Applications of Geo Spatial Modeling Techniques for Urban Storm Water Flood Control of Bengaluru City Using Best Management Practices

Abstract

A growing number of floods in urban areas have been witnessed world over newlineduring last decades. Rapid urbanization and climate change is aggravating this trend. newlineFlooding incidents in urbanized catchments have led to serious public concern and their newlineeconomical impact is severe. The floods are common in the Bengaluru city in monsoon newlineseason. Modern approaches like use of BMPs have been found effective in management newlineof floods in urban areas. The present study is focuses on i) Identification of flood newlinevulnerability zones in the study area Vrishabhavathi Valley watershed, Bengaluru using newlineremote sensing, GIS and AHP techniques ii) Identification and Analysis of various causal newlinefactors for flooding in various Flood Affected Areas (FAAs) iii) Identification and newlineEvaluation of storm water Best Management Practices (BMPs) iv) Performance newlineevaluation of SWMM based BMPs model under different storm events v) Assessment of newlineflood volume and peak flow reduction by the designed BMPs. newlineInitially flood vulnerability zones are identified in Vrishabhavathi valley newlinewatershed area (92 sq. Km), Bengaluru considering a variety of factors which influence newlineurban flooding viz. slope, buildings density, roads density, extinct natural drainages, newlineextinct lakes, landuse, drainage density and rainfall. A GIS based thematic map for each newlineof the factors was prepared and converted into raster. Proper weightage is assigned to newlinethematic maps based on their relative importance to urban flood vulnerability as per the newlineSatty s Analytical Hierarchy Process (AHP). The Urban Flood Vulnerability Zone newline(UFVZ) map was generated by integrating all thematic maps together in weighted overlay newlineanalysis tool of Arc GIS 9.3 software. The UFVZ map is classified into very high, high, newlinemoderate, low and very low flood vulnerability zones. To assess the accuracy of results newlineUFVZ map was compared with the reported flood affected areas (28 numbers) existing in newlineVrishabhavathi valley watershed study area. Plot of FAAs on UFVZ map shows that, newline57% (16 out of 28) of FA