Inland hydro-climatic interaction: Effects of human water use on regional climate

This study has quantified the regional evaporation and evapotranspiration changes, and the associated latent heat flux and surface temperature changes in the Central Asian region of the Aral Sea drainage basin and the Aral Sea itself from the pre-1950 period of the 20th century to 1983-2002. The human water use for irrigation yielded an average regional cooling effect of -0.6 degrees C due to increased evapotranspiration and latent heat flux from the irrigated land. The runoff water diverted for irrigation was more than 80% of the pre-1950 runoff into the terminal Aral Sea, and was largely lost from the regional water system by the evapotranspiration increase. The Aral Sea shrank due to this water loss, resulting in decreased evaporation and latent heat flux from the pre-1950 Aral Sea area extent, with an average regional warming effect of 0.5 degrees C. In general, the endorheic (land-internal) runoff and relative consumptive use of irrigation water from that runoff determine the relative inland water area shrinkage, its warming effect, and to what extent the warming counteracts the cooling effect of irrigation. Citation: Destouni, G., S. M. Asokan, and J. Jarsjo (2010), Inland hydro-climatic interaction: Effects of human water use on regional climate, Geophys. Res. Lett., 37, L18402, doi: 10.1029/2010GL044153.