118. Urban Flood Management by Non-structural Measures

Rapid urbanization in major cities in India has resulted in increased stormwater runoff exceeding the capacity of many existing stormwater drains thereby resulting in overflow of polluted stormwater and consequent outbreak of epidemics. Structural measures to reduce local flooding, for example enlarging the stormwater channels may not be possible because of the non-availability of space. Hence, non-structural measures like optimization of the capacity of the existing drainage system by regulating the flows at key control points in the drainage system will be appropriate. In most of the developing countries, rainfall records are usually available, but the flow measurements in urban drainage systems are rarely available and most of the decisions have to be made with limited or no flow data sets. In this paper, a methodology has been developed to model the flows in the drainage system by using an implicit finite difference solution of the Saint-Venant equations. The application of the model has been demonstrated by applying it to a drainage system in the highly populated catchment (population 1.2 million), Kalyan (near Mumbai), in India. The computed water surface profile show good agreement with the observed levels.