The Role of Spatial Water Right Data in Understanding Anthropogenic Effects on the Water Balance

ABSTRACT Water regulation, extraction, and application have major effects on water availability. We investigated the impact of anthropogenic water use on the water balance in two intensively irrigated headwater watersheds in Wyoming using geospatially comprehensive water right data in a watershed hydrologic‐allocation modeling framework. Water balance variables were compared under natural flow conditions and scenarios representing water right appropriative demands. Across both watersheds, the full appropriative demand scenario resulted in a 54% decrease in streamflow, an 18% increase in evapotranspiration, and a 6% decrease in watershed storage during the growing season. The study watersheds exhibited distinct responses to the scenarios with incremental changes in potential return flow and appropriative demand, reflecting differences in water right network structure, spatial density, use, and appropriative demand. Testing the effects of spatial and non‐spatial water right characteristics revealed significant relationships between changes in streamflow and factors such as trans‐watershed transfers and water right spatial density. Resource distribution among water balance components varied by sub‐watershed, with reduced variability at larger watershed scales. The differences in water balance changes between scenarios within the study watersheds highlight the importance of geospatially comprehensive water right data in incorporating abstractions in hydrologic models.