Climate change impacts on agricultural water availability in the middle Rio Grande Basin

Authors: SAMIMI, MARYAM - Oklahoma State University; MIRCHI, ALI - Oklahoma State University; TOWNSEND, NOLAN - University Of New Mexico; GUTZLER, DAVID - University Of New Mexico; DAGGUBATI, SUBHASH - Oklahoma State University; AHN, SO RA - Texas A&M Agrilife; SHENG, ZHUPING - University Of New Mexico; Moriasi, Daniel; GRANADOS-OLIVAS, ALFREDO - Non ARS Employee; ALIAN, SARA - Oklahoma State University; MAYER, ALEX - University Of Texas - El Paso; HARGROVE, WILLIAM - University Of Texas - El Paso

Submitted to: Journal of the American Water Resources Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2022
Publication Date: 2/7/2022
Citation: Samimi, M., Mirchi, A., Townsend, N., Gutzler, D., Daggubati, S., Ahn, S., Sheng, Z., Moriasi, D.N., Granados-Olivas, A., Alian, S., Mayer, A., Hargrove, W. 2022. Climate change impacts on agricultural water availability in the middle Rio Grande Basin. Journal of the American Water Resources Association. 58(2): 168-184.

Interpretive Summary: Overexploitation of limited water resources to meet diverse uses in arid/semi-arid regions like the southwestern U.S. makes them vulnerable to severe water stress under changing climate. Specifically, increased frequency of prolonged droughts will likely intensify water shortages in irrigated agricultural areas in this region. In this study, we analyzed future (through year 2100) water availability projections in the heavily irrigated Elephant Butte Irrigation District (EBID) agricultural watershed located within the Rio Grande Basin in the U.S. Desert Southwest. We used streamflow projections under a wide range of climatic conditions and the Soil and Water Assessment Tool model to evaluate future inflows to the main surface water reservoirs, possible future reservoir releases, and groundwater pumping needed to sustain irrigated agriculture. Results indicate declining reliability of reservoirs to meet the water demand for irrigated agriculture in the EBID. An option that can be used to mitigate the impact associated with declining surface water is groundwater, which, however, increases pressure on this already-strained water resource. Instead, the region should be prepared to use marginal-quality groundwater (TDS > 3000 mg/L) as fresh groundwater is depleted during the 21st century under hotter and drier conditions and current agricultural land and water management practices. In addition, it is necessary for water resource managers to improve the efficiency of irrigation with the ultimate goal of reducing net agricultural water consumption in the region.

Technical Abstract: Robust analysis of water availability under plausible future climate conditions is essential for adaptive water resources management, especially in water scarce regions. We analyzed water availability projections in a heavily irrigated agricultural watershed located in the middle section of the Rio Grande Basin in the U.S. Desert Southwest. We used a subset of future managed streamflow scenarios (through year 2100) from among 97 scenarios developed based on downscaled, bias-corrected global climate model outputs to evaluate future inflows to the principal surface water storage reservoirs, possible future reservoir releases, and groundwater pumping to sustain irrigated agriculture. The streamflow projections describe a wide range of dry and wet conditions compared to the average historical flows in the river, indicating significant uncertainty in future water availability in the Rio Grande Basin. We applied the Soil and Water Assessment Tool (SWAT) to illustrate the impact of climate futures on different components of the water budget at a watershed scale. Results indicate declining reliability of reservoir storage to meet the water demand of irrigated agriculture in the Elephant Butte Irrigation District (EBID). The impact of declining surface water can be offset by increasing the pressure on the already-strained groundwater resources. However, the region should be prepared to use marginal-quality groundwater (TDS > 3000 mg/L) as fresh groundwater is depleted within the 21st century under hotter and drier conditions and status quo agricultural land and water management practices.