Urban Floods

How does a strong El-nino affect Chennai? Are you curious? Read the Explainer as well!

Urban Floods

I-FLOWS: Mumbai Flood Management System

Note4Students

From UPSC perspective, the following things are important :

Prelims level : IFLOWS

Mains level : Urban floods in India

Integrated Flood Warning System for Mumbai (I-FLOWS Mumbai), a state-of-the-art flood warning system has been developed for the city.

Practice question for mains:

Q. Urban floods in India are consequences of unplanned urbanization in India. Discuss with references to the frequent annual floods in Mumbai.

What is IFLOWS-Mumbai?

  • IFLOWS is a monitoring and flood warning system that will be able to relay alerts of possible flood-prone areas anywhere between six to 72 hours in advance.
  • The Ministry of Earth Sciences (MoES) has developed the system with in-house expertise and coordination with the Brihanmumbai Municipal Corporation (BMC).
  • The system can provide all information regarding possible flood-prone areas, likely height the floodwater could attain location-wise problem areas across all 24 wards and calculate the vulnerability and risk of elements exposed to flood.
  • Mumbai is only the second city in the country after Chennai to get this system. Similar systems are being developed for Bengaluru and Kolkata.

How will it work?

  • The primary source for the system is the amount of rainfall, but with Mumbai being a coastal city, the system also factors in tidal waves and storm tides for its flood assessments.
  • The system has provisions to capture the urban drainage within the city and predict the areas of flooding.
  • The system comprises seven modules- Data Assimilation, Flood, Inundation, Vulnerability, Risk, Dissemination Module and Decision Support System.

Why was this system needed in Mumbai?

  • Mumbai, the financial capital of India, has been experiencing floods with increased periodicity.
  • Floods, especially the ones in 2005 and 2017, are etched in everyone’s memory.
  • Last year, post-monsoon and unseasonal rainfall as late as October, two tropical cyclones in the Arabian Sea had caught authorities off guard and left a trail of destruction.
  • The flood during 26th July 2005, when the city received a rainfall of 94 cm, a 100 year high in a span of 24 hours had paralyzed the city completely.
  • Urban flooding is common in the city from June to September, resulting in the crippling of traffic, railways and airlines.
  • As preparedness for floods before they occur, the system will help in warning the citizens so that they can be prepared in advance for flooding conditions.

Benefits

  • IFLOWS-Mumbai will enhance the resilience of the city by providing early warning for flooding, especially during high rainfall events and cyclones.
  • Using this, it will be possible to have an estimate of the flood inundation three days in advance, along with immediate weather updates.
  • The Union Minister said the system was “one of the most advanced” ones and will help the city, which has been experiencing floods with increasing periodicity.
  • The hi-tech system will predict floods before they occur, therefore enabling Mumbaikars to take due precautions in advance.

Urban Floods

Private: Urban Flood Management

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Not Much

Mains level : Urban flood management

Context

  • Urban flooding is a common experience in most of the cities around the world. 
  • In India, it becomes more pronounced on the onset of monsoons and hampers the daily activities of the huge urban population. 
  • To prevent flooding there is a need for efficient urban water management systems, especially in cities, which are largely based on traditional engineering approaches till date.

Urban Flooding:

What is urban flooding?

  • Flood is defined as “an overflow of a large body of water over areas not usually inundated”. Thus, flooding in urban areas is caused by intense and/or prolonged rainfall, which overwhelms the capacity of the drainage system.
  • Urban flooding is significantly different from rural flooding- urbanization increases flood risk by up to 3 times, increased peak flow results in flooding very quickly. Further, it affects large number of people due to high population density in urban areas

Causes of urban flooding

Meteorological Factors:

  • Heavy rainfall, cyclonic storms and thunderstorms

Hydrological Factors:

  • Overbank flow channel networks, occurrence of high tides impeding the drainage in coastal cities.

Anthropogenic Factors:

1.Unplanned Urbanization:

Unplanned Urbanization is the key cause of urban flooding. A major concern is blocking of natural drainage pathways through construction activity and encroachment on catchment areas, riverbeds and lake beds.

Some of the major hydrological effects of urbanization are:

  • Increased water demand, often exceeding the available natural resources;
  • Increased wastewater, polluting rivers and lakes and endangering the ecology-
  • Destruction of lakes is a major issue in India cities. Lakes can store the excess water and regulate the flow of water. However, pollution of natural urban water bodies and converting them for development purposes has increased risk of floods
  • Reduced infiltration due paving of surfaces which decreases ground absorption and increases the speed and amount of surface flow
  • Reduced groundwater recharge, increased use of groundwater, and diminishing base flow of streams
  • Increased peak flow

2.Climate Change:

  • Climate change due to various anthropogenic events has led to extreme weather events

3.Poor Solid Waste Management System:

  • Improper waste management system
  • Clogging of storm-water drains because of silting, accumulation of non-biodegradable wastes and construction debris.

4.Drainage System:

  • Old and ill maintained drainage system is another factor making cities in India vulnerable to flooding.

Impact of Urban Flooding:

1.Impact on Human:

  • Loss of life & physical injury
  • Increased stress; psychological trauma

2.Disease outbreak:

  • Contamination of water supplies leading to diseases
  • Rise in mosquito borne diseases

3.Impact on Economy:

  • Damage to buildings, roads and other infrastructures
  • Disruptions to industrial production
  • Disruptions to utility supplies
  • Impact on heritage or archaeological site
  • Post-disaster rescue and rehabilitation adds to financial burden of the government

4.Impact on Transport and Communication:

  • Increased traffic congestion, disruption in rail services
  • Disruption in communication- on telephone, internet cables

5.Impact on environment:

  • Loss of tree cover, loss of habitat
  • Impact on animals in zoo, stray animals

Notable Urban Flooding Events in India since 2000:

  • Hyderabad in 2000
  • Ahmadabad in 2001
  • Delhi in 2002 and 2003, 2009, 2010
  • Chennai in 2004, 2015
  • Mumbai in 2005, 2017
  • Surat in 2006
  • Kolkata in 2007
  • Jamshedpur in 2008
  • Guwahati in 2010
  • Bengaluru in 2017

National Disaster Management (NDMA) Guidelines on Urban Flood Management:

  • In 2010, NDMA had issued guidelines on Urban Flood Management in India to create a National Hydro-meteorological Network.
  • The guidelines say that for providing early warning, the Central Water Commission (CWC) CWC should maximize the real-time hydro-meteorological network to cover all urban centres to effectively deal with the problem of urban flooding
  • Use of Doppler Weather Radarsto be expanded to cover all urban areas in the country
  • An inventory of the existing storm water drainage system to be prepared. The inventory will be both watershed based and ward based.
  • Catchment to be the basis for planning and designing the storm water drainage systems in all ULBs
  • All future road and rail bridges in cities crossing drains to be designed such that they do not block the flows resulting in backwater effect
  • Every building in an urban area must have rainwater harvesting as an integral component of the building utility.
  • Low-lying areas in cities have to be reserved for parks and other low-impact human activities.
  • Encroachments on the drain should attract penal action.
  • Pre-monsoon desilting of all major drains to be completed by March 31 each year.
  • Urban Flooding has to be dealt as a separate disaster, de-linking it from riverine floods which affect the rural areas.
  • Suitable interventions in the drainage system like traps, trash racks can be provided to reduce the amount of solid waste going into the storm sewers.
  • Inlets to be provided on the roads to drain water to the roadside drains and these has to be designed based on current national and international practices.
  • Every building in an urban area must have rainwater harvesting as an integral component of the building utility.
  • Concept of Rain Gardens to be incorporated in planning for public parks and on-site storm water management for larger colonies and sites those are to be developed.
  • Flood hazard assessments should be done on the basis of projected future scenarios of intensities and duration of rainfall and land use changes.

Way Forward:

  • Better forecasting of rainfall events; timely dissemination of information to the mass- ‘Nowcasting’ alerts or real-time weather updates

Example: The Municipal Corporation of Greater Mumbai has installed 60 automatic weather stations for recording the rainfall every 15 minutes. This information is disseminated through the GMDMA (Greater Mumbai Disaster Management Authority) web portal in real-time during the monsoon.

  • Installation of proper, functional drainage system. Maintenance of existing drainage channels, providing alternative drainage path
  • Develop ‘sponge’ cities in line with cities in China
  • Proper solid waste management system- control of solid waste entering the drainage systems
  • Restrict encroachments in natural drainage areas; clearance of river beds, proper implementation of Coastal Regulation Zone rules.
  • Each city should have their Flood mitigation plans strongly embedded within the master plan of the city.
  • There should be prompt, well-coordinated and effective response in case of urban floods to minimize casualties and loss of property and also facilitate early recovery.

Global case studies

  • Heavy rainfall in July 2011 prompted the city of Copenhagen to develop a Cloudburst Management Plan in 2012 to prepare the city for one of the biggest climate change challenges — extreme rainfall and pluvial flooding.
  • The plan contains site identification, developing stormwater roads and pipes that transport water towards lakes and harbour, detention areas to store large volumes of water, green roads to detain and hold back water in smaller side streets.
  • The Netherlands is dotted with ponds, lakes, seaside parking garages and city plazas that double up as water storage ponds during flooding events.
  • To address the urban flooding issue, China’s sponge city initiative set an ambitious goal — by 2020, 80 percent of urban areas should absorb and re-use at least 70 percent of rainwater.
  • The initiative seeks to reduce the intensity of rainwater runoff by enhancing and distributing absorption capacities more evenly across targeted areas.
  • The resulting groundwater replenishment increases availability of water for various uses.

URDPFI guidelines:

  • According to guidelines from the Urban and Regional Development Plans Formulation & Implementation (URDPFI), 2016, the maximum percentage of land is allotted to residential areas in different sizes of urban centres — metropolises to small towns.
  • Residential clusters, which occupy the largest share (35 to 45 per cent, apart from recreational areas of 18 to 20 per cent) of land use in cities and towns, comprise building rooftops, sidewalks, paved parking spaces and previous areas that could be gardens or just open land and accessible roads.
  • According to the guidelines, the average built-up area for an urban area is 24 per cent, while for an open space, it is 76 per cent.
  • The standards and guidelines provide enough open areas to design such stormwater management projects.
  • The 2019 manual on storm water drainage systems, prepared by Central Public Health and Environmental Engineering Organisation, included a chapter on innovative stormwater management practices.
  • It talked about integrating smart practices such as water sensitive urban design.
  • However, it is a herculean task to be incorporated at city level.

Conclusion:

  • There is a need to include public open spaces within urban fabric in the form of storm management infrastructure, which could help our cities transform into water-sensitive cities.
  • It requires effective policy implementation, addressing technical integration problems, legislative constraints, social equity, and community acceptance for Urban management of flooding.  

 

Urban Floods

[op-ed snap] Mumbai marooned

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Nothing Much

Mains level : Urban Floods in Mumbai

CONTEXT

Mumbai once again struggled to stay afloat after the first heavy spell of rain this year, bringing back memories of the July 2005 flood. Each massive rainfall event is making it evident that the city is putting on a brave front and projecting resilience, but the failure of the Maharashtra government to upgrade its tattered infrastructure is taking a heavy toll and weighing down on the financial capital.

Impact of monsoon

  • A single day of rain has killed 22 people in a wall collapse in north Mumbai, while many more died in Pune and elsewhere.
  • In Ratnagiri, a dam gave way creating a catastrophe; flights have been cancelled and normal life is affected.
  • Clearly, the State government should have regarded the 94 cm of rain that paralysed Mumbai in one day 14 years ago as the baseline disaster to prepare for.

Ineffective Administration

  • That it could not manage 37 cm in 24 hours, that too after incurring a massive expenditure on management projects, shows a lack of resolve among political leaders, rampant inefficiency and lack of integrity in the administrative machinery.
  • As one of the wettest metropolises in India getting about 210 cm of rain annually, it should have been a top order priority to restore rivers and canals to manage floods.
  • The government s needs to explain why Mumbai is yet unprepared to cope, especially when rainfall is projected to become erratic in coming years, and when scientific insights point to intense rainfall in a short span of time, driven by warmer oceans and hotter cities.

CAG’s Report on ineffectiveness

  • In a recent report, the Comptroller and Auditor General identified prolonged delays in the upgrading of storm water drain infrastructure in Mumbai.
  • On the other hand, after the deluge of 2005, the consensus was for the flood-carrying capacity of the Mithi river in the city to be increased.
  • But the choked and polluted river was again overflowing this year.

Change in monsoon rainfall pattern

  • Beyond the sclerotic management of flood waters that relies on storm drains in Mumbai, and several other Indian cities, there is a need for a new urban paradigm.
  • For one thing, Mumbai, Thane, Ratnagiri and Raigad have, during the last century, displayed a high seasonality index, indicating a relatively small monsoon window bringing a lot of rain.
  • This is in contrast to steady, prolonged rain in the central districts in Maharashtra.
  • So a new climate change-influenced normal could mean fewer days of torrential rain and erratic monsoons.

Way Forward

  • Managing them calls for a new approach that is ecological, and makes restoration of existing urban wetlands and creation of reservoirs and water channels a high priority.
  • The water question is the biggest challenge for Indian cities today, as both drought and flood are common.
  • State governments should give it priority and address it by making urban planning people-centric. A strong framework is needed to manage water, starting with Mumbai.

Urban Floods

[pib] Flood Management and Border Areas Programme (FMBAP)

Note4students

Mains Paper 3: Environment| Disaster and Disaster Management

From UPSC perspective, the following things are important:

Prelims level: FBMAP

Mains level: Flood management


News

  • The Union Cabinet has approved the “Flood Management and Border Areas Programme (FMBAP)” for Flood Management Works in entire country and River Management Activities and works related to Border Areas.

FMBAP

  • The Scheme “FMBAP” has been framed by merging the components of two continuing XII Plan schemes titled “Flood Management Programme (FMP)” and “River Management Activities and Works related to Border Areas (RMBA)”.
  • The aim of the scheme is to assist the State Governments to provide reasonable degree of protection against floods in critical areas.
  • The works under the scheme will protect valuable land from erosion and flooding and help in maintaining peace along the border.
  • The Scheme aims at completion of the on-going projects already approved under FMP.
  • Further, the scheme also caters to Hydro-meteorological observations and Flood Forecasting on common rivers with the neighbouring countries.

Funding Pattern

  • The funding pattern for FM Component for works in general category States will continue to be 50% (Centre): 50% (State).
  • For projects of North Eastern States, Sikkim, J&K, Himachal Pradesh and Uttarakhand, the funding pattern will continue to be 70% (Centre): 30% (State).
  • RMBA component being specific to activities in border areas, the project works will continue to be funded as 100% grant-in-aid / central assistance.

Benefits

  • The FMBAP Scheme will be implemented throughout the country for effective flood management, erosion control and anti-sea erosion.
  • The proposal will benefit towns, villages, industrial establishments, communication links, agricultural fields, infrastructure etc. from floods and erosion in the country.
  • The catchment area treatment works will help in reduction of sediment load into rivers.

Urban Floods

[op-ed snap] A series of unfortunate missteps

Note4students

Mains Paper 2: Polity| Functions and responsibilities of the Union and the States, issues and challenges pertaining to the federal structure, devolution of powers and finances up to local levels and challenges therein.

From UPSC perspective, the following things are important:

Prelims level: Basic knowledge of the federal structure of India.

Mains level: The news-card analyses the federal fallout of the Kerala flood relief funding row, in a brief manner.


Context

  • The differences between the Kerala and Central governments over the denial of external assistance to rebuild the State after the devastating floods of August last year surfaced again last month.

Background

  • The Kerala Governor Justice in his policy speech in the Assembly had said that the Kerala government had requested the Centre to enhance its borrowing limit to mobilise additional resources for rebuilding the flood-hit State.
  • The state government is still awaiting a favourable response from the Central government in this regard.
  • Further, a Kerala Minister who represented Kerala at the Pravasi Bharatiya Divas in Varanasi, complained that he was not allowed to raise the issue there.
  • The bitterness over the flood money still persists.

Competitive federalism: a double-edged sword

  • Competitive federalism, in the context of interaction with foreign countries as promoted by the Prime Minister, has proved to be a double-edged sword.
  • Kerala Chief Minister now stands accused of violating rules regarding the seeking of foreign assistance.
  • He remains unclear on how to make up for the shortfall, of several crores.
  • The Central government is unable to provide the funds while Kerala has been stopped in its tracks from seeking resources from abroad, either from the Kerala diaspora or from friendly foreign governments.

Misunderstandings on both sides

  • The present situation is a result of a series of errors of judgment and misunderstandings on both sides.
  • Mutual political suspicion and a lack of appreciation of the complexities of the international situation have brought about a confrontation.
  • The Chief Minister may have even made diplomatic and tactical mis-judgements.

Diplomatic trajectory

  • India had no qualms about receiving foreign assistance for disaster management till 2004.
  • But when India’s aspiration for permanent membership of the UN Security Council met with strong resistance, New Delhi hit upon the idea of forcing a vote in the General Assembly.
  • The plan was to secure a two-thirds majority and then attempt to embarrass the permanent members into supporting the expansion of the Security Council.
  • The two false presumptions were that India would win the required number of votes and that the Security Council would wilt under pressure from the General Assembly.
  • In fact, many Assembly members were opposed to the veto even for the existing permanent members and had no interest in creating more permanent members with veto.
  • India thought that it could win over the other countries if it was seen to be helping them in emergencies rather than seeking such assistance for itself.

Rules were laid regarding foreign assistance to bring some clarity

  • The tsunami of 2004 and the threat of piracy in the Indian Ocean provided India an opportunity to test its new posture.
  • Everybody was grateful, but it made no difference to India’s claim to permanent membership.
  • However, the present government decided to lay down the rules regarding foreign assistance in order to bring some clarity to the situation.
  • The rules which were framed in 2016 clarified that India would not solicit any assistance but would receive relief assistance, even as cash, from individuals, charitable institutions and foundations.
  • If cash were to be offered bilaterally by foreign governments, the matter would be considered on a case-by-case basis.

The UAE’s offer

  • The Prime Minister was informed by the United Arab Emirates (UAE) authorities that relief assistance was being put together as a special gesture and the Prime Minister reciprocated with a warm reply of gratitude.
  • However, the Kerala Chief Minister’s announced that the UAE would provide ₹700 crore, made on the same day as the Central government’s announcement of a provision of ₹500 crore.
  • It appeared as the UAE was more generous than New Delhi was to Kerala and that the Central government was not empathetic to Kerala’s plight because of political considerations.
  • An embarrassed UAE government then asked its Ambassador in New Delhi to deny that there was any specific offer of ₹700 crore.

Consequences

  • An immediate consequence was a reluctance by other governments to make any offer of bilateral assistance.
  • No one could answer the question whether any offer from other governments would be accepted.
  • When the Thai Ambassador in Delhi was stopped from being at a ceremony to hand over relief goods to an Indian official, the world was convinced that India would not accept resources.
  • The issue was also politicised.

Unwise decision by Kerala government

  • Against this backdrop, Kerala put forward an unwise proposal to despatch its Ministers abroad to collect donations.
  • This was unacceptable in the context of the policy that had crystallised after the floods in Kerala and the Central Government having refused permission for Ministers other than the Chief Minister to travel to countries.
  • Apart from the ignominy of soliciting donations, there was a clear likelihood of receiving very little by way of cash donations.
  • The possibility of loans from the International Monetary Fund and the World Bank became distant as the Centre refused to raise the limits on loans from these global organisations that a State government could take.
  • The emergence of the Sabarimala crisis further eroded the credibility of the State Government and much of the empathy over the flood damage was also lost.

Way Forward

  • Marshalling of resources is the responsibility of the Union government according to the Constitution.
  • The only option before Kerala is to demand more funding from the Centre to make up the shortfall.
  • The situation is a tragedy of errors caused by an inadequate familiarity with decision making and the complexity of international relations.
  • India is a federal state, but unitary in nature when it comes to national security and foreign policy.
  • Individual States may have some advantages in dealing with some countries in their neighbourhood, but they will do well not to transgress the thin line when it comes to managing international relations.

Urban Floods

Govt. teams up with Google for flood warning

Note4students

Mains Paper 3: Science & Technology | developments & their applications & effects in everyday life

From UPSC perspective, the following things are important:

Prelims level: Central Water Commission (CWC), India Meteorological Department, Artificial intelligence, machine learning, geospatial mapping,

Mains level: Flood management in India and need of better practices to ensure minimal loss of life and property


News

Better flood warning

  1. Union Water Resources Ministry has teamed up with Google to generate flood warnings
  2. If there are signs of an imminent flood, a Google Maps user will be able to see what regions are likely to see water logging first and if their neighborhood is under threat
  3. Google will provide a visualization via Google Maps and people will be able to see water levels build up in a region

Technology sharing

  1. CWC and Google will share technical expertise in the fields of artificial intelligence, machine learning, geospatial mapping and analysis of hydrological observation data to improve flood prediction systems, provide location-targeted, actionable flood warnings
  2. Google Earth Engine will be used to help visualize and improve flood management and initiate a cultural project to build online exhibitions on the ‘Rivers of India’

Present system of warning

  1. Currently, the Central Water Commission (CWC) warns of floods based on the rising water levels in reservoirs and if these are nearing a dam’s ‘danger marks’
  2. Last year, it began a trial programme to give 3-day flood forecasts
  3. The India Meteorological Department now provides inputs to the CWC on whether heavy rainfall is likely and if this could translate into large amounts of rainwater overflowing from river banks or catchments

Urban Floods

Extreme rainfall not because of global factors

  1. Context: A study by Indian Institute of Science, Bengaluru (IISC) on rainfall
  2. Findings: Global warming and El-Nino are not the only factors responsible for extreme rainfall seen in some cities like Chennai
  3. Such rainfall is influenced more by changes in conditions like local temperature & urbanisation
  4. Global factors: like ENSO, climate change have lesser influence than local temperature
  5. Method: analyzing historically observed rainfall data, and land and sea surface temperatures for the period between 1969 and 2005 across 2,000 locations in the country

Urban Floods

Chennai to focus on flood mitigation measures

  1. The proposal made to the Centre focussed on the vision of an attractive, productive and inclusive Chennai, providing a smart urban network environment.
  2. The majority of its residents live and work within walking distance of high quality rapid transit.
  3. With accessible and reliable urban services and whose public spaces support a good quality of life.

Smart proposals for flood mitigation, non-motorised transport, smart parking management, improved water supply and drainage under the Smart Cities Mission.

  1. The proposal made to the Centre focussed on the vision of an attractive, productive and inclusive Chennai, providing a smart urban network environment.
  2. The majority of its residents live and work within walking distance of high quality rapid transit.
  3. With accessible and reliable urban services and whose public spaces support a good quality of life.

Urban Floods

Panel to inspect drainage system sought

  1. A petition filed in the SC sought direction to the Centre and the TN govt to set up an expert committee to inspect stormwater drainage system.
  2. It will inspect and scientifically re-design the existing stormwater drainage system to manage floods and prevent water-logging.
  3. It comes in the backdrop of the highly prone nature of annual cyclones in coastal regions, esp. in TN, AP and Puducherry.
  4. It lead to floods because of encroachment of natural water bodies and improper rainwater drainage management system.
  1. A petition filed in the SC sought direction to the Centre and the TN govt to set up an expert committee to inspect stormwater drainage system.
  2. It will inspect and scientifically re-design the existing stormwater drainage system to manage floods and prevent water-logging.
  3. It comes in the backdrop of the highly prone nature of annual cyclones in coastal regions, esp. in TN, AP and Puducherry.
  4. It lead to floods because of encroachment of natural water bodies and improper rainwater drainage management system.

Chennai floods: Unfolding the real cause

Chennai witnessed its worst rainfall in 100 years. Let’s take a look at what are the main causes, it’s impact and possible ways forward to achieve [long and short term targets]

flood-head-for-blog


What exactly happened that wrecked a havoc in Chennai?

  • The catastrophic flooding in Chennai is the result of the heaviest rain in several decades.
  • This forced authorities to release a massive 30,000 cusecs from the Chembarambakkam reservoir into the Adyar river over two days. Causing it to flood its banks and submerge neighbourhoods on both sides.
  • It did not help that the Adyar stream is not very deep or wide, and its banks have been heavily encroached upon over the years.
  • Similar flooding triggers were in action at Poondi and Puzhal reservoirs, and the Cooum river that winds its way through the city.
  • So, unusually heavy rain has exposed the city’s broken urban planning, revealed its stolen natural waterways, and exposed its tolerance of illegal construction.

3 important Geo-climatic factors for heavy rain in 100 years – 

  • Strong el-nino
  • Upper Air divergence
  • High moisture content

How does a strong El-nino affect Chennai?

  • The summer (southwest) monsoon is adversely affected, while the northeast monsoon or the winter monsoon is favourably affected.
  • In mid-November, the sea surface temperature in the central tropical Pacific was 3 degrees Celsius warmer than normal, the largest positive deviation in recorded history.
  • To officially beat the 1997-98 El Niño as history’s worst, sea surface temperatures must stay at these levels for three months.

How does inefficient urban planning causes floods?

  • 1.5 lakh Illegal construction
  • Chocking of water exits
  • Badly planned or unimplemented projects

But, what was wrong with the Urban planning?

  • Chennai is located in a relatively flat area, hence it depends on natural water bodies, canals and rivers to drain the heavy water runoff during rains.
  • Its drainage and stormwater network, which is absent in many places, is inadequate even to convey water during moderate rains.
  • As a result, the city has a high exceedance flow (excess water that cannot be drained through the drainage system).
  • It often inundates neighbourhoods, particularly those in the suburbs, which are built in low-lying areas and poor roads. This scenario was foreseeable.

Chennaifloodinfograph


Let’s get into some details of unplanned Urban Space

  • Today, Chennai has a host of expensive infrastructure aimed at ushering in a “Make in Chennai” boom, a brand-new (though leaky) airport built on the floodplains of the River Adyar.
  • A sprawling bus terminal in flood-prone Koyambedu, a Mass Rapid Transit System constructed almost wholly over the Buckingham Canal and the Pallikaranai marshlands.
  • An IT corridor and a Knowledge Corridor consisting of engineering colleges constructed on waterbodies, and automobile and telecom SEZs and gated residential areas built on important drainage courses and catchments.
  • So, fact remains that the mindless development of Chennai over the last 2 decades, the filling up of lowlands and choking of stormwater drains and other exits for water has played a major part in the escalation of the crisis.

Way forward : Lessons from International Practices

First task : To enhance Preventive measures

  • It can learn a lesson or two from cities in Japan, Malaysia and Europe.
  • Well-prepared cities have 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 neighbourhoods and decide where to move or buy new homes.
  • More importantly, this data is used to regulate development.
  • The United Nations Office for Disaster Risk Reduction has collated data spanning 3 decades, starting from the 1980s, for various places in Tamil Nadu including Chennai.
  • The city corporation can quickly build on it.

Second task : 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 6.5 km, and the tank can hold 6,70,000 cubic metre of diverted water, which is later pumped into safe watercourses using turbines.
  • Canals such as the Veerangal Odai, which connected Adambakkam lake with Pallikaranai marsh in the suburbs, have almost disappeared. Reclaiming these water bodies is critical.
  • The city should also explore, as many others have done, the possibility of designing highways to conduct runoff water.
  • All this would warrant a thorough review of its urban engineering.

Third task : To enhance Response measures

  • In the first week following the heavy rains, ground reports reveal that the government response was inadequate and uncoordinated.
  • The spirited effort of citizens propelled rescue efforts, without which the damages would have been more severe.
  • As cities increasingly face natural hazards and terrorist attacks, they are investing in setting operation centres for early warning and rescue work.
  • For example, Rio de Janeiro has spent $14 million and created a real-time monitoring centre of infrastructure and traffic flows.
  • The recent experience clearly shows the need for early warning and dissemination of reliable information about floods and rescue.
  • Improved governance and non-interference of political parties in relief measures are critical.

Can you ponder on any long or short term solutions or any way ahead?

Let us know, as UPSC is fond of asking such solution based questions in Mains!


 

Published with inputs from Arun
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