flood wave simulation case study for natural water stream by numerical solutions of unsteady equations

 modeling of river conditions and flood routing operations by numerical methods show a high accuracy. the beginning of the modern study of unsteady flow in open channels can be traced to the latter half of the nineteenth century when the french engineer saint-venant introduced the partial differential equations of continuity and momentum governing free surface flow in open channels. these equations are highly nonlinear and therefore do not have analytical solutions. this paper present the results of two different numerical methods, namely; preissmann and lax diffusive schemes for numerical solution of saint-venant equations that govern the propagation of flood wave, in natural rivers, with the objective of the better understanding of this propagation process. the results have shown that the hydraulic parameters play important game in the flood wave propagation. the results of these numerical solutions are compared with the mike.11 commercial computer model.