Urban Flooding—A Case Study of Chennai Floods of 2015

Abstract

Urban areas are the centres of economic activities having vital infrastructure. Damage to these infrastructures can have a bearing not only on the country but also globally. Urban flooding is generally caused due to inadequate drainage system in an urban area. Owing to rapid urbanization, the extent of open spaces for percolation of surface water in the ground has considerably reduced. Inadequate drainage system coupled with large intensity rainfall has often been the major cause of urban flooding. Water may even enter the sewage system in one place and then get deposited somewhere else in the city on the streets. Major cities such as Mumbai in 2005 and Chennai in 2015 have witnessed the loss of life and property, disruption in transport and power and incidence of epidemics. This demands the need for management of urban flooding. The present paper analyses the reasons for Chennai flood of 2015 that affected several sub-urban areas of the city, especially those in the basin of River Adayar. The factors analysed in this paper are the effect of the series of rainfall events in the month of November–December 2015, operation of Chembarambakkam Lake, effect of increased urbanization and infrastructure and the local storages which play a major role in flood moderation in catchment. This paper also discusses the how well the flood events have been managed in terms of emergency preparedness. The paper finally tries to comprehend the key areas where the improvement is required in terms of urban flood preparedness.