Comprehensive Analysis on Calculation Iterative Methods for Natural River and Open Channel Water Curve

The flow pattern is slow flow because of slow slope of natural water in plain zones. The numerical calculation methods of water surface line. In mountain zones, the slope is steep and the flow pattern is rapid flow. The iterative calculation method for slow flow is not suitable for rapid flow. For non-prism channel, the relationship between section geometric elements and process coordinates is the similar. When both of them are slow flow, the water depth or water level term in unit kinetic energy is as main function value in iterative calculation, Otherwise, both of them are rapid flow, the main function value is the water depth or water level term in unit potential energy. The examples show the methods can get satisfied results.