Unsteady flows´ water depth in open-channel

A high-accurate experimental systems were established for unsteady flows in open channel. And then 40 experiments were conducted to study variation of continuous unsteady flows´ water depth. Experiments show that unsteady flows water depth is close to H_Qmax at flow wave peak and to H_Qmin at flow wave bottom for long period. While the period is short, water depth at wave peak and wave bottom are both close to H. Here, H_Qmax is the water depth of the maximal discharge for the constant flow of the same discharge, H_Qmin is the water depth of the minimum discharge for the constant flow of the same discharge, and H̅ is the water depth of the averaged discharge for the constant flow. Finally a formula for calculating the water depth both of wave peak and wave bottom was developed, which´s accuracy was proved by measured data.