Because the geological reasons for floods vary for different cities, there is no one-size-fitsall solution to preventing urban floods. The following steps can be taken to mitigate the frequent urban flood situations in million-plus cities:

• In the case of South Indian cities, especially Hyderabad and Chennai, flooding takes place mainly due to sudden downpours caused by cyclonic activities in the Bay of Bengal. The problem with these cities, in particular, is the existence of large catchment areas. In fact, the whole city acts as a catchment. In order to reduce the events of floods, the need is to reduce the catchment areas so that the amount of water available to flow in a particular lane is considerably reduced. To ensure this, there is a need to begin clearing critical areas of encroachments in the outskirts of the cities.
• In the Himalayan areas, cloud burst events, especially during monsoon season, resulting in flash floods. To counter the same, check dams, small-scale levees and sandbag embankments need to be developed. Also, there is a need to increase the width and base level of river flow in the region. This, in turn, will increase downstream flow and prevent the overflowing of rivers, thereby reducing floods.
• In the case of cities like Patna and Kolkata lying in plain areas, the ‘normal’ riverine floods occur, which are easy to predict and counter in comparison to flash floods in the Himalayas. New roads, buildings, colonies and infrastructure have been erected over the past few decades. Large scale migration from rural to urban areas has increased the population of these cities and created pressure on the existing sewage system. The best way to mitigate such urban floods is through restructuring the city. The need is to construct a ‘sponge city’ with a larger number of gardens, parks, wetlands and floodplains nearby and use modern technologies to divert surplus water from the city to mentioned areas. This initiative will not only recharge depleted aquifers but will also prevent the fast-changing hydrology of the rivers and mitigate the chances of urban floods.

The concept of a smart city includes things like infrastructure enhancement, improving transportation and social services, etc. The delay in identifying projects, shortcomings in urban planning, poor coordination and site management have resulted in damaging the existing infrastructure of cities, which ultimately results in flood situations during the rainy season. The government, through publicprivate partnerships, should try to address the problem at the earliest.