Adaptive Agricultural Water Management to Cope with Warm-Dry Future in the US Desert Southwest

Abstract:

Adaptive water resources management is necessary to sustain agricultural activities and food security in arid and semi-arid regions dealing with water scarcity exacerbated by climate variability, groundwater depletion, and intensified non-agricultural competition for water. We examine the middle section of the Rio Grande River basin as an example of an arid watershed with heavily irrigated agriculture to support cultivation of water-intensive crops like pecan and alfalfa. Water availability analysis taking into account plausible surface water projections in this region indicates growing risk of decline of water resources below the supply needed to sustain present-day agricultural production by mid-twenty first century. Diminished projected flow of the Rio Grande into Elephant Butte Reservoir, the main surface water supply in the region, increases the pressure on limited fresh to slightly saline groundwater storage. This means that farmers should prepare to adapt to the unfolding water availability challenges. We applied soil and water assessment tool (SWAT) and SWAT+ to determine the long-term impacts of potential options for land and water management adaptation, such as crop pattern change, deficit irrigation, and drip irrigation, and to identify opportunities for agricultural water conservation while maintaining the current production levels of high-value crops. Results inform adaptation pathways that can be considered by agricultural producers as they prepare to operate under conditions of increased renewable water variability and groundwater depletion.