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Context

Parts of Bengaluru, India’s IT and startup capital faced unprecedented floods last week. This is not the first instance of urban flooding in India.
In fact, urban flooding is becoming increasingly common in many parts of the country with this monsoon season itself seeing many such instances in the states of Rajasthan, Gujarat, and Madhya Pradesh.
In this context, this edition of the burning issue will look at the rising problem of urban flooding in India, its causes and consequences, and finally few solutions to it.

Some major Urban Flooding incidents

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.
The most notable amongst them are Hyderabad in 2000, Ahmedabad in 2001, Delhi in 2002 and 2003, Chennai in 2004, Mumbai in 2005, Surat in 2006, Kolkata in 2007, Jamshedpur in 2008, Delhi in 2009 and Guwahati and Delhi in 2010. The most recent devastating ones were Srinagar in 2014 and Chennai in 2015

What is urban flooding?

Urban flooding is the inundation of property in a built environment, particularly in more densely populated urban areas, caused by heavy rainfall on increased amounts of impervious surfaces and overwhelming the capacity of drainage systems.

Urban floods stem from a combination of various meteorological and hydrological extremes, such as extreme precipitation and flow in short spans of time.
Thus, flooding in urban areas is caused by intense and/or prolonged rainfall, which overwhelms the capacity of the drainage system.

Features of Urban Floods

Faster Flow times: Consequently, flooding occurs very quickly due to faster flow times, sometimes in a matter of minutes.
Catchment destruction: Urban flooding is significantly different from rural flooding as urbanization leads to developed catchments which are the most vulnerable areas.

Causes of Urban Flooding

Natural factors:

Meteorological Factors: Heavy rainfall, cyclonic storms and thunderstorms cause water to flow quickly through paved urban areas and impound in low-lying areas.
Hydrological Factors: Overbank flow channel networks, the occurrence of high tides impeding the drainage in coastal cities.
Climate Change: Climate change due to various anthropogenic events has led to extreme weather events.

Anthropological factors:

Unplanned Urbanization: Unplanned Urbanization is the key cause of urban flooding. A major concern is the blocking of natural drainage pathways through construction activity and encroachment on catchment areas, riverbeds and lakebeds.
Destruction of lakes: A major issue in Indian cities. Lakes can store excess water and regulate the flow of water. However, pollution of natural urban water bodies and converting them for development purposes has increased the risk of floods.
Unauthorized colonies and excess construction: Reduced infiltration due to paving of surfaces which decreases ground absorption and increases the speed and amount of surface flow
Poor Solid Waste Management System: Improper waste management system and clogging of storm-water drains because of silting, accumulation of non-biodegradable wastes and construction debris.
Drainage System: Old and ill-maintained drainage system is another factor making cities in India vulnerable to flooding.
Irresponsible steps: Lack of attention to the natural hydrological system and lack of flood control measures.

Human determinism: The fact is that our cities have been built with little to no regard for the natural topography and severely lack holistic action.
Weaker laws: We have in place the provisions of rainwater harvesting, sustainable urban drainage systems, etc, in regulatory mechanisms like the EIA notification 2006 but still these are on paper majorly.
Weaker Urban bodies capacity: Public bodies’ focus is largely on de-silting of stormwater drains before monsoon and expansion of the over-burdened infrastructure, but at a crawling pace.

Lacunae in Urban Planning

No mapping of water bodies: The preliminary work of mapping and documentation of the surface water bodies even though mentioned by NDMA under the National Database for Mapping Attributes has not been undertaken.
Failed early-warning system: During the floods of Uttarakhand in 2013, there were questions about the role of NDMA, where it failed to implement the early warning systems to inform people about the floods and landslides.
Response rather than mitigation: The importance of preparedness for disaster situations like urban floods was realized by the government agencies only after the devastations during Chennai Floods in 2015 and Kerala Floods in 2018.
Responsiveness of Local bodies: Sufficient training, equipment, and facilities for immediate response and tackling the disaster situation efficiently are not being carried out by the local governments. More onus of mitigation lies with NDMA/SDMA.
Misutilization of Funds: NDRF/SDRF constituted by the government to deal with the disasters, were used for expenses that were not sanctioned for disaster management. There were cases of financial indiscipline in state management of funds.

Consequences of Urban Floods

On the economy: Damage to infrastructure, roads and settlements, industrial production, basic supplies, post-disaster rehabilitation difficulties etc.
On human population and wildlife: Trauma, loss of life, injuries and disease outbreak, contamination of water etc.

On the environment: Loss of habitat, tree and forest cover, biodiversity loss and large-scale greenery recovery failure.
On transport and communication: Increased traffic congestion, disruption in rail services, disruption in communication- on the telephone, internet cables causing massive public inconvenience.
Diseases: the stagnation of flood water causes pollution of drinking water and accumulation of waste in dustbins and on the open road, thus acting as a host of several pathogens and resulting in the spread of diseases like Dengue, Malaria etc.

Tangible losses: The losses that can be measured physically and can be assigned an economic value. These losses can be direct or indirect. Direct – Structural damage to buildings, property damage and damage to infrastructurewhereas Indirect – Economic losses, Traffic disruption, and emergency costs.

Intangible losses: Intangible losses include loss of life, secondary health effects, and infections or damages to the environment which are difficult to assess in monetary terms since they are not traded such as Casualties, health effects, ecological losses, the Post-flood recovery process, mental damage to the people.

Solutions to Urban Flooding

Improved flood warning systems: effective flood warning systems can help take timely action during natural calamities and can save lives. Pre-planning can significantly reduce the effects of floods, giving people time to migrate to safer locations and stock up on essentials.
Building flood-resilient housing systems: concrete floors can be very useful during floods. Houses should be waterproofed and electric sockets should be placed at higher levels up the walls to reduce the chances of shocks.
Constructing buildings above flood levels: buildings should be constructed a meter above the ground to prevent flood damage and evacuation during floods.
Resilience to Climate change: drastic climate changes have increased the frequency of natural disasters in many parts of the world. Governments should bring about environment-friendly policy level changes and eliminate the ones hazardous to the environment to tackle the problem of global warming.
Create wetlands and encourage reforestation: creating more and more wetlands can help soak up excessive moisture since wetlands act as sponges. Wooded areas can also slow down heavy water flow, minimizing the effects of floods. Reforesting upstream regions can significantly reduce the effects of flood damage.
Installing flood barriers: these are flood gates designed to prevent the area behind the barrier from flooding. They can also be kept around buildings to keep floodwaters outside the boundary created.

Some international Models of Urban flood control

(A) To enhance Preventive measures

It can learn a lesson or two from cities in Japan, Malaysia and Europe. These cities have well-prepared mapped flood zones.
By combining field surveys, historical records, satellite imagery and infrastructure assessment, they have identified vulnerable areas.
Such maps and data are shared with citizens, which help them understand the status of their neighborhoods and decide where to move or buy new homes.

(B) To enhance Mitigation

Kuala Lumpur and Tokyo have built extensive water discharge tunnels to divert and store floodwater. This reduces the volume of water that washes the city.
Tokyo has one of the largest underground tunnels, running to a length of 6.5 km, and the tank can hold 6,70,000 cubic metres of diverted water, which is later pumped into safe watercourses using turbines.

(C) To enhance Response measures

As cities increasingly face natural hazards and terrorist attacks, they are investing in setting operation centers for early warning and rescue work.
For example, Rio de Janeiro has spent $14 million and created a real-time monitoring center of infrastructure and traffic flows.
The recent experience clearly shows the need for early warning and dissemination of reliable information about floods and rescue.

(D) The Dutch Model of Flood Management

‘Live with Water, Built with Nature’ sees cities as ‘waterscape’ and not ‘landscape’ as most of our cities are built along water bodies like river banks or coastal areas. The model proposes nature-based solutions for flood management in cities.

(E) Yongning River Park model

Of China where artificial wetlands are created in and around cities to allow periodic flooding in these parks and act as a buffer for cities and thus preventing flooding.

Way forward

Building Resilience: The rapid transformation in rainfall characteristics and flooding patterns demands building the resilience of people and urban infrastructure.
Reconsider projects: Construction projects that impede the movement of water and sediment across the floodplain must be reconsidered.
Use of technology: At the same time, climate-imposed exigencies demand new paradigms of early-warning and response systems and securing livelihoods and economies.

Climate variability assessment: As the incidence of climate variability and extreme weather events increases, it is inevitable that we look at the issue from a broad-based perspective.
Innovation: Water-sensitive urban design and planning techniques — especially in the context of implementation — are of utmost importance. Ex. Sponge Cities.
Environmental determinism: Planning must take into consideration the topography, types of surfaces (pervious or impervious), and natural drainage and leave very less impact on the environment.
Vulnerability Analysis: Vulnerability analyses and risk assessments should form part and parcel of city master plans.
Extending IN-FLOWS flood control systems which have been installed in Chennai and Mumbai to other major cities also.

Conclusion

A June 2020 Ministry of Earth Sciences climate change assessment report noted how the increased frequencies of heavy rainfall had enhanced flood risk all over India, particularly in urban areas. This requires an urgent fix.
Thus, Flooding in India is also all set to increase in magnitude and intensity. The need of the hour is to adopt the Sendai framework’s Disaster risk resilience approach in Urban flood management in India to better cope with urban floods and reduce their impact as much as possible.