Simulation of Actual Evapotranspiration and Evaluation of Three Complementary Relationships in Three Parallel River Basins

Based on observed precipitation and runoff data, the monthly actual evapotranspiration (ETa) was calculated using hydrological budget balance method in three parallel river basins. The performance of complementary relationship methods, namely, nonlinear advection-aridity (non-AA) method, generalized (B2015), sigmoid function (H2018), for simulating ETa evaluated. evaluation results showed that methods could accurately simulate series. Nash–Sutcliffe efficiency coefficients between simulated by non-AA, B2015, H2018 water balance-derived were 0.74, 0.78, 0.79, respectively. correlation 0.84, 0.89, 0.90, root mean square errors 10.76 mm mon−1, 10.01 9.78 increased spatially from upstream region to downstream at catchment scale. Annual models significant increasing trends during years 1956–2018 basins, with magnitudes 1.53 mm/a, 1.66 1.47 Research influence meteorological factors a positive precipitation, temperature, wind, hours sunshine, average 0.40, 0.64, 0.63, 0.72, value relative humidity –0.38. basins highly sensitive wind speed, sensitivity 0.26, 0.21, 0.27, Moreover, it moderately humidity, –0.18.