Assessing the impacts of long-term climate change on hydrology and yields of diversified crops in the Texas High Plains

Simulating the potential impacts of future climate change on hydrology and crop yields provides opportunities to select suitable crops and improve the climate change resilience of agricultural systems. The Texas High Plains (THP), a significant agricultural region in the United States (U.S.), is confronted with substantial challenges from climate change risks and the depletion of the Ogallala Aquifer’s groundwater supply. This study quantified the influences of climate change on water demands and yields of staple crops under both irrigated farming and dryland farming in addition to continuous fallow at Bushland of the THP using an improved Soil and Water Assessment Tool (SWAT) model. The model incorporates management-allowed depletion (MAD) irrigation scheduling and a dynamic carbon dioxide (CO2) input method (SWAT-MAD-CO2). Future climate data projected by the latest bias-corrected 22 General Circulation Models (GCMs) of the Coupled Model Intercomparison Project 6 (CMIP6) under three Shared Socioeconomic Pathway (SSP) emission scenarios of SSP1–2.6, SSP2–4.5, and SSP5–8.5 were used. The modeling results indicated a mixed change in actual evapotranspiration (ETa) across different irrigated crops, while ETa generally increased (2.4%-11.5%) for dryland crops and continuous fallow under the future climate change scenarios compared to the baseline period (1986–2015). Irrigation water use (except irrigated cotton) was expected to decrease, with larger reductions under three SSP scenarios for future irrigated winter wheat (16.1%-85.5%) and irrigated sorghum (18.1%-78.0%) compared to other irrigated crops over two 30-year periods. Regarding crop yields, the annual yield for future irrigated cotton, irrigated sunflower, and dryland cotton was expected to increase by 109.3%-142.7%, 1.1%-9.4%, and 93.9%-150.2%, respectively, compared to the baseline period. Conversely, the simulated yields of the irrigated sorghum and dryland soybean showed the greatest reductions of 6.4%-27.3% and 5.9%-51.3%, respectively, under the climate change scenarios relative to the baseline period.