3.-Two-dimensional modelling of overland flow urban catchment

Abstract

The world growth-of urbanisation over the years is very high. This rapid process of urbanisation has tremendous effect on hydrology of the region. With increase in impervious area due to urbanisation, there has been increase in runoff peak. runoff volume and decrease in time to peak. Design of drainage facilities, which do not account for this increased runoff volume, are inadequate and therefore, it is important to develop an overland flow model for urban catchment in order to estimate the exact runoff and time to peak. In this study, a two-dimensional overland flow model has been developed considering random roughness coefficients and irregular boundaries for the analysis of surface flow component. One-dimensional subsurface flow equation has been used for calculating infiltration from pervious area. The surface and subsurface flow components of the model are linked explicitly at the ground surface through the processes of infiltration. The present model is validated separately for surface flow and subsurface flow using earlier results. It is used to simulate a hypothetical urban subcatchment.