Urbanisation – which is rapidly increasing in all cities — increases the flood risk by up to three times and, unlike rural flooding, affects more people owing to the dense population clusters. The loss is immense as houses, infrastructure, industry and commerce are affected.
In this paper, researchers Farhat Rafiq, Sirajuddin Ahmed, Shamshad Ahmed, and Amir Ali Khan review urban flood events in India, highlighting the causes of localised flooding as well as its impact and consequences. The paper focuses on urban floods that occurred in the cities of Mumbai, Chennai, Delhi, Noida, Kolkata, and Bharuch. Mumbai floods on July 26, 2005, is a case study, which finds 60 per cent of the city was submerged, at various degrees. The study cites causes such as low-lying areas, encroachments along nullahs, dilapidated drains, loss of holding ponds, garbage-choked nullahs among others.
Incidents of urban flooding are likely to increase if changes are not made to the unplanned construction of buildings and infrastructure and poor management of drainage systems, their report suggests. As climate models predict that winter rainfall will increase by 20-30 per cent by the 2080s, it is important to study and debate urban flooding, and plan cities by factoring the extreme climate events.