On the regional characteristics of actual evapotranspiration derived from landsat MSS and elevation data

Abstract

Abstract The system to estimate actual evapotranspiration (ET) over wide area has been developed. The method of estimation is based on modified Penman's method and utilized Landsat MSS, elevation and ground observed meteorological data. The distinctive feature of this system is that it estimates ET not by directly using spectral data but by combining empirical parameters. Therefore once landuse data are produced from Landsat MSS data, various climatic condition can be applied to calculation. To examine the regional characteristics of ET, several watershed areas are selected in Japan. Then both local characteristics of landuse and topography and regional characteristics of climate are found to be equally influencing the amount of ET. Moreover the calculation in the case of occurring landuse conversion according to land grading is executed. Its result has given the possibility to parameterize the amount of ET using a few parameters, that is the regional averaged value of albedo and/or soil heat flux constant.