Climate Change Impacts on Spatiotemporal Soil Water Extremes in Geophysically Diverse Watersheds: A Comparison between East and West Tennessee Watersheds

AbstractClimate change impacts hydrologic processes, compelling more regional water budget studies to understand spatiotemporal hydrological extremes. This study investigates the effects of climate change on water budgets, with a focus on soil moisture, in two Tennessee watersheds with different geoclimatic characteristics, the Obion and Nolichucky Rivers. Using the variable infiltration capacity (VIC) hydrological model, the study projects water budgets for these watersheds until 2099, analyzing annual and seasonal runoff, recharge, and soil moisture to identify trends and extremes. Results showed that an increase in temperature of 2.7°C–6.4°C and a change of precipitation by 1%–4% is predicted for Tennessee, which will impact seasonal patterns, water balances, and soil moisture regimes. The overlapping of such impacts can lower soil moisture below the wilting point during 40%–50% of the growing season, impacting crop yields. The study identifies field capacity, clay soil percentage, and organic matter as key factors impacting the spatial extremes of croplands’ irrigation requirements. These findings underscore the need to understand soil moisture variability and extreme soil water conditions to optimize soil water management scenarios and mitigate future water shortage risks.