In this study the Penman-Monteith reference evapotranspiration at 150 meteorological stations during 1960-2000 in the Changjiang (Yangtze River) catchment in China are calculated，compared and regionally mapped. Their spatial distributions andrntemporal variations are examined and the causes for the variations are discussed. For the whole catchment，there is a significant decreasing trend in the reference evapotranspiration and which is mainly caused by a significant decrease in the net total radiation and wind speed over the catchment.
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