The impact of human activities and climate change on the eco-hydrological processes in the Yangtze River basin

Study region: The Yangtze River Basin Study focus: To accurately quantify the impact of climate change and human activities on the hydrological regime, the Long Short-Term Memory (LSTM) models for meteorology-runoff simulation are constructed for the multi-year average monthly flow process. The Indicators of Hydrologic Alteration (IHA) method is used to quantitatively evaluate the hydrological processes in the watershed. Additionally, the grey relational analysis method is employed to explore key indicators affecting the ecological effects of fish. New hydrological insights for the region: The streamflow of the Yangtze River mainstem and its seven tributaries increases as the distance from the river mouth decreases. The degree of hydrological changes in various basins is moderate (33-66%). Except for the Jialing River, Wu River, and Poyang Lake, the streamflow changes in other basins are mainly influenced by human activities. Among them, Yichang is most affected by human activities (75.43%), while Wu River is most affected by climate change (67.05%). The rate of land use development has reached 116.9% over the past 20 years, and vegetation coverage has been increasing at a linear rate of 0.003 per year, Summer rainfall is significantly positively correlated with flow, while temperature is significantly negatively correlated. The Three Gorges Dam has reduced the spawning scale of fish and identified "October runoff" as the key indicator. These findings contribute to a deeper understanding of the response of watershed water resources and ecological effects.