Flood routing models through dam reservoir

Flood routing through reservoirs constructed on natural rivers is an important water resources problem which is frequently encountered in real life, especially applied in design of spillways and determination of water demand running. Two different methods, hydrologic and hydraulic routing, are used in computation of outflow hydrographs through spillways which is to be formed by flood hydrograph inflowing into reservoir. Hydrologic flood routing method İs based on solution of the continuity equation only, so dynamic effects of the water are not taken into account. However, hydraulic routing reflects actual motion of water mass along reservoir valley by taking into account dynamic effects of water and wall friction losses. Therefore, the result is attained by solving continuity and momentum equations simultaneously. Due to the fact that the governing equations are nonlinear differential equations, analytical solution is impossible so numerical solution methods are applied. In this study, a numerical model has been developed by applying four point implicit scheme to the governing equations of hydraulic routing. A computer program developed for this numerical model produces the solution by using Newton Raphson Iteration technique under upstream and downstream boundary conditions. This program has been applied to nine long and narrow valley reservoirs chosen from several regions of Turkey and the results have been compared with those of hydrologic routings. Key Words :Unsteady Flow, Flood Routing, Hydraulic Routing Method, Saint- Venant Equations, Newton Raphson Iteration Technique. II