Model Of Actual Evapotranspiration For The Yellow River Valley

It was substantiated that the complementary relationship of evapotranspiration on the Yellow River valley exists by using ground observed data from weather stations, hydrological and solar radiation observer. Actual evapotranspiration was reckoned by model and results were verified by explored the secular annual mean basin actual evapotranspiration which was calculated from water model. The result shows that the secular annual mean basin actual evapotranspiration is 378mm in the Yellow River valley and the error can be controlled in 8%. It can be used in the larger scale calculation in next research. The main achievements of this project were concluded as follows:1. Substantiation of complementary relationship for area evapotranspirationBased on nearly 30 years data from 432 weather stations and 512 hydrological stations in China, using means of water balance, the secular annual mean actual evapotranspiration was established. By thoroughly analyzing the concept of "potential evaporation" and "wet environment area evapotranspiration", using index of comparatively potential evaporation and comparatively actual one, the complementary relationship between actual and potential evapotranspiration was testified entirely with data integration technique.2. Study of radiation balance on the Yellow RiverDifferent radiation factors were established in different temporal and spatial scales. Through error analysis, the optimized parameters were confirmed. Area net radiation was accurately calculated by using remotesensing technique. This project may provide the credible data for area evapotranspiration.3. Estimation of the actual evapotranspirationWith the complementary relationship of evapotranspiration, the actual evapotranspiration were calculated in the Yellow river. The result shows that the secular annual mean actual evapotranspiration is 378mm in the Yellow river and the error can be controlled in 8%.4. Distribution of the actual evapotranspirationThe maximum of the actual evapotranspiration is on July and the minimum on December. The east's value is greater than the west's.