Distributed modeling of evapotranspiration in the Yellow River basin

In the traditional models for areal evapotranspiration estimation, net radiation and its composition elements were generated by simulation of foreign empirical formulas or by interpolation of site observation data, which was one of the key reasons influencing the simulation accuracy of areal evapotranspiration. Using the developed models fitted by the meteorological observation data and the land surface albedo derived by remote sensing data, we achieved distributed modeling results of meteorological elements such as net radiation, air temperature, vapor pressure etc in the Yellow River basin. The heterogeneity of land surface such as topography and land cover diversity was considered in these simulations. With confirmation that the complementary relationship between actual evapotranspiration and potential evapotranspiration is available on a basin-wide scale, distributed simulation of evapotranspiration in the Yellow River basin was generated by coupling the distributed modeling results of the above elements with the advection-aridity model which was founded on the complementary relationship theory. Comparison shows that the spatial distribution of the simulated annual evapotranspiration has a good consistency with the isograms which was derived by water balance and sub-region tests showed that the minimum relative error is 1.14%, the maximum is 26.80% and the whole river basin average is 1.50%. Furthermore, the simulated evapotranspiration indicts the details more fine. The integrated distributed model for areal evapotranspiration simulation was founded on the complementary relationship theory, which takes into account the feedback of regional evapotranspiration upon the near-surface layer atmosphere, and it is easy to use for only taking DEM data and conventional meteorological data as input.