ESTIMATION OF EVAPOTRANSPIRATION FOREST AREAS IN SNOWY AND COLD REGIONS

This paper deals with estimation of actual evapotranspiration in order to evaluate the hydrologic cycle in a catchment area. Estimation of the hydrologic cycle is required for effective water use, flood control, and evaluation of water environment. However, it is difficult to estimate evapotranspiration in a wide area because of a scarcity of measured data. A method for using remote sensing data to estimate evapotranspirasion is proposed. In previous studies, NDVI values were applied to estimate the evapotranspiration. However, estimated results did not consider water balance in the catchment area scale. We calculate the evapotranspiration several dam catchmment areas in a snowy and cold region. The study areas are covered by mountains with steep slopes and its land use is entirely forested. In these areas, topographic effects on rainfall as well as snowfall must be taken into account. Rainfall and snowfall are accurately estimated by taking into account topographic factors such as elevation and direction of slope. As a result, actual evapotranspiration is calculated by applying the water balance method based on precipitation data. Finally, actual evapotranspiration is related to NDVI values so that it can be generally estimated in a wide catchment area