Tuesday, 16 January 2007: 2:00 PM
Atmospheric Transfer of Surface Water between Basins and Between Nations
214A (Henry B. Gonzalez Convention Center)
We generally think of surface water draining from networks of streams and rivers within a basin to the sea, often crossing international boundaries and carrying with it economic and environmental consequences as those waters resources are managed or altered that can heighten tensions between nations. However, the atmosphere is a medium for transporting vast quantities of water across basin and national boundaries. Since terrestrial evapotranspiration is a major source of water vapor in the air, there is in effect an atmospheric channel for the transfer of water between river basins, between countries, or between any arbitrarily delineated areas of the land surface. We have calculated the inter-basin and international transfers of water by the atmosphere that falls as precipitation over delineated land areas using a quasi-isentropic back-trajectory analysis based on observed precipitation and atmospheric reanalyses. Evaporative sources for key basins and nations will be presented in terms of their mean seasonal cycle and interannual variability. We will focus on some of the hydrologic and political implications of the results, and put forward a new perspective for thinking of water resource exchange.