Analyzing precipitationsheds to understand the vulnerability of rainfall dependent regions

[摘要] It is well known that rivers connect upstream and downstream ecosystemswithin watersheds. Here we describe the concept of precipitationsheds to showhow upwind terrestrial evaporation source areas contribute moisture forprecipitation to downwind sink regions. We illustrate the importance ofupwind land cover in precipitationsheds to sustain precipitation incritically water stressed downwind areas, specifically dryland agriculturalareas. We first identify seven regions where rainfed agriculture isparticularly vulnerable to reductions in precipitation, and then map theirprecipitationsheds. We then develop a framework for qualitatively assessingthe vulnerability of precipitation for these seven agricultural regions. Weillustrate that the sink regions have varying degrees of vulnerability tochanges in upwind evaporation rates depending on the extent of theprecipitationshed, source region land use intensity and expected land coverchanges in the source region.

[学科分类] 地球化学与岩石