Heavy rains created a waterlogging conditions in several parts of Chennai and nearby districts. Chennai experienced waterlogging after overnight heavy downpours, which affected connectivity and movement.
The India Meteorological Department (IMD) predicted that due to the influence of the low-pressure area over the Southwest Bay of Bengal off the Sri Lankan coast, heavy rain will continue in several parts of Tami Nadu for the next three days, and it is likely to get worse in the next 24 hours.
The flooding of land or property in a built environment, especially in densely populated cities where rainfall exceeds drainage systems' capacity, is known as urban flooding. It is a manmade disaster.
Urban flooding, in contrast to rural floods, which are caused by heavy rain over a flat or low-lying area, is caused not only by higher precipitation but also by unplanned urbanization.
India's urban population is anticipated to reach 814 million by 2050. As a result, it is important for the government to focus on city master plans and urban renewal initiatives as essential components in order to reduce urban flooding.
Urban floods are now a national problem in India, affecting mega and metropolitan areas almost every year. Ahmedabad was inundated by heavy rainfall in July 2022. The ground floors of many housing societies and bungalows were submerged.
Due to heavy rainfall in November 2021, several areas were submerged in Chennai which also led to blackouts and a few Chennai territories were marooned. Hyderabad faced unprecedented precipitation levels in October 2020, resulting in the deaths of nearly 50 people and the destruction of property worth over Rs 5000 crores. At various times, cities like Delhi, Mumbai, Patna, and Pune,? were also flooded, bringing them to a halt for several days.
The original built-up area of Indian cities has expanded dramatically over the past two decades. New developments are taking place in low-lying areas of Indian cities and towns due to rising land prices and less availability of land in the city centre. Most of the time, these developments take place on encroachments over lakes, wetlands, and riverbeds.
In order to accommodate the higher flows of stormwater, it would have been ideal to widen the natural drains but large-scale encroachments have occurred without widening the natural drains. Thus, flooding occurs as the capacity of the natural drains is decreased.
Climate change is leading to extreme weather and causing an increase in the frequency of short-duration heavy rainfall resulting in higher water run-off. Apart from that, floods in urban areas are also caused by the sudden and unplanned release of water from dams and lakes without giving the public enough time to respond.
According to NASA studies, the urban heat island effect also causes more rain to fall on urban areas and cause flooding. The hot air pushes the rain-bearing clouds higher as they pass over the urban heat island, resulting in highly localized and occasionally intense rainfall.
Floods in urban areas frequently result in deaths and injuries, either directly or indirectly by causing water-borne diseases to spread during the event.
It causes structural damage to buildings, property, crops, etc. and also disrupts infrastructure like the water supply, sewerage, power lines, transmission lines, communication, and traffic on roads and railways.
Health problems including epidemics and plagues are invited by stagnant stormwater, contaminated drinking water and solid waste and sewage.
The most effective strategy for minimizing property and life loss is to construct them away from floodplains and other flood-prone areas. Also, rainwater harvesting should be included in all infrastructure constructions to ensure better water management. Along the sides of roads, bioswales should be constructed so that rainwater can percolate into the ground and flow toward them.
The development of blue-green infrastructure will help in the situation. The term "Blue-Green Infrastructure" refers to a network that uses infrastructure, ecological restoration, and urban design to connect people with nature to solve urban and climate problems. Blue denotes tanks and water bodies, while green denotes parks, gardens, and trees.
For better development planning, geospatial technology should be used for flood vulnerability mapping. Further, natural water bodies should be strictly desilted and maintained to ensure the free flow of excess water.
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