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5 Reasons Why Urban Floods Are Happening

By Snigdha Dev Roy

Urban floods are on the rise at an alarming rate. It has slowly become a regular phenomenon in most of the metropolitan cities of India. Our country has a long history of urban floods since the last 20 years, the most damaging ones repeatedly happening in cities like Hyderabad, Ahmedabad, Delhi, Chennai, Mumbai, Surat, Kolkata, Guwahati, Uttarakhand, Kashmir, Madhya Pradesh and Mumbai.


In the last few years, the number of events and scale of urban floods has sharply increased which is a great challenge to cities all over India that urgently needs effective and structured flood management. The impacts of such disasters are very complex and has caused a lot of devastation and economic losses and will continue to do so. According to a 2008 research [1] by the National Institute of Disaster Management, annual economic losses from urban floods are far greater than those from other disasters.


Furthermore, increased urbanization, land use changes, and meddling with natural watersheds have damaged Indian cities' capacity to withstand heavy rainfall. Thus, it is an urgent call for cities to be ready to deal with urban floods. Let’s take a look at five major causes of urban floods in Indian cities with possible solutions to improve upon them.


OLD & POOR DRAINAGE INFRASTRUCTURE

Many cities still rely on stormwater, water supply, and wastewater systems that were designed for conditions that existed decades ago and comprise infrastructure that has significantly deteriorated or is undersized for contemporary standards. For example, Mumbai, which houses the second largest slum settlement – Dharavi – in Asia, struggles with inadequate urban infrastructure problems. The city's outdated colonial-era drainage system which is around 140 years old, is heavily silted and damaged. Having been grown organically over the years, which needs to constantly adapt to emerging demands, it is a victim to recurrent urban floods. In a survey done by the Ministry of Urban Development [2] in 2010, 56 out of 104 large cities had coverage below 50% which needed immediate action for improvement and 93 had coverage below 75% with caution for improvement.

The cities have been planned with little to no regard to the natural drainage patterns, terrains and severely lacks holistic action. Water sensitive urban design and planning techniques — especially in the context of implementation — take into consideration the natural topography and drainage patterns, types of surfaces (pervious or impervious), and leave very less impact on the environment. Thus, planning has to have a long-term perspective and infrastructure should keep pace with growth of population to cope with future urban flooding risk.


SLUMS & SQUATTER SETTLEMENTS IN LOW-LYING AREAS

In most developing countries, urban growth creates poorer neighborhoods, which we typically call, slum or informal settlements. These usually pop-up around the low-lying regions like nallahs, railway lines, roads and highways in any city, which lack adequate housing, infrastructure and services, making these areas more prone to flooding, making them vulnerable, especially the women and children. Improper construction of buildings with makeshift materials and obstructions in ditches, culverts and streams by solid waste and refuse can be a considerable obstacle to the efficient conveyance of storm water especially in such areas which can cause the water to back up and spread laterally into their homes. As a result of this, many people lose their residence with recurring floods, which never gets accounted for. This is typically the case in Delhi's Yamuna Pushta area where slum areas flood almost every year now and Mithi river basin in Mumbai where 70% occupancy is of slums and pavement dwellers (Kranti Nagar Slums).

Floor Risk Assessments (FRAs) and vulnerability analyses should be a part of all levels of plans - city master plans as well as zonal and local area plans. Sprawling of informal settlements in sensitive zones can be disabled by providing adequate affordable housing that can eventually reduce the number of persons vulnerable to changing climate.


CONSTRUCTION & ENCROACHMENT ON FLOODPLAINS

Builders have been increasingly constructing on reclaimed wetlands, flood plains, and low-lying areas of the cities owing to rapid urban expansion, as these areas have relatively cheaper land rates. Despite the fact that the Central Water Commission (CWC) passed a bill for floodplain zoning in 1975 and directed it to the states to enact and implement, only three states – Manipur, Uttarakhand, and Rajasthan – have done so till date, and even in these states, implementation is almost non-existent. It is very common in our country for mega-projects to overlook environmental regulations. For instance, the Commonwealth Games Village (CWG) and Akshardham Temple Complex in Delhi were built right on the Yamuna's floodplain in the 2000s. Majority of the Chennai International Airport was constructed on the riverine floodplains of Adyar River, which led to massive flooding in 2015. Even recent developments such as Andhra Pradesh’s Amaravati Capital City Project, proposed major areas to be developed on the floodplains of Krishna River.

The construction could follow passive design approach, which requires incorporating nature’s characteristics into planning and understanding how they interact with human-built aspects of the environment. Strong land use controls, Environment Impact Assessments (EIAs) and other regulatory mechanisms are important to ensure that fragile wetlands and floodplains are not concretised.


EXTENSIVE LAND-USE CHANGE IN COASTAL AREAS

Removal of vegetation and soil, grading land surface due to construction of large new developments as well as drainage networks disrupts the natural drainage patterns and natural watercourses. By changing pervious natural surfaces to less or non-pervious artificial surfaces, stormwater runoff rate and total runoff volume increases as a result of declining natural land water storage capacity, frequently overwhelming their capacity and creating flood problems. More than 600 water bodies, lakes and wetlands like Velachery in Chennai have been converted into IT hubs, commercial and residential areas, reducing the water retention capacity of the ponds [3]. In Mahim Creek of Mumbai, deforestation of coastal mangrove belts has been a big contributor to frequent flooding. The impact of the cyclone Hudhud in October 2014, which wreaked havoc on coastal cities including Vishakhapatnam, could have been mitigated if there had been a healthy mangrove cover.


It should be ensured that Coastal Zone Management Plans (CZMPs) are prepared for all the coastal states along with the establishment of Coastal Zone Management Authorities. They should be mandated to identify ecologically sensitive areas and delineate economically important stretches in these areas.


FRAGMENTED INSTITUTIONAL RESPONSIBILITIES

The central government has taken up various initiatives for flood management and to address flood risks. These initiatives mostly addressed riverine floods and described flood control measures such as dams, embankments, and drainage channels. Flood control and management is handled by a number of agencies in India. The flood control is overseen by the water resources ministries of various states in consultation with the CWC. Their primary responsibility is to collect hydrological data at the national level and to notify states of any impending or potential floods. In addition to this, the Union Jal Shakti Ministry has established the Ganga Flood Control Commission (GFCC) to deal with floods and its management in the Ganga basin states. The India Meteorological Department (IMD) provides rainfall or cyclonic event forecasts, which are used by all agencies in their flood preparedness. The National Disaster Response Force (NDRF) works with state equivalents to provide relief and rescue. But it was only in 2010 that the issue of urban floods was de-linked from the broader topic of flood control and management, and the National Disaster Management Authority (NDMA) decided to deal with urban flooding separately, formulating the National Guidelines for Management of Urban Flooding.


Despite such a plethora of agencies working at different levels across the country, urban flood management still remains a problem in India. There is a lack of streamlining and coordination among the wide network of agencies. There has been an overlapping of structural and administrative setups that constitute lack of organizational capacity and service provisions. These organisations should have a common goal with separate responsibilities under a common management strategy. This can be done by focusing on developing a platform that brings all of the information together and allows it to be used effectively and efficiently. Once a shared framework gets established, it is easier to coordinate the working of different agencies and monitor their progress.


So the question is: What does this mean for cities? What are the solutions we should start looking for? These could only be answered when we start looking at the problems that have been mentioned above and experiment with it. The impacts of urban flooding can be minimized only by making changes to the way we plan our cities, otherwise, India which is already ranked fifth on the Global Climate Risk Index [4], will drop even more.


References


[1]

NIDM, "Annual Report," National Institute of Disaster Management, MoHUA, Delhi, 2008.

[2]

"The alarming deficit in stormwater drainage in urban India," mint, 3 August 2016. [Online]. Available: https://www.livemint.com/Politics/pL6qalnBUQmulQZRuorELP/The-alarming-deficit-in-stormwater-drainage-in-urban-India.html. [Accessed 16 July 2021].

[3]

CSE, "CSE PRESS NOTE: Chennai in crisis," Centre for Science and Environment, 2015 December 2015. [Online]. Available: https://www.cseindia.org/cse-press-note-chennai-in-crisis-6160. [Accessed 16 July 2021].

[4]

J. Nandi, "India 5th most vulnerable to climate change: Global Climate Risk Index 2020," Hindustan Times, 4 December 2019. [Online]. Available: https://www.hindustantimes.com/india-news/india-5th-most-vulnerable-to-climate-change-global-climate-risk-index-2020/story-W9WR8cquip39dVcC6IWmxH.html. [Accessed 16 July 2021].


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