Print Friendly, PDF & Email

Insights into Editorial: Why North Chennai is the worst-hit in this year’s heavy rains

 

 

 

Context:

The Madras High Court pulled up the Greater Chennai Corporation for flooding in the city due to heavy rain and said that it would start Suo motu proceedings if the situation did not improve soon.

Chennai and several other parts of Tamil Nadu have been receiving heavy rainfall since 3 days, leading to waterlogging and damage to homes.

At least five people have died because of the rain and over 1,400 have been moved to relief camps.

The Madras High Court brought up the flooding in Chennai while hearing a public interest litigation on removing encroachments to ensure that roads in the city are wide enough.

In 2015 and during many such extreme weather systems that Chennai has witnessed, it was mostly central and southern parts of the Tamil Nadu capital that bore the brunt.

However, in the rains that have lashed Chennai in the past five days, North Chennai, the city’s congested neighbourhood with a largely working class population and several industries, is worst-affected.

 

Why is North Chennai more impacted due to heavy rains than other areas?

That is largely thanks to its low-lying topography. While the entire Chennai city is vulnerable to waterlogging for many reasons, including a much lower elevation above the sea level, which is often about six metres, what has made things worse for North Chennai is the absence of storm water drain networks and poor desilting of canals.

Multiple officials of Chennai Corporation, who had been managing waterlogging in North Chennai said the debris from construction and other commercial activities was another key factor that has led to flooding in North Chennai.

Storm water drains here are inadequate in number and those existing networks and canals too were blocked.”

 

Polluting and destroying natural urban water bodies:

  1. As the incidence of climate variability and extreme weather events increases, urban flooding becomes more and more common.
  2. While the untimely heavy rains can be attributed to climate variability, the urban flooding is largely due to an unplanned urbanisation.
  3. A major issue in India cities. Lakes can store the excess water and regulate the flow of water.
  4. Indian cities are becoming increasingly impervious to water, not just because of increasing built up but also because of the nature of materials used (hard, non-porous construction material that makes the soil impervious).
  5. However, pollution of natural urban water bodies and converting them for development purposes has increased risk of floods.
  6. Reduced infiltration due paving of surfaces which decreases ground absorption and increases the speed and amount of surface flow.
  7. Old and ill maintained drainage system is another factor making cities in India vulnerable to flooding.
  8. Lack of attention to natural hydrological system and lack of flood control measures.

 

Unplanned urbanisation of Anthropogenic activity:

  1. India has a long coastline of 7,500 km and an estimated 14% of India’s total population lives alongside it that traverses nine states, 77 towns and cities including some of the fastest-growing such as Mumbai, Chennai, and Kochi making them more prone to flood due to adjacent sea and erratic monsoonal behaviour.
  2. Aside from the present danger posed by extreme weather events such as heavy rainfall and cyclonic storms, more slow-onset impacts brought about by climate change also threaten the coastline.
  3. A 2016 UN report estimated that 40 million people in India will be at risk from sea-level rise by 2050.
  4. Urban flooding is significantly different from rural flooding 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.

 

Way Ahead steps:

  1. The management of urban flooding has to be treated holistically in a multi-disciplinary manner.
  2. Science and technology can play a significant role in improved monitoring, modelling/ forecasting, and decision-support systems.
  3. One method for improving the preparedness for urban flooding is by setting up a vulnerability-based geospatial framework to generate and analyze different scenarios.
  4. It helps in identifying and planning for the most effective/ appropriate actions in a dynamic way to incorporate day-to-day changes that take place in urban areas, having the potential to alter the prevailing vulnerability profile.

 

Solutions:

  1. Innovative approaches like Sponge Cities- wetland restoration, flushing systems using collected rooftop water, bioswales, and public spaces as flexible water retention facilities can be applied to Indian urban areas.
  2. Other such methods include permeable material for roads and pavement, green roofs and harvesting systems in buildings.
  3. Urban Flood management will not just help control recurring floods but also respond to other fault lines, provide for water security, more green spaces, and will make the city resilient and sustainable.
  4. Watershed management and emergency drainage plan should be clearly enunciated in policy and law.
  5. Proper management of the drainage system is necessary to ensure that the water does not get stored in one place.
  6. Solid waste increases hydraulic roughness, causes blockage and generally reduces flow capacity.
  7. These drains need to be cleaned on a regular basis to permit the free flow of water.
  8. Vulnerability analyses and risk assessments should form part and parcel of city master plans

 

Conclusion:

In most of the streets and neighbourhoods that were flooded this time, it took longer than usual for the water to recede.

That happened not only due to lack of drains but also because of faulty road planning wherein re-laid roads and several concrete road stretches have been higher than houses and building complexes either side.

As the world continues to urbanize, sustainable development depends increasingly on the successful management of urban growth, especially in low-income and lower-middle-income countries where the pace of urbanization is projected to be the fastest.

Integrated policies to improve the lives of both urban and rural dwellers are needed, while strengthening the linkages between urban and rural areas, building on their existing economic, social and environmental ties.