Analysis of hydrological regime evolution and ecological response in the Min River, China

Abstract Natural fluctuation of the hydrological regime is the key to maintaining river ecosystem function. Given the shortcomings of previous studies on hydrological regime change and the ecological response of the Min River, this study combined two change degree evaluation methods and Budyko theory to quantify the degree of ecohydrological change and its driving factors. Ecological significance indicators (ecosurplus and ecodeficit) and the Shannon index (SI) were used to identify the characteristics of ecohydrological variation and ecological response mechanisms. The results showed the following: (1) The hydrological regime in the Min River basin had an abrupt change in 1993, with the overall alteration degree reaching 44%, which further led to a decrease in ecological surplus and an increase in the ecological deficit in ecological indicators. (2) Budyko's theoretical results show that climate change and human activities together lead to an 83.83 mm reduction in Min River runoff, with human activities contributing 54.20% of the change in the mean annual runoff, while rainfall and evapotranspiration contribute 43.88 and 1.92%, respectively. (3) The SI index indicates a decreasing trend in Min flow biodiversity. The results of the study can provide a reference for enhancing ecological protection and restoration in the Min River basin.