Quantifying Baseflow Changes Due to Irrigation Expansion Using SWAT+gwflow

Baseflow, the portion of streamflow sustained by groundwater discharge, is crucial for maintaining river ecosystems. Irrigation practices significantly influence this interaction, with varying impacts depending on the method and intensity of water use. Excessive groundwater extraction can deplete aquifers, reduce baseflow, and disrupt the balance between groundwater and surface water. This study evaluates the effects of irrigation expansion on baseflows and develops a predictive tool to assess future agricultural impacts on water resources. The SWAT+gwflow model is applied to the San Antonio Catchment, Uruguay, a region dominated by intensive horticulture and citrus farming, where irrigation relies on groundwater pumping. With increasing irrigation demands, the study finds a decline in both baseflow and groundwater levels due to higher extraction rates. This modeling approach enables the identification of spatial variations in baseflow, surface water–groundwater exchanges, and groundwater storage, providing valuable insights at a sub-catchment scale. The findings contribute to a better understanding of hydrological responses to irrigation expansion, supporting sustainable water management strategies in agricultural regions.