URBAN FLOOD MANAGEMENT AND MONITORING IN VRISHABHAVATHI VALLEY

Urban flood is mostly seen in urban areas. They may be due to heavy rainfall, adverse topographical conditions and anthropogenic factors, lead to destruction of drainage, damage to buildings, and even loss of life and property. Now in order to control such problems, systematic urban flood studies are necessary. This study is focused on the mapping and spatial analysis of urban flood vulnerability in Vrishabhavathi valley watershed, Bengaluru using Analytical Hierarchy Process (AHP), GIS and remote sensing techniques. Few causative factors for flooding considered are rainfall, slope, drainage density, land use, building density, road density, non-existing natural drainage and non-existing Lake. The thematic map of these factors was converted into raster maps. Numerical weight and ranking scores will be assigned to each element factor according to fundamental scale of AHP technique. Urban Flood Vulnerability Zone (UFVZ) map is computed using weighted overlay analysis of GIS technique and classified into five categories, viz., very low, low, moderate, high and very high flood zone classes. UFVZ map was compared with the flood prone locations exist in Bengaluru city to assess the accuracy of result. The plot of flood prone locations on flood vulnerability zone map evident that, 50% of flood prone locations found under moderate flood vulnerability zone. This result depicts the fact that, urban flood vulnerability is highly influenced by anthropogenic factors than natural factors in urban environmental study area. The predicted flood vulnerability zones are found to be in good agreement with known flood prone locations.