downwind

Jul

2022

Megacity precipitationsheds reveal teleconnected water security challenges

Megacities depend on downwind evapotranspiration: Our results reveal that 19 of 29 megacities depend for more than a third of their water supply on evaporation from land. We also show that for many of the megacities, the terrestrial dependence is higher in dry years. This high dependence on terrestrial evaporation for their precipitation exposes these cities to potential land-use change that could reduce the evaporation that generates precipitation. […] reveals four highly vulnerable megacities (Karachi, Shanghai, Wuhan, and Chongqing). A further six megacities were found to have medium vulnerability with regard to their water supply.

Jul

2022

Analyzing precipitationsheds to understand the vulnerability of rainfall dependent regions

Concept of precipitationsheds, defined as the upwind atmosphere and surface that contributes evaporation to a specific location’s precipitation.:

We illustrate the importance of upwind land cover in precipitationsheds to sustain precipitation in critically water stressed downwind areas, specifically dryland agricultural areas. […] This work demonstrates that seemingly separate parts of Earth’s biophysical system are interlinked with its social systems. Indeed, our results and analysis suggest that food security in some of the world’s most water-constrained rainfed agricultural regions could be very sensitive to distant land cover changes.