洪水在河渠中的运动是一种非常复雜的不穩定流,要作出完整而精确的解算是極为困难的。所以在解决許多实际工程方面的洪水运动問题时,僅能采取近似解算法。河渠中的流泄情况应該服从液体的連續性条件与水能平衡条件。本文所介紹的兩个圖解法是以連續性条件作为基本条件,然后根据水能平衡条件对所得結果進行校算。水流的連續性方程式是 Flood movement in a river channel is a very complicated and unstable flow, and it is extremely difficult to make a complete and accurate solution. So in solving many practical engineering aspects of flood movement, only the approximate solution algorithm can be adopted. The discharge in the canal should be subject to the continuity of the liquid and the conditions of equilibrium of the water. The two schemes introduced in this paper are based on the continuity condition as the basic condition, and then calculate the result based on the equilibrium condition of water energy. The continuity equation of the water flow is