Blog: Increasing groundwater salinity changes water and crop management over long timescales
Salinity has often become a major limit for irrigated agriculture in semi-arid regions, from ancient Mesopotamia to parts of California today. A previous blog post showed that conjunctive use with more saline groundwater can differ fundamentally from freshwater aquifers. Higher salinity limits groundwater use for irrigation during dry years, when less surface water is available to dilute groundwater salinity, and increases aquifer pumping in wetter years to avoid water-logging. Brackish groundwater can no longer serves as drought storage, but becomes a supplemental water supply in all years, limited by availability of fresh surface water for diluting salts. This greatly reduces groundwater’s ability to support permanent crops and increases variability in annual crop acreage across different water years, thus reducing profit.