In this study, a two-dimensional overland flow model has been developed considering random roughness coefficients and irregular land surface for the analysis of surface flow component. The one-dimensional Richards equation for subsurface flow component has been used for calculating the infiltration from the pervious area.
The rapid process of urbanization is causing heavy demand for water necessitating an increase in the concentration of water supply and drainage facilities. With the increase in impervious area due to urbanization there has been an increase in runoff peak & runoff volume and a decrease in time to peak. The drainage facilities, which do not account for this increased runoff volume, are insufficiently designed and there is a need to develop an overland flow model for urban catchment in order to estimate the exact runoff and time to peak.
The surface and subsurface flow models are linked explicitly at the ground surface through the processes of infiltration. These two models have been validated separately for surface flow and sub-surface flow using earlier results. The overland flow model is used to simulate a hypothetical urban catchment.
This model should be applied to the real urban catchment considering the soil moisture characteristic of the catchment. Routing sub-routine should be added to this program so that the runoff hydrograph can be calculated at any point of the outlet drainage ditches. Furthermore, another sub-routine for networking of the drainage system should be added and design of the suitable drainage system should be introduced to this code.
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