Coastal Urban Flood Simulation Using FEM, GIS and Remote Sensing

Abstract

In this paper, a rainfall runoff model for coastal urban watershed considering the effects of tidal variations using Finite Element Method (FEM) is presented. Overland flow is modeled using the mass balance equation considering the impervious character of the urban watershed. Storm water flow through the channel is modeled using the diffusion wave form of the Saint Venant’s equations and considering the tidal variations. Galerkin’s FEM is used in the approximation of the governing equations. One dimensional linear line elements are used in the channel discretization. Further the mass balance based overland flow model and diffusion wave based channel flow model have been integrated for prediction of flood. Slope values for the overland flow are determined using the Geographical Information System (GIS) from the Digital Elevation Model (DEM) of the area. The landuse is determined using the remote sensing data. Remote sensing data is analyzed using the ERDAS Imagine and ArcGIS and the Manning’s roughness is calculated for each subdivision of subcatchment. The developed models have been verified with the models available in literature and are found to be satisfactory. Further, the integrated model has been applied to the runoff simulation of a coastal urban watershed in Navi Mumbai, in Maharashtra state of India to analyze the flooding in monsoon season along with the tidal influences. The model could satisfactorily predict the runoff due to monsoon rains coupled with the tidal variations. The developed model will be useful in the urban coastal flood analysis due to heavy rainfall and tidal effects.