Study on the annual runoff change and its relationship with fractional vegetation cover and climate change in the Chinese Yellow River Basin

In the context of global climate change and ecological restoration projects, there have been significant changes in the Fractional Vegetation Cover (FVC) in the Yellow River Basin. The growth of vegetation accelerates the consumption of water resources, further exacerbating the situation of drought and water scarcity in the Yellow River Basin, leading to increased regional water resource shortage risks. This study focuses on the Yellow River Basin in China and uses a pixel-based model to convert NDVI into an FVC datasets. It establishes a pixel-wise mathematical model for annual runoff and environmental factors based on residual analysis and methods like multiple linear regression. Climate model data from CMIP6 is used as independent variables, and in combination with the statistical model established, it provides the spatiotemporal characteristics of annual runoff in the Yellow River Basin under future climate scenarios. The results show that under four climate scenarios, the average annual runoff in the Yellow River Basin is increasing, with increases of 0.008 mm/a, 0.065 mm/a, 0.25 mm/a, and 0.24 mm/a for SSP126, SSP245, SSP370, and SSP585, respectively. From 2022 to 2040, the spatial distribution of runoff change rates is similar for SSP245 and SSP370 scenarios, with an increasing trend in upstream areas like the Qinhe and Longmen regions, with rates ranging from 6.00 to 8.61 mm/a. From 2041 to 2060, in all four climate scenarios, there is little change in the depth of runoff in the northern part of the Yellow River Basin. From 2061 to 2080, under SSP126 and SSP245 scenarios, the spatial distribution of runoff shows significant increases in the river source area and a decreasing trend in the middle reaches, with rates ranging from 4.52 to 11.39 mm/a. In the period from 2081 to 2100, the runoff change rates vary significantly under the four climate scenarios.