Application of geodetector in sensitivity analysis of reference crop evapotranspiration spatial changes in Northwest China

Abstract

Reference crop evapotranspiration (ET0) is an important parameter in the research of farmland irrigation management, crop water demand estimation and water balance in scarce data areas, therefore, it is very important to study the factors af‐ fecting the spatial variation of ET0. In this paper, the Penman-Monteith formula was used to calculate ET0 which is the de‐ pendent variable of elevation (Elev), daily maximum temperature (Tmax), daily minimum temperature (Tmin), daily average temperature (Tmean), wind speed (U2), sunshine duration (SD) and relative humidity (RH). The sensitivity analysis of ET0 was performed using a Geodetector method based on spatial stratified heterogeneity. The applicability of Geodetector in sensitivity analysis of ET0 was verified by comparing it with existing research results. Results show that RH, Tmax, SD, and Tmean are the main factors affecting ET0 in Northwest China, and RH has the best explanatory power for the spatial distribu‐ tion of ET0. Geodetector has a unique advantage in sensitivity analysis, because it can analyze the synergistic effect of two factors on the change of ET0. The interactive detector of Geodetector revealed that the synergistic effect of RH and Tmean on ET0 is very significant, and can explain 89% of the spatial variation of ET0. This research provides a new method for sensitivity analysis of ET0 changes.