GS1- Urbanisation and GS3- Disaster management
Explain the principle reason behind chronic urban flooding in Indian cities like Delhi, Bengaluru and Mumbai. And also suggest what are Mitigation Strategies for Urban Floods?
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. Consequently, flooding occurs very quickly due to faster flow times (in a matter of minutes).
Principal Reasons Behind Chronic Urban Flooding
1. Centres of economic activity
- Urban areas are also centres of economic activities with vital infrastructure which needs to be protected 24×7.
- Ex: attraction of urban opportunities
2. Current drainage systems
- Cities are witnessing more such bursts of rain, and their current drainage systems cannot cope, leading to flooding.
- Ex: state of Kerala in 2019.
3.Encroachments on Water Bodies
- Poor migrants are unable to find housing in the formal market and often seek shelter on or near riverbanks, mangroves, and land along drains.
4. Poor Urban Planning:
- Rapid urbanization without adequate urban planning affects the natural drainage system
5. Climate Change
- Global climate change is resulting in changed weather patterns and increased episodes of high intensity rainfall events occurring in shorter periods of time.
6.Solid Waste and Debris
- Improper disposal of solid waste, including domestic, commercial and industrial waste and dumping of construction debris into the drains also contributes significantly to reducing their capacities.
7.Deforestation
- The destruction of forests, wetlands, and green spaces reduces the ability of the land to absorb water.
Mitigation Strategies for Urban Floods
1. Adoption of green roofs and infiltration
- Mitigation requires that the quantum of infiltration that has been lost on account of the construction of a building should be made up by provisions on the rooftop. Infiltration beds can be installed on roofs.
2. Rooftop rainwater harvesting
- Flood risk can be reduced using rooftop rainwater harvesting tanks that can hold vast amounts of water.
3.Integrated Urban Planning
- Develop a water master plan that gives urban development’s water management first priority.
4. Sponge Cities Concept
- China launched the Sponge City Initiative in 2015, investing in projects that can absorb floodwater.
5.Blue Green Infrastructure
- Blue-Green Infrastructure refers to a network that provides the “ingredients” for solving urban and climatic challenges by a combination of infrastructure, ecological restoration and urban design to connect people with nature.
6.Public Awareness
- Ensure prompt, well-coordinated, and effective response to urban floods to minimize casualties, and property damage, and facilitate quick recovery.
India must closely examine the over-densification of its cities and articulate a national policy that disincentives demographic density beyond an accepted limit based on economic, environmental, and social sustainability.
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