Abstract: Appropriate flow rate is an important factor affecting the reproduction of domestic fish. This study focuses on determining the suitable flow velocity and acceleration for spawning in domestic fish spawning grounds, as well as the area of water with the appropriate velocity for fertilization. To achieve this, simulations and comparisons were conducted on typical non-constant high and low flow processes before and after cascade development. Results indicate a significant change in the water area suitable for the reproduction of four major Chinese carps. The optimum flow rate for spawning, the flow rate triggering spawning, the suitable flow rate for spawning, the maximum flow rate for fertilization, and the water area for maximum fertilization rate all declined drastically after the cascade development. Cascade development is unfavorable for domestic fish reproduction. However, concerning the suitable acceleration for domestic fish spawning, the regulation effect of cascade development on low flow tends to be advantageous. These findings pose further scientific requirements for the ecological joint operation and scheduling of cascades in the mainstream of the Xiangjiang River based on flow regulation.

Key words: cascade development, four major Chinese fishes, suitable flow rate for reproduction, water area, Xiangjiang River