Xinyu Sun , Kendra Spence Cheruvelil

Quantifying and predicting precipitation and its influence on ecosystems is challenged by the asynchrony between precipitation and water fluxes. To account for this asynchrony, scientists and managers use “water year” to estimate precipitation and its impacts on water flow and ecosystems. However, traditional water year definitions either do not consider areal variation in climate and hydrology or cannot be applied at the regional or continental scale. Using an existing definition whereby the water year begins in the month with the lowest average monthly streamflow, we developed a local water year (LWY) that considers spatial variation and can be applied at the continental scale. We employed a spatial interpolation technique to assign LWY start and end months to 202 subregions across the conterminous U.S. that range from 4,384 to 134,755 km2. This dataset can be linked with diverse climate, terrestrial, and aquatic data for broad-scale studies.