Proceedings of the 2019 Mississippi Water Resources Conference

Year: 2019 Authors: Ouyang Y., Jin W., Feng G., Yang J.

Groundwater depletion due to anthropogenic activities is an issue of water resource concern worldwide, while climate change adds the uncertainties to this concern. Currently, very few efforts have been devoted to projecting the impact of climate change on groundwater resources in forest and crop lands in Mississippi, which is crucial to water resource managers and farmers in the region. In this study, we modify the USGS's MERAS (Mississippi Embayment Regional Aquifer Study) model to assess the impact of potential climate change on groundwater flow and level in the Upper Yazoo River watershed (UYRW), Mississippi. This watershed consists of two major land uses: one is the forest land and the other is the crop land. Three simulation scenarios were developed in this study. Scenario 1 is a base scenario with the input parameter values similar to those of MERAS model. Scenarios 2 and 3 are the same as Scenario 1 except that Scenario 2 increased while Scenario 3 decreased the groundwater recharge rates by 1 and 2%. The latter two scenarios were developed based on our observations of the past 100 plus years' rainfall trends. In general, the impact of climate change on groundwater flow in the UYRW was primarily through its impact on groundwater recharges due to the changes in rainfall events. Simulation results showed that a 2% increase in groundwater recharge rate increased average groundwater head by 0.39 ft after 21 years, whereas a 2% decrease in groundwater recharge rate decreased groundwater head by 0.36 ft after 21 years. Furthermore, a 2% increase in groundwater recharge rate increased groundwater volume by 201,401 ft³/y after 21 years, while a 2% decrease in groundwater recharge rate decreased groundwater volume by 185,909 ft³/y after 21 years. Impacts of climate change through its impacts on groundwater recharge due to rainfall change were discernable. Further study is therefore warranted to apply the same approach to estimate impacts of climate change on groundwater resources for the entire Mississippi Embayment Regional Aquifer by combing the MERAS and HSPF models using the Integrated Hydrologic Model.