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Systemic Causes of Urban Flooding in India

Context

  • As India approaches the tipping point of transitioning from a predominantly rural to an urban society, urbanisation is inextricably linked to development and is frequently a major driver of economic growth. By 2030, urban areas are expected to house 40.76% of the country’s population.
  • However, urban planning machinery has not kept pace with urbanisation and technological advances. Unplanned development and climate change are causing a slew of tragic events, including urban flooding, that demand immediate attention.
  • Thousands of houses in Hyderabad were submerged during the 2020 floods. The 2015 Chennai flood serves as a stark reminder of how rapid urbanisation is making cities more vulnerable to urban flooding. And, most recently, during this monsoon season, Bengaluru has been the site of numerous such flooding incidents.

Relevance

GS Paper – 3: Disaster Management, Environmental Pollution & Degradation

Mains Question

India’s urban planning machinery has not evolved at the same rate as the country’s population has. Provide appropriate arguments to back up your claim. (150 Words)


Flooding in Cities

  • The inundation of land or property in a built environment, particularly in more densely populated areas (such as cities), caused by rainfall exceeding the capacity of drainage systems is known as urban flooding.
  • In contrast to rural floods (heavy rain over a flat or low-lying area), urban flooding is caused not only by increased precipitation but also by unplanned urbanisation (catchments) that:
    • multiplies the flood peaks by 1.8 to 8 times
    • multiplies flood volumes by up to six.

India’s Urban Flooding Causes

  • Encroachment on Drainage Channels: In Indian cities and towns, due to rising land prices and a scarcity of land in city centres. New developments are springing up in low-lying areas, often as encroachments on lakes, wetlands, and riverbeds.
    • Ideally, the natural drains should have been widened to accommodate higher stormwater flows (similar to road widening for increased traffic).
    • On the contrary, large-scale encroachments have occurred without widening the natural drains. As a result, the capacity of natural drains has decreased, causing flooding.
  • Climate Change: Extreme weather events are exacerbated by changing climate. Climate change has increased the frequency of short-duration heavy rainfall, resulting in greater water run-off.
  • According to NASA research, the urban heat island effect causes increased rainfall over urban areas, which causes flooding.
  • When rain-bearing clouds pass over an urban heat island, the hot air pushes the clouds up, resulting in highly localised rainfall that can be quite intense at times.
  • Unplanned Tourism Activities: For decades, water bodies have been used as a draw for tourism development. Water plants that slow runoff are being removed from rivers and lakes in order to maintain tourism activity
  • Throwing non-biodegradable waste into rivers and lakes during religious and cultural events degrades water quality. Floods cause suspended particles and pollutants to overflow into cities, posing health risks. For example, oil spillage from boats polluted Ashtamudi Lake in Kollam, Kerala.
  • Uninformed Dam Release: The unplanned and unexpected release of water from dams and lakes causes floods in urban areas, without giving the public enough time to respond. For instance, the 2015 Chennai floods were caused by the release of water from Chembarambakkam Lake.
  • Illegal Mining: Illegal mining of river sand and quartzite for building purposes depletes the natural bed of rivers and lakes.
  • It causes soil erosion and reduces the waterbody’s water retention capacity, increasing the speed and scale of water flow. For instance, Jaisamand Lake in Jodhpur and the Cauvery River in Tamil Nadu.

The Effects of Urban Flooding

  • Loss of Life and Property: Urban floods are frequently associated with loss of life and physical injury, either directly as a result of floods or indirectly as a result of infections spread by water-borne diseases during the inundated period.
  • Localized effects of urban flooding include structural damage to buildings, property, and crops. Furthermore, it disrupts water supply, sewerage, power and transmission lines, communication, traffic-road and railway infrastructure, and other infrastructure.
  • Ecological Impacts: During extreme flood events, trees and plants are washed away, and high-speed flood water causes riverbank erosion.
  • Impact on Animal and Human Health: Localized stormwater stagnation and contamination of consumable water causes a variety of health issues, including plagues/epidemics.
  • Sewage and solid waste washing into houses and neighbourhoods spreads a variety of diseases.
  • Psychological Effects: The loss of shelter and relatives causes emotional turmoil in the stranded’s mental health. In such cases, the recovery process is arduous and time-consuming, and it frequently results in long-term psychological trauma.

Way Forward

  • Creating Blue Green Infrastructure: Blue Green Infrastructure is an effective method of providing a long-term natural solution to urban and climatic challenges.
    • In order to create more pleasant, less stressful living environments, water management and robust infrastructure development should be prioritised equally.
    • Additionally, ensuring that Rainwater Harvesting is an integral component of every building in the city.
      • Blue denotes bodies of water such as rivers and tanks.
      • Green represents trees, parks, and gardens.
  • Flood vulnerability mapping: Identifying vulnerable areas can be done by analysing topography and historical inundation data at the city level.
    • Keeping track of all water bodies and wetlands at the city and village levels is also critical for flood avoidance, tolerance, and resilience.
  • Effective Water-Shed Management: Flood walls, raised platforms along flood-prone river basins, and timely cleaning and deepening of drainage channels should be built along the entire river basin rather than just in urban areas.
    • Roadside bioswales can be constructed so that rainwater from the road flows towards them and percolates into the ground.
    • Additionally, catchment areas of water bodies must be well maintained and free of encroachment and pollution in order to keep the flow of water clear.
  • Public facilities such as hospitals and schools, as well as basic services such as food, water, health, and sanitation, should be disaster resilient.
    • They should be located or relocated so that they can function normally during inundations.
  • Sensitization and Rehabilitation: Flood preparedness and mitigation measures, as well as response drills, should be promoted.
    • Residents must be educated about the dangers of illegal constructions along drains and water bodies. The government should also think about moving the poor to other areas.
  • Institutional Arrangements – It is critical to establish a unified flood control implementing agency at the city level, which will include city administrative officials, doctors, police, firefighters, non-governmental organisations (NGOs), and other emergency service providers.

 


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