The world's climate is changing. While we are all talking about climate change in 2022, let’s make sure that Urban Flooding is part of that conversation in the new year.

URBAN FLOOD RISK IN INDIA

There has been an increasing trend of urban flood disasters in India over the past several years whereby major cities in India have been severely affected almost on an annual basis. The most notable amongst them are Hyderabad in 2000, Ahmedabad in 2001, Delhi in 2002 and 2003, Chennai in 2004 and 2015, Mumbai in 2005 and 2017, Guwahati 2010, Surat in 2006, Kolkata in 2007, Jamshedpur in 2008, Delhi again in 2009 and Guwahati and Delhi in 2010. Gurugram over the last few years, Hyderabad again in 2020, Bengaluru in 2017 and 2022. Ahmedabad again in 2022, Chennai in 2021

For example, in the last decade alone droughts and floods have affected an estimated 338 million people in India and 383 million people in China.

What is Urban Flooding ?

Urban flooding is NOT just “flooding that happens in an urban area.” The American Federal Emergency Management Agency defines urban flooding as :

…the inundation of property in a built environment, particularly in more densely populated areas, caused by rain falling on increased amounts of impervious surfaces and overwhelming the capacity of drainage systems.

We can split the definition into three separate components: urban flooding is
(1) caused by rain that
(2) falls on impervious surfaces and
(3) overwhelms local stormwater drainage capacity.

Each of these components :
(a) heavy precipitation (which is expected to become more frequent due to climate change),
(b) increased urbanization,
(c) and insufficient or outdated stormwater infrastructure
presents a challenge in and of itself. With urban flooding sitting at the intersection of all three, it’s no wonder that this is a complex problem.

NDMA ( National Disaster Management Agency ) highlights that Urban Floods are significantly different from rural floods as urbanization leads to developed catchments, which increases the flood peaks from 1.8 to 8 times and flood volumes by up to 6 times. Consequently, flooding occurs very quickly due to faster flow times (in a matter of minutes). Urban areas are densely populated and people living in vulnerable areas suffer due to flooding, sometimes resulting in loss of life. It is not only the event of flooding but the secondary effect of exposure to infection also has its toll in terms of human suffering, loss of livelihood and, in extreme cases, loss of life.
Urban areas are also centres of economic activities with vital infrastructure which needs to be protected 24x7. In most of the cities, damage to vital infrastructure has a bearing not only for the state and the country but it could even have global implications. Major cities in India have witnessed loss of life and property, disruption in transport and power and incidence of epidemics. Therefore, management of urban flooding has to be accorded top priority.
Increasing trend of urban flooding is a universal phenomenon and poses a great challenge to urban planners the world over. Problems associated with urban floods range from relatively localized incidents to major incidents, resulting in cities being inundated from hours to several days. Therefore, the impact can also be widespread, including temporary relocation of people, damage to civic amenities, deterioration of water quality and risk of epidemics.

data source ndma, ndrc

At ZEN-THINK we have aligned ourselves with CLIMATE ACTION and are applying deep-tech to extremely intractable issues such as urban flooding.