UPSC Mains General Studies Paper – 1 Mains 2020Important Geophysical phenomena, geographical features, and their location
Structure of the Question
- In Introduction,
- Define urban flooding and where it was in the news recently.
- In Body,
- Write factors responsible for urban flooding. Give measures to mitigate this problem.
- In Conclusion,
- Mention the suggestions like NDMA and various rejuvenation initiative plans for cities across the country.
The term ‘urban flood’ can be simplified as “excessive runoff in developed urban areas, where the stormwater doesn’t have anywhere to go due to poor capacity of the drainage system, causing inundations. As climate variability and extreme weather events increase, urban flooding becomes more and more common in many Indian cities, like Hyderabad. While the untimely heavy rains can be attributed to climate variability, the urban flooding is mainly due to unplanned urbanization.
Factors causing urban floods in India
IMD’s data reveal that in the past century (1901-2015), there has been a rise in widespread extreme rainfall events across the Indian subcontinent by three-fold. This results in the occasional high-intensity cyclones from the Arabian Sea to the western coast and Bay of Bengal to the eastern coast, resulting in heavy rains lasting for at least 2–3 days, which, when spread over a large region, causes flash floods.
Flood risk arises when the surface runoff is more than the infiltration rate during precipitation. It causes overbank flow of channel networks, the occurrence of high tides impeding the drainage in coastal cities.
- 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. Pollution of natural urban water bodies and converting them for development purposes has increased the risk of flood
- Encroachments: Encroachments are also a major problem in many cities and towns. As a result of this, the flow of water has increased in proportion to the urbanization of the watersheds. The capacity of the natural drains has decreased, resulting in flooding.
- Cities Becoming Impervious: 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, a non-porous construction material that makes the soil impervious).Moreover, irreversible damage has been done to the city by property builders, property owners, and public agencies by flattening terrain and altering natural drainage routes.
- Climate Change: Climate change due to various anthropogenic events has led to extreme weather events.
- No Community Participation: Flood control measures planned without participation of the affected community are unsustainable as they do not meet the needs of relevant stakeholders.
- Poor Implementation of EIA: Even with provisions of rainwater harvesting, sustainable urban drainage systems, etc., in regulatory mechanisms like the Environmental Impact Assessment (EIA), adoption at the user end and enforcement agencies remains weak.
- Inadequate Drainage Infrastructure: Cities like Hyderabad, Mumbai rely on a century-old drainage system, covering only a small part of the core city. In the last 20 years, the Indian cities have grown manifold with their original built-up area. However, not much was done to address the absence of adequate drainage systems
Remedial Measures for Urban Flooding
Urban floods cannot be contained by the municipal authorities alone. Floods cannot be managed without concerted and focused investments of energy and resources. The Metropolitan Development Authorities, National Disaster Management Authority, State revenue, and irrigation departments along with municipal corporations, should be involved in such work together.
Utilising International best practices:
Implementing ‘Mobile Walls’ like in Germany, and ‘sponge’ cities in line with cities in China which involves replacing concrete pavements with porous pavements to ensure better filtration.
Urban flooding may increase if wetlands are not protected. Centre for Science and Environment (CSE) has recommended strong laws to protect urban lakes, their catchment and feeder channels.
Water Sensitive Urban Design:
These methods take into consideration the topography, types of surfaces (permeable or impervious), natural drainage and leave very less impact on the environment.
Sustainable usage of land:
Low-lying areas in cities have to be reserved for parks and other low-impact human activities, restrict encroachments in natural drainage areas; clearance of river beds, proper implementation of Coastal Regulation Zone rules. Planting drought resistant and flood resistant sturdy trees in vulnerable areas also helps.
These can all be delivered effectively through an urban mission along the lines of the Atal Mission for Rejuvenation and Urban Transformation (AMRUT), National Heritage City Development and Augmentation Yojana (HRIDAY), and Smart Cities Mission.
Overburdened drainage, unregulated construction, no regard for the natural topography, and hydro-geomorphology all make urban floods a man-made disaster. India has to learn its lessons from recent floods, in Assam, Bihar, Tamil Nadu, Karnataka and Kerala. Addressing the underlying causes and taking immediate effective corrective measures is the most important need to tackle and overcome the floods and its devastation.
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