Climate change impacts on spatio-temporal soil water extremes in geophysically diverse watersheds: A comparison between east and west Tennessee watersheds

Authors: SAHA, PROBAL - University Of Tennessee; HATHAWAY, JOHN - University Of Tennessee; SCHWARTZ, J - University Of Tennessee; WILSON, CHRIS - University Of Tennessee; ABBAN, BENJAMIN - Us Bureau Of Reclamation; Papanicolaou, Athanasios - Thanos

Submitted to: Journal of Hydrology: Regional Studies
Publication Type: Review Article
Publication Acceptance Date: 12/29/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: In the Southeast United States, urbanization and agricultural expansion under a changing climate threaten crop yields, infrastructural sustainability, and river ecosystems, making the region a hotspot for future soil water deficits. Because of the large variability in land cover, topography, and geology in Tennessee moving from east to west, a study comparing the spatial and temporal patterns of soil water extreme conditions would provide valuable insight for understanding the role of these watershed-scale characteristics in regulating climate change effects. Understanding the climate change impacts across different geo-climatic watersheds is vital for sustainable short and long-term management of the soil water deficits. This information will be valuable to scientists and natural resources managers to understand these complex interactions which occur in agricultural fields/watersheds and adapt accordingly to water shortages.

Technical Abstract: With climate change impacts on hydrologic processes becoming more prevalent, there is need for more regional water budget studies to understand better the spatio-temporal hydrological extremes. Two watersheds in Tennessee, Obion, and Nolichucky River watersheds, with substantially different geo-climatic characteristics, were selected for this study to demonstrate the importance of landcover, topography, and pedology for regulating climate change effects on soil moisture. The hydrological model was used to predict water budgets for the watersheds until 2099. Annual and seasonal analyses of runoff, recharge, and soil moisture were conducted to identify trends and hotspots/ hot moments and discover explanatory variables for these trends. An increase in temperature by 17-45% 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 impacts of increasing temperature and decreased rainfall can lower soil moisture below the wilting point during 40-50% of the growing season, impacting the crop yields. Spatial hotspots were identified in west-central Obion and western Nolichucky, showing both watersheds at risk of extreme soil moisture deficits (Below the critical ratio of 15.6%). These results suggest that understanding soil moisture variability and extreme soil water conditions will be vital for optimizing soil-water management scenarios for croplands and abating regional water shortage risks in the future.