil-biochar mixture was plotted against pH. The pH buffering capacities of the soil and the soil-biochar mixtures were obtained from the graph's slope. The soil pH buffering abilities were largely dependent on the added biochar's alkalinity and ash contents.

Investigating Water Quality Trends in Watersheds with Changing Conservation Adoption
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Lucore A.E., Baker B.H., Hill M.J.

Alongside significant investments in agricultural conservation to address water quality degradation through US government programs is a need to assess conservation efficacy. Conservation practices such as cover crops and reduced tillage have been identified as management strategies with potential to improve water quality outcomes at the edge-of-field scale. However, documenting water quality improvements in impaired waters at the watershed scale is more difficult to monitor and detect. This study aims to address that data gap by assessing historical data in three impaired watersheds in conjunction with more current monitoring data following the implementation of cover crops and reduced tillage conservation practices to detect water quality trends. Historical water quality data was retrieved from U.S. Geological Survey monitoring stations over a ten-year period. Water quality data was also collected in the field by Mississippi State University at each monitoring location following the adoption of cover crops and reduced tillage in each watershed. Data collected from 2018-2020 in Porter Bayou (HUC12 080302071000 ) was analyzed at the Mississippi State Water Quality Laboratory and samples collected from Richies Bayou (HUC12 080302070303) and Overcup Slough (HUC12 080302070302) from 2020-2021 were analyzed at the Mississippi Department of Environmental Quality. Linear regressions will be utilized to explore trends in turbidity, total nitrogen, and total phosphorus concentrations overtime within in each watershed. Results of this study are expected to provide valuable information on water quality trends in impaired watersheds and provide insight for conservation planning.

Irrigation threshold and cover crop impacts on corn production in Mississippi
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Russell D., Kaur G., Singh G.

The Mississippi River Valley Alluvial Aquifer (MRVAA) is the main source of groundwater for irrigation in the Mississippi Delta region. Increases in irrigated crop acreage, as well as frequent droughts throughout the growing season, have caused continual groundwater decline in this aquifer. The objective of this study was to determine if combinations of irrigation scheduling thresholds (-40 kPa, -90 kPa, and no irrigation control) and cover crops [cereal rye (Secale cereale L.), hairy vetch (Vicia villosa R.), wheat (Triticum aestivum L.) + radish (Raphanus sativus L.) + turnip (Brassica rapa L.) mix, and no cover crop control] could improve corn grain yield and quality, water productivity, and irrigation water use efficiency. A field experiment was conducted from 2019 to 2021 at the National Center for Alluvial Aquifer Research in Leland, MS, and the experimental design comprised of a randomized complete block with four replications. In 2020, cover crops reduced corn yield by 9 to 26% compared to the no cover crop control. Minimal or negative impacts from cover crops were also observed for water productivity, irrigation water use efficiency, and corn grain quality in the first year of the study. In 2021, -40 kPa irrigation treatments had 8 and 9% higher corn yield compared to no irrigation and -90 kPa irrigation treatments, respectively. No irrigation treatments showed 6 and 17% higher water productivity compared to -90 kPa and -40 kPa, while hairy vetch was at least 7% higher in water productivity among cover crop treatments in year two of this study. While cover crops showed improvements over the course of two years, no cover crop treatments under the -90 kPa irrigation threshold was the most profitable treatment when averaged over both years. Continued evaluation of cover crops and irrigation thresholds is needed to determine which combination is best for corn production in the Mississippi Delta region.

KTS Wireless/High Yield Ag Solutions
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Koos W.

Since 2014 KTS Wireless (KTS) and subsidiary High Yield Ag Solutions (HYAG) have been collecting and managing data from sensors connected to our wireless products. The data has been delivered to our cloud-based servers where web applications have been created to provide decision making tools for growers and researchers. We have worked closely with Delta F.A.R.M. and Mississippi State University scientists to provide insight into water related agricultural field inputs and outputs. In addition to decision support insights for growers, the raw data is compiled for ease of direct download for research purposes. The sensors and tools include water levels, soil moisture and salinity, well flow rates, outflow pipe flow rates and volumes with water sampler triggering from changes in flow rate, irrigation pump control and weather data from our own agricultural weather station as well as third party sources. Our intent has been to develop a central data platform for capturing agricultural water data in a practical and affordable manner that provides value to growers and researchers alike.

Machine Learning Based High Resolution Soil Moisture Estimation from Small UAS utilizing Signals of Opportunity
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Senyurek V., Farhad M.M., Gurbuz A.C., Kurum M.

Soil moisture (SM) is one of the essential factors for agricultural science and related studies. Low or saturated SM negatively affects crop growth. Traditionally SM content is measured in-situ using SM probes. Although in-situ measurements provide accurate and high temporal SM information in a single point, it is costly, inefficient, and time-consuming for high spatial resolution. Spaceborne remote sensing platforms are practical for a global scale. However, their low spatial resolution (10-40 km) and low temporal resolution (2-3 days) are too coarse for many site-specific precision agriculture applications.

This study proposes a low-cost and practical technique based on Global Navigation Satellite Systems-reflectometry (GNSS-R) utilizing a small drone. A random forest machine algorithm is used to develop an SM estimation model that uses reflected GPS signals, vegetation indices from a multispectral camera, and crop size information from LIDAR as input features. The field experiment was conducted on a 2.48 ha corn and cotton field at MSU's heavily instrumented North Farm. The needed data for the machine learning model was acquired from April to October 2021.

The study results showed that the 2.48 ha field could be covered by GPS reflectometry with about 12 mins flight time, and SM can be mapped with 5m x 5m spatial resolution with high accuracy. We will present the data collection, machine learning based soil moisture estimation approach and the obtained results over the test area.

Microbial Contamination of Drinking Water Supplied by Private Wells after Hurricane Harvey
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Jones C.N., Pieper K.J., Rhoads W.J., Rome M., Gholson D.M., Katner A., Boellstorff D.E., Beighley R.E.

Hurricane Harvey made landfall on the Texas Gulf Coast on August 25, 2017, as a Category 4 hurricane and caused widespread flooding. We explored spatial and temporal distributions of well testing and contamination rates; relationships between contamination and system characteristics and recovery behaviors; and efficacy of mitigation strategies. We estimated that over 500,000 well users (~130,000 to 260,000 wells) may have been affected, but only around 15,000 well users (~3,800 to 7,500 wells) had inundated systems based on inundation maps. Total coliform occurrence was 1.5 times and Escherichia coli was 2.8 times higher after Hurricane Harvey compared to baseline levels. Microbial contamination was more likely (1.7-2.5 times higher) when wells were inundated and/or residents felt their water was unsafe. Although more wells in urban counties were affected, E. coli rates were higher in wells in rural counties. Disinfection did not always eliminate contamination, highlighting concerns about the implementation and efficacy of chlorination procedures. Despite this extensive well testing conducted after Hurricane Harvey, we estimate that only 4.1% of potentially affected wells were tested, underscoring the magnitude of recovery assistance needed to assist well users after flooding events.

Mississippi River Valley alluvial aquifer groundwater ages from lumped parameter models fit to measured tracer concentrations
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Gratzer II M.C., Knierim K.J., Solder J.E., Kingsbury J.A., O'Reilly A.M.

Lumped parameter models (LPM) were used to estimate groundwater ages from age tracer concentrations in samples collected from 89 wells in the Mississippi River Valley alluvial aquifer (MRVA) and Mississippi Embayment aquifer system (MEAS). The type of LPM for each well was chosen based on confinement, likely sources of water, and observed age-tracer concentrations. Ages for 47 MRVA wells were estimated with LPMs representing unconfined conditions, and ages for 25 MRVA and all 17 MEAS wells were estimated with LPMs representing confined conditions. Ages for 55 MRVA wells and 14 MEAS wells were estimated with LPMs representative of distributed recharge (as opposed to localized recharge) within the areal extent of the MRVA. Age dates for 17 MRVA wells and 3 MEAS wells were modeled as binary mixtures of distributed recharge and localized recharge or water from an adjacent aquifer. Mean ages of MRVA samples (n=72) range from 12 to 24,000 years, with more than 70% of the ages being less than 830 years. Mean ages of MEAS samples (n=17) range from 350 to >50,000 years, with more than 70% of the ages being greater than 8,800 years. This presentation will discuss relations between estimated ages and various types of related hydrologic data, including water chemistry data, airborne electromagnetic resistivity surveys of the Mississippi Alluvial Plain, and numerically modeled groundwater flow paths. Improved knowledge of the distribution of groundwater age in the MRVA will refine groundwater flow models and improve understanding of groundwater chemical evolution in the aquifer, ultimately helping water resource managers decide how best to use and protect one of the most heavily used aquifers in the United States.

Model performance and uncertainty analysis of APEX for hydrologic predictions in the Mississippi Delta region
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Mendez J., Ramirez Avila J.J., Locke M.

An uncertainty analysis assesses the effects of knowledge gaps with respect to understanding the model output and performance. In order to study the impact of using different weather stations and soil conditions (inputs) on model outputs, the Agricultural Policy/Environmental Extender (APEX) model was used to predict runoff from agricultural fields in the Mississippi Delta. Two scenarios were proposed: (i) varying climate inputs from five stations located within a radius of 40-km from the study site (Minter at 37.8km-N, Greenwood at 15.9km-NE, Belzoni at 36km-SW, Lexington 37km-SE, and Moorhead at 25km-W); and (ii) assuming a homogeneous soil type in the fields from the actual four soil series present in the study site. An APEX model (v.1501) was calibrated and validated using four years (1996 to 1999) of available information for runoff, water quality, soil characteristics and in-situ climate dataset from two fields (DH1-18ha and DH2-12ha) within the Deep Hollow Watershed (DH) in Leflore county, MS. The APEX baseline scenario used the actual soil series distribution in the fields (Alligator, Dubbs, Dundee and Tensas) and climate information collected in-situ. For all the scenarios, APEX model performance of runoff predictions was assessed using three objective functions: Nash Sutcliffe Efficiency (NSE), percentage of bias (PBIAS), and Kling-Gupta efficiency (KGE). The baseline scenario yielded satisfactory results in the prediction of monthly runoff with NSE values of 0.67 and 0.90; PBIAS values of 29% and 21%; and KGE values of 0.61 and 0.73 for DH1 and DH2, respectively. For the DH2 field, APEX runoff predictions were only satisfactory when using information from the nearest weather station to the study site (Greenwood). For DH1 the same station yielded a better performance than the other three stations, but none yielded satisfactory. For both fields the use of the Greenwood dataset represented an underestimation of runoff. When assuming a homogeneous soil series for the entire fields' area, the use of the Alligator and Tensas soil series (silty clayly and clayly soils with hydrologic groups C and D, respectively) improved the APEX runoff estimations and performance. When assuming the soil series Dubbs and Dundee (very fine sandy loam and loamy with hydrologic groups C and B, respectively) runoff underestimation increased with respect to the baseline. Overall, results offer valuable information to modelers of watershed in the Mississippi Delta, in their decision-making regarding model setup and output interpretation for areas with limited climate and soil information.

MS Phosphorus Index: Can it adequately guide nutrient management plans in the Mississippi Delta?
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Fernandez-Martinez F., Rodriguez L.S., Ramirez Avila J.J., Locke M., Achury S.O., Oldham L.

Agricultural nutrient runoff from fields in the Mississippi (MS) Delta contribute to surface and groundwater quality impairment in the region. The phosphorus (P) indices are tools widely used to assess the vulnerability of agricultural fields to P loss and support nutrient management strategies. The objective of this study was to identify the impact of each MS P-Index input on the assessment of P loss vulnerability for sites in the MS Delta. The probability distribution of the different input parameters (i.e. soil erosion rate, soil test P, P application rate, P fertilization source and method, and runoff class) was determined by using historical crop management data from Stoneville and Beasley Lake watershed, various USDA web tools, and GIS data for the region. Monte Carlo simulations (10,000 iterations) were generated to evaluate the existing MS P-Index and a version in which the model inputs are unweighted. Simulations showed that the distance to water, followed by the organic P2O5 application method were the parameters that most affected the P-Index score, while the inorganic P2O5 application rate was the least sensitive parameter. Stepwise regression showed that 87% of the variance of the P-Index scores was explained by five input parameters (distance to water, organic P2O5 application rate and method, inorganic P2O5 application method, and soil erosion), while all eight input parameters explained 89% of the variance. The mean P-Index scores derived from the simulations were 2.49 and 3.16 for the general and unweighted models, respectively, scoring a low P loss vulnerability in 94% and 83% of the cases, respectively. Since the outputs of this tool are not consistent with the reported issues related to nutrient leakage from agricultural watersheds in the region, results indicate the need for a more in-depth analysis of the MS P-Index and its ability to represent P-loss vulnerability of fields in the MS Delta. An adequate calibration and validation process with analyses of water quality are needed for further research and improvement of the MS P-index tool.

Multi Criteria Decision Analysis (MCDA) for Mapping Watershed Erosion Potential
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Cartwright J.H.

Evaluating soil erosion is often assessed with traditional soil loss models like the Revised Universal Soil Loss Equation (RUSLE) and the Soil and Water Assessment Tool (SWAT). These models provide quantitative output for sediment yield and are often integrated with Geographic Information Systems (GIS). The work described here is focused on transitioning towards a qualitative assessment of erosion potential with Multi-Criteria Decision Analysis (MCDA) for improved decision support and management prioritization. The foundation of this work conceptually defined watershed erosion potential based on terrain slope, geomorphology, land cover, and soil erodibility. These criteria were evaluated with a weighted linear combination (WLC) model for generalized erosion potential. Expert input was added through MCDA with the Analytical Hierarchy Process (AHP). The AHP allows for experts to rank criteria, providing a quantitative metric (weight) for qualitative data. The individual AHP weights were altered in one percent increments to help identify areas of alignment or commonality. These areas were used to identify outliers and to develop an analysis mask for management area prioritization. The WLC, AHP, and SWAT output data were compared. There was some visual alignment between the WLC and AHP erosion potential output with the SWAT sediment yield output. The comparisons however were not a direct correlation between the data sets. General observations show similar results between the qualitative and quantitative erosion assessment approaches with alignment in the upper and lower ranks of erosion potential and sediment yield.

Multiannual variability of low flow events over the Southeastern United States
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Raczynski K., Dyer J.

Understanding the patterns of low streamflow (a.k.a., low flow) frequency and intensity is critical in defining potential environmental and societal impacts on processes associated with surface water resources; therefore, the objective of this study is to quantify the multiannual variability of low flow river conditions over the Southeastern US. The study was performed using National Water Model retrospective simulations (v2.1), aggregated to daily mean flow values at 73,891 stream segments (of Strahler order 3 and higher) for the period 1979 to 2020. The data were used to calculate annual sums of outflow deficit volumes, from which the autocovariance function (ACF) and the Hurst exponent (H) were calculated to quantify low flow patterns. The ACF approach is commonly used for examining the seasonal and multiannual variation of extreme events, while the Hurst exponent in turn allows for classification of "process memory", distinguishing multi-seasonal processes from white noise processes. The results showed diverse spatial and temporal patterns across the Southeast US study area, with some locations indicating a strong seasonal dependence. These locations are characterized by a longer temporal cycle, whereby low flows were arranged in series of several to dozens of years, after which they didn't occur for a period of similar length. In these rivers, the values of the Hurst exponent were in the range 0.8 +/- 0.15, which indicates a stronger relation with groundwater during dry periods. In other river segments within the study region the probability of low flows appeared random, determined by the Hurst exponent oscillating around the values for white noise 0.5 +/- 0.15. The initial assessment of the Hurst exponent distribution, as well as results of the ACFs, suggests no strict spatial relationships. Also, the correlation coefficients between low flow patterns and river order do not indicate the occurrence of a statistically significant relationship (r ≈ 0.08). The results of the research provide useful information about the spatial and temporal patterns of low flow occurrence across the Southeast US, and also indicate that the NWM retrospective data are able to differentiate the time processes for the occurrence of low flows. The next stage of work will be to estimate the accuracy of the NWM retrospective data in terms of low flow analysis through comparison with observed data from available USGS gauges.

Numerical Simulation of Fate and Transport of Chemical Contaminants in Dan River Due to Coal Ash Spill Accident
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Chao X., Zhang Y., Al-Hamdan M.

Large quantities of stored coal ash nationwide pose a serious threat to the environment and wildlife when accidently released into surface water systems. On February 2, 2014, the failure of a storm water pipe under the primary coal ash pond of the Dan River Steam Station owned by the Duke Energy released about 39,000 tons of coal ash and 27 million gallons of pond water into the Dan River near Eden, N.C., about 130 miles upstream of the Kerr Reservoir. Together with the coal ash, a number of contaminants attached to the particles and dissolved in the pond water were also released into Dan River.

Numerical model is an effective tool to simulate the transport processes of coal ash and associated chemical contaminants in river flow. In this case, the entire study reach of the river-reservoir system extends from the USGS Wentworth gauge on Dan River, about 22 km upstream of the spill location to the Kerr Dam, about 182 km downstream of the spill location. For such a long river-reservoir system, the CCHE1D model developed by National Center for Computational Hydroscience and Engineering at the University of Mississippi was applied to simulate the fate and transport of contaminants due to the Dan River coal ash spill accident. The processes of advection, diffusion, sedimentation, and adsorption/desorption of contaminants were considered in the model. Several chemical contaminants, including arsenic (As), mercury (Hg), and selenium (Se) were simulated, and their concentration distributions in water column and bed sediment were obtained. The simulated results were validated using the measured data obtained from EPA. Those results provide useful information for water environment evaluation and water resource management.

Numerical study of groundwater flow and heat transport to assess the hydrogeological effects of the groundwater transfer and injection pilot project in the Mississippi Delta
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Fang J., Al-Hamdan M.Z., O'Reilly A.M., Ozeren Y., Rigby J.R.

In the Mississippi River Valley alluvial aquifer (MRVAA), declines in groundwater levels caused by agricultural irrigation have been observed and reported for the past several decades, indicating that the current practices for groundwater resources management are not sustainable. To mitigate this problem, the Groundwater Transfer and Injection Pilot (GTIP) project was initiated by the U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS) at Shellmound, Mississippi, which consists of one extraction well, two injection wells and 17 observation wells. An experimental operation was conducted to test the feasibility of managed aquifer recharge (MAR) technology, which included measurement of groundwater hydraulic heads and groundwater temperatures in the observation wells. In this study, the hydrogeological properties of the study area are obtained through the coupled inverse modelling of groundwater flow and heat transfer. The variably saturated groundwater flow is simulated by CCHE3D-GW developed by NCCHE, The University of Mississippi, and heat transport is simulated using the MT3D-USGS developed by the USGS. A weighted multiple-variate least squares objective function, which is used to minimize the discrepancies between the measured and simulation results, is formulated for the inverse problem. To obtain a unique solution, Tikhonov regularization is applied, in which the high-resolution data derived from an airborne electromagnetic geophysical survey measured by USGS is adopted as prior information. The local scale hydrological processes governing extraction and injection, i.e., the infiltration flow of water from the Tallahatchie River to the MRVAA and the spread of injection water in the aquifer, are then analyzed based on the calibration results, which will provide detailed understanding of the hydrogeological effects of the GTIP Project to complement other regional modeling activities.

Occurrence and Characteristics of Microplastics in Wastewater Treatment in Oxford, Mississippi
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Gao Z., Cizdziel J.

Microplastics (MPs) are a diverse suite of contaminants commonly found in wastewater. However, wastewater treatment plants (WWTPs) were not designed to remove MPs. Further, MP pollution has not been examined in wastewater stabilization ponds (WSPs), which serve rural and small communities worldwide, and in WWTPs that serve universities where sudden and drastic changes in on-campus populations occur. Here, we characterized MPs (~45 μm-5 mm) in a WSP serving ~500 houses and in an adjacent lake as well as in a modern oxidation ditch WWTP at the University of Mississippi. In the pond, putative MPs were most abundant in duckweed (Lemna minor) and sludge (75 ± 22 and 12.8 ±3.1 particles/g, respectively: ±1 standard deviation (SD), n = 6, dry weight). In the water, average concentrations (particles/L ± 1 SD, n = 6) were highest in the WSP (4.1 ± 0.6), followed by WSP effluent (3.9 ± 0.5) and the lake (2.6 ± 0.6). Over 20 types of MPs were identified, with the distribution varying somewhat between the water, sludge, and duckweed. Polyester and polyethylene were the predominant types, followed by polyethylene terephthalate, polyacrylate, PVC, and polystyrene. Morphologies consisted of fibers (62-71%), fragments (28-37%), and beads (1-6%). High-density polymers were more frequently found in sludge. Potential sources include synthetic textiles from laundry and plastics washed down household drains. Overall, with ~786,000 MPs/day released from the pond and with duckweed a source of food for waterflow, we demonstrate that WSPs can be point sources of MPs to both aquatic and terrestrial ecosystems. At the University WWTP, we observed the highest abundance of MPs after a football game (62.3 ± 7.6 particles/L, average ± 1SD, n=3), followed by 46.3 ± 9.5 particles/L sampled the prior week, and 22.8 ± 4.5 particles/L during a period with little on-campus activity. Over 90% of the MPs were removed in the primary treatment. MPs were most abundant in the oxidation ditch biological unit (1962 particles/L) as the MPs accumulate in the activated sludge. Concentrations of MPs in secondary clarifier and final effluent were <4 particles/L during higher-flow periods and between 16-39 particles/L during lower flow periods. MPs were mainly composed of polyester, acrylic paint, PVC, polyethylene, polypropylene and polyurethane. Most MPs in the effluent were fibers (61%), fragments (21%), and films (13%), with beads and foams contributing the rest (5%).

Operation and Maintenance of the Groundwater Transfer and Injection Pilot Project at Shellmound, MS
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Cummins B., O'Reilly A.M., Wren D.G.

The Groundwater Transfer and Injection Pilot (GTIP) project is an innovative effort to not only mitigate further depletion of the Mississippi River Valley Alluvial Aquifer (MRVAA), but also to potentially raise water levels in an area of excessive drawdown by artificially recharging the aquifer. This project is a collaborative effort between the U.S. Army Corps of Engineers (USACE) Vicksburg District and the U.S Department of Agriculture - Agricultural Research Service (USDA-ARS). The Pilot Study project site is located in Shellmound, MS, which is approximately 8 miles northwest of Greenwood, MS, and is situated to the west of the Tallahatchie River.

The system extracts water from within the MRVAA at a natural recharge zone, due to bank filtration of the adjacent Tallahatchie River, and then conveys the water approximately two miles, via subsurface pipeline, to two injection wells where it is re-introduced into the MRVAA. The USACE managed design and construction of the facility and collaborates with USDA-ARS to maintain its operation and conduct maintenance activities. To evaluate the aquifer's response to the artificial recharge, USDA-ARS has been monitoring, sampling, and analyzing data from multiple observation wells near and within the project vicinity.

Each injection well was receiving water at a rate of 750 gpm and the system was running 24 hours a day, seven days a week for nearly 3 months. The system was functioning as designed; however, after approximately 3 months of continuous injection, both injection wells experienced hydrostatic pressures that exceeded the threshold of the top-stratum blanket of fine-grained sediments, causing cracks due to soil heaving and the presence of boils at the ground surface. Additionally, upon visual inspection of the wells using a downhole camera, the presence of iron-related bacteria and/or iron oxides were observed coating the inside of the well screens. Rehabilitation efforts were performed by USACE Vicksburg District using chemical treatment with a dilute oxalic acid solution at each injection well, and then site repairs were completed using low-strength flowable fill to re-establish the top-stratum blanket. Future planning for optimal operation and maintenance of the GTIP project facility is an ongoing mission to ensure (1) that the data needed to determine feasibility is achieved and (2) that best practices and procedures are identified for use if it is determined that larger scale aquifer recharge is feasible for this region.

Overview and status of the Groundwater Transfer and Injection Pilot Project at Shellmound, Mississippi
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Wren D.G., O'Reilly A.M., Locke M.A., Bolton W.J., Mirecki J.E.

In the Mississippi Delta region (Delta), long-term declines in groundwater levels in the Mississippi River Valley alluvial aquifer (MRVAA) indicate that groundwater-use practices are unsustainable. Managed aquifer recharge (MAR) has potential for reducing groundwater depletion in the Delta. In partnership with local stakeholders and the U.S. Army Corps of Engineers, the USDA Agricultural Research Service is conducting the Groundwater Transfer and Injection Pilot (GTIP) project, which combines riverbank filtration and aquifer storage to capture water from the Tallahatchie River for direct injection into the MRVAA. The system consists of one extraction well near the river, a 1.8-mile transfer pipeline, and two injection wells. The system has a design capacity of 1,500 gpm with 750 gpm sent to each injection well. Monitoring includes continuous groundwater level and temperature in 17 monitor wells (14 MRVAA, 3 Sparta aquifer); semimonthly field parameters (temperature, specific conductance, pH, dissolved oxygen) at six MRVAA monitor wells; monthly water samples for analysis of major ions, metals (Fe, Mn, As), and nutrients (N, P, C) from all monitor wells, extraction and injection wells, Tallahatchie River, and Lake Henry (lake adjacent to the injection wells); and annual water samples for a large suite of trace metals and pesticides from 4 monitor wells and both injection wells. Hydraulic connection between the river and MRVAA is suggested by variations in groundwater level, temperature, and specific conductance. Ambient groundwater prior to operation was less mineralized at the extraction site than the injection site, and water levels in monitor wells near the river showed responses to river stage that were not evident in more distant wells near the injection site. Operation began April 2021, and an 89-day test injecting a total of 550 ac-ft of water has been completed. This resulted in a groundwater mound of 6.9 ft near the injection wells and a drawdown of 4.6 ft near the extraction well, prior to commencement of regional drawdowns in June caused by irrigation pumping. Clogging of the injection wells necessitated periodic backflushing followed by treatment with a dilute oxalic acid solution, which resulted in returning injection well specific capacities to within 85% of initial values. Current plans are to resume operation and data collection for an additional 3 to 6 months. Knowledge acquired during the GTIP project will be used to assess feasibility of a full-scale implementation of MAR technology in the Delta.

Prediction of Groundwater Level Lag Times Using Spectral and Trend Analyses: Implications for Water Management and Drought Assessment
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Guthrie G.M., Jin G.

Groundwater data is commonly used by state and federal organizations as a component of drought assessment during dry seasons. The incorporation of this data in monthly assessments may be of limited usefulness due to the delayed response, or lag time, of water levels to precipitation events resulting from the time required for recharge waters to migrate to the saturated zone. Daily water-level measurements are traditionally presented as time series hydrographs that are seemingly complex, noisy, and thus difficult to interpret due to diurnal, seasonal, and even decadal variations. Continuous water level (WL) data from eight drought monitoring wells in different hydrogeologic provinces and precipitation (PPT) data from nearby stations have been analyzed using spectral analysis by discrete Fourier transform to evaluate primary seasonal and trend events. The technique can reveal both the periods and magnitudes of all seasonal, cyclical, and/or long-term (more than one year) wet and drought events and provide important parameters to decompose time series data into seasonal, trend, and random components using seasonal and trend decomposition. The resulting trend components are then evaluated with correlation analysis to establish groundwater lag time in the wells in response to precipitation events. Lag time is determined from cross-correlation diagrams as the amount of time shift required to attain a peak correlation coefficient for both WL and PPT trend curves. Lag time is not consistent among wells, ranging from 60 to 180 days, and the differences may reflect different environmental and hydrological properties of the wells, such as elevation, confining conditions, distance from recharge area, permeability, hydraulic conductivity, unsaturated zone hydraulic properties. Lag time analysis provides an invaluable tool to accurately model/forecast groundwater changes using machine learning and statistical techniques and the ability to predict anticipated groundwater levels at the beginning of the drought season. Using this methodology will be an invaluable tool for water managers and stakeholders to assess potential water availability issues.

Resource recovery from dairy and municipal wastewater sources in a terracotta-biochar bioelectrochemical system
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Ghimire U., Gude V.G., Magbanua B.S.

Agricultural and municipal wastewater effluents contain valuable nutrients which can be recovered and recycled for agricultural applications. Microbial electrochemical systems facilitate recovery of nutrients from wastewater sources with concurrent electricity production. There is a strong potential for these systems; however, the electrode and membrane separator components of the process are still expensive. Moreover, for safe recovery and recycle of nutrients, natural and sustainable materials should be utilized. We explored the use of novel and sustainable materials for the construction of microbial electrochemical systems. Terracotta clay (an earthly material) and agricultural waste derived biochar materials were used to construct a microbial electrochemical system to enable nutrient capture and electricity generation from the organic substrates present in agricultural effluents. Municipal and agricultural (dairy production) wastewaters were evaluated for the potential resource recovery in the novel, sustainable microbial electrochemical systems. The effect of influencing parameters such as external resistance and COD concentrations on the performance of terracotta-biochar bioelectrochemical systems was studied. Appreciable levels of COD, N and P removals were observed. Moreover, power densities of 0.45 W/m3 and 1.26 W/m3 were recorded for synthetic municipal (500 mgCOD/L) and dairy wastewater (2500 mgCOD/L) sources, respectively. The SEM and EDX analysis results from this study confirm the beneficial use of sustainable materials for resource recovery applications in agricultural systems.

Soil physical responses from integrating conservation agriculture and implications on water quality in the Mississippi Alluvial Valley
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Firth A., Brooks J., Locke M., Morin D., Brown A., Baker B.

Agriculture is the greatest contributor to overall consumptive water use with deleterious effects seen in river depletion and groundwater over draft. Despite negative documented effects of agricultural land use (i.e. soil erosion, compaction, nutrient runoff) on critical natural resources (i.e. water), food production must increase in order to meet the demands of a rising human population. Given the environmental and agricultural productivity concerns of intensely managed soils, there is a growing interest in conservation practices that mitigate the negative effects of crop production and enhance environmental integrity. In the Mississippi Alluvial Valley (MAV) region of Mississippi, USA, the adoption of cover crop (CC) and no-till (NT) management practices has been low because of a lack of research specific to the regional nuisances. Therefore, this study assed the long-term soil physical responses from integrating CC and NT management to agricultural soils in the MAV region of Mississippi. It was hypothesized that the combination of a diverse CC mixture and NT management would provide more favorable soil physical properties compared with single CC mixtures or tillage treatments. Bulk density, aggregate stability, water holding capacity and water infiltration were measured after 5 years of CC and NT treatments. Data on soil properties were subjected to analysis of variance to assess the effects of tillage, CC and time on soil physical response (bulk density, aggregate stability, moisture retention, moisture porosity, water infiltration). Generalized linear mixed models were used to determine how dependent variables interact with independent treatments. Bulk density was found to be significantly lower in NT plots and aggregate stability was greatest in plots with a single CC species (elbon rye) as a CC. No differences were found in water infiltration; however, data collection may not have used optimal methods. Water porosity was greatest in a NT-CC combination, suggesting that conservation agriculture can improve soil physical characteristics that are linked with decreased water runoff.

Status and Trends of Total Nitrogen and Total Phosphorus Concentrations, Loads, and Yields in Streams of Mississippi, Water Years 2008-18
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Hicks M.B.

To assess the status and trends of nutrient conditions of surface waters throughout Mississippi, the U.S. Geological Survey, in cooperation with the Mississippi Department of Environmental Quality, summarized concentrations and estimated loads, yields, trends of total nitrogen (TN) and total phosphorus (TP) between 2008 and 2018 water years for 22 streams in Mississippi.

Relation of streamflow to concentrations of TN and TP varied among sites and were generally related to land use: sites with high agriculture land use in the drainage basin generally had positive correlations between streamflow and nutrient concentration, suggesting influence of event-driven nonpoint-source runoff; sites near urban (developed) areas generally had negative correlations, suggesting chronic point-source influences during low-flow conditions; sites with high forest land use and lower agriculture and urban land use had little to no association between streamflow and concentration.

Seasonal distributions of concentrations of TN and TP also corresponded closely with differences in land use among sites. Sites near urban (developed) land had the highest nutrient concentrations in late summer and fall, whereas nutrients were highest during the spring among sites with a high percentage of agricultural land. However, seasonal patterns in nutrient concentrations were not apparent among sites that were primarily forested or with little developed land

Trend analyses of TN loads between 2008 and 2018 water years indicated that eight sites had statistical likelihoods for upward trends of TN loads, seven sites had statistical likelihoods for downward trends, and six sites had no statistical trend. Trend analyses of loads of TP resulted in 16 sites with upward trends, 3 sites with downward trends, and 2 sites considered "about as likely as not."

Results of estimated nutrient yields calculated for sites across MS in this study varied in consistency compared to predicted regional-scale nutrient yields generated by 2012 SPAtially Referenced Regressions on Watershed attributes (SPARROW) model. Notably, yields of TN and TP at four sites in the highly agricultural area of northwest Mississippi (Delta) were underestimated by SPARROW model by an average of 25 percent and 44 percent, respectively.

Overall, data indicate yields of TN may have slightly decreased over the last 20-30 years, but TP yields remain constant or are increasing and SPARROW model estimates for Mississippi streams may be improved with additional calibration sites and data, especially in the Delta.

Stream channel characterization in the Catalpa Creek/Red Bud Creek watershed in Mississippi
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Roldan M., Ramirez Avila J.J., Achury S.O., Schauwecker T., Czarnecki J.

The Catalpa Creek watershed is located in the northeastern part of Mississippi, in Oktibbeha and Lowndes County. The Mississippi department of environmental quality (MDEQ) has listed Catalpa Creek as an impaired waterbody due to sediments. As the city of Starkville and the Mississippi State University Campus are in the headwaters of the watershed, they play an important role in the generation of runoff and acceleration of stream processes in the watershed. A study is conducted hypothesizing the Rosgen's bankfull indicator based classification system can be systematically and consistently applied to the Catalpa Red Bud/Catalpa Creek watershed and potentially, the Tombigbee River Basin in Mississippi. The morphological classification of benchmarked stream channel reference sites along the mainstream and tributaries within the Red Bud/Catalpa Creek Watershed is conducted at the level II of the Rosgen's Classification. Physiographic characterization of the reaches has been performed since October 2021. Stratification of the Catalpa Creek/Red Bud Creek streams into the correct stream type could lead to a more appropriate prioritization and design of streambank-stabilization, stream restoration, and habitat-rehabilitation projects, and to the potential stratification of assessment and monitoring sampling programs.

Streaming potential response associated with pump-induced surface-groundwater interaction
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Mamud M.L., Hickey C.J., Holt R.M., Wodajo L.T., Rad P.B., O'Reilly A.M., Bolton W., Wren D.

Groundwater flow induced by pumping from an aquifer near a river generates Streaming Potential (SP) signals that can be recorded at the ground surface around a pumping well. The SP signal produced by pumping near a river is influenced by groundwater flow within an aquifer, water flow from the river into the aquifer, and mixing of waters with different chemical compositions and temperatures. SP measurements can be used to identify and quantify characteristic time scales associated with these processes. SP measurements were conducted around a groundwater extraction well drilled for an Aquifer Storage Recovery pilot project located about 40m away from the Tallahatchie River in Shellmound, MS. SP data were recorded at 5 minute intervals using 80 non-polarizing CuSO4 electrodes in a radial pattern centering on the extraction well. Pumping rates varied from ~300 to ~1500 gallons per minute over a ~4 hour period. Time series and spatial distribution of SP data shows that the river might have interacted with groundwater after 1 hour of pumping at an extraction rate of ~1500 gallons per minutes. This preliminary study suggest that measured SP data can be used to identify surface-groundwater interaction. Furthermore, hydraulic conductivity of aquifer, aquitard and riverbed; specific storage; and hydraulic head could be estimated from inversion of SP data.

Surveys for Invasive Aquatic and Native Marine Vegetation on the Mississippi Barrier Islands
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Turnage G., Sample A.

Barrier island lagoons may act as refugia for seagrass species; many of which are vital components of marine ecosystems in the Gulf of Mexico and the Mississippi Sound. Seagrass beds serve as feeding and spawning habitat for many species of marine fauna (i.e., fish and invertebrates) and reduction of seagrass beds can have a cascading effect on ecosystem processes (e.g., fish feeding) that can affect economic opportunities by reducing commercially and recreationally important fish species (e.g. speckled trout) that utilize this habitat. Unfortunately, lagoons may also be invaded by aquatic invasive plant species AIS capable of surviving brackish water environments (i.e., torpedograss, common reed, and Eurasian watermilfoil) that can form dense plant beds that shade out and kill native plant species. Loss of ecosystem function has been documented in many systems that have AIS present, including brackish and saline habitats, suggesting that AIS invasion could further reduce seagrass abundance in island lagoons such that these sites no longer function as nursery populations that replenish seagrass beds in the Mississippi Sound. The goal of this project was to survey the aquatic and marine vegetation in select lagoons on the four major barrier islands (Petit Bois, Horn, Ship, and Cat) of Mississippi to 1) determine the aquatic/marine plant community of each lagoon and 2) determine if AIS were present in these systems. Islands were surveyed using the point-intercept method in the fall of 2020 under research permit #GUIS 00283. Twelve lagoons over 0.4 ha (1 ac) in size were identified from historical satellite imagery. Six reference sites in the Mississippi Sound were identified adjacent each island and also surveyed to generate baseline density of seagrasses, against which seagrass densities from individual lagoons were statistically compared. All lagoons had vegetation present with Shoal grass (native) and torpedograss (AIS) being the most prevalent species. Seagrass was recorded in 58% of lagoons with 70% of those populations potentially serving as nursery populations for offshore sites adjacent to each island and approximately 40% serving as nursery sites across the Mississippi Sound. However, AIS were present in 66% of lagoons and co-occurred with seagrass populations in 25% of lagoons. To our knowledge, this is the first work to document AIS co-occurring with seagrasses on the Mississippi Barrier islands. Future reduction of AIS in lagoons may allow for subsequent colonization by seagrasses which could further increase the abundance of nursery seagrass populations in the Mississippi Sound.

Terracotta as a natural adsorbent for nutrient recovery from agricultural effluents
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Sauers J., Gude V.G.

Nutrients released through agricultural effluents cause eutrophication of receiving water bodies. In this research, the adsorption capacity of terracotta clay was evaluated due to its promising benefits in nutrient and water retention. The efficacy of terracotta clay to act as a solid-phase sorbent was studied for two main nutrients, nitrogen and phosphorus. The phosphate solutions were prepared at three difference concentrations (20 mg/L, 35 mg/L, and 50 mg/L). The phosphate solutions were mixed with the terracotta clay in a mixer at 8 different time intervals of 0, 5, 10, 20, 40, 60, 300, and 1440 minutes at 25℃ and 50℃. Samples were collected at the aforementioned predetermined intervals. The ammonium nitrogen solution was prepared in a similar manner to the phosphate solution, but only tested at a concentration of 50 mg/L at 25℃.

The kinetics of nutrient absorbance by the terracotta clay was studied by fitting the Pseudo-first-order, pseudo-second-order models. The adsorption capacity for the phosphate was similar at both temperatures for ammonium. The terracotta clay absorbed the phosphate for the first 20 minutes followed by desorption at the 40-minute interval. The phosphate absorbance capacity was better at 25℃ than 50℃. The pseudo-second order model fitted the adsorption kinetic data with high correlations. The R2 values for the three concentrations range from 0.9765 to 0.9977 at 25℃, while the confidence intervals for the three concentrations at 50℃ ranged from 0.9672 to 0.9952. The phosphate adsorption capacity at a temperature of 50℃ but the capacity varied at each time interval. This presentation will also include thermodynamic analysis of the adsorption studies.

Testing of a full-scale floating wave barrier for reducing wave erosion in a working irrigation reservoir
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Rossell W., Ozeren Y., Wren D.

In order to reduce the demand on groundwater resources, on-farm irrigation reservoirs are used for storing irrigation water in the Mississippi Delta region. The embankments surrounding these reservoirs are routinely damaged by wind-generated waves, resulting in high maintenance costs over time. It is thus necessary to identify cost-effective methods to protect the inner slopes of the embankments from wave action. Floating wave barriers (breakwaters) have been shown to reduce wave impact on offshore and coastal structures, and by identifying a simple, cost-effective design that maintains good efficacy, the use of a floating breakwater should reduce the frequency of required maintenance associated with the use of irrigation reservoirs. In this study, the use of floating pipe breakwater for reducing wave energy was investigated. Specifically, an efficient design for the cable system that holds the floating barriers in place was needed. The proposed breakwater uses common HDPE irrigation piping moored to the reservoir bottom by steel cables. A model floating breakwater was constructed and tested for various mooring configurations and a variety of wave characteristics in a wave tank at the USDA-ARS National Sedimentation Laboratory. Results of these experiments will be discussed in this presentation, as well as details of a full-scale floating pipe breakwater for deployment in a working irrigation reservoir.

Testing requirements and results on water for fruit and vegetables under the Produce Safety Regulation
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Abdallah-Ruiz A., Bond R.F., Silva J.L.

The US Food and Drug Administration has a new regulation as part of their Food Safety Modernization Act, titled "Standards for the Growing, Harvesting, Packing, and Holding of Produce for Human Consumption." Under this rule there is a subpart proposed titled "Agricultural Water." The rule states that farmers should evaluate risks associated with water as a possible source of contamination of product that will reach commerce and develop mitigation strategies to minimize these risks. Water has been known to be the source of many produce foodborne outbreaks. Water has been implicated as the possible vector of E. coli STEC (O157:H7) in romaine and other leafy greens, affecting the health of many consumers, leading to hospitalization and death in some cases. One of the factors is the source of water and possible contamination sources. Testing of the water source and at any other points could help assess the quality/safety of it and whether mitigation strategies are needed. The analyte to test, whether it is well or surface water, is E. coli. Sampling and testing procedures approved usually follow those approved by EPA for recreational waters. In addition, farmers can test for possible pathogens that may be in the water. Limited testing has shown that well water usually meets the desired quality (GM and STV of 126 and 410 CFU or MPN/ml in 100 ml, respectively). However, surface water samples at times do not meet the criteria for E coli and have been found positive for some pathogens (Salmonella most often).

The influence of marsh edge and seagrass habitat on fish and macroinvertebrates in a northern Gulf of Mexico coastal system
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Gilpin R., Cebrian J., Baker R., Offner T., Ramsden S.

Habitat is one of the most important services provided by coastal ecosystems. In estuaries in the northern Gulf of Mexico (nGOM), marsh grasses and seagrass beds provide habitat for many fish and crustacean species (i.e., nekton) of ecological, commercial, and recreational importance. Namely, the structural complexity of marshes and seagrass beds provides excellent refuge and food resources, making them ideal nurseries for the recruitment of estuarine-dependent juveniles. Although both marshes and seagrass beds have been widely recognized as important nursery habitat for estuarine species, few have analyzed how these habitats interact and function together, thereby limiting our understanding of the variability of juvenile recruitment to coastal systems. Our objective is to assess the interaction between fringing marsh and adjacent seagrass for the provision of habitat for nekton. Our preliminary analyses point to evidence of functional habitat redundancy between fringing marshes and adjacent seagrass beds. Namely, indicating that in the location of study, fringing marsh and seagrass beds offer similar levels of habitat value to recruiting juveniles. At any rate, further analysis of our data is needed to confirm these preliminary results. Understanding how intertidal marshes and adjacent seagrass beds interact and function together is essential for implementation of concerted conservation and management efforts for these important nursery habitats.

The University of Mississippi Lead in Drinking Water Project
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Otts S., Green J.J., Surbeck C., Willett K.L.

Childhood lead poisoning is a challenging social issue that requires the coordination of health, housing, and environmental law and policy. Little is known about the contribution of lead pipes and water treatment to lead poisoning in Mississippi. The University of Mississippi Lead in Drinking Water Project (UM Lead Project) launched in 2017 and is headed by an interdisciplinary team of researchers from the University of Mississippi (Stephanie Otts, J.D.; Dr. Cristiane Surbeck; and Dr. Kristie Willett) and the Southern Rural Development Center (Dr. John Green). The team takes a community-engaged, research-based approach to address lead in water-related health gaps in the state. To date, the Team has organized almost twenty lead education and sampling events, tested drinking water for more than 300 families, presented annually at the Mississippi Water Resources Conference, taught an Honors College Experiential Course, established a referral program with the Mississippi State Department of Health (MSDH), partnered with Mississippi State Extension's SipSafe program to sample water at childcare facilities for lead, and published two academic journal articles. Our research has revealed that lead in drinking water is an issue of statewide concern, especially for Mississippians who obtain their drinking water from private wells. In 2021, the UM Lead Project received funding from the University of Mississippi to organize and host a statewide lead forum in October 2022. This presentation will provide an overview of the UM Lead Project's work and research findings, as well as provide an opportunity for conference participants to provide input into the planning of the Lead Forum.

Tile Drainage, Sub-Irrigation and Furrow Irrigation for Soybean Production in Mid-South Mississippi Delta
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Singh G., Kaur G., Quintana N., Gholson D., Krutz L.J., Dodds D.

Mississippi State receives annual average precipitation of 1372 mm. More than 60% of the annual total precipitation is received during late winter or early spring (December to March). Low temperatures along with greater precipitation results in drainage issues in the Mississippi Delta Region. In this region land under row crop production is land-formed to 0.05 to 0.1% slope to help with better surface drainage. Surface and subsurface drainage has been a long-term issue that growers face during every growing season. Due to inadequate subsurface drainage planting, corn and soybean are often delayed in this region. Delayed planting combined with lower precipitation and higher temperatures during summers often results in yield drags. Therefore, supplemental irrigation as furrow irrigation is a common practice among the Mississippi growers. Tile drainage and sub-irrigation are new concepts in the Mid-South US. Sub-surface drainage using tile can be a potential game-changer for the Mississippi growers. Early planting windows for row crops in Mississippi are narrow. Tile drainage can help to drain the subsoil and can help with widening the planting windows. The overall objective of this study was to evaluate tile drainage plus subirrigation system in the Mississippi Delta. The specific objectives were to evaluate soybean production on non-tile drained non-irrigated, non-tile drained furrow irrigated, tile-drained furrow irrigated, and tile-drained sub-irrigation treatment plots and to evaluate the effect of the tile drainage on the drying and wetting of the soil profile for two different tile spacings. This research project was established in summer 2021 on a Sharkey clay soil series having more than 70% clay content with two tile spacings 15' and 20'. The year 2022 will be the first year to evaluate the effect of drainage treatments on soybean production. Sentek soil moisture sensors were installed in Jan. 2022 to a depth of 91 cm to monitor soil moisture changes from non-tile drained and tile-drainage treatments. Tile drainage installation design and preliminary data on soil and soil moisture will be presented at the conference.

Understanding the Effects of Soil Moisture on Iron Deficiency Chlorosis (IDC) in Soybean
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Waldrep K., Tagert M.L., McCoy J., Harrison M.

Iron deficiency chlorosis (IDC) of soybeans is a frequent problem in certain areas of the United States, including the Blackland Prairie regions of Mississippi. Previous research has found that the severity of IDC in soybeans can be related to pH, temperature, CaCO3 content, and moisture in the soil. However, even with these contributing factors identified, variety selection for tolerance has been the primary strategy for alleviating the effects of IDC. This study began in 2019 and focuses on a cropping system approach to manage the effects of IDC and thus increase grain yield in dryland soybeans. The project was established as a split-plot design, with seven different cropping systems as the main plots and six soybean varieties as the subplots. Little field-scale research has been conducted to understand the effect of soil moisture on IDC symptoms. This project evaluates the relationship between soil water tension and IDC severity across the seven cropping systems. Visual ratings and chlorophyll readings were recorded weekly (weather permitting) to evaluate IDC symptomology, and soil water tension was measured continuously throughout the growing season. Soil water tension was measured using Watermark granular matrix sensors installed at 30.5- and 61-cm depths—one set in a tolerant variety subplot and one set in a susceptible variety subplot. The sensors were connected to Watermark 200SS dataloggers and set to record each hour. Soil water tension is being compared to IDC visual ratings and grain yield for each cropping system to identify how soil moisture affects IDC severity.

Understanding the impacts of silvicultural activities on downstream sediment export and ecosystem function via experimental sediment additions
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Kohler L.D., Speir S.L., Atkinson C.L.

Increased sediment export in streams has significant downstream impacts, decreasing water clarity, negatively impacting aquatic organisms, and increasing the export of sediment-bound nutrients. However, the construction of forest roads and other silvicultural activities are considered "non-point sources" of pollution under the Clean Water Act. This "silvicultural exemption" allows forestry companies to directly dispose of dredged material into streams without permits. Thus, it is critical to determine the impacts of dredged material on sediment dynamics in streams. Here, we quantified the impacts of sediment discharge on stream ecosystem function using a Before-After Control-Impact (BACI) design. We simulated a sediment discharge event in our impact stream reach, then measured stream turbidity, total suspended solids, and phosphorus concentrations in both the control and impact reaches; this was repeated twice to capture both low- and high-flow conditions. We also deployed dissolved oxygen sensors at the top and bottom of each reach to estimate stream metabolism. Preliminary results indicate that increased turbidity, associated with the disposal of dredged material, results in decreased light penetration in the water column and reduces in-stream primary productivity. Our study will shed light on the impacts of forestry-related sediment disposal on both in-stream function and sensitive downstream systems that can inform forestry best management practices and legislation.

Use of geophysics and UAS-based thermal for mapping potential underseepage of levees
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Counts R., Davidson G., Yarbrough L.D.

Subsurface erosion due to underseepage during large floods, particularly through piping and the formation of sand boils, poses a significant threat to the integrity of floodplain levees in certain geologic settings. Research using natural geochemical tracers indicates that seepage beneath levees can follow both shallow and deep flowpaths. Though effective, tracking geochemical tracers is somewhat labor intensive and takes time. This project uses ground penetrating radar (GPR) and unmanned aerial system (UAS) imagery, which can be rapidly deployed with real-time viewing of the data as it is acquired, to test their effectiveness in mapping seepage and piping flowpaths. In 2019, the lower Mississippi River valley experienced significant and sustained flooding. During this historic event, GPR profiles and UAS thermal imagery were acquired in between Mississippi River mainline levees and multiple active sand boils north of Vicksburg, MS to identify active seepage flow paths and locate new sand boils in heavily vegetated areas. Despite recent mitigation efforts in the study area, which included constructing a 3-m thick clay pad over the region of older sand boil formation, new sand boils formed on the floodplain surface beyond the edge of the mitigation area during the 2019 flooding. GPR surveys using 160 MHz and 450 MHz hyperstacking antennae and UAS thermal imagery were acquired in between the actively flowing sand boils and the levee with promising results. Although wet, clay-rich soils are among the worst conditions for GPR, the 160 and 450 MHz antenna imaged to depths of 14 m and 6.5 m, respectively, and revealed multiple anomalies that could be seepage flowpaths. Additionally, actively flowing sand boils were apparent in the thermal imagery. Not only can GPR and UAS surveys be rapidly deployed, they can also cover very large areas in short time spans, and our proof-of concept results show these methods could be valuable tools for real-time levee assessments during flood conditions.

Water Use Efficiency & Reuse
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Vargas A., Singh G., Kaur G.

Groundwater resource is the most exploited resource for furrow irrigation used in Mississippi The overuse and excessive pumping from agriculture and fisheries has exceeded the natural water recharge of the Mississippi River Valley Alluvial Aquifer. There is limited research available on the use of overhead irrigation systems in corn production systems in the Mississippi Delta. Therefore, understanding the relation between sensor-based irrigation scheduling and nitrogen management using a lateral move system is essential to effectively apply water and nitrogen (N) for sustainable production. The objective of this study was to evaluate the effects of sensor-based irrigation with different nitrogen rates on corn yield and yield components. This study was conducted at Delta Research and Extension Center, Mississippi State University, Stoneville, MS in 2021. Treatments included in this study were three irrigation scheduling thresholds (-40, -70, and -100 kPa) and a rainfed treatment, four N rate applications (0, 112.3, 224.5, and 336.8 kg ha-1), and two distinct soil textural classes (Sandy Loam and Clay). The experimental design was a 4✕4✕2 factorial arrangement of treatments in a randomized complete design, with five replications. Data collected included plant height, plant population, SPAD meter readings, corn biomass to estimate N uptake in irrigation and N rate treatments. At harvest, grain samples were collected to determine grain N uptake and grain quality. Corn grain yield was adjusted to 15.5% moisture. Data collected was analyzed using the GLIMMIX procedure in SAS statistical software at a p-value of 0.05. The results for this research will be presented at the conference.

Watershed planning for sustainable irrigation expansion in Alabama
Proceedings of the 2022 Mississippi Water Resources Conference

Year: 2022 Authors: Newby A., Ellenburg L., Estes M.

Although the Southeast enjoys more annual rainfall than most of the U.S., it still experiences periodic droughts and the rainfall distribution throughout the year is not ideal for agriculture. In Alabama, agriculture is further impacted because of relatively poor water holding soils and lack of widespread irrigation. The need to pursue sustainable irrigation expansion and resource conservation in water rich states such as Alabama has been identified in farmer listening sessions. According to the irrigation status of harvested cropland in a agricultural census, Florida had about 1.3 million acres under irrigation, Georgia irrigated around 1.2 million acres, Mississippi had 1.8 million and Alabama had only 162,000 irrigated acres.

The Natural Resources Conservation Service (NRCS) Alabama office is working with the Alabama Soil and Water Conservation Committee to allocate financial assistance to sustainably expand irrigation in Alabama. Auburn University and the University of Alabama in Huntsville are supporting the effort through the development of a statewide resource assessment and follow up watershed plans for selected HUC-8 basins. The irrigation watershed plans examine alternatives for increasing acres of on-farm irrigation, identify natural and cultural resources that might be negatively impacted by expanded irrigated agriculture, estimate economic benefits, and evaluate environmental sensitivity concerns. Data at the HUC-12 level is provided where available to assist with the determination of sustainable expansion. Farmers selected for participation are prioritized using recommendations from the watershed plans and by categories including access to water and a record of stewardship practices.

The plans are developed with coordination and guidance from diverse stakeholders including government agencies, non-government organizations, landowners, and others that are interested. This presentation will cover aspects of the overall project, provide updates on completed watershed plans, and share future steps in planning for sustainable water use in Alabama's agricultural industry.

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