Regional Evapotranspiration Estimation by the Improved MOD16-sm Model and Its Application in Central China

Evapotranspiration (ET) is a key component of the hydrological cycle, but traditional monitoring approaches are always based on measurements, which cannot satisfy requirements research regional scale. Hence, ET estimation by remote sensing essential. MOD16 remote-sensing model P-M equation and has good applicability. However, it describes soil moisture indirectly RH, etc., may cause uncertainties in estimating, so this study attempts to utilize NDWI as supplement information makes improvements (with resultant new being named MOD16-sm). Specific work includes two aspects: one verification through making comparisons between estimates other application effect test analyzing spatiotemporal characteristics exploring how responds climate land-use changes. Model indicated that accuracy improved MOD16-sm increased, with higher R2 0.71, lower RMSE 0.9 mm, MAE 0.91 was convincing. The showed average relative change rate annual 1.7%, showing an upward trend, areas growth trends also had high vegetation coverage. As for impacts changes ET, positively correlated precipitation, whereas no relevant correlation air temperature most areas, all types displayed significant increasing resulting from change. demonstrated were reasonable.