Projection of Climate Change Impacts on Groundwater Resource in Forestlands of Mississippi Embayment

Abstract:

Climate change exacerbates vulnerability and uncertainty to groundwater resources. Currently, few efforts have been devoted to evaluating the impacts of climate change on groundwater resources in forestlands. In this study, the US Geological Survey’s MERAS (Mississippi Embayment Regional Aquifer Study) model was applied to estimate the past- and future-climate changes on hydrological processes, budgets, and spatial distributions of groundwater in the forestlands of Mississippi Embayment, US. The modeled domain of MERAS encompasses Alabama, Mississippi, Louisiana, Arkansas, Tennessee, Kentucky, Illinois, and Missouri. Two simulation scenarios were employed in this study. The first scenario estimated the past century-long (from 1900 to 2014) climate change impacts on groundwater resource in forestlands, whereas the second scenario projected the future climate change impacts on groundwater resource with the ±5% changes in net groundwater recharge rate that represent the wet and dry climatic conditions. On average over the century-long simulation period, the groundwater recharge ranged from 0.40 to 1.48 m³/d/ha; the stream leakage to groundwater was 0.65 m³/d/ha; and the groundwater storage ranged from 0.23 to 2.13 m³/d/ha. Results demonstrated that groundwater recharge and stream leakage played an important role in the forestland groundwater storage. In general, the groundwater level declined with a range from 2.1 to 16.0m as time elapsed from 1900 to 2014, which occurred primarily due to the intensive groundwater pumping for crop irrigation. Simulations further revealed that future climate change impacts on groundwater level decline were not discernable because of the thick clay layer presented in large parts of Mississippi Embayment. This clay layer reduces precipitation entering into the deep aquifer. Overall, the groundwater pumping rather than climate change is a key driving force for groundwater depletion in the Mississippi Embayment.