Abstract
The amount of evapotranspiration in the Minamitani, which experienced a period of forest decline and Kitatani that had no forest decline, was calculated by the short-time period water-budget method of calculating critical discharge based on the discharge duration curve in the Tatsunokuchi-yama Experimental Watershed from 1960 to 1965. As for the results calculated by the proposed method, daily evapotranspiration were estimated throughout a consultation period in both watersheds. Using the different average discharge duration curves of 1∼22 water years to establish the average discharge duration curve, the difference between the annual evapotranspiration based on the proposed method and the annual loss by the water budget was from 1.5 to 3.2%. It was possible for the proposed method to accurately estimate daily evapotranspiration in the Tatsunokuchi-yama Experimental Watershed, which experienced a period of forest decline.
