Evaluation method of ecological water demand threshold of natural vegetation in arid-region inland river basin based on satellite data

The ecological water demand (EWD) of natural vegetation is a key issue in regional water resource allocation and ecosystem management. Although the evaluation of the EWD of vegetation has been emphasized in numerous studies, research on the threshold EWD of vegetation, including the minimum and optimum EWD, as well as an effective quantitative analysis framework, are still lacking. Therefore, in this study, the evapotranspiration of natural vegetation in the plain area of the Tarim River Basin over the last22 years was estimated based on remote sensing image data. Additionally, the multi-year dynamics of the EWD of natural vegetation were analyzed. In this study, the concept of "latitude" was adopted from studies of ecosystem resilience, to propose a novel analytical framework to measure the minimum and optimal EWD of natural vegetation in inland arid areas. The results show that the average minimum and optimum EWD of natural vegetation is105.45 and 135.53 mm, respectively. The average minimum EWD of woodland and high- and low-coverage grassland is 129.13, 284.38, and 111.40 mm, respectively, and the mean value of the optimum EWD is 152.96, 382.05, and 141.16 mm, respectively. The novel approach of this study is simple and easy to use, and provides an effective method for quantitative evaluation of the EWD threshold of natural vegetation.