Comparing Crop Evapotranspiration Estimation Methods to Evaluate Water-Saving Potential of Alternative Land Uses in the San Joaquin Valley, California

This study explores strategies for water conservation by repurposing agricultural land in California’s San Joaquin Valley (SJV) for alternative uses like habitat restoration, groundwater recharge, and solar energy development. Water availability in the region has become increasingly constrained due to climate variability and regulatory restrictions under the Sustainable Groundwater Management Act (SGMA), which mandates groundwater sustainability through reduced extraction and enhanced recharge. Climate change and expansion of water intensive high-value crops are further increasing agricultural water demand and exacerbating water scarcity. One proposed water demand management strategy is land fallowing, but leaving land idle can have significant financial and environmental trade-offs. Repurposing fallowed land for alternative uses can address these trade-offs and deliver benefits beyond water savings. Using the VIC-CropSyst, an agrohydrology model, this study assesses water savings across various land-use and climate change scenarios. Results show annual water savings between 370 and 3,740 million m3, requiring the fallowing of 838 to 4,360 km2 of farmland, with estimated revenue losses ranging from $0.87 billion to $4.4 billion. Habitat restoration and groundwater recharge are identified as the most effective strategies for reducing water demand, while solar development offers moderate savings. Perennial crops, particularly almonds, demonstrate the highest water demand reductions, while corn shows the least. The findings underscore the importance of crop-specific and farm-centric strategies to optimize water use. These insights will aid policymakers in developing multi-benefit land repurposing policies to support sustainable water management in the SJV amidst climate challenges.