Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Maierhofer M., Huff D.

How does the lifecycle of a raindrop affect a crop? How do you know you have the right amount of water in the right place at the right time? We will discuss what water management encompasses and the benefits behind the different practices that may be misunderstood.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Wodajo L., Rad P., Islam S., Hickey C., Wilson G.

Ephemeral gullies result from the junction of rills that form a branching or tree-like pattern of channels. They can also be formed by internal erosion that leads to pipe (tunnel) collapse. These gullies usually appear on a cultivated field during the planting or growing season and can be partially or totally erased and filled by tillage operations. The filling leaves the nutrient-rich topsoil vulnerable to erosion leading to soil deterioration and poor crop production over a larger area than the gully itself. This paper evaluates the feasibility and efficiency of two geophysical methods, ground penetrating radar (GPR) and electromagnetic induction (EMI), for delineating soil pipes in cross-sectional and plan-view maps. The study site, currently used for pasture and crop production, is located within the Goodwin Creek experimental watershed (GCEW) of North Mississippi. The area is affected by multiple pipe collapse features, such as flute holes, sinkholes, and small to large gully windows. The erosion pipes are located at a shallow depth of less than 2m with varying lengths and widths. Geophysical signatures from the two methods are evaluated using a composite (combined) cross-section plot that includes results of an invasive technique known as cone penetrologger testing (CPL). These signatures are then used to construct plan-view maps of the area. The EMI results allow for the delineation of larger zones of fields having soil pipe networks. The GPR data provides a much better resolution. The GPR data can be used to construct maps (depth slices) representing different depths. The results demonstrate the high potential of EMI and GPR as valuable tools for studying internal soil pipes. This work was supported by the U.S. Department of Agriculture under Non-Assistance Cooperative Agreement 58-6060-6-009. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the U. S. Department of Agriculture.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Hammett A.

Amy Hammett serves as the Director of Regional and National Collaborations for the Alabama Water Institute (AWI), which is developing a Technology Innovation District with a water tech accelerator and a National Water Training Center in partnership with USGS. AWI promotes water research in areas of remote sensing, biodiversity of aquatic systems, water quality, water and wastewater treatment, groundwater assessment, flood and drought forecasting, hydro-informatics, and disaster planning and management. During this session she will provide an overview of the many water-related programs and projects going at The University of Alabama, including CIROH, the Cooperative Institute for Research to Operations in Hydrology, a partnership between NOAA and the University of Alabama.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Nelson A.

In the Mississippi Delta region, tailwater recovery (TWR) systems are an important best management practice to address both water quality and quantity issues. TWRs are surface water capture and irrigation reuse systems, using a combination of a ditch to capture surface water, an on-farm storage (OFS) reservoir to store captured surface water, and pumps to move surface water from the ditch into the OFS reservoir and to irrigate nearby fields. To determine if TWR systems are an effective way to reduce groundwater use, a ditch-only TWR system in Sunflower County, MS has been equipped with velocity and flow meters, auto-samplers, level loggers, and rain gauges. The objective of this long-term study is to determine a fully measured water budget for a closed TWR system. This is the first year of the study and an analysis of select storm events will be discussed.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Simek V., Joeksema J., Taylor J.

The global human population continues to grow exponentially, and agriculture will need to become more productive to meet growing food demands. Humans also need clean water and other services that ecosystems provide. This requires future agriculture production to reduce environmental and wildlife impacts through improved efficiencies and best management practices. Migratory shorebirds rely on wetlands throughout North and South America as stopover habitat for rest and refueling during migration. Temporarily flooded farmlands in the Mississippi Delta have proven to be beneficial locations for shorebirds during migrations along the central flyway. This conservation practice also enhances wetland properties that promote excess nitrogen (N) retention or removal. However, little research has been conducted to evaluate how shorebird activity influences N cycling in these temporary wetland habitats on agricultural lands. Shorebirds potentially influence N cycling through several pathways including top-down control of sediment properties via movement and foraging as well as bottom-up processes by recycling nutrients via the deposit of fecal matter. The proposed study will investigate the influence of migratory shorebirds on N cycling in fallow agricultural fields flooded for migratory habitat. We will collect soil cores from plots that either exclude or allow access to shorebirds to assess bird effects on soil properties and invertebrate biomass, as well as different N cycling processes including denitrification and N uptake. Nitrogen cycling processes will be measured using intact sediment core incubations coupled with dissolved inorganic nitrogen (DIN) and dinitrogen (N2) gas measurements. Results from the proposed experiment will provide a better understanding of how interactions between wildlife and habitat created through best management practices may enhance ecosystem services in managed agroecosystems.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Grala K., Cartwright J.

Coastal infrastructure systems experience severe impacts due to high tide flooding, storm surge, and reoccurring extreme weather events. Geospatial technologies are commonly used to assess the severity of these impacts. However, the selection of custom-made geospatial tools that would allow decision-makers to produce rapid assessments of these impacts is limited. This is particularly true for tools supporting adaptive management decisions that must account for unknown factors when evaluating critical infrastructure systems such as roads, powerlines, and wastewater disposal sites. We used Geographic Information Systems to improve data analysis and assess current and future threats related to the projected sea level rise (SLR) scenarios. This presentation highlights the work of two geospatial efforts for the infrastructure assessments at both the regional and local scales. These efforts include a multistate vulnerability assessment of the SLR impacts on transportation infrastructure and a local-level analysis of on-site wastewater disposal systems. Methodologies for these projects are based on geospatial science and consider spatial relationships between the SLR layers and different segments of infrastructure systems. The results are disseminated via interactive web-based applications (maps and dashboards) to help identify the most vulnerable coastal communities. These efforts produced geospatial tools to automate assessments of the projected SLR scenarios and data extraction across multiple layers. Decision-makers can use the developed tools to augment their decision-making processes and find better adaptive management solutions to ensure that the coastal communities are more resilient to potential SLR impacts.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Alim M.S., Mamud M.L., Holt R.M., Wodajo L.T., Hickey C.J., O'Reilly A.M., Samad M.A.

Goodwin Creek is located in the northwestern part of the Yocona Watershed (Panola County, Mississippi) where the Sparta Sand aquifer outcrops. The creek is a tributary of the Yocona River, which flows into the Yazoo River which is a tributary of the Mississippi River. Surface and internal soil erosion are very common problems near the creek due to the surface runoff and groundwater flow. This soil erosion generates soil pipes that collapse and gullies that directly affect the agricultural fields and the pasturelands. To monitor groundwater flow in the unsaturated and saturated zones and to understand surface-groundwater interaction, multidisciplinary geophysical and hydrogeological research is being conducted at Goodwin Creek. An electrical resistivity tomography (ERT) survey was carried out at the study site to map the underlying aquifer, characterize its heterogeneity, estimate drilling depths for proposed monitoring wells, and propose an optimal location for a groundwater extraction well. A 501-m long ERT profile with 3 m electrode spacing was acquired using a mixed dipole-dipole and strong gradient array, starting at the northwestern bank of Goodwin Creek and towards the pastureland. ERT results demonstrate that the aquifer is relatively thin (<10 m) near the creek and thicker (>30 m) under the pastureland. The aquifer outcrops over a short distance (<10 m) in the pastureland but is confined on both sides of the outcrop. Disturbed and undisturbed soil samples were collected down to 1.5 m at multiple locations along the ERT profile. Soil samples collected at the outcrop location are composed of sand and gravel which is consistent with the high resistivity values on the ERT tomograms. Soil samples collected away from the outcrop consisted of clayey soil consistent with low electrical resistivity values from the ERT survey. The underlying aquifer is delineated assuming a threshold value for the resistivity of non-aquifer materials. The aquifer map is used to determine the drilling depths for monitoring wells and provide a recommendation of an optimal location for installing an extraction well.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Abdallah-Ruiz A., Anderson J.F., Bond R.F., Atwill E.R., Silva J.L.

The proposed US FDA water rule subpart under the Produce safety Rule of FSMA will require an annual assessment of the agricultural water system of covered farms by the grower or other party to identify, evaluate the risks associated with their water system, and develop mitigation strategies to minimize water contamination. The assessment should include evaluation of the location and nature of the water source, water distribution system, type of application method for water, and the time between the last direct application and harvest, and degree of protection of the system from contamination. The latter includes assessing the impact of other users of the water system, animal impacts, adjacent and nearby land uses, and any other factors. The UC Davis Western Center for Food Safety developed an assessment tool which has been modified to the region's reality with the aid of Mississippi State University. In addition, the US FDA developed an online/offline water system assessment. We will also discuss the application of these tools in a pilot study in a small, exempted (from the rule) farm in Mississippi.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Yang Y., Anderson M., Hain C.

The Lower Mississippi Alluvial Plain (LMAP) is one of the most productive regions in the United States, with large area of corn, soybean, rice and cotton planted. Associated with the intensified agricultural activities, this region has been experiencing a rapid decrease of ground water table that can threaten the sustainability of water supply and this condition may get worse under the changing climate. To solve the issue with groundwater depletion, it is critical to understand how the irrigation water is currently used by various crop types and different fields. Evapotranspiration (ET) represents the land surface water use and is a key parameter in the hydrological cycle. Field-scale ET retrieved from satellite data has been heavily evaluated by comparing with flux tower observations and proved to be efficient for agriculture management impact study, crop water use accounting, crop yield estimation, and irrigation scheduling. This work will assess ET in the LMAP region at field scale to provide critical local water use information for improved agriculture and water resource management. The energy balance model based on remotely sensed data will be used to estimate field-scale daily ET with key inputs from Landsat 8 and Landsat 9 from NASA. Through the OpenET project, with six widely used ET models implemented into Google Earth Engine to leverage the strong cloud computational power, field-scale large area ET over the LMAP region will be estimated. This work will help to address the challenge of water resource sustainability under the changing climate over the environmental vulnerable area.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Venishetty V., Parajuli P.B.

Water quality due to anthropogenic change of land use and land cover (LULC) had been the major factors for impairment. Developing a critical understanding in hydrologic and water quality outputs with change in LULC is essential. Therefore the main objective of this study is to assess the effect of LULC change on surface water quality in Yazoo River Basin (YRB). YRB is the largest watershed in the state of Mississippi, spanning over an area of about 50,000 Km2, with varied land-use conditions, quantifying the change in LULC through in-situ methods was not practical. Soil and Water Assessment Tool (SWAT) a GIS based modelling application was used in this study. LULC layers had been obtained from 2002 to 2019 for Mississippi, were used to simulate streamflow, sediment, total Nitrogen (TN) and total Phosphorus (TP). Model performance was good and satisfactory in predicting hydrologic and water quality outputs respectively. Significant LULC change had been observed for Pasture, forests, and wetlands. There was a decrease in pastureland, from about 39% in 2002 to 7% in 2019. Alternatively, increase in forest land was observed from 2002 to 2019 from about 15% to 30% and increase in wetlands from about 1% to 15%. With increase in vegetation, a decreasing trend had been observed in flow, sediment, and nutrient loads; from 2002 to 2019. Therefore, results from this study proves that there is significant impact on water quality and quantity with temporal LULC change. LULC change at watershed scale for YRB had never been conducted before, hence this study could be a novel addition that could help in optimal use of natural resources and improve water quality.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Rodgers K.

The U.S. Geological Survey in cooperation with the Gulf Coast Ecosystem Restoration Council and the U.S. EPA are collaborating to assess the climatic, physiographic, and anthropogenic factors driving spatial variability and temporal trends in the freshwater delivery to the Gulf of Mexico. The timing and magnitude of freshwater delivery influences terrestrial and aquatic communities, changing community composition and altering habitats necessary to support indigenous life. The 9-year, 8.9 million dollar projects examine multiple aspects of streamflow including streamflow trends, alteration of flow, lowflow statistics, and flow-ecology relationships in the southeast United States. Data produced as part of the Baseline Flow study is served on the RESTORE Data Visualization tool which utilizes modern web technologies and numerous free and open-source software (FOSS) libraries to provide user with an engaging experience through a high degree of interactivity and responsiveness. The web application provides a map-based interface for viewing spatial patterns of basin characteristics, streamflow statistics, and various metrics of flow alteration across the Gulf Coast region.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Hicks M., Taylor J., Devilbiss S.

Large alluvial plain landscapes, such as the Mississippi Alluvial Plain (MAP) ecoregion, are some of the most agriculturally productive lands in the world but often have modified stream ecosystems due to cultivation history. This context requires consideration when establishing water quality management goals and expectations. We analyzed state water quality databases to demonstrate MAP streams are distinct from streams in other ecoregions of Mississippi. Streams in the MAP have elevated alkalinity, specific conductivity, and nutrients and lower macroinvertebrate diversity compared to streams in other ecoregions. Our results also suggest that water-quality between MAP-confined drainages and MAP-Mississippi Valley Loess Plain drainages differs substantially and should be considered when setting water quality goals and expectations for streams in the MAP. We also explored whether the use of threshold indicator taxa analysis (TITAN) could effectively be used to assess the biological health of the study drainages. Our results from TITAN suggest that macroinvertebrate taxa responses in MAP streams occurred at higher concentrations of alkalinity, total organic carbon, and total phosphorus in comparison to other ecoregions in Mississippi. In addition, many indicator taxa identified by TITAN were only responsive in MAP streams suggesting that biological responses in the MAP are driven by unique taxa that respond to water-quality gradients at higher levels as compared to other ecoregions. We establish the potential for a taxa-based approach to provide a tool for guiding and monitoring success of nutrient reduction efforts in MAP watersheds and other alluvial plain agroecosystems where local and regional taxa pools are less diverse and may not support full recovery of ecological assemblages.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Heintzman L., McIntyre N.

Established by Jeffersonian Era laws, 16th Section Lands of Mississippi are protected areas that often contain aquatic resources. Historically, these areas were subject to diverse policy, market, and environmental controls; as a consequence, their current agroecological and regulatory patterns are diverse. Land use/land cover (LULC) patterns associated with this diversity are known to influence aquatic resource planning in other protected areas. However, very few studies have examined agroecological and regulatory patterns within 16th Section Lands of Mississippi, and for the few studies that do exist, their foci were forestry or educational caselaw. Even fewer studies have focused on 16th Section Lands of the Yazoo-Mississippi Delta (YMD), and to our knowledge, none have documented spatiotemporal fluctuations in land use/land cover at the landscape scale. This lack of knowledge may hinder enforcement of permitted activities, reduce efficacy of irrigation/groundwater managements, and stymie regional conservation initiatives. Currently, the Mississippi Department of State has administrative oversight of 16th Section Lands, but the lands are managed by local school districts on a parcel basis. Parcels within 16th Section Lands of Mississippi are classified into nine possible categories, each with distinct LULC regulations (permitted activities). Modern leases are subject to decadal evaluation, yet legacy arrangements and indeterminate records complicate educational funding and aquatic resource planning. Therefore, to address coupled scientific and social concerns, we documented landscape changes within 16th Section Lands of the YMD from 2008-2021. We documented dynamics of six socio-ecologically relevant LULC attributes for 16th Section Lands of the YMD: proportionality, variety, baseline stability, sequential stability, embedded parcels counts, and mean rent. We mapped unique patterns among each of the six LULC attributes and identified their subsequent distributions of "hot spot neighborhoods" and "cold spot neighborhoods" Overall, however, wetlands and urban areas featured highest stability, whereas cropped areas had highest mean rents. These results showcase heterogeneity among agroecological and regulatory perspectives for the 103 local school districts that either manage or receive income from 16th Section Lands

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Schmid S., Turnage G., Ervin G.

Alligator weed (Alternanthera philoxeroides) was first introduced into the United States in 1897 from Argentina and has since become a widespread invasive species that threatens global water resources. In infested systems, alligator weed can form dense mats that displace native plants and interfere with natural ecosystem processes. Alligator weed has been a persistent problem in Mississippi and is the most commonly surveyed aquatic plant in the state. Foliar herbicide applications are commonplace for reducing alligator weed biomass, and although the plant has shown high susceptibility to these methods, its extensive stolon network facilitates robust and rapid regrowth. However, many herbicides labeled for use in aquatics can be applied directly to the water column as a submersed injection; this method allows herbicides to be taken up by roots rather than foliage and may provide more efficacious biomass reduction than foliar herbicide applications. For this study, we compared the efficacy of five herbicides (bispyribac-sodium, fluridone, imazamox, penoxsulam, and topramezone) applied as submersed injections at maximum and half-maximum label rates to reduce alligator weed grown in outdoor and greenhouse mesocosms. Our results identify multiple highly successful control methods to be tested on field populations of alligator weed and tested as part of an integrated control strategy. Aside from chemical control, the alligator weed flea beetle (Agasicles hygrophila) has been used as a biocontrol agent in the U.S. but it is very intolerant to cold climates. Therefore, a secondary biocontrol agent, the alligator weed thrips (Amynothrips andersoni), may be of use as part of an integrated control strategy as it is more cold tolerant. However, research on the thrips is diminutive compared to the flea beetle. Our future work will assess these chemical control strategies integrated with alligator weed thrips with a goal of developing an effective integrated pest management plan for alligator weed in Mississippi.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Bhattarai S., Parajuli P.B., To F.

In this study, the variation in streamflow due to climate change was assessed at two coastal watersheds: Wolf River Watershed (WRW) and Jourdan River Watershed (JRW) of Mississippi. The Soil and Water Assessment Tool (SWAT) model was used to simulate the hydrology of WRW and JRW. Further, the flood frequency of the simulated peak flow events was analyzed. The baseline models for both watersheds were auto-calibrated with SWAT-Calibration and Uncertainty Programs (SWAT-CUP). Kling-Gupta Efficiency (KGE) ranges from 0.8 to 0.7 in WRW and from 0.55 to 0.68 in JRW during model calibration-validation. Results in WRW indicated that the monthly average baseline flow was 1% greater than historical and 8.88% less than future climate. Likewise, monthly average baseline flow was 10.9% greater than historical and 5.73% less than future climate in JRW. Annual maximum series and partial distribution series of all climatic conditions were fitted to Log-Pearson Type-III distribution to analyze and compare flood frequency. Thus, this study could support watershed managers and planners to prepare for flood occurrence likelihood in the future.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Benthota Pathiranage W., Surbeck C.

A stormwater detention basin is designed for the mitigation of possible hazards from stormwater runoff like flooding and erosion by temporally storing the excess runoff water and releasing it at a more controlled speed. The detention basin in front of the Robert C. Khayat Law Center, University of Mississippi, also has been designed for the same purpose. This detention basin was recently converted into a bio-infiltration basin with dry wells and cypress trees to further reduce stormwater runoff and pollution to receiving water bodies. Dry wells are used to increase the overall infiltration volume of the stormwater runoff. This can be specifically called a 'bio-infiltration basin' because the vegetation is used to help regulate the water content of the soil and intercept the rainwater. Five cypress trees have been planted in the detention basin. It was hypothesized that the quality of the water leaving the detention basin would be improved compared to the water entering it once it was converted to a bio-infiltration basin. The quality of the runoff water in the basin was evaluated in terms of total coliforms, E. coli, inorganic metals and suspended solid concentration based on the samples collected before and after the conversion into the bio-infiltration basin. Data collected since the basin conversion are not quantitatively enough to support or reject the project hypothesis. Still, the bio-infiltration basin is in its initial stage. This presentation reports on the test results that belong to the samples collected before and soon after the conversion to the bio-infiltration basin. It will take time for the plants' roots to grow and develop the tree canopy for a better infiltration performance. So, this is a continuous project that expects to collect more water quality data to investigate whether the infiltration mechanisms would really improve the quality of the stormwater runoff. It is recommended to test more water quality parameters that are influential to human health and aquatic ecosystems of the receiving water bodies.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Turnage G., Thompson W.

Alligatorweed (Alternanthera philoxeroides) is the most widespread aquatic weed in Mississippi. Alligatorweed is capable of growing in aquatic, wetland, and terrestrial sites and switches growth form from a rhizomatous mat forming plant (aquatic) to a prostrate growth form with tap roots (terrestrial) which allows it to survive stressors such as drawdown or drought. Much is known regarding the impacts and control of alligatorweed in aquatic sites, however, less is known regarding control of alligatorweed in terrestrial sites. Muscadine Farms Wildlife Management Area (WMA) is a series of 90 ponds (each 6.1-8.1 hectares in size) that covers approximately 809 ha in the Mississippi flyway in western Mississippi; the WMA is primarily managed for waterfowl habitat. The terrestrial form of alligatorweed has infested many ponds in the WMA and displaced desirable vegetation utilized as waterfowl forage. In 2022, an herbicide trial was conducted and repeated two weeks later to assess the reduction of alligatorweed at Muscadine Farms by herbicides utilized for operational control of alligatorweed as well as newer herbicides labeled for use in aquatics in the last two decades. Herbicides were applied to 83.6 m-2 (9.1 by 9.1 m) plots at Muscadine Farms. High and low rates of imazapyr (8.2 and 4.1 kg a.e. ha-1), bispyribac-sodium (0.11 and 0.055 kg a.i. ha-1), topramezone (11.4 and 5.7 kg a.e. ha-1), florpyrauxifen-benzyl (0.02 and 0.01 kg a.i. ha-1), and fluridone (10.9 and 5.4 kg a.i./ha-1) were tested as stand-alone foliar herbicide treatments. Glyphosate (11.0 kg a.i. ha-1), triclopyr (11.7 kg a.e. ha-1), metsulfuron-methyl (0.036 kg a.i. ha-1), and two-way tank mixes of the three were also tested as foliar treatments. All herbicide applications included a 0.5% v:v MSO surfactant and were applied at a 467.7 L ha-1 (50 gal ac-1) diluent rate. Each treatment was replicated four times. This is the first report of alligatorweed control by bispyribac-sodium (88 to 94% reduction), topramezone (76% reduction), florpyrauxifen-benzyl (85% reduction), or fluridone (76 to 93% reduction) suggesting that these herbicides may provide another alligatorweed control option for resource managers. A follow up trial found that disking or mowing alone provided 99 and 72% reduction (respectively) of alligatorweed biomass suggesting these may be suitable non-chemical control techniques for alligatorweed in terrestrial systems.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Kovvuri N.R., Feng G., Bi G., Tewole H., Shankle M.

Conservation cropping systems followed with sustainable management practices have many benefits, such as water use efficiency and infiltration. To improve the soil hydraulic function, several management practices can be adapted, which can restore soil health and prevent water erosion. Integration of cover crops and application of poultry litter is identified as the most commonly used management practices for improving soil health and crop productivity. This study was conducted at the Pontotoc Ridge-Flatwoods Branch Experiment Station with five cover crop treatments to understand the influence of different cover crops like the winter wheat, cereal rye, vetch, cereal rye combined with mustard, and native vegetation on soil hydraulic properties and water quality that can impact the crop yield. For this study, core soil sampling was done after the harvest of the cash crop. Data collection included soil hydraulic and physical properties, such as water-stable aggregates, bulk density, available water content, and saturated hydraulic conductivity, which have been measured after five years of cover crop and poultry litter treatments. The results indicated that the integration of cover crops showed little effect on the soil properties as compared to no cover crop treatment. Data on soil properties were subjected to analysis of variance to assess the effects of cover crops and poultry litter on soil hydraulic responses. There was a significant difference between the fertilizer treatments, and the plots applied with poultry litter performed well at p < 0.05, indicating high infiltration and less bulk density as compared to inorganic fertilizer and no fertilizer treatments. However, the asserted influence of the combined effect of poultry litter and cover crops on soil hydraulic and physical properties is largely unknown.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Roberts C., Gholson D., Locke M., Spencer D., Quintana N.

Improved cropping systems are needed to reduce irrigation water use of cotton where irrigation water is drawn from the declining Mississippi River Valley Alluvial Aquifer. A study conducted in Stoneville, MS, from 2021 to 2023 is assessing viable cropping systems for the mid-south to conserve irrigation water. Study treatments were established in the fall of 2020 and include reduced tillage, subsoil, winter fallow (RT); strip till, winter fallow; strip till, cover crop; strip till, subsoil, cover crop; no till, winter fallow; no till, cover crop; and no till, minimal surface disturbance subsoil, cover crop. Each treatment was individually irrigated based on tension-based soil moisture status. In the first year of full study implementation (2021), high amounts of timely rainfall made irrigation unneeded. In 2022 precipitation was closer to normal. Cover crops improved soil moisture by as much as 47 kPa compared to the conventional, RT treatment. Compared to all winter fallow treatments, the treatments with a cover crop retained more soil moisture with soil moisture tension being 57% lower. This resulted in more irrigation water used in treatments with winter fallow. There were few differences in lint yield between the treatments, and yields were not improved by increased irrigation. Cover crops can be used to conserve water in cotton without reducing yield in the mid-south during years with normal precipitation.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Roberts C., Gholson D., Locke M., Spencer D., Steinriede R.W.

Improved cropping systems are needed to reduce irrigation water use of cotton where irrigation water is drawn from the declining Mississippi River Valley Alluvial Aquifer. A study conducted in Stoneville, MS, from 2021 to 2023 is assessing viable cropping systems for the mid-south to conserve irrigation water. Study treatments were established in the fall of 2020 and include reduced tillage, subsoil, winter fallow (RT); strip till, winter fallow; strip till, cover crop; strip till, subsoil, cover crop; no till, winter fallow; no till, cover crop; and no till, minimal surface disturbance subsoil, cover crop. Each treatment was individually irrigated based on tension-based soil moisture status. In the first year of full study implementation (2021), high amounts of timely rainfall made irrigation unneeded. Lint yield during that year was decreased in no-till treatments by up to 16% (1382 kg ha-1) compared to conventional reduced tillage (1647 kg ha-1). In 2022 precipitation was closer to normal. Cover crops improved soil moisture by as much as 47 kPa compared to the conventional, RT treatment. Compared to all winter fallow treatments, the treatments with a cover crop retained more soil moisture with soil moisture tension being 57% lower. This resulted in more irrigation water used in treatments with winter fallow. There were few differences in lint yield between the treatments, and yields were not improved by increased irrigation. Cover crops can be used to conserve water in cotton without reducing yield in years with normal precipitation.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Lizotte R.

Intensive row-crop agriculture in the Mississippi Delta has increased eutrophication and cyanobacteria blooms in freshwater systems in western Mississippi. Two study lakes, Beasley Lake and Roundaway Lake, are shallow riverine lakes influenced by agricultural activity typically found in the Mississippi Delta. During 2018, both lakes were monitored for nutrients and cyanobacteria (measured as phycocyanin concentration). Both monitored lakes indicated eutrophic to hypereutrophic conditions. Total nitrogen (TN) ranged from 0.7 to 2.1 mg/L (average: 1.3 mg/L) and 1.1 to 3.6 mg/L (average: 1.8 mg/L) in Beasley and Roundaway, respectively. Total phosphorus (TP) ranged from 0.05 to 0.49 mg/L (average: 0.18 mg/L) and 0.08 to 0.46 mg/L (average: 0.22 mg/L) in Beasley and Roundaway, respectively. Cyanobacteria blooms ranged from 5 (March) to 112 (June) µg phycocyanin/L and 4 (April) to 210 (June) µg phycocyanin/L in Beasley and Roundaway, respectively. Cyanobacteria nutrient limitation was assessed during summer and fall (June-November 2018). Cyanobacteria nutrient sensitivity was measured in October 2018 when ambient nutrient concentrations were lowest to ascertain nutrient concentrations eliciting cyanobacteria blooms. Results indicate that summer and fall cyanobacteria biomass were primarily nitrogen + phosphorus co-limited in both lakes. Nutrient sensitivities indicated that lake cyanobacteria blooms occurred when: NO3-N > 0.15 to 0.28 mg/L; TN > 0.38 to 0.48 mg/L; PO4-3 > 0.03 to 0.06 mg/L; and TP > 0.04 to 0.07 mg/L. Regression analysis showed that summer to fall increased lake cyanobacteria nitrogen + phosphorus co-limitation responses occurred with elevated PO4-3 and decreased NH4-N during summer and fall (adjusted R2 0.42, p = 0.036, N = 12). Monitored Roundaway Lake summer to fall cyanobacteria biomass increased with elevated TN and decreased NO3-N (adjusted R2 0.82, p < 0.001, N = 14). Monitored Beasley Lake summer to fall cyanobacteria biomass increased with elevated NH4-N and decreased NO3-N (adjusted R2 0.45, p = 0.021, N = 13). This study provides insight and understanding of necessary nutrient controls to better manage and mitigate cyanobacteria blooms and improve water quality in Mississippi Delta agricultural lake watersheds.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Smyly A., Gholson D., Bond J., Bowman H., Bryant C.

Rice (Oryza sativa L.) is one of the most water demanding crops in the Southern United States due to rice typically being grown using a continuous flood production system. Mississippi River Valley alluvial aquifer (MRVAA) serves as a major irrigation water delivery source for rice farmers in the Mississippi Delta. Irrigation water is extensively withdrawn from the MRVAA, and the aquifer is beginning to deplete. Determining an efficient rice irrigation approach is vital to prolong the usage of the aquifer for agricultural needs. Research in Mississippi has shown furrow-irrigated rice (FIR) to produce rice with less water, but there is limited information on proper irrigation and fertilization strategies in FIR. This study was conducted to determine an irrigation management plan in FIR by evaluating rice response to different irrigation frequencies. Research was conducted at the Delta Research and Extension Center in Stoneville, MS on Sharkey clay soil in 2021 and 2022. Four irrigation frequencies (irrigating every day, every 3, 5, and 7 days) replicated three times were arranged using a randomized complete block design. WaterMark® Soil Moisture Sensors®, Pani-Pipes®, Precision King AgSense Sensors®, and flowmeters were used to collect soil moisture, water depth levels, and water usage data from each plot before and after every irrigation occurrence. Rice grain yield was determined for each treatment plot and zones within each plot. On average, irrigation plots in 2021 resulted in greater yields for plots irrigated every day, no difference in yields for plots irrigated every 3 or 5 days, and lower yields for plots irrigated every 7 days. However, 2022 yield data indicated no difference in yield across irrigated frequencies. In 2021, no difference was found in the combined average yield for all treatments between top, middle, and bottom zones. In 2022, top zone average yields were significantly greater from bottom zone average yields, but no difference was seen when compared to middle zone average yields. This research study will be conducted again in 2023.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Zhang Y., Al-Hamdan M., Bingner R., Wren D.

The Sediment transport, defined as sediment driven by water and moving in water, is one of the most important processes when studying morphological and environmental problems. Sediment transport may result in sediment deposition in lakes, reservoirs and coastal wetlands; erosions along riverbanks, coastal lines, and at downstream of dams; local scour downstream of hydraulic structures; gully erosion in agricultural lands; channel evolution; adsorption/de-adsorption and resuspension, etc. In addition to conventional physical models, with the advancement of computer technology and numerical methods, numerical models have become powerful tools to study sediment transport in water bodies such as rivers, lakes, reservoirs, and coastlines. This paper presents the development of a two-dimensional hydrodynamic sediment transport model. The model is a single-phase, non-equilibrium, and non-uniform sediment transport model for unsteady turbulent flows, considering multiple sediment transport processes, such as deposition, erosion, transportation, and bed sorting. The governing equations for the flow and the sediment transport are discretized on an unstructured hybrid mesh system consisting of triangle and quadrilateral cells, which is more suitable for geometrically complex domains with higher adaptivity compared to the structured mesh system. Selected examples and applications will be used to demonstrate and validate the newly-developed sediment transport model

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Ellepola A., Yarbrough L., Ghaffari Z., Easson G., Yasarer H.

Satellite imagery has become an increasingly valuable tool for watershed management. Remote sensing systems such as multispectral and radar imaging can provide detailed information about soil moisture levels, vegetation cover, and topography. These data can be used to identify areas of high soil moisture, monitor changes in soil moisture over time, and assess the impact of human activities on watersheds. A commonly used system in orbit for monitoring soil moisture is the Soil Moisture Active Passive Mission (SMAP). For SMAP, and all spaceborne systems, one of the major limitations for users to implement satellite-based data is the extreme coarseness of the pixel (~9 km). This talk presents an overview of a machine learning technique that is currently being used in soil moisture monitoring and watershed management in north Mississippi.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Bhattarai S., Parajuli P.

Best management practices (BMPs) are implemented in coastal plains to reduce sediment and nutrient loss. This study assessed the effectiveness of BMPs in two coastal watersheds: Wolf River Watershed (WRW) and Jourdan River Watershed (JRW), using the Soil and Water Assessment Tool (SWAT) model. The coefficient of determination (R2) and Nash-Sutcliffe Efficiency (NSE) were used to evaluate the model performance. Effectiveness of impoundments and buffer were analyzed after successful model calibration-validation. Ponds reduced up to 75% Total Suspended Solids (TSS), 12% of Mineral Phosphorous (MinP), and wetlands reduced up to 75% of TSS, and 13% of MinP. The highest reduction of TSS and MinP was achieved by 30 m buffer in both watersheds. Furthermore, combined BMP reduced TSS by 30% and MinP by 52% in WRW, whereas TSS was reduced by 75% and MinP was reduced by 27% in JRW. Impoundments were more effective in reducing TSS and buffer were more effective in reducing MinP. This study demonstrated the effectiveness of BMPs in reducing TSS and MinP loss from coastal watersheds.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Russell D., Gholson D.

Prior research has shown that implementing irrigation water management practices can reduce total water applied while maintaining or improving crop yield and profitability. However, to effectively utilize these proven practices, a complex understanding of the soil-water-crop dynamics and the irrigation scheduling tools and technologies is required. Modeled after the award-winning Master Irrigator Program from the North Plains Groundwater Conservation District in Dumas, Texas, the Mississippi Master Irrigator Program is designed to educate producers on soil health, agronomics, irrigation scheduling, irrigation systems and equipment maintenance, the economics of irrigated agriculture, and policy and management. This course will be delivered through a hybrid approach consisting of online modules and in-person training and demonstration activities. The course is also designed to facilitate peer-to-peer engagement and to inform producers of the numerous resources available to them. Instructors for the online modules and in-person training events will be MSU Extension Specialists, as well as other individuals/entities with specialized experience in each of the program topics. Once the online modules are complete, the online portion of the course will be available for registration. Participants will be required to complete prerequisite modules to be eligible for the in-person training. This presentation will focus on the development and implantation of a new Extension education program designed to equip producers with the knowledge they need to make the right irrigation water management decisions that improve soil health, water use efficiency and conservation, and profitability on their operation.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Green Z., Tagert M.L., Paz J., Lo T.

Mississippi's average annual precipitation is approximately 127 cm, of which 70% occurs in the winter and spring months outside of the growing season. Accordingly, an increasing number of on farm water storage (OFWS) systems have been built in northeast Mississippi in recent years. These systems capture and store off-season precipitation and runoff that can later be used for irrigation. With limited rainfall during the growing season, farmers solely dependent on surface water have a finite amount of water to use for irrigation through the growing season and therefore must irrigate efficiently. This study evaluates the costs and benefits of sector control variable rate irrigation (VRI) on an 18-hectare corn and soybean production field under sprinkler irrigation in Noxubee County. During the 2022 growing season, corn was planted on April 25 and harvested on August 20. Elevation, yield, and soil moisture data collected from 2018-2021 were analyzed in Esri's ArcMap software, and two irrigation management zones were created in the field. A soils layer was not included in this geospatial analysis because previous gridded soil sampling confirmed a homogeneous soil type of silty clay loam with small areas of silt loam. A 'dry' irrigation management zone was placed in the southern section of the field, and a 'wet' irrigation management zone was placed in the northwestern section of the field. Each management zone is approximately one quarter of the area under the center pivot. Each zone was then sub-divided into six different pie-shaped sectors. The three control sectors received 1.9 cm of water, which was the conventional amount of irrigation applied by the farmer. The other three test sectors received 1.5 cm of water, which was a 20% reduction from the conventional amount. The center pivot is equipped with a Linsdsay Growsmart IM3000 magnetic flow meter to measure water use. Two sets of Watermark 200SS granular matrix soil moisture sensors were placed in the centroid of each sector at depths of 30 and 61 cm to measure soil water tension throughout the growing season, and sensors were removed just before harvest. Yield data was recently obtained from the farmer, and soil tension data is currently being analyzed with yield data to determine if water savings were realized without a loss in yield. This presentation will include preliminary results from this multi-year study.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Heintzman L., McIntrye N.

Industrial agricultural systems are subject to land use/land cover (LULC) changes via field rotation. These pattern changes may consequently influence a diversity of embedded ecological processes. Even though wetlands—which are integral components of, and provide interfaces for, ecosystem services—are not directly subject to crop rotation, their structure (and, thus, function) may be shaped by LULC changes. Among the most productive North American agroecosystems, the Yazoo-Mississippi Delta (colloquially, "The Delta") exemplifies the challenges faced by these areas with dual aquatic and terrestrial status within mosaics of land ownership and legal protections. Although historical LULC within The Delta is well-documented, few studies have examined contemporary field rotation patterns and corresponding LULC effects on wetlands. To address this gap, we used NASS Cropland Data Layers from 2008–2021 to quantify LULC change around 43,524 wetland features in The Delta. We initially reclassified >35 LULC classes in the NASS data to nine mutually exclusive LULC types. We then identified 43,524 features which had been classified as wetlands during all focal years. For each of those wetland features, we buffered by 90m and grouped these results into four buffer size categories (small [x < 3.63 ha], medium [3.63 ha < x < 4.17 ha], large [4.17 ha < x < 9.25 ha], and extra-large [x > 9.25 ha]). We quantified LULC change within buffers of each wetland feature on a pixel-by-pixel basis, measuring LULC variety, majority LULC type, minority LULC type, and LULC stability (relative to baseline data from 2008). Overall, our results indicated that wetlands were dispersed throughout The Delta, with highest concentrations in Bolivar, Leflore, Sunflower, and Washington counties. LULC variety and stability were positively associated with spatial scale. Soybeans were the majority LULC type around wetlands at all spatial scales and years, indicating relative LULC stability around wetlands. LULC minority was other agriculture for medium, large, and extra-large categories. For the small category, LULC minority was wetlands- indicating isolation effects. Our study examined regional field rotation patterns and highlighted mixed management of wetlands in Delta agroecosystems. Our results indicate that wetlands of The Delta are especially subject to practices associated with soybeans. Our approach and results can be used to direct conservation efforts for ecosystem services and wetland resources. Additionally, our study augments emerging theory that dynamic landscape pattern management is necessary in industrial agricultural systems.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: O'Reilly A., Yarbrough L.

The Mississippi embayment aquifer system comprises six regional aquifers. The shallowest aquifer is the Mississippi River Valley alluvial aquifer (MRVAA), which is intensively pumped for agricultural irrigation in the Delta region of Mississippi. With long-term decreases in the water level and continuing groundwater withdrawals, long-term groundwater availability from the MRVAA is a concern. Thus, the U.S. Department of Agriculture, Agricultural Research Service, National Sedimentation Laboratory is implementing the Groundwater Transfer and Injection Pilot (GTIP) project to determine the effectiveness of using managed aquifer recharge (MAR) to support groundwater availability from the MRVAA in the Delta. The MAR technology being tested by the GTIP project uses source water obtained by riverbank filtration from the Tallahatchie River and transfers and injects the water into the MRVAA where water levels have declined. However, by inducing the infiltration of river water into the aquifer, the quality of the source water and groundwater must be examined. The water quality of the MRVAA in other locations has been previously reported, but these results do not reflect the water quality after transfer and injection. Thus, a new collection of chemical analysis is needed to determine the potential impact of groundwater transfer and injection on water quality. The water quality samples were collected at 17 observation wells, one extraction well, two injection wells, discharge pipe for injection well backflush water, three sites in Lake Henry and the river. For each collection site, values for pH, specific conductivity, temperature, and dissolved oxygen were also measured. One sampling event was conducted prior to operation in March 2021, and monthly sampling events were continued during two operational periods—April to July 2021 and February to August 2022—for a total of 13 sampling events. In 1978, the water quality of the MRVAA was analyzed in the Delta. These results showed that the groundwater had the following characteristics: a hard calcium bicarbonate type, dissolved iron concentration greater than 3 mg/L, elevated concentrations of manganese, and a range of dissolved solids concentrations (153-751 mg/L). Thus far, our sampling results have demonstrated the groundwater to be of calcium bicarbonate type in the MRVAA, with total iron and manganese concentrations exceeding 1.5 and 0.2 mg/L, respectively. Generally, the higher levels of iron in the MRVAA have occurred at observation wells west of the Tallahatchie River and northeast of Lake Henry. The total dissolved solids range from 86-622 mg/L. Variation of this range is presented in the observation wells. However, the lowest total dissolved solids are more prevalently identified at the Tallahatchie River and in Lake Henry at the sampling site where backflush water is discharged. Further work contributes to the understanding of natural and MAR induced evolution of water quality.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Samad M.A., Wodajo L.T., Rad P.B., Mamus M.L., Hickey C.J.

Soil erosion severely deteriorates agricultural fields by removing top fertile soil, increasing surface runoff, and reducing the soil's water-holding capacity. Increased loss of fertile agricultural land seriously threatens human habitat and livelihood, hampering agri-food production and impeding agricultural sustainability. Although soil erosion due to surficial processes (surface runoff, gully erosion, and channel erosion) is well-studied, contributions from subsurface processes such as internal soil pipes are difficult to study. As the diameter of a soil pipe increases over time, flute holes, sinkholes, and gullies develop and enhance soil erosion. Therefore, to implement early mitigation of soil erosion, it is essential to locate, map, and measure the extent of soil pipes in agricultural fields. The hidden and uncorrelated nature of soil pipes with surface features limits the applicability of remote sensing-based detection and mapping techniques. This study is conducted at a small area in Goodwin Creek Watershed, a site with established internal soil pipes, to test the applicability of two traditional geophysical methods, seismic refraction tomography (SRT), electrical resistivity tomography (ERT), and a new non-invasive acoustic method for mapping and tracking internal soil pipes. The geophysical and acoustic results were correlated with cone penetrologger (CPL) data to verify anomalies associated with internal soil pipes. The SRT indicated the location of internal soil pipe-affected zones with low seismic wave velocity anomalies. The ERT results indicated the location of soil pipe-affected zones with high resistivity anomalies. However, SRT and ERT lacked the resolution to identify individual soil pipes. The geophysical methods identified the fragipan layer that hinders the vertical flow, promotes the lateral flow of water, and accelerates the formation of soil pipes within the study area. The acoustic method identified five primary and eight secondary networks of soil pipes. Planting geophones at multiple locations, irrespective of source position, may provide the trajectory of soil pipes in the whole agricultural field.

This work was supported by the U.S. Department of Agriculture under Non-Assistance Cooperative Agreement 58-6060-6-009. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the U. S. Department of Agriculture.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Wodajo L., Buskes E., Mamud M.L., Hickey C.

Complex hydrogeological formations and high spatial variability due to various hydrogeological processes make groundwater exploration challenging. Geophysical methods can address the methodological need for groundwater mapping and identifying optimal locations for extraction. The University of Mississippi Field Station is a 740-acre lot owned by the University of Mississippi for ecological research. The University's Geology and Geological Engineering Department proposed a location to place a groundwater extraction well in the field station. This study is conducted to investigate if the proposed location is optimal for groundwater extraction and to test the capabilities of two ground-based electrical resistivity geophysical methods, electrical resistivity tomography (ERT) and vertical electrical sounding (VES), in mapping aquifers and providing actionable information. New and available well logs are used to identify the different soil layers and calibrate the geophysical results. The geophysical results and the well logs provided information that could be used to identify the location of the aquifer at that site. ERT results provided spatial images of the electrical resistivity distribution of the subsurface that filled in the information gap between adjacent boreholes. This study showed that the aquifer at the site changes from confined to unconfined over short distances. The original proposed well location is not optimal for groundwater extraction, and more suitable locations for well drilling are identified. This research is sponsored by the Mississippi Water Security Research Initiative Seed Grant provided by the Robert M. Hearin Support Foundation. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the sponsor's views.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Cartwright J., van der Zwaag J., Grala K.

The frequency of flooding events in coastal areas has been increasing for several decades. Current sea level rise projections for this century will make the extreme events of today the norm by 2100. As the frequency of these events increases so does the need for improved education and decision-making. Through the Geospatial Education and Outreach (GEO) Project, efforts have focused on the development of a suite of applications to simulate and visualize sea level rise. GeoCoast3D is an interactive web-based application that allows users to visualize inundation along the MS coast. Using routing analysis, users can visualize the impact of inundation on transportation and service areas for critical infrastructure. This provides them with an enhanced view of the dangers in relation to rising sea levels and hurricanes in coastal communities. The GeoLidar Viewer was created based on colorized LiDAR datasets combined with other layers, including 3D buildings, sea level rise extents, LiDAR-based elevation, and satellite imagery. These layers are displayed in a single interactive 3D scene that is publicly available online. Individual layers can be turned on and off to change the focus of the display to various landscape features. These efforts are being coupled with augmented and virtual reality for in situ 3D modeling of coastal flooding. GeoInundation uses detailed, realistic models generated from LiDAR data, satellite imagery, and site photos. GeoPanorama combines 360° panoramic photos with LiDAR data to create immersive, realistic virtual reality experiences. Both allow the user to simulate water surface height or select a predefined historical high water marker. GeoCoast AR (currently in beta development) allows users to increase and decrease simulated inundation levels on the actual landscape as they navigate the area through the camera on their mobile device.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Martins V., Sparks E., Aires U.R. V. ., Rogers A., Doan L.

Satellite imaging systems have been widely used to support water quality and quantity management as it allows water quality analysis using empirical and semi-analytical relationship between optically active constituents (e.g., sediments, chlorophyll-a, dissolved organic matter) and spectral water reflectance. NASA Landsat 8/9 OLI and ESA Sentinel-2 MSI are the most relevant medium spatial resolution data sources for water applications, and the data harmonization from both optical sensors into a single data set, a so-called "virtual constellation", creates an unpreceded opportunity with a repeat frequency of ~ 3 days on average, and higher probability to obtain a cloud-free mapping of water constituents than Landsat or Sentinel-2 alone. This study developed a harmonized Landsat-Sentinel-2 framework for turbidity retrieval in Mississippi Sound. Standard top-of-atmosphere Landsat 8/9 OLI and Sentinel 2A/B MSI imagery were acquired with cloud cover lower than 50%, and both imagery were integrated in the same tile grid area. Cloud and shadow pixels were derived from Fmask algorithm and filtered as no data. We applied "Dark Spectrum Fitting" approach for atmospheric correction, and satellite-based water reflectance was used to model the water turbidity with USGS turbidity records on the Mississippi Gulf coast. The mapping results illustrate the complex freshwater inflow along the Mississippi Sound caused by Bonnet Carré Spillway openings, located about 28 miles northwest of New Orleans, and highlight the abrupt water quality changes in the oyster habitat. We showed the satellite observations are useful to complement the spatiotemporal analysis of recent water quality changes in the coastal region.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Adele Bolaji B., Davidson G., Hossain M.R., Mamus M.L., Hickey C.J.

Over-drafting of regional aquifers such as the Mississippi Valley River alluvial aquifer (MRVA) has prompted a greater focus on methods of managed aquifer recharge. Previous work has demonstrated that oxbow lake-wetland systems on the floodplain of the Mississippi River can serve as significant sources of recharge, which could be enhanced by impounding water. Subsequent attention is needed on the potential ecological impacts of altering the natural hydroperiod. While it is typically assumed that flooding quickly results in anoxic soil conditions that diminish plant growth, some studies have reported increased in growth of wetland-adapted trees, such as bald cypress (Taxodium distichum), with increasing water level. A possible cause is a flux of oxygenated surface water through the root zone under greater vertical hydraulic gradients. Given the heterogeneous nature of forested wetland soils, caused in large part by buried decomposing tree remains, it is anticipated the soil redox response to rising water levels is highly variable, with the greatest increases corresponding to localized zones of higher permeability (preferential flow pathways). Preliminary data from redox and temperature probes deployed at two different elevations in the forested perimeter of Sky Lake, MS, are consistent with the hypothesis. Wet but aerated soils of some probes show rapid increases in redox potential following rainfall events, with smaller increases observed even if the soil is already saturated. Other probes indicate very little response, suggesting placement in zones of very low permeability. Under deeper water conditions, response to changes in water level and precipitation appear to be more complex.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Raczynski K., Dyer J.

Drought is a complex phenomenon that is difficult to predict due to the variety of associated environmental drivers; however, its cyclic reoccurrence provides a basis for time-scale pattern analysis. The time factor reflects a complex structure of meteorological, geological, and surface factors affecting the specific way that drought develops in each region. In terms of the precipitation to evaporation ratio, seasonal dry periods indicate a time of increased probability for hydrological drought to form; however, underground water inertia within a region might affect the process in the opposite way, depending on the aquifer stage and general impact on runoff. The combination of long- and short-term changes in runoff structure might provide valuable insights into drought risk assessment and, especially due to climate change, improve the recognition of temporal patterns of drought occurrence. The objective of this work is to apply the Harmonic Oscillator Seasonality-Trend (HOST) model framework to analysis of hydrologic drought patterns, using a simulated streamflow dataset covering the Southeast US. Daily flow data from the National Water Model retrospective dataset v.2.1 were used for the period Feb. 1979–Dec. 2020, which provides long-term simulated streamflow data at a high spatial resolution across the study region . Droughts are identified using an objective threshold approach and aggregated on monthly scales. The temporal changes are assessed by a set of superimposed harmonic functions calculated for decomposed time series, representing drought occurrences and minimal flows. The HOST model can capture and reflect drought patterns on both short- and long-term time scales, with the first reflecting annual precipitation patterns and the second occurring close to the El Nino-Southern Oscillation cycle. Input data are divided with a 70/30 split for training and testing, respectively. Results are evaluated using contingency statistics and indicate about 80% accuracy for trained models (with an IQR between 74% and 87%) and around 60% accuracy in testing sets (with an IQR between 47% and 76%). In terms of spatial distribution, areas in southern Mississippi and eastern South Carolina are identified as regions with extended function periods, indicating prolongation of dry conditions. The work presents an early stage of model software development and initial results, with current limitations identified and discussed.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Maierhofer M., Huff D.

Take a deep dive into water management and how it can work in southern and Mississippi Delta soils, specifically sub-surface drainage and sub-surface irrigation. Contrary to popular belief, pairing these practices together can play an integral role in enhancing your farming practices. This presentation will focus on how each practice can be implemented in different soil types and how a system is designed.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Hendon D.

Hydraulic modeling is the process of using a numerical model to simulate flow in the real-world. This presentation will focus on 1D and 2D hydraulic models, as well as touch on CFD and physical scale models. Their similarities, differences, numerical schemes, and appropriate applications for each will be discussed.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Nepal D., Parajuli P.B.

Ponds have the capacity to regulate and store water, helping to reduce the effects of droughts and floods. They can recharge groundwater aquifers and enhance water quality by capturing sediments and nutrients. This study aims to identify the ponds within Big Sunflower River Watershed (BSRW) using Google Earth Engine (GEE) and evaluate the effects of projected climate change on hydrological process in ponds using Soil and Water Assessment Tool (SWAT). The model was calibrated and validated against streamflow, groundwater level changes, and sediments with acceptable model accuracies. Downscaled future precipitation and temperature data were generated by using Climate Model data for hydrologic modeling (CMhyd) tool. The future climate scenario was generated for Representative Concentration Pathway (RCP) 8.5 of the global climate model Geophysical Fluid Dynamics Laboratory Earth System Model 2M (GFDL-ESM2M) for mid-century (2040-2060) and late century (2079-2099). In the mid-century, increase in the annual average maximum and minimum temperatures were observed by 6% and 13% respectively; whereas increase in the annual average precipitation were observed by 26% as compare to the baseline condition. Similarly, 15% and 28% rise in the annual average maximum and minimum temperatures along with a 24% increase in the annual average precipitation in the late century were observed as compared to the baseline. This study was expected to demonstrate that the ponds will be able to capture runoff, reduce erosion, and contribute to aquifers recharge. However, the results will also indicate that the effectiveness of ponds are impacted by changing climatic circumstances. The results of this study will be useful for the development of plans for managing and preserving the pond ecosystem in the face of climate change by enabling an understanding of the interaction between hydrology, land use and climate change.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Wu W., Feldpausch K.

Coastal wetlands are highly productive ecosystems that provide important ecosystem services and are threatened by extreme hydrological events. We evaluated how Bonnet Carré Spillway openings in Louisiana, US, affected vegetation productivity in coastal wetlands on the neighboring Mississippi Gulf Coast, US. Our study area is two estuarine systems that differ in their proximity to the Bonnet Carré Spillway, elevation, and salinity including Hancock County Marshes on the west, and Grand Bay National Estuarine Research Reserve (NERR) on the east in Mississippi. We collected above- and belowground biomass samples in 2020 and 2021, developed linear mixed-effects models to predict vegetation productivity based on spectral information of Landsat and Sentinel satellite images. We applied the models to hindcast vegetation productivity based on historical satellite images approximately during May and August of years with and without Bonnet Carré Spillway openings to assess the openings' impact on vegetation productivity. We found that as the frequency and duration of the Bonnet Carré Spillway openings increased, the peak green aboveground biomass decreased in both estuaries in the year when the spillway opened and was concentrated in the region that is closer in proximity to the Bonnet Carré Spillway. The research calls for development of flooding management strategies that could reduce the frequency and duration of Bonnet Carré Spillway openings.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Kovvuri N.R., Feng G., Bi G., Adeli A., Jenkins J.

Soil health can be evaluated by the ability of the soil to absorb, store and discharge water while preventing water erosion. The common management practices to restore soil health sustainably is the integration of different cover crops, manure application, and crop rotation. Studies have shown that the cultivation of different cover species for a long period of time has the potential to improve soil structure, aiding in infiltration and porosity, resulting in improved soil health by increasing soil organic carbon and total nitrogen content. An ongoing field study started in the year 2019 at the R.R Foil Plant Science Research Center with seven cover crop treatments to understand the influence of different cover crops like elbon rye, daikon radish, Austrian winter field peas, and a mixture of these cover crops on soil health, water quality that can impact crop production and climate change and resilience. This field has been incorporated with two tons of poultry litter every year, which is potentially known to improve the soil structure and several soil properties. Several soil health indicators can be chosen for assessing soil health. For this study, core soil sampling was done at the depths of 0-5 and 5-10 cm, and loose soil sampling was done at the depths of 0-5, and 5-10, 10-15 cm, and 15-30 cm after the termination of cover crops. We measured soil physical and hydraulic health indicators such as water stable aggregates, bulk density, available water content, and saturated hydraulic conductivity at the USDA-ARS Soil Physics and Hydrology Laboratory, Starkville. Soil chemical health indicators were also measured, such as total carbon, total nitrogen, pH, K, P, Mn, and organic matter. All those indicators have been used to calculate the overall soil health score. The Principal component analysis (PCA) was applied to perform the soil health assessment. The results indicated that the integration of cover crops improved soil properties as compared to no cover crop treatment. There was a significant difference between the cropping systems and the depth of the soil, indicating that the cotton crop responded well to the cover crop treatments than the corn crop, and the topsoil (0-5 cm) was found to be healthier at p < 0.05. However, no significant differences have been observed within the cover crop treatments, and long-term studies are necessary to understand the influence of different cover crops on soil health.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: O'Reilly A., Wren D., Locke M., Rossell W., Mirecki J.

To assess the potential for managed aquifer recharge to mitigate declining groundwater levels in the Mississippi River Valley alluvial aquifer (MRVAA) and support irrigated agriculture in the Delta, the U.S. Department of Agriculture, Agricultural Research Service, National Sedimentation Laboratory, in partnership with local stakeholders and U.S. Army Corps of Engineers, is conducting the Groundwater Transfer and Injection Pilot (GTIP) project. The system consists of one extraction well, a 1.8-mile pipeline, and two injection wells, with a design capacity of 1,500 gpm. Groundwater is filtered by passing through sands adjacent to the Tallahatchie River and subsequently is extracted, transferred, and then injected into a depleted section the MRVAA. Data collection at 17 observation wells and the river includes continuous groundwater level and monthly water quality samples. Prior to operation, observations indicate ambient groundwater was less mineralized at the extraction site than the injection site but both exhibited suboxic iron-reducing redox conditions, and groundwater levels responded to seasonal weather cycles, irrigation withdrawals, and river stage. Operation began in 2021, and two injection tests have been conducted for durations of 89 and 204 days, yielding total injected volumes of 550 and 575 ac-ft, respectively. During the first test the injection rate averaged 730 gpm/well with both wells running simultaneously, causing 6.7-ft increase in groundwater level at the injection site and 4.7-ft decrease at the extraction site. During the second test, both wells were run simultaneously for the first 13 weeks at a rate averaging 570 gpm/well, but due to declining capacity of the extraction well, injection wells were thereafter operated individually on a weekly schedule at 600 gpm. By the end of the second test, impacts were observed 1 mile from the injection wells where the groundwater level increased 0.3 ft. During both tests, differences in water chemistry between the river and extraction well indicate increased mineralization due to rock-water interactions and biogeochemical processes during riverbank filtration, whereas relatively small changes in water chemistry occurred in the MRVAA at the injection site. Clogging of the injection wells by iron bacteria terminated the first test; treatment with a dilute oxalic acid solution returned both wells to their prior capacities. No effects of clogging were observed during the second test. However, the extraction well experienced increasing drawdown over time, which was likely related to low river stage and possibly further impaired by formation of an adjacent sinkhole. Findings from the GTIP project demonstrate its technical feasibility in the Delta and the importance of considering the unique hydrogeology of the region, maintaining similar water chemistry between the injected water and ambient groundwater, and coordinating operating schedule with river stage and riverbank filtration capacity.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Jones C.N., Hayes W., Peterson D., Terry L., Barrett J.

Along the Gulf Coast, private drinking water wells play an important role in delivering water to rural communities. Yet, these systems also present a public health concern due to inconsistencies in water quality testing, regular maintenance, and construction practices. Here, we focus on how hurricanes and the associated inland flooding impact private well systems using a combination of community science sampling campaigns and geospatial modeling. We conducted a community science sampling campaign after Hurricane Ida, and our results highlighted widespread bacterial contamination of private drinking water wells. To put these results into context, we used a combination of modeled well locations and remotely sensed inundation estimates to quantify the potential extent of flooding impacts on the well user community. Taken together, these initial results highlight widespread impacts of hurricanes on rural drinking water resources.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Freeland T., Gholson D., Singh G., Kaur G., Larson E.

In the Mississippi Delta, over 40% of the farmland is classified as clay soils. Corn is mainly produced on sandy loam to silt loam textured soils. However, the recent economic returns on corn have led producers to start utilizing clay soils for corn production. Clay soils frequently flood and waterlog. Each day waterlogging occurs corn can lose between 5-30% of yield depending on the stage of growth. The overall objective of this research is to determine whether altering irrigated furrow spacings on Sharkey clay soils can reduce flooding and waterlogging to better benefit corn yield. The experimental design was a randomized complete block design with four replications. Furrow irrigation spacing treatments include every row irrigation, skip row irrigation, 4-row skip irrigation, and 8-row skip irrigation. The 4-row and 8-row skip treatments were further broken down to differentiate furrows that were irrigated and non-irrigated. They are noted as 4R-I, 4R-NI, 8R-I, and 8R-NI, respectively. Data on irrigation water applied, volumetric water content, plant population, plant heights, crop water stress index, multispectral imagery, corn yield, and grain quality are collected from this study. In 2021, the 4R-NI treatment yielded the highest in the trial at 177 bu/ac, while the 8R-NI had the lowest yield at 161 bu/ac. When looking at the volumetric water content in 2021, the 4-row skip treatments held the highest volumetric water content. The yield for the 2022 season was skewed by disease, so it will not be considered. In 2022, the skip row treatment held the highest volumetric water content. A third year will be conducted to further our understanding of the present data shown.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Kappaui J., Turnage G.

Aquatic invasive plants (ANS) can negatively affect water chemistry, disrupt ecological processes, lower biodiversity, and impact human uses of water resources. Because of their ability to rapidly colonize new habitat, many states and the federal government have placed invasive aquatic plants on noxious weed lists with the aim of reducing their spread. The states of the southeastern U.S. (TX, LA, MS, AL, FL, GA, SC, TN, AR, and KY) have dozens of invasive aquatic plants but only a few are listed as noxious weeds. Many states have varying definitions and classes of noxious weeds thus complicating efforts to control the spread of these species across state lines. This project aims to describe and combine the current legislation regarding noxious weeds in each state of the southeastern U.S. into a factsheet in an effort to provide resource managers and stakeholders a common resource to help slow the spread of these problematic species.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Bond R.F., Silva J.L., Abdallah-Ruiz A., Atwill E.R.

Irrigation is an important practice for agriculture in Mississippi and Alabama, but the use of contaminated water can lead to the spread of harmful microorganisms. This study was conducted through the 2018-2019 produce season to evaluate the microbial water quality of irrigation water in both states by analyzing samples from different agricultural water systems. We measured the levels of indicator microorganisms such as enterococcus, fecal coliforms, and Escherichia coli (E. coli) as well as pathogens such as Salmonella, Shiga-toxin producing E. coli and E. coli O157:H7. With this understanding we will provide insight into the potential health risks associated with the use of irrigation water in Mississippi and Alabama and will inform recommendations for improving water quality in these systems. Additionally, we investigated identifying these sources of contamination and worked to develop strategies to reduce the spread of harmful microorganisms in irrigation water.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Roland V., Crowley-Ornelas E.

In recent history, interest in the conservation of riverine ecosystems has grown as people have become more knowledgeable about the functions of these habitats. Anthropogenic hydrologic alteration is a direct threat to the health of these ecosystems because it often triggers a range of negative effects on the biological, physical, chemical, and hydrologic characteristics of impacted waters. Understanding important factors and drivers of hydrologic alteration is essential to the planning effective conservation action plans. This study explores the application of machine learning to predicting hydrologic alteration and identifying important predictors of hydrologic alteration in the Pearl and Pascagoula River Basins in Mississippi. Modeled daily streamflow for 12-digits hydrologic unit code (HUC12) watershed pour points was used to compute the net change in streamflow volume and to conduct a confidence interval hypothesis test across pre- and post-alteration periods between 1950 and 2009. Cubist models were developed for each basin to predict the p value of the confidence interval test as a function of the net change and a range of other physical and meteorological watershed parameters. Analysis of the net change and confidence interval test results indicated the basins had similar amount of altered HUC12 watersheds. Moreover, patterns of altered watersheds tended to coincide with the locations of densely populated areas, dams, and in areas with substantial land cover change in both basins. The cubist models developed for the basins produced accurate predictions of the confidence interval test results in most HUC12 watersheds. The importance of model predictors demonstrated differences in the relationships between basin geomorphology, land cover, and hydrologic alteration in the basins. The results of this study are evidence of the potential of the cubist algorithm in hydrologic alteration assessments. More broadly, machine learning and other data driven approaches can be applied to a variety of complex water resources issues to inform local, state, and federal resource managers.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Ozeren Y., Rossell W., Wren D.

Irrigation reservoir embankments are subjected to rapid erosion and retreat due to wind-generated waves. Accurate prediction of embankment recession rate is necessary to correctly assess the level of impairment and identify protection strategies. In this study, two different models were used to predict the embankment recession rates for soil embankments subjected to waves: XBeach, an open-source coastal modeling software developed by Deltares, and the USDA-ARS Bank-Stability and Toe-Erosion model (BSTEM). A one-dimensional numerical wave tank was created using the XBeach and simulations were carried out in order to understand the mechanisms involved during the recession of earthen embankments and provide accurate prediction methods. The simulation results were compared with the laboratory experiments in a wave tank at the USDA-ARS National Sedimentation Laboratory. BSTEM simulations were carried out at both laboratory and field scales. The results showed that the XBeach model reasonably predicted the embankment recession, except during the initial formation of the beach slope. A comparison of these simulations will be presented.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Gann L.

Protecting children from lead exposure plays a critical role in ensuring they develop into healthy adults. Children under the age of 6 have shown slowed growth, learning disabilities and other physical and mental impairments after prolonged exposure to environmental lead. The SipSafe Program seeks to limit children's exposure to lead via drinking water by screening water in qualifying schools and childcare facilities across Mississippi, as well as offering remediation assistance and educational materials on the dangers of lead. Mississippi State Extension Service receives funding for the SipSafe Program via the EPA WIIN Grant and has implemented their 3Ts model. With assistance from Mississippi State Department of Health, Mississippi Department of Education, Mississippi State Chemical Laboratory and other cooperating partners, SipSafe has developed into a program that:

• Trains directors and staff at participating facilities how to protect their children from lead exposure.
• Tests drinking water in participating facilities for lead and its sources.
• Takes action to help facilities reduce the amount of lead in their drinking water and further raise state-wide awareness of lead exposure in children.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Albertin A., Zhuang Y.

The Florida Well Owner Network (FWON) is a drinking water quality and septic system educational program that was developed for Florida decentralized water users. Our goals are to educate residents about well water quality and best management practices to ensure well and groundwater protection, facilitate water testing, and provide disaster relief assistance after major storms. To successfully achieve these goals at state and local levels, FWON has brought in multi-level partnerships and collaborations. These include internal and external state specialists, county extension agents, local health departments, water management districts, and state-certified water quality testing labs. Extension specialists provide research on drinking water contamination and treatment. County extension agents organize workshops through their established networks and help teach residents. Local health departments and water management districts provide local well water information and funding for well water testing. State-certified water testing labs enable drinking water testing through standardized methods. Since 2017, 1,289 residents have been educated about water quality and septic system maintenance through FWON and 451 people have had their well water tested for bacterial contamination. Due to COVID-19, we switched from in-person workshops to webinars, reaching approximately 500 well users in 2021 and early 2022. Our efforts are currently focused on providing workshops both in-person and online, and as FWON grows major challenges include organizing larger sampling events and funding to process analyses.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Ford G., Rokooei S., Hatami A.

A common treatment in municipal wastewater systems in the United States is aeration. Aeration promotes growth of microbes which feed on organic waste, easily removed from wastewater through flocculation. Aerators are often the most expensive treatment component in municipal systems from an electrical cost standpoint. They can also be challenging to maintain. Blower CFM, manifold pressure, leaking pipes, gearbox malfunction and motor failures are a few of the operation issues posed by aerators. If the aerators are not providing enough oxygen to the wastewater, the treatment system effectiveness may be severely impaired. To minimize maintenance and operating costs and to ensure system effectiveness, holistic maintenance and treatment plans must be considered. This discussion will examine aeration at a local wastewater treatment plant in northeastern Mississippi and recent issues experienced with Aerator gearbox failures. The causes of these failures and the chosen solution will be presented.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Rossell W., O'Reilly A., Wren D.

In an effort to address the impact on groundwater resources caused by widespread pumping for irrigation in the Mississippi Delta region, the Groundwater Transfer and Injection Pilot (GTIP) project was undertaken by the U.S. Department of Agriculture, Agricultural Research Service, National Sedimentation Laboratory to assess the potential benefits of such a managed aquifer recharge practice. The GTIP project transfers source water obtained by riverbank filtration to an area of declining groundwater levels and recharges the aquifer using two injection wells. The facility has completed two pumping tests, a 3-month duration in 2021 and a 6-month duration in 2022. Throughout both tests, the inactive period between, and the inactive period following the 2022 test, groundwater level and groundwater quality data has been routinely recorded to evaluate the impacts of the project on the local environment. However, complicated circumstances and problematic events have also been encountered beyond those which were originally anticipated. This presentation will introduce some of these issues to the greater community and provide some current working hypotheses of causative factors. In particular, this presentation will briefly present the following topics: sinkhole formation on the GTIP project site, difficulties presented by the high iron concentration in the region's groundwater, the problem of injection well-screen clogging by iron-related bacteria, and unexpected groundwater drawdown during riverbank filtration. While the cause of many of these events is still under investigation and others may have been unavoidable, the benefit of presenting these negative results from the GTIP project is to better focus and expedite future research, leading to improved design criteria and more efficient operation and maintenance activities.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Westerfield R.

The Mississippi Department of Transportation (MDOT) bridge hydraulic design has evolved significantly over the past ten years by using the emerging two-dimensional (2D) hydraulic modeling software. Two-dimensional (2D) hydraulic modeling software, graphical interfaces, and supporting resources are available that can be applied to infrastructure design to improve understanding of the complex interactions between river or coastal environments and transportation assets. Recent advances in computer hardware, modeling software, Geographic Information Systems, and survey practices have made 2D modeling very efficient, intuitive, and accessible to engineers and designers. This emerging technology provides the following benefits:

• Improved Quality and Resiliency. 2D modeling results provide more accurate representations of flow conditions, including depths and velocities. Improved project quality may often be realized by using 2D modeling results to inform the location and size of structures, determine depths of bridge foundations, and analyze environmental impacts.
• Enhanced Collaboration. 3D graphical visualizations derived from 2D modeling offer better tools for communicating the often complex interaction between waterways, the transportation infrastructure, and the surrounding environment.
• Streamlined Delivery. Improved collaboration can help streamline project development, including environmental, regulatory, and engineering activities.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Taylor J., Moore M., Hoeksema J., Locke M.

Important wetland properties associated with retention of excess nutrients and sediments in agricultural watersheds, as well as provision of critical food and habitat resources for migratory shorebirds, may be stimulated through novel implementation of existing wildlife BMPs in Lower Mississippi River Basin (LMRB) agroecosystems. We evaluated how novel timing (fall) of the implementation of NRCS EQIP 644 influenced nutrient runoff and denitrification in three inundated corn fields over a 3-month period. We observed significant positive N2-N flux rates (8 mg m2 h-1) soon after inundation that were sustained throughout the inundation period and culminated in an estimated 33-45 kg ha-1 of excess N removed by denitrification. We observed significant reductions in mean storm event loads for suspended sediments, NO3-N and PO4-P. We also observed significant reductions in TP loads, but NH4-N and TKN loads were not significantly affected by flooding. Flooded fields supported rapid colonization and maintenance of benthic macroinvertebrate densities (peak = ~5000 indv. m2) dominated by Chironomidae. Flooded fields provided critical habitat and food resources for migratory shorebirds with a minimum of 2100 individuals representing six shore bird species observed over four surveys during the fall migration period. Fields implementing shallow water habitat management in the fall had slight increases in soybean yields the following growing season. Our results suggest that novel timing of EQIP 644 provides temporary wetland structure and function that may support water quality improvements and provide critical shorebird habitat, without impacting yields within LMRB agroecosystems.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Chao X., Al-Hamdan M., Bingner R., Zhang Y., Witthaus L.

Goodwin Creek Experimental Watershed (GCEW) located in Panola County, Mississippi, is a 21.3 square kilometers Conservation Effects Assessment Project (CEAP) benchmark watershed monitored by USDA-ARS National Sedimentation Laboratory (NSL). The main concern in this watershed is soil erosion due to rainfall and runoff in the upland fields. In addition, the sediment associated nutrients are also transported into downstream channel networks due to soil erosion. The Annualized Agricultural Non-Point Source (AnnAGNPS) watershed model, developed at the NSL, was applied to simulate the loads of water, sediment and nutrients from the upland fields of GCEW. In this model, the effects of land use/land cover, soil properties, climate, agriculture management, etc. on the watershed loads were considered. The results produced from AnnAGNPS were used as boundary conditions for the Center for Computational Hydroscience and Engineering 1-Dimensional (CCHE1D) model developed at the National Center for Computational Hydroscience and Engineering, to simulate the flow, sediment, and nutrients in downstream evolving channel networks of GCEW. This model computes the non-equilibrium sediment transport with non-uniform size mixtures. It can also simulate the transport and fate of nutrients and other pollutants in channel networks, including the biogeochemical reactions that take place in the streams and sediment bed layers. Simulated results were calibrated and validated using field measured data collected by the NSL. This research provides useful tools to assess the impacts of upland sediment and nutrient loads on the downstream channel networks.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Fang J., Al-Hamdan M., O'Reilly A., Ozeren Y., Rigby J.

Sustainable groundwater management is a topic of interest in the Mississippi River Valley alluvial aquifer (MRVAA) where declines in groundwater levels have been reported over the last few decades. To find a solution to this problem, the Groundwater Transfer and Injection Pilot (GTIP) project is being conducted at Shellmound, Mississippi, by the U.S. Department of Agriculture (USDA), Agricultural Research Service (ARS), National Sedimentation Laboratory. The managed aquifer recharge (MAR) technology being tested takes source water acquired via riverbank filtration and then transfers and injects the water into a depleted section of the MRVAA. Field measurements are essential to the GTIP project for assessment of the feasibility of this MAR technology, while numerical modeling is important for the evaluation of potential designs. Therefore, a numerical groundwater model was developed for this pilot study site. In this area, the vadose zone of the MRVAA consists mainly of fine-grained sediments. Our numerical experiments revealed that the hydraulic properties of the unsaturated soil can significantly affect the hydrological processes controlling groundwater pumping during riverbank filtration and groundwater injection in the aquifer. Hence, in this study, precipitation, evapotranspiration and soil moisture data from the North American Land Data Assimilation System (NLDAS) were used to estimate the soil properties in the vadose zone through data assimilation. The estimated unsaturated soil properties were then implemented into the groundwater model in which aquifer resistivity data derived from airborne geophysical surveys by USGS were incorporated to consider the spatial variability of the aquifer hydraulic conductivity. An empirical formula was applied to translating the resistivity data into hydraulic conductivity. The coefficients in the empirical formula were determined by calibration of the numerical model with the measured groundwater hydraulic heads. Good agreement was found between the simulation results and the field data in both calibration and validation periods, indicating the potential of using this modeling technique to facilitate decision-making on the potential implementation of the MAR technology being tested by the GTIP project.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Cizdziel J., Wontor K.

Awareness of microplastics (MPs) as a global pollutant continues to grow among scientists, politicians, and the public. MPs are a diverse suite of contaminants that range in size from 1 μm to 5 mm and that occur in a variety of shapes. The Mississippi River acts as a conduit continually transporting plastic litter in runoff to the Gulf Coast where MPs accumulate and can affect susceptible organisms. Filter-feeding species, like oysters, are particularly vulnerable. The proportion of MPs in aquatic ecosystems stemming from urban runoff has grown with urbanization. Here we report our findings on MP pollution in runoff from parking lots and roads in Oxford, MS as well as in oysters (Crassostrea virginica) from the Mississippi Gulf Coast. We used a YSI ProSampler to collect rainwater runoff at set intervals during storm events, conducted a density separation to isolate MPs, and used stereomicroscopy and FTIR micro-spectroscopy to characterize the particles. We observed >150 MPs/L at the start of the rain event, with concentrations declining with time. Most MPs were fragments (~80%), followed by fibers (~18), and most (~80%) were <200 μm in size. MPs were mainly composed of polyethylene, polyester, polypropylene, polyvinyl chloride, and polystyrene. For oysters, locations inside bays near population centers had higher average concentrations. Oysters seem to accumulate more MPs on their external tissues than in their digestive system. MP concentrations in oysters was not correlated with oyster condition index. Further characterizing the types of MPs present in oysters may provide insight into likely sources of contamination at different sites. Overall, this work provides much-needed empirical data on the abundances and sizes of MPs in both urban runoff and in oysters from the Mississippi Sound, and suggests that lawmakers need to consider federal legislation to address MP pollution in river systems at a national level.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Ford G., Rokooei S., Garshasby M.

Recent incidents in Scottsdale and Rio Verde Foothills, Arizona regarding water use in single family dwellings has drawn renewed national attention to climate change, population growth and limited resources on a community-sized scale with real, immediate effects on the residents of this community. Suffering from a long-term drought, the city of Scottsdale administrators are concerned about water supplies for their residents. This concern has resulted in cutting off tanker transported, water supplies for 500 neighboring Rio Verde Foothills homes. Rio Verde Foothills residents have already initiated legal action against the City of Scottsdale. What other alternatives do the Rio Verde Foothills residents have? Local building codes regarding water supplies for single family residences generally specify water requirements, but can a practical, waterless home be built for arid or overpopulated regions? This paper discusses the potential designs for waterless or near waterless homes. Water for drinking, bathing and bathroom uses are typically needed end uses, at a minimum. Potential designs providing for these end uses for single family homes in several different regions of the United States are discussed. Maintenance and installation costs, and ease of installation and maintenance are the primary considerations.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Huff D., Maierhofer M., Henderson C., Miles M.

Presentation will focus on how these practices can benefit southern farmers from southern farmers. What have we learned from our trials from the last couple of years and where do we go from here.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Peterson D., Jones C.N., Wolford M., Zarek K., Speir S.

Non-perennial streams (i.e., streams that dry regularly) comprise over 50% of the global river network and play an important role in influencing the physical, chemical, and biological characteristics of downstream waters. In the Southeastern United States, non-perennial streams occur in the headwaters of river networks, and their unique patterns of drying have not been well-characterized. In these systems, heterogeneity of watershed physical features, including stream slope, subsurface architecture, and preferential flowpaths, play a key role in spatial and temporal variation in streamflow and drying. Our goal is to develop a predictive understanding of spatiotemporal patterns of stream drying across watersheds representative of three distinct physiographic regions in Alabama: the Coastal Plain, Piedmont, and Appalachian Plateau. We characterized longitudinal network connectivity over an annual drying cycle with empirical water presence data collected using Stream Temperature Intermittency and Conductivity (STIC) loggers dispersed throughout the watersheds. We also characterized watershed structural features, including elevation, slope, soil depth, and valley shape, using publicly available data. Combining these data sources allowed us to compare spatial and temporal patterns of network drying to identify potential drivers. Our initial results suggest that each physiographic region may have a unique drying regime, and that drying occurs hierarchically within watersheds. Our work provides insight into the drivers of stream drying in the Southeast, better informing our understanding of the structure and function of these important stream networks.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Khanel P., Feng G., Huang Y., Han M.

Estimation of crop yield with approximate acreage is critical to crop production management decision support. This research aims to estimate the soybean yield and acreage during the wet, normal and dry years in Mississippi State using APEX (Agricultural Policy/Environmental eXtender) model which was developed to extend EPIC (Environmental Policy Integrated Climate model)'s capabilities of simulating management and land use impacts for whole farms and small watersheds (https://blackland.tamu.edu/models/apex). APEX model uses data from the past to establish trends such as rainfall average, precipitation, soil, wind etc. to determine how the climate trend, management practices, and soil can affect the future of agriculture. APEX model is capable of long-term simulation of the fields ranging from small-scale to cross-country boundaries. For the research, APEX model was implemented for all soybean fields county by county across the entire state. The results from the research provide valuable information on the total area of soybean planted and the total yield of specific soybean fields in every county in Mississippi. The APEX model was implemented by utilizing various databases, including data of soil, weather, crop, field management, and spatial locations. The database provided reference for APEX model to determine which data to run for each simulation. The Gridded Soil Survey Geographic Soil Map (gSSURGO-30) (USDA Natural Resources Conservation Service (NRCS)) and the Gridded Cropland data layer (CDL-30 m) (USDA National Agricultural Statistics Service (NASS)) were downloaded and then uploaded into ArcGIS to apply Spatial Analyst tools in ArcGIS (ESRI, Redlands, CA) to overlay and clip the two data layers to fit into the area of interest. We then conducted georeferencing to get the geographic coordinates of the individual fields in the area of interest. In ArcGIS, we then used the SSURGO's table to link the field with type of soil in field. We then created the individual fields based on the soil, field size, and geographic coordinates using parameters such as type of soil found on the field, geographic coordinate, crop to be run, management file and weather station near to the field. Accordingly, weather data, such as wind, precipitation , daily/monthly temperature, and soil data, were converted into the required format for APEX model with Python programming. As a result, soil, and weather data files for all soybean fields in the entire state were created and the area and location of soybean fields was determined. Those data files were used by APEX model to simulate soybean yield for individual fields and the total yield for all fields in each county of the entire state. The output from APEX model was compared with the total area of soyabean field planted and yield data reported by the USDA NASS. The study will contribute to improving accuracy of those NASS reports for stakeholders in commercial community and researchers in scientific community.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Temple J.M., Paul V.

Groundwater-derived phosphorus (P) has often been dismissed as a significant contributor towards surface water eutrophication, however, this dismissal is unwarranted, making the quantification of P concentrations in groundwater systems immensely important. Machine learning models have been employed to quantify the concentrations of various contaminants in groundwater, but to our best knowledge have never been used for the quantification of groundwater P. The goal of this research was to use a boosted regression tree framework to produce one of the first machine learning model of P variability in groundwater, with the High Plains aquifer serving as the study area. Boosted regression tree models that could explain and predict the statistical variance of P throughout the aquifer (under standard conditions) were developed, but with low predictive capacity. Observed P values from testing dataset compared to predicted values had a R2 of 0.7265, though this value could be skewed by better correlation between the actual and predicted at lower concentrations of P (< 0.05 mg/L). Lack of sufficient data and the raster file extraction method employed were identified as possible reasons for the low predictive capacity, and could be improved by more data. The research provides important variable correlation data that can potentially be incorporated into future studies that aim to further understand P dynamics in groundwater.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Maskey M.L., Al-Sudani A., Nelson A.M., Quintana Ashwell N.

The Mississippi Delta is one of the largest contiguous agricultural production areas in the United States. Overlying an alluvial plain, this area is known for producing row crops such as cotton, soybeans, and corn, as well as rice and catfish. Therefore, this region is a major economic contributor to the state and nation, with $6.8 billion in annual agriculture revenue. The Delta receives over 54 inches of rain annually, but most of that precipitation occurs outside the growing season. Consequently, the region depends on irrigation to sustain agricultural production in the state largely depends on. Over time, the number of wells has expanded to meet abundant and accessible water of sufficient quality for the ever-increasing expansion of irrigated acreage. According to the Mississippi Department of Environmental Quality, the number of permitted wells increased from 10,571 to 21,000 between 2000 and 2022. As a result, groundwater levels in the shallow Mississippi River Valley aquifer have declined. However, data gaps make it difficult to interpret water conditions in this alluvial aquifer, which limits the ability to make realistic recommendations. Therefore, we propose a protocol to develop a coupled groundwater model that incorporates hydrologic dynamics and economic behavior in the presence of surface water sources. Therefore, we propose a protocol to develop a coupled groundwater model that incorporates hydrologic dynamics and economic behavior in the presence of surface water sources. This protocol addresses different agricultural management practices to study groundwater and surface water interactions. Additionally, the integrated groundwater model will be used to optimize water delivery costs, crop yields, and extraction from existing wells. We propose an economic modeling tool widely used in policy analysis: "Positive Mathematical Programming," that replicates observed economic behavior under alternative hydroeconomic circumstances. At this stage, we present a conceptual framework to develop the integrated modeling platform with the available data. We also plan to extend this study by generating historical and future plausible scenarios that will inform decision-makers about viable strategies to address groundwater concerns in the Delta. We envision that this research will serve as a multi-benefit protocol in a) generating timeseries of groundwater data from the past to the future, to understand subsurface dynamics; b) optimizing groundwater well extraction levels under different land use, agriculture management practices and climate conditions; and c) informing feasible water delivery costs, crop yields, and groundwater withdrawal under sustainable aquifer conditions.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Ouyang Y., Wei J.

Groundwater depletion due to the increasing water demand for agricultural, domestic, and industrial usages under a changing climate is a critical concern worldwide. Many regions of the world are now experiencing a certain degree of groundwater resource depletion. Mississippi Embayment (ME), encompassing parts of Missouri, Illinois, Kentucky, Arkansas, Tennessee, Mississippi, Alabama, and Louisiana, is an intensive crop production region in midsouth US and is one of the fastest groundwater resource depletion regions in the world. An understanding of the long-term stream and aquifer water exchange is crucial to groundwater resource planning, allocation, and management in the ME. Using the US Geological Survey's MERAS (Mississippi Embayment Regional Aquifer Study) groundwater model, we estimated the stream and aquifer water exchange in the ME over a 115-year simulation period from 1900 to 2014 under the following six different scenarios: (1) a base case scenario represents the current agricultural practices, groundwater pumping, and natural conditions existing in the ME; (2) an extreme wet scenario that is the same as the base case scenario except that the precipitation rate is increased by 20%; (3) an extreme dry scenario that is the same as the base case scenario except that the precipitation rate is decreased by 20%; (4) a no-pumping scenario that is the same as the base case scenario except without groundwater pumping; (5) a scenario without pumping with 20% increase in precipitation, which is the same as the extreme wet scenario except for without groundwater pumping; and (6) a scenario without pumping with 20% decrease in precipitation, which is the same as the extreme dry scenario except for without groundwater pumping. Simulations showed that more waters leaked from the aquifers to the streams than from the streams flowed into the aquifers over the past 115 years. There was about 3 times more aquifer water leaked to the streams without pumping than with pumping. Our study suggested that the groundwater pumping rather than the extreme precipitation played a vital role in stream and aquifer water exchange of the ME.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: DeVilbiss S., Taylor J., Hicks M.

Agricultural intensification has caused substantial alterations to aquatic ecosystems including habitat degradation and eutrophication. Establishing water quality goals to guide management efforts for reducing agricultural impacts to surface waters relies on developing stressor-response relationships between biological assemblages and water quality stressors. Traditional approaches for developing stressor-response relationships depend on historical tolerance values that quantify the ability of different biological taxa to survive in degraded conditions. However, many tolerance values for macroinvertebrates, which are perhaps the most widely used biological assemblage for monitoring and management purposes, were developed in less altered regions and may not reflect the unique ecology of highly modified agroecosystems. Thus, developing effective management and monitoring tools for highly modified regions may require re-examining how we define and characterize biological tolerance. Using data from the Mississippi Alluvial Plain (MAP), an intensely cultivated ecoregion in Mississippi, we outline a method for identifying regionally-specific groups of tolerant and intolerant taxa for individual water quality stressors like nitrogen and phosphorus, eliminating the need to rely on historical tolerance values. We further demonstrate how modeling approaches can be applied to these regionally-specific taxa groups for water quality monitoring and establishing reasonable expectations for biological improvements following the implementation of best management practices. Lastly, we apply this novel approach to DNA-based bacterial assemblage data as an example of how multi-assemblage responses can be combined to better constrain water quality goals.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Awawdeh A.R., Yasarer H., Pulla S., Kumar M.

The importance of having accurate and high-resolution hydrological data has risen with recent climate change and ongoing dependence on underground water. The launch of the Gravity Recovery and Climate Experiment (GRACE) in 2002 made it possible to acquire such data, enabling researchers to extract information on terrestrial water storage, ice loss, and sea-level change at a temporal resolution of one month. However, this data is not adequate for smaller regions due to the coarseness of the GRACE data grids, which have a resolution of 56 km by 56 km. This study aims to investigate the effectiveness of using Feedforward Artificial Neural Networks (ANNs) with the backpropagation error algorithm to scale down GRACE data for the State of Mississippi to smaller grids of 4 km by 4 km that can be used in smaller regions. This process utilized Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) and TerraClimate databases. CHIRPS provides high-resolution rainfall data, while TerraClimate provides a dataset of monthly climate and climatic water balance for global terrestrial surfaces. A script in Python programming language executed via Jupyter Notebook was developed to download all the necessary data and develop the ANN model. Initial results indicated that the ANN approach performed well with an R2 of 0.93, and the developed models can be utilized to predict equivalent water thickness with high accuracy in the Mississippi region. The current effort is focusing on validating the model by comparing the downscaled GRACE data against well-water data in the Mississippi Delta area and assessing the model's ability to identify drought activities that occurred within the study period from 2002 to 2020.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Quick K.

In February 2020, a major flood event occurred on the Pearl River that caused significant bridge scour, bank erosion, and the failure of existing streambank stabilization countermeasures at U.S. Highway 98 (US 98) near Columbia, MS. The Mississippi Department of Transportation (MDOT) maintains US 98, and in 2018 began planning and designing a new structure over the Pearl River to replace the 90-year-old eastbound bridge that was constructed in 1933. The US 98 westbound bridge was built in 1970 and was not originally scheduled to be replaced. The Pearl River is significantly meandering, and in 1986 MDOT constructed a series of five (5) jetties along the left descending channel bank to stabilize the lateral channel migration that was occurring immediately upstream of US 98. The 2020 flood caused significant scour along the jetty system, causing failure of one of the structures and severe bank erosion at a second structure. The scour along the jetties contributed to additional local scour at the US 98 bridge opening which led MDOT to implement a real time scour monitoring plan of action, and accelerated plans to replace the US 98 westbound bridge. This presentation will provide background for the US 98 bridge replacement project, lateral stream migration, and will discuss how technologies such as multi-beam bathymetric surveying, two-dimensional (2D) hydraulic modeling, and underwater acoustic imaging lead to a more informed and accurate decision-making process for MDOT. This will include both short-term and long-term plans to address stream and scour issues at the US 98 crossing over the Pearl River.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Witthaus L., Pawlowski E., Locke M., Stevens E., Chatterjee A.

Colloquially, Mississippi Delta soils are known to be high in phosphorus. While soil phosphorus levels do not reach those of the Upper Midwest or areas applying animal manure, Delta soils retain a high level of phosphorus without continual application. However, there are limited publications conveying soil and sediment nutrient levels in this region. Understanding baseline soil nutrient levels, as well as nutrient dynamics, can improve simulations of nutrient transport in models and provide valuable information for watershed water quality management. This presentation will showcase results from a study evaluating properties of soils in both agricultural and forested areas within four different soil series common in the MS Delta: Dundee, Forestdale, Alligator, and Sharkey. We found that Mehlich-3 phosphorus (P) levels were similar across Alligator, Dundee and Sharkey soils in both land uses, but they differed in Forestdale soils. Soils in forested areas exhibited higher total carbon (C), and nitrogen (N) concentrations (p<0.01) compared to soils in cropped areas. Mehlich-3 iron had a positive correlation with Mehlich-3 P in three of the soil series in cropland, but the relationship was negative for natural soils. A suite of other variables was measured and relationships between these characteristics will be explored in this presentation. In addition, we will demonstrate potential uses for such a database through a modeling example.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Vargas A., Gholson D., Lo H., Singh G., Krutz J.

Groundwater is the most exploited resource for furrow irrigation in Mississippi. The overuse and excessive pumping from agriculture and fisheries have exceeded the natural water recharge of the Mississippi River Valley Alluvial Aquifer. Limited research is available on using 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. This is our second year, the field was established at Delta Research and Extension Center, Mississippi State University, Stoneville, MS in 2022. 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). Data collected included SPAD meter readings, grain N uptake, corn grain yield, and irrigation water use efficiency. Results will be presented at the conference. Corn grain yield was adjusted to 15.5% moisture prior to analysis. Data was analyzed using the GLIMMIX procedure in SAS statistical software at a p-value of 0.10. The results of this research will be presented at the conference.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Nekooei M., Paz J.

In recent years, significant water withdrawal from the Mississippi River Valley Alluvial Aquifer (MRVA) for irrigated agriculture in the Mississippi Delta region have caused considerable declines in aquifer water levels, to the extent that withdrawals have outstripped the recharge. Therefore, water managers have a major concern about the ability of aquifers to meet increasing water demand in the Delta. In this research, the MODFLOW groundwater flow model with GMS software was used to compare the simulated daily groundwater levels with the water-level measurements in the period of the growing season from April through September between 2016 to 2021. The daily groundwater data for 11 observation wells were collected from USGS for the period, along with a few available pumping data from the irrigated wells in the Delta. In addition, the data for areal recharge, rivers, adjacent aquifers, boundaries, and the characteristics of the aquifer were considered as the other GMS packages to construct the model. The discretized was established by using a single layer rectangular-grid and oriented north-south with 1-kilometer square cells to represent the alluvial aquifer. The part of the grid covering the Delta area has 76,039 active cells. The model-generated April to September water levels for each year of the simulation were compared to the corresponding measured water levels. The average root-mean-square (RMS) error determined for the calibrated model was 1.4 meter. Assessing the daily data, a declining trend in groundwater levels was observed during the growing season throughout the studied area. However, the aquifer experienced a more reduction in the water table in 2016 and 2017 in comparison with the other years. In addition, the counties of Sunflower, Leflore, and Washington experienced more fluctuations in the water table due to the excessive withdrawals. Overall, the model results indicated that the simulated hydrographs in all the wells are reasonable representations of the measured water levels. A long-term modeling scenario that assumes the same 2021 pumping rate will likely result in the depletion of grid cells located in the three counties. Based on the model results, the net recharge from the Mississippi River and from the adjacent aquifers was small.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Albertin A., Stevenson C., Bean E., Deitch M., Reisinger A.J.

The Florida Panhandle has the highest average total rainfall in the state (65"), with average totals increasing in recent years. Limited and aging stormwater management has led to legacy water quality and flooding problems across the region. A need exists for local leaders and stakeholders to better understand how development occurs, its impact on hydrology and water quality, and solutions to mitigate impacts. We developed a regional stormwater education program to build technical capacity among stakeholders to incorporate sustainable stormwater management practices. Our audience includes municipal employees, extension faculty, professional engineers, landscape architects, and residents. We held an in-person stormwater management workshop in 2019 (22 attendees), and 2-part webinar series in 2020 (83 attendees), 2021 (136 attendees), and 2022 (101 attendees). In 2021 and 2022, participants received professional CEU's. Topics taught included hydrology and pollutant load dynamics, green stormwater infrastructure (GSI) and maintenance, low impact development (LID), permitting, planning tools, local case studies, and funding opportunities. Post-workshop 5-month follow-up surveys indicate that attendees are using the information they learn at work and several have modified decisions related to stormwater management based on what they have learned. The annual increase in participation and enthusiasm from stormwater professionals, along with innovative projects designed in local municipalities shows that these workshops are achieving our initial objectives. We are currently planning our 2023 workshop series.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Manning M.

The Mississippi River is one of the most extensively controlled rivers in the world. Man-made changes to the system have been documented as early as the 1700's. Today, flood-control levees are located along nearly 5,800 kilometers of the river's length; there are 29 lock-and-dam structures between Minneapolis, Minnesota and St. Louis, Missouri for navigational control; as well as many flow-diversion structures. All these alterations combined have created many positive water quality improvements, but has also created several unexpected negative impacts, including the reduction in the amount of transported sediment, in addition to the occurrence, duration, and extent of flooding.

The U.S. Geological Survey (USGS) collects hundreds of suspended sediment and water quality samples each year to support water resource managers in timely access of data. In conjunction with these efforts, the USGS also maintains a network of real-time continuous streamflow and water quality stations along the Mississippi River main stem, tributaries, and distributaries to support local, state, and federal agencies flood control and aquatic health decision-making.

In mid-2022, to continue to support these efforts, the USGS began working to develop a new generation sampler. This new sampler would incorporate all aspects of previous large river bag and point samplers into one unique sampler. Also, this new generation sampler can be deployed hosting sensors including turbidity, acoustic backscatter, and other parameters to record at depth. The USGS is also currently using panoptic live scope sonars to view samplers in real-time as they descend and ascend the rivers depths collecting suspended data. These and other data collected by the USGS provide invaluable information to many agencies who strive to sustain, safeguard, and monitor the Mississippi River during various hydrologic conditions.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: San Antonio K., Holifield M., Wu W., Huang H.

Sea level rise is an escalating threat to saltmarsh ecosystems as increased inundation can lead to decreased biomass, lowered productivity, and plant death. Another potential stressor is elevated nitrogen, which has a controversial impact on belowground biomass, potentially affecting the stability of saltmarshes and is relevant due to additional nitrogen brought into coastal regions via freshwater diversions. Our research objective is to examine the combined effects of inundation and nitrogen on common saltmarsh plants (Spartina alterniflora and Spartina patens). We set up two marsh organs with six rows and eight replicates in each row, one planted with S. alterniflora that occupies low, emergent marsh zones, the other with S. patens—a high marsh plant less tolerant of inundation and salinity. We randomly selected four replicates in each row to add 25 g/m2 of nitrogen in the form of ammonium nitrate every two or three weeks in the growing season. With the same frequency, we collected morphological characteristics such as plant height and leaf count to represent vegetation conditions in different dimensions over time. Furthermore, we harvested half of the marsh organ vegetation in Year 1 and the remaining in Year 2 to evaluate the short- and long-term impact of inundation and nitrogen on above- and belowground biomass (Year 2 belowground biomass still in processing). To help the inference, we developed multilevel Bayesian models. Our results show that inundation positively affected most of the characteristics of S. alterniflora measured over time while negatively affected S. patens, with both plants exhibiting some quadratic relationships for certain measurements and biomass. Exceptionally, leaf count and stem width of S. alterniflora showed maximum values at an intermediate inundation time, while stem width of S. patens reached the minimum at an intermediate inundation time. Aboveground biomass of both species responded to inundation differently in the short- and long-term. In the short-term, aboveground biomass of S. alterniflora reached the minimum at an intermediate inundation time, while there existed an optimum inundation time for long-term aboveground biomass and short-term belowground biomass. For S. patens, there existed an intermediate inundation level at which the short-term biomass reached the minimum, while inundation negatively affected long-term aboveground biomass and short-term belowground biomass. Additionally, for both species, plants with the nitrogen addition had higher aboveground biomass when compared to non-fertilized plants, while nitrogen addition had little to no impact on short term belowground biomass. This work will facilitate more-informed restoration and conservation efforts in coastal wetlands while accounting for climate change and sea-level rise.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Powell J., Simek V., Rosson A., Taylor J., Moore M.

Nitrogen (N) is a vital nutrient necessary for all living organisms. The bulk of N is in N2 gas and not bioavailable. Bacteria facilitate natural fluxes of N from the atmosphere to the biosphere and back through nitrogen fixation and denitrification, maintaining a balanced nitrogen cycle. However, increased fertilizer production and cultivation of N fixing crops has led to excess N in the environment and runoff of excess N from agricultural and urban landscapes can cause many problems, including harmful algal blooms and hypoxia which degrade aquatic habitats. Managing fallow agricultural land in the Mississippi Delta for wildlife wetland habitat in fall and winter can enhance wetland properties that promote denitrification. We collected sediment cores from flooded agricultural fields across ten farms representing different timing of flooding, crop rotations, and soil properties, and incubated them using the same source water to assess how different factors influence N2 flux rates during flooding. We collected water samples from core inflow and outflow lines and measured N2:Ar and O2:Ar ratios using membrane inlet mass spectrometry (MIMS). Net N2 flux and sediment O2 demand were estimated for 30 cores representing replicates from the 10 farms.We then extracted the upper 5cm of the sediment core for characterization of particle size, organic matter content, and carbon, nitrogen and phosphorus concentrations, as well as later DNA extraction to characterize microbial communities. We will present results that seek to link crop rotation, sediment properties, and flooding duration to net N2 flux rates. Understanding how crop rotation, soil properties, and timing of flooding influence N2 flux in agricultural fields managed for fall/winter wetland wildlife habitat can help identify how the nutrient mitigation potential of these conservation practices varies across different conditions throughout the Delta and provide managers with novel ways of managing excess nitrogen in agricultural watersheds.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Pawlowski E., Witthaus L., Taylor J., Moore M., McNamara S.

Agricultural drainage ditch networks are an important pathway for nutrients. Changing environmental conditions within drainage ditch networks caused by intermittent drying and rewetting can control nutrient fate and transport. We delivered a phosphorus pulse to six experimental stream channels that subsequently underwent four wet and dry cycles to describe phosphorus retention and mobilization in agricultural ditch environments. Experimental stream channels were filled with sediment from the Mississippi Alluvial Plain and three of the channels were planted with vegetation (Leersia oryzoides) that was allowed to establish prior to the nutrient addition. We monitored discharge, conductivity, pH, salinity, and dissolved oxygen during each of the rewetting periods and during the initial addition of phosphorus salt. Following each wet period, the streams were drained and allowed to dry before the next wet cycle. We collected water samples during each of the rewetting periods and during natural precipitation events that generated flow within the constructed channels. We sampled sediments before and after each rewetting event and measured moisture content, particle size, and water extractable phosphorus on both field moist and air-dried samples. Sediment samples were stratified across channel features (two runs and two pools). Average dissolved phosphorus concentrations were approximately four times higher in unvegetated (0.35 mg L-1) verses vegetated streams (0.09 mg L-1) during the initial wetting event, but subsequent rewetting events had similarly low concentrations (0.01 to 0.03 mg L-1) among both treatments. Sediment increased in phosphorus concentrations following the initial phosphorus addition in all channels. By the fourth wet cycle those concentrations had generally decreased but showed variability throughout each cycle based on channel position and which wet-dry cycle the sediment was collected in. Vegetated sediments did not have as substantial of an increase in phosphorus as sediment from unvegetated channels (2.36 mg kg-1 vs. 4.07 mg kg-1 respectively). These results suggest that both vegetated and unvegetated ditches can store phosphorus through repeated drying and rewetting cycles, but vegetation and likely biological uptake reduces phosphorus in both the water column and sediment. These results show that vegetation may be a promising mitigation tool in ditch networks with intermittent flow but future work is needed to assess phosphorus storage over longer temporal scales.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Otts S., Willett K.

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. 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. This presentation will provide an overview of the team's work in 2022, including the results of a statewide lead forum hosted in Jackson, MS in October 2022.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Holifield M., Wu W.

Frequent flooding is dangerous to both short- and long-term health, and the expenses of constant repair and upkeep wear down both citizens and city government. Moss Point, Mississippi is an underrepresented and marginalized community on the coast, well known for its frequent flooding for the last few decades. As global climate change shifts local weather patterns towards heavier rainfall and more intense tropical storms, stormwater management becomes a pressing issue concerning existing grey infrastructure. Green infrastructure has shown efficacy in mitigating flood risks while providing other co-benefits such as habitats, carbon sequestration and improved air and water quality, and can be affordable in construction and maintenance. Here we evaluated the impact of low-cost rain garden and high-cost permeable pavement on peak runoff and total runoff in three areas that are most vulnerable to flooding using the EPA's Storm Water Management Model (SWMM). The preliminary results show that both rain garden and permeable pavement led to more reduction in peak and total runoff in the more suburban catchment than in the more rural catchment. In the same catchment, permeable pavement showed more reduction of runoff than rain garden. Permeable pavement could reduce total runoff up to 21% in total runoff and 17% in peak runoff, while the percentages of reduction for rain garden were up to 1.3% and 3.8% respectively. Combining these two types of infrastructure showed effect dominated by permeable pavement. However, permeable pavement can be extraordinarily expensive, and its replacement of existing infrastructure is unrealistic. Future analysis will focus on evaluating additional green infrastructure types with different design parameters individually and combined with multiple storm event intensities. The research will facilitate implementation of low-maintenance green infrastructure in the city of Moss Point to mitigate flood risks.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Carlisle A.

The presentation will review several case studies in which the hydraulic analysis and design was improved using two-dimensional hydraulic modeling. The Standard for Hydraulic Modeling is a One-Dimensional Modeling Routine developed by USACE Hydrologic Engineering Center (HEC-RAS, HEC River Analysis System). The model computes water surface elevations (WSE) by solving the energy equation using a standard step method between cross sections, using inputs such as geometry (cross section data), roughness Parameters (Manning "N" values), boundary conditions, and discharge/flow data (steady or unsteady). The model predicts average WSE and velocity for the cross section, main channel, and both overbanks. Certain site-specific conditions can present challenges when using 1D modeling, including a) project areas with flood flows that vary spatially, b) floodplain encroachments with skewed alignments to overall floodplain, c) Modeling multiple openings within one floodplain, and d) assessing and quantifying lateral discharge. When these constraints arise, 2D modeling can improve the modeling and subsequent design. The 2Dhydraulic models include the generation of a mesh with variable number of elements over the project domain, and computes hydraulic parameters at each element node using a finite volume approach. (HEC-RAS 2D, SRH-2D, FLO-2D, Others). The 2D models aide with the challenging constraints mentioned above. Other advantages include assessing the impact of flood storage in project domain, and the impact of floodplain encroachment ineffective flow area zones (useful in bridge scour / approach XS estimation). 2D models utilize similar inputs as 1D, including discharge data, boundary conditions, terrain (geometry), and roughness Parameters (Manning's "n"). Within 2D models, the terrain and roughness inputs are included for the entire project domain (floodplain) instead of at specific cross section locations (1D). For terrain, utilize available LiDAR elevation data and merge with field survey topographic data. This creates a mesh with elements to simulate actual field conditions. or roughness parameters, the National Land Cover Datasets can be used for large project domains or digitize roughness polygons for smaller domains. It is noted that 1D models are still utilized to obtain boundary conditions for the 2D analyses. In this presentation, we will review four case studies to demonstrate examples of each application below and discuss how 2D capabilities improved the hydraulic modeling at each Case Study.

1. Subject areas with flood flows that vary spatially.
2. Floodplain encroachments with skewed alignments to overall floodplain.
3. Modeling multiple openings with floodplain.
4. Assessing and quantifying lateral discharge.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Buie T., Farmer M.

The Mississippi Department of Transportation (MDOT) has the responsibility to ensure the safety of the traveling public along Mississippi's highways and interstates. This includes highway crossings that occur over water. The riverine systems at these crossings are constantly evolving based on their own geomorphology and independent dynamic factors upstream and downstream of the site. The channel banks of these systems can become unstable due to stream migration and potentially threaten the bridge abutments and highway embankments. This presentation will explore two examples of countermeasures that MDOT plans to implement for bank stabilization throughout the state—Bendway Weirs and Longitudinal Fill Stone Toe Protection (LFSTP). Based on guidance from the Federal Highway Administration, these countermeasures are modeled using 2-dimensional (2D) modeling methods as opposed to 1-dimentional (1D) modeling due to the former resulting in greater detail around the countermeasures. Each of these countermeasures has their own design challenges, and the greater detail provided by 2D modeling processes provide a higher level of confidence in design.

Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Gitter A., Bauer C., Wu F., Chavarria C., Mena K.

Community-specific wastewater monitoring programs gained international attention during the COVID-19 pandemic due to their ability to detect SARS-CoV-2 genes in wastewater and consistently predict spikes in clinical cases one to three weeks in advance. The border city of El Paso, Texas - a predominantly Hispanic community with nearly 52% of its population experiencing a low socioeconomic status- acutely suffered from the COVID-19 pandemic. In April 2020, the water utility, El Paso Water, initiated a SARS-CoV-2 wastewater monitoring program to assess virus trends and the appropriateness of a wastewater monitoring program for the binational city. Weekly sample collection continues to occur at four wastewater treatment facilities, serving distinct regions of the city. Previous work analyzing SARS-CoV-2 genes using the CDC 2019-Novel coronavirus Real-Time RT-PCR diagnostic panel identified a lag time between virus concentrations in wastewater and reported COVID-19 case rates ranging from 4 to 24 days. While the wastewater monitoring program at El Paso Water continues to expand (now monitoring for 10 viral pathogens), a critical need remains to translate wastewater data for public health preparedness and community health needs. Engaging local communities to identify public health concerns and experiences, through community health workers and surveys, will be needed to not only inform future wastewater monitoring directions, but also develop trust in the science. Additionally, utilizing quantitative microbial risk assessment to evaluate population-level health risks and potentially establish baseline concentrations for pathogens in wastewater (i.e., SARS-CoV-2) should be pursued. Establishing a framework for collecting, monitoring, translating and disseminating wastewater data will assist disease prevention efforts in the region. Wastewater is a critical resource to meet not only the limited water supply needs of El Paso, located in the arid Chihuahuan Desert, but also the public health needs of its community.