Simulating the impact of climate change on hydrology and crop production in the Northern High Plains of Texas using an improved SWAT model

Authors: CHEN, YOUNG - Texas A&M University; Marek, Gary; MAREK, THOMAS - Texas A&M Agrilife; Moorhead, Jerry; HEFLIN, KEVIN - Texas A&M Agrilife; Brauer, David; Gowda, Prasanna; SRINIVASAN, RAGHAVAN - Texas A&M University

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2019
Publication Date: 4/30/2019
Citation: Chen, Y., Marek, G.W., Marek, T.H., Moorhead, J.E., Heflin, K.R., Brauer, D.K., Gowda, P.H., Srinivasan, R. 2019. Simulating the impact of climate change on hydrology and crop production in the Northern High Plains of Texas using an improved SWAT model. Agricultural Water Management. 221:13-24. https://doi.org/10.1016/j.agwat.2019.04.021.
DOI: https://doi.org/10.1016/j.agwat.2019.04.021

Interpretive Summary: Climate change including increased air temperatures and CO2 concentrations are expected to influence crop growth in the future. Current field research focuses on optimizing crop selection and management under existing climate conditions. However, modeling studies are required to evaluate potential impacts of future climate change on crop water use (ET), yield, irrigation requirements, hydrology, and land use. Researchers from USDA-ARS Bushland, TX and Texas A&M University compared Soil and Water Assessment Tool (SWAT) simulations of irrigated corn, irrigated and dryland sorghum, and fallow through the end of the 21st century using climate prediction data. Results were compared to historical data from the CPRL. Results indicated that climate change would result in decreased ET and yield for both crops due to inhibited transpiration and decreased precipitation. These findings have implications for on regional land use planning.

Technical Abstract: Modeling the effects of climate change on hydrology and crop yield under different land uses provides opportunities for choosing appropriate crops and management practices for adapting to climate change. In this study, the impacts of climate change on irrigated corn and sorghum, dryland sorghum, and continuous fallow land uses in the Northern High Plains of Texas were evaluated using an improved Soil and Water Assessment Tool (SWAT) model equipped with management allowed depletion (MAD) irrigation scheduling. Projected climate data (2020-2099) from the Coupled Model Intercomparison Project Phase 5 (CMIP 5) of 19 General Circulation Models (GCMs) were used. Climate data were divided into four 20-year periods of near future (2020-2039), middle (2040-2059), late (2060-2079), and end (2080-2099) of the 21st century under two Representative Concentration Pathway (RCP) emission scenarios (RCP 4.5 and RCP 8.5). For irrigated corn, median annual crop ET and irrigation decreased by 8%-25% and 15%-42%, respectively, under the climate change scenarios compared to the historical period (2001-2010). The median yield was reduced by 3%-22% relative to the historical yield with exponentially decreased in the latter half of the 21st century. For sorghum, the median annual crop ET and irrigation reductions ranged from 6%-27% and 4%-49%. The median irrigated sorghum yield declined by 6%-42% compared to the historical yield. The median annual crop ET of dryland sorghum decreased by 10%-16%. The reduction in median yield was within 10% of the historical dryland (rainfed) sorghum yield. The decrease in median annual evaporation varied from 15%-23% under future continuous fallow conditions. However, median annual percolation substantially increased by 92%-167%.