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Abstract

Urban and socio-economic expansion along with shifts in hydroclimatic trends (e.g. precipitation, temperature, evapotranspiration) significantly affect surface water resources, causing serious threats for humans and the environment. The identification of key controls contributing to changes in the extent of surface water bodies is key to guarantee the preservation of freshwater ecosystems and limit water scarcity. In this work, we evaluate the change in surface water extent and the variation of several potential anthropogenic and hydroclimatic drivers that occurred between 1984 and 2020 within the river basins of the contiguous United States (CONUS). Our analysis reveals that there has been an expansion of surface water extent over the majority of the CONUS, which was mainly induced by an increase in the mean annual precipitation, mostly in river basins with a continental and temperate climate. Conversely, river basins across the arid southwestern region of the CONUS show a reduced surface water extent, mainly influenced by temperature rise and population growth. River basins sharing the same climatic condition present similar trends of change in surface water extent and its drivers. In particular, arid river basins show a distinct pattern of variations with respect to other climatic regions of the CONUS, which highlight the need to further analyze these vulnerable areas where surface waters are greatly affected by anthropogenic activities and climatic variability.