Impacts of ongoing land-use change on watershed hydrology and crop production using an improved SWAT model

Authors: LI, BAOGUI - China Agricultural University; Marek, Gary; MAREK, THOMAS - Texas A&M Agrilife; PORTER, DANA - Texas A&M Agrilife; ALE, SRINIVASULU - Texas A&M Agrilife; MOORHEAD, JERRY - Xcel Energy; Brauer, David; SRINIVASAN, RAGHAVAN - Texas A&M Agrilife; CHEN, YONG - China Agricultural University

Submitted to: Land
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2023
Publication Date: 3/1/2023
Citation: Li, B., Marek, G.W., Marek, T.H., Porter, D.O., Ale, S., Moorhead, J.E., Brauer, D.K., Srinivasan, R., Chen, Y. 2023. Impacts of ongoing land-use change on watershed hydrology and crop production using an improved SWAT model. Land. 12(3). Article 591. https://doi.org/10.3390/land12030591.
DOI: https://doi.org/10.3390/land12030591

Interpretive Summary: Decades of pumping combined with limited recharge has resulted in decreased groundwater levels in the southern Ogallala Aquifer. Alternative cropping systems using less water intensive crops such as cotton may extend limited groundwater resources in the Texas Panhandle region. Traditionally, cotton was grown predominately in the Texas Southern High Plains (SHP) but recently, cotton acreage has increased in the Texas Northern High Plains (NHP). Researchers from Texas A&M and USDA-ARS Bushland simulated associated crop water use for watersheds in the SHP and NHP using the Soil and Water Assessment Tool (SWAT) equipped with recently developed management allowed depletion (MAD) auto-irrigation function. Simulations of cotton production in the NHP resulted in reductions of 18%, 7%, and 44% in annual irrigation, crop water use, and runoff, respectively. These reductions are likely understated due to the lack of cotton production data for the NHP, which use anecdotally less water than those used in the simulations.

Technical Abstract: The southern Ogallala Aquifer continues to deplete due to decades of irrigation pumping with minimal groundwater recharge. Corn (Zea mays L.), which requires intensive irrigation management, has been the predominant irrigated crop in the Northern High Plains (NHP) of Texas. Cotton (Gossypium hirsutum L.), a relatively less water-intensive crop, which is mainly cultivated in the Southern High Plains (SHP) of Texas, has been grown on increasing number of acres in the NHP in the recent times. This change in land use from corn and winter wheat (Triticum aestivum L.) cropping systems to cotton could serve as an option to prolong the availability of the Ogallala Aquifer in the NHP. The goal of this study is to evaluate the performance of a newly developed management allowed depletion (MAD) auto-irrigation method in the Soil and Water Assessment Tool (SWAT) model in the Double Mountain Fork Brazos watershed in the SHP and the Palo Duro watershed in the NHP, and assess the impacts of land use change from corn/wheat to cotton in the Palo Duro watershed on water balance using the SWAT-MAD model. Results indicated the MAD auto-irrigation method resulted in improved simulations of cotton irrigation and yield compared to the plant water demand (PWD) auto-irrigation method in the Double Mountain Fork Brazos watershed. In the Palo Duro watershed, the MAD method outperformed the PWD method in simulating corn irrigation and streamflow. Land use change from irrigated corn to irrigated cotton in the Palo Duro watershed led to the reduction in average (2000-2014) annual irrigation, evapotranspiration (ET), and surface runoff by 18%, 7%, and 44%, respectively. However, replacement of irrigated wheat with irrigated cotton caused 5%, 3%, and 28% reduction in those hydrologic parameters. Land use conversion from dryland wheat to dryland cotton showed 1% and 12% decrease in ET and surface runoff.