Estimation of Evaporation Trends in Six Major River Basins of China Using a New Nonlinear Formula of the Complementary Principle of Bouchet

Abstract

Evaporation (Ea) is a key component of the hydrological cycle. Under the impact of global change, Ea has changed significantly, both globally and regionally. A number of methods have been developed to estimate Ea and its trends. Among them, methods based on the complementary principle of Bouchet estimate Ea using only routine meteorological data as inputs and greatly simplify the Ea estimation. In this study, a new nonlinear formulation of this principle was tested for estimating Ea trends in 6 major river basins of China. The results indicate that the estimated annual Ea trends were in good agreement with that obtained from the water balance approach with the relative errors ranging from -12.0 to 11.2%. In addition, in two humid basins of this study, decreasing Ea trends were estimated from decreasing potential evaporation, although the nonlinear formulation is based on the complementary principle between Ea and potential evaporation. One advantage of the method is that only routine meteorological data are required as inputs and that it can be used to estimate Ea trends, wherever such data are available.