Long-term conjunctive water management for agriculture with groundwater salinity

Authors: YAO, YIQING - University Of California, Davis; LUND, JAY - University Of California, Davis; Levers, Lucia

Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2026
Publication Date: 7/16/2026
Citation: Yao, Y., Lund, J., Levers, L.R. 2026. Long-term conjunctive water management for agriculture with groundwater salinity. Journal of Irrigation and Drainage Engineering. 152(5):04026028-1-04026028-11. https://doi.org/10.1061/JIDEDH.IRENG-10727.
DOI: https://doi.org/10.1061/JIDEDH.IRENG-10727

Interpretive Summary: Overuse of groundwater and saline groundwater in agricultural regions lead to lower crop yields and difficulties managing water. Using an optimization model, we look at water and crop management, including aquifer recharge, over the long term in California’s San Joaquin Valley. We show that increasingly saline groundwater impacts perennial crop potential. Saline aquifer management must be approached differently than freshwater aquifers. Saline aquifers require earlier recharge and slower extractions to maximize their agricultural use.

Technical Abstract: Chronic groundwater overdraft and salinity limit irrigated agriculture, threaten crop yield, and reduce flexibility in groundwater management in California and other (semi-)arid regions. Higher salinity reduces groundwater’s ability to irrigate in drier years, when fresher water is less available to dilute more saline groundwater. This paper examines long-term water and crop management with groundwater salinity and hydrologic variability, similar to conditions in California’s western San Joaquin Valley using hydro-economic optimization. A decadal stochastic quadratic optimization model is embedded within a 10-stage dynamic program to suggest optimal long-term decisions for perennial crop acreage and groundwater storage for various aquifer recovery targets to maximize net expected economic benefits of crop production and conjunctive use including groundwater salinity. Results show that salts accumulating in groundwater in an undrained aquifer decreases perennial crop acreage with time regardless of the final groundwater storage target (either net recharging or net extraction). Groundwater management with greatly reduced net extraction and much earlier aquifer recharge to slow salinity accumulation and prolong the long-term utility of groundwater.