Ten-stage discrete flood routing for dams having gated spillways

Ten-stage operation policies for routing of flood hydrographs from very small magnitudes up to the probable maximum flood (PMF) for any dam having a gated spillway are suggested. The gate opening rules are determined based on the recent pool level. Without having to predict the magnitude of the incoming flood hydrograph beforehand, the fixed rules of the ten-stage operation policy will provide quasi-optimum routing for any floods, which are classified into 10 different groups. 0.1 PMF, 0.2 PMF,..., and PMF are the upper limits of the ten groups. When the PMF is routed, the rising and falling limbs of the outflow hydrograph make 10 sudden jumps and sudden drops at definite times and smoothly vary between steps. The developed flood routing model is applied sequentially to Catalan and Seyhan dams on the Seyhan River in Turkey.