REGIONAL EVAPOTRANSPIRATION OVER THE ARID INLAND HEIHE RIVER BASIN IN NORTHWEST CHINA

摘要

Evapotranspiration is the combined process wherebyrnwater is lost from the soil surface by evaporation andrnfrom the plants by transpiration. It is not only a criticalrncomponent in the hydrological cycle but also a main partrnof energy balance because liquid water absorbs largernamount of heat when it transfers into water vapour.rnTherefore, it is very important to give an accuraternestimate of evapotranspiration in water resourcernmanagement and climate change studies. The objectivernof this research presented in this paper is to estimaternspatial and temporal distribution of actual ET andrnquantify the actual ET in Heihe River Basin usingrnremote sensing technology, combining with groundrnobservations. This study has been carried out using thernModerate-resolution Imaging Spectroradiometerrn(MODIS) images and meteorological data for achievingrnthe objective. The physically based Surface EnergyrnBalance System (SEBS) model was applied forrnassessing the spatial and temporal distribution of actualrnET. Based on the SEBS output of evaporative fraction, arntime series of actual ET is generated by means ofrnFourier series analysis method, which provided thernquantity of actual ET in the study area. However,rnanother method of generating time series of actual ETrnwas also carried out by applying Fourier series analysisrnmethod to the SEBS output of discreternevapotranspiration values. Both methods were analyzedrnin different aspects. Finally, the limitations andrnrecommendations for further study were addressed.