Abstract: Type Ⅱ broken-line practical weir has been widely used in small and medium-sized water conservancy projects. Nevertheless, a comprehensive and correct solution to the flow coefficient of broken-line weir with varied water head and ratio of weir height is still in lack. In view of this, we determined the flow coefficient of type-II broken-line practical weir based on indoor measurements of hydraulic model test, and further deduced a simple and practical calculation formula for type II broken-line weir in association with correlation analysis and linear regression. In the laboratory hydraulic model test, the slope gradient in the upstream and downstream of weir ranges between 0.5 to 3.0, which is commonly adopted in engineering, and the relative weir height is limited between 2.0 and 0.5, and relative weir crest’s thickness between 1 and 2.5. The proposed method provides basis and reference for engineering design.

Key words: broken-line practical weir, flow coefficient, calculation method, linear regression, correlation analysis