It is well known that rivers connect upstream and downstream ecosystems within watersheds. Here the authors describe the concept of ‘precipitationsheds’ to show how upwind terrestrial evaporation source areas contribute moisture for precipitation to downwind sink regions.

The authors illustrate the importance of upwind land cover in precipitationsheds to sustain precipitation in critically water stressed downwind areas, specifically dryland agricultural areas. The authors first identify seven regions where rainfed agriculture is particularly vulnerable to reductions in precipitation, and then map their precipitationsheds.

The authors then develop a framework for qualitatively assessing the vulnerability of precipitation for these seven agricultural regions. The authors illustrate that the sink regions have varying degrees of vulnerability to changes in upwind evaporation rates depending on the extent of the precipitationshed, source region land use intensity and expected land cover changes in the source region.

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