GS1 PYQ (Mains Answer Writing): Flooding in Mega Cities | Geography for UPSC CSE PDF Download

Account for the huge flooding of million cities in India including the smart ones like Hyderabad and Pune. Suggest lasting remedial measures (UPSC GS2 Mains)

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. 

• The coastal urban flooding is a complex phenomenon which may occur in various forms such as: urban flooding due to high intensity rainfall; due to inadequate drainage and flooding caused by overtopping in the channels or rivers; flooding due to high tides, etc.A 2016 UN report estimated that 40 million people in India will be at risk from sea-level rise by 2050. Reasons for Urban Flooding in million plus cities. 
• Urban flooding is caused by three main factors – meteorological, hydrological and human factors. – Meteorological factors include heavy rainfall, cyclonic storms and thunderstorms. – Hydrological factors include presence or absence of overbank flow channel networks and occurrence of high tides impeding the drainage in coastal cities. – Human factors include land use changes, surface sealing due to urbanization (which increases run-off), occupation of flood plains and obstruction of flood flows, urban heat island effect (which has increased the rainfall in and around urban areas), etc. – Water logging. — a prelude to urban flooding — is a common sight in urban India during the monsoon. Urban flooding has also become increasingly common, as the changing weather pattern resulted in more high intensity rain in fewer rain days. While this was initially seen only in cities like Mumbai and Delhi now the scourge has been extended to smart cities like Hyderabad and Pune which have a high ease of living index performance. 
• Urbanisation: Rapid urbanization combined with a lack of efficient waste disposal systems have left several water bodies in the cities in poor condition. Blocked waterways and reduced width and depth of canals, while the speed and scale of construction reduces the permeability of the ground.
• Improper Drainage: In Indian cities and towns, large habitations are coming up in low-lying areas, often encroaching over drainage channels. Encroachment in the immediate upper catchments of hilly urban area has also caused serious flooding in the flood plains of cities surrounded by hills. 
• Population Growth: Most of our cities have now reached a saturation point in terms of population growth and accommodation, and the developmental activities have now shifted to low-lying areas and areas next to the riverbanks. So, whenever a city experiences a large amount of rainfall within a short time, there are chances it gets flooded. 

Impact of the devastation due to floods: 

• On economy: Damage to infrastructure, roads and settlements, industrial production, basic supplies, post disaster rehabilitation difficulties etc. 
• On human population and wildlife: Trauma, loss of life, injuries and disease outbreak, contamination of water etc. 
• On environment: Loss of habitat, tree and forest cover, biodiversity loss and large scale greenery recovery failure. 
• On transport and communication: Increased traffic congestion, disruption in rail services, disruption in communication- on telephone, internet cables causing massive public inconvenience. 
• Measures to address urban flooding in India: 
• Water-Sensitive Urban Design and Planning (WSUDP) and a green infrastructure approach for storm water management: Identification, protect and use of open spaces and water bodies as critical green infrastructure to manage run-off and mitigate urban flooding. This must be done in addition to identification of urban catchments and prioritisation based on level of risk and vulnerability. 
• Drainage Infrastructure: Prepare drainage master plans for cities with short-, medium-, longterm and periodic strategies to augment storm water infrastructure in cities. This must be aided by state-of-the-art urban watershed modelling. 
• Identifying Risk Prone Areas: Identify vulnerable and high-risk areas and prepare monsoon action plans for those areas, based on context. Informal areas are more vulnerable due to high built-up area density and lack of infrastructure. This needs to be aided by a state-of-the-art rain atlas for cities, providing spatial rainfall maps with 15-minute intervals. 
• Urban Storm water Management: Formulate a nodal authority for urban storm water management which should be responsible for preparation of drainage master plan at the local level and coordinate strategies with city master plan preparations. 
• 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. 
• National Disaster Management (NDMA) Guidelines: In 2010, NDMA had issued guidelines on Urban Flood Management in India -to create a National Hydro-meteorological Network for providing early warning, use of Doppler Weather Radars to be expanded to cover all urban areas in the country, an inventory of the existing storm water drainage system to be prepared etc. 
• Rainwater Harvesting: Due to urbanisation, groundwater recharge has decreased and the peak runoff from rainfall and consequent flooding has increased. It will serve the twin purposes of lowering the peak runoff and raising the ground water table. 
• Many municipal corporations in India have already made rainwater harvesting compulsory.

Way Forward: 

• It is important to note urbanisation is an inevitable process and urban areas will continue to grow demographically and spatially. Hence, all existing and new developmental programmes and projects shall incorporate disaster resilient specifications in design and construction. 
• Mumbai launched a state-of-the-art Integrated Flood Warning System (IFLOWS) in June, 2020. The warning system helps identifying imminent floods due to high rainfall or cyclones. 
• The Chennai Flood Warning System — that provides spatial flood warnings for the city — was launched in October 2019. 
• These systems help build resilience and can inform the public and authorities regarding risks. The India Meteorological Department launched the Mausam mobile application that provides rain forecasts including warnings. 
• The Karnataka government launched the Meghasandesha mobile application, which provides real-time rainfall measurements, along with forecasts for rain, flooding and thunderstorms for capital city Bengaluru. 
• While these measures look good on paper, they must be followed through by effective implementation, taking operation and maintenance and coordination with stakeholders including architects, planners, hydrologists, groundwater experts, etc, into account. 
• These strategies must be prepared and implemented with the support and contribution of and the local community.

Topics covered - Rainfall in India, Floods and Landslides in India