Application of One- and Two-Dimensional Surface Runoff and Infiltration Models for Maroon Valley Watershed in Fars Province

In order to simulate surface runoff and depth of flow on surface area of watershed and outflow rate, a new hydrological model with numerical structure has been designed and presented. In this model, surface flow governing Saint- Venant equations in one- dimensional and two- dimensional forms along with the Parlang infiltration model parameters, have been solved using a finite difference numerical method, for the kinematic wave approximation using an implicit scheme. In order to solve the system of nonlinear equations resulting from discretization of the flow and infiltration equations, the Newton Raphson method was used. An algorithm and program of this model in one- and two-dimensional modes have been developed by using MATLAB software and their results have been analyzed. For checking the accuracy of the presented numerical model in estimation of the height and volume of the surface flow, the model was implemented for the Maroon valley watershed in Fars province. Topographic condition and slope of the basin surface used in the surface flow equations and the parameters required in infiltration equation have been prepared using the GIS maps and elevation models for feeding the numerical model. Comparison of the model computational hydrographs with the observed results at the hydrometric station in the basin outlet and also investigation of the statistical coefficients calculated from the results showed similarities and good accuracy in simulation of the flood hydrographs by the numerical model. Also, the kinematic wave had a good approximation in predicting the amount and occurrence time of the selected floods peak discharges. The average accuracies of the one- and two- dimensional models in predicting the amount and occurrence time of the selected floods peak discharge were c 97.3 and 97.2 percent and 95.45 and 98.47 percent, respectively.