Ecological Scheduling of River Intakes Based on Larval Flow Monitoring and Entrainment Impact

River intakes are critical to national water supply networks and water resource utilization, but intake operations in river channels can cause entrainment effects that lead to the loss of early fish resources and disrupt functional ecological connectivity between key habitats. This study investigated the Jingangtuo intake on the Yangtze River using 28 larval flow events recorded between 2021 and 2022. Each event lasted about 4 d on average and showed a strong positive correlation with flood duration. Based on these observations, a larval drift model was developed by coupling an Eulerian concentration diffusion method with a Lagrangian particle-tracking approach. The model simulated larval passage time and behavior near the intake during different events. Results indicated that at river discharges of 5,700 to 13,100 m 3 /s, larval passage time ranged from 3.8 to 5.0 h, with a 1,000 m 3 /s increase reducing passage time by 0.16 h. Nonuniform upstream larval distribution—shaped by flow field heterogeneity—markedly affected downstream movement. Higher larval densities in the main channel led to a 0.5-h reduction in passage time. To reduce entrainment risk, a tiered ecological scheduling strategy was proposed, integrating real-time larval flow monitoring with dynamic response timing, shutdown durations, and optimized monitoring layouts. This approach ensures sufficient early warning and operational flexibility. The study provides a theoretical and practical basis for ecological intake operation and protection of early-stage fish.