Response Characteristics of Key Habitat Factors in the Lower Jinsha River to Cascade Reservoir Impoundment

ABSTRACT The construction of cascade reservoirs has brought numerous benefits to human society; however, it has also altered natural hydrological regimes and affected aquatic habitat conditions. The impact of cascade reservoir impoundment on key habitat factors across different development phases remains poorly understood. To address this, our study leverages a long‐term hydrological dataset from the lower Jinsha River, applying Bayesian hierarchical models and generalized additive models to quantify the effects of multi‐stage reservoir construction on these key factors and to assess their specific responses to impoundment. The study reveals that, under the influence of cascade reservoirs, peak streamflow in the Panzhihua–Sanduizi (Pan–San) and Xiangjiaba–Zhutuo (Xiang–Zhu) river sections shows a gradual attenuation trend. Under the influence of cascade reservoirs, the monthly average streamflow increased by approximately 0.94 m 3 /s per kilometer, while the monthly average water temperature increased by only 0.071°C. Monthly average streamflow increased overall across the cascade reservoir sections. Specifically, the Pan–San and Xiang–Zhu sections rose by approximately 220 and 704.97 m 3 /s, respectively. In contrast, monthly average water temperature showed only minor fluctuations. The correlation between monthly mean discharge and water storage was significantly stronger than that between monthly mean water temperature and storage. In the upstream reaches of the cascade reservoirs, the response of key habitat factors to water storage was most strongly influenced by the first reservoir in the cascade. Furthermore, when water levels reached a critical ecological threshold, habitat conditions became more favorable for fish reproduction and survival. The response of key habitat factors to reservoir storage in upstream reaches of cascade reservoirs was strongly influenced by the first‐stage reservoir. These findings offer valuable insights for the management and restoration of aquatic ecosystems.