Abstract: Previous hydraulic model tests of the Qianping reservoir hub project revealed a reasonable overall design and arrangement of its diversion tunnel, spillway and flood discharge tunnel, a smooth inflow entering the deep water, and a relatively calm water surface across its whole impoundment. No large unfavorable flow patterns were observed in its flood releasing operation, and the capacity of its flood discharge facilities meets the requirements. However, transverse flow deflection occurs in front of the guide walls on the both sides of the spillway inlet and it influences the flow through the spillway sluices, because the spillway, located at the hillside entrance on the left of the dam, is subjected to transverse water flows in the reservoir. To improve the flow pattern, this study conducts scale model tests on six types of the right guide wall, and optimizes the shape of the left guide wall of the recommended scheme under three working conditions. Results show that the optimal scheme is effective and satisfactory.

Key words: Qianping reservoir, model test, spillway, intake canal scheme, design optimization