Megacity precipitationsheds reveal tele-connected water security challenges

摘要: Urbanization is a global process that has taken billions of people from the rural countryside to concentrated urban centers, adding pressure existing water resources. Many cities are specifically reliant on renewable freshwater regularly refilled by precipitation, rather than fossil groundwater or desalination. A precipitationshed can be considered "watershed sky" and identifies origin precipitation falling in given region. In this paper, we use concept determine sources supply watersheds largest world. We quantify for 29 megacities analyze their differences between dry wet years. Our results reveal 19 depend more third evaporation land. also show many megacities, terrestrial dependence higher This high exposes these potential land-use change could reduce generates precipitation. Combining indicators stress, moisture recycling exposure, economic capacity, vegetation-regulated evaporation, change, dry-season sensitivity reveals four highly vulnerable (Karachi, Shanghai, Wuhan, Chongqing). further six were found have medium vulnerability with regard supply. conclude understanding how upwind landscapes affect downwind municipal resources key component complexity security.