URBAN FLOOD RISK MAPPING FOR BINDAL RAO CATCHMENT OF DEHRADUN

Abstract

Urban Flood has been a pressing global concern over the last decade. There have been numerous occurrences of flooding in various towns and cities across India such as that of 2017 and 2005 Mumbai Floods, 2016 Delhi Floods, 2015 Chennai Floods. The country has suffered from huge economic losses, infrastructural damages, human casualties, and even loss of lives during these floods. India, being a developing nation, would witness rapid urbanisation in the coming years further aggravating the issues of urban floods. Thus, it becomes very crucial to map the risks of urban floods for the purpose of efficient mitigation and management. Dehradun being affected by urban floods in almost every two years, the Bindal Rao catchment of the city has been considered for mapping of risks. The entire area of the Bindal Rao catchment has been categorised into five risk zones according to levels of risks, i.e., negligible, low, moderate, high and very high. To carry out the risk zonation, the flooding and vulnerabilities of the study area have been mapped performed considering the topographical characteristics, urbanisation trends, precipitation trends and Land Use Land Cover characteristics. For the purpose of flood simulation, the United States Environmental Protection Agency - Storm Water Management Model has been used while the mapping activities have been performed using Arc GIS 10. The other software and tools that have been used in the study are ERDAS IMAGINE and Geospatial Storm Water Management Model. The study area is found to be mostly in low to high vulnerability zones with very small areas under high vulnerability zone in terms of landuse and social factors. Nearly half of the study area is found to be susceptible to urban floods. It is found to be extremely variable in terms of urban flood risks, while approximately one-sixth part of the catchment fall under high to high very high risk zones and about one-fourth of it under low and moderate risk zones. The finding of the study comes under the framework of Sendai Framework of Disaster Risk Reduction for 2015-2030 in understanding disaster risks and strengthening disaster risk governance.