The relationship between climate and water supply in the American West has been altered by changes in water storage management, water diversion, and agricultural and urban water infrastructure. The strength of coupling between water supply and climate is measurable, should vary with rate of water development in a basin, and will vary geographically from headwaters to downstream. However, most existing literature on coupled climate-watershed systems focuses on either the highest elevation headwaters where water is sourced or the large agricultural and urban centers much further downstream. While management of headwater regions of the western United States determine the strength of coupling between climate and water availability downstream, more attention is needed on how water is managed in between upland source areas and large-scale agricultural and population centers. To this end, I focus on First Users areas, which sit between the highest and lowest parts of a basin. First Users areas are often characterized by lower agricultural capacity and population, a relative lack of political power in water management decisions, distinct land-use patterns (e.g., hay production for use in grazing rather than row crops), proximity to publicly managed lands, and the presence of senior but relatively low quantity water rights. Using a set of physical and social criteria, I delineate western basins into archetypes to develop a preliminary social-environmental model of the First Users areas. I will show a method of evaluation for the strength of coupling with regards to recorded and future projected climate variability and subsequent responses to basins in the American West. Physical and social relationships in western basins are nonlinear and occur in both upstream and downstream directions, and this research will further the understanding of these relationships as water availability changes in the region.
Geography and Earth Lab Graduate Student, CU Boulder
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