The return of the deluge to Mumbai and the paralysis suffered by the city bring up the question of why Indian cities are unable to improve their resilience to extreme weather events. It t is the second highest rains recorded in a 24 hour period in the last 44years. This event comparable to the 2005 floods in Mumbai resulted in water-logging, halting of all three modes of transport, power-cuts and some casualties as well. Big cities like Delhi, Chennai and Bengaluru also have slowed down during heavy rains.

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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.

Reasons for inundation in Mumbai, post rains:

• Meteorological Factors: Heavy rainfall, cyclonic storms and thunderstorms
• Hydrological Factors: Overbank flow channel networks, occurrence of high tides impeding the drainage in Mumbai and other coastal cities.
• Anthropogenic Factors:
  • 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 lakebeds.
  • Destruction of lakes is a major issue in India cities. Lakes can store the excess water and regulate the flow of water. However, pollution of natural urban water bodies and converting them for development purposes has increased risk of floods
  • Reduced infiltration due to concretization of surfaces which decreases ground absorption and increases the speed and amount of surface flow
  • Reduced groundwater recharge, increased use of groundwater, and diminishing base flow of streams
• Climate Change: Climate change due to various anthropogenic events has led to extreme weather events
• Poor Solid Waste Management System: Improper waste management system leads to clogging of storm-water drains because of silting, accumulation of non-biodegradable wastes and construction debris.
• Disaster management: As far as NDRF is concerned, there is technology, equipment and training about it. Whenever the information is given, they are ready to take action. But the cooperation from the state government, metrological departments, equipment available at the place and help of NGOs, there is lack of communication and coordination.
• Almost negligible power to local government: Issue of urban governance has two aspects- local government empowerment and motivation to local government to take decisions

Problems plaguing Mumbai’s urban drainage system:

• The drainage capacity of the entire city isn’t impressive as such, experts have explicitly conceded that at least major roads and traffic junctions fall far short of the required.
• Although contour maps for drains were prepared it remains incomplete for the rest of the city. This means, although the prediction of the drainage flow is possible, there is no data point to predict how a river’s flood waters will rush out
• Massive underground sewers built during the colonial era dating back to 1860-1900 are impressive with some of it still in use, but is limited to South Mumbai.
• The suburbs of Mumbai are served mostly by open drains, into which tonnes of garbage are dumped each year by citizens.
• Pre-monsoon ‘desilting’ exercises are carried out every year, which has proved to be ever-inadequate.
• Much of these sewer networks flow several kilometres through congested localities before discharging into the sea, often through outfalls located below mean sea level.
• This means if it’s raining heavily when the tide is sufficiently high, drainage is impossible.

Measures needed:

• Lot of unauthorized activities are done in drainage areas. Natural nalas are covered with habitation, jhuggis. If these are allowed and water is able to take natural course, there will be prevention of flooding.
• Municipalities have to be empowered. For e.g.: There is Delhi municipality and also there is Delhi Jal Board which handles the sewerage system and water supply system. So these are interlinked issues where sewage-drainage-water supply is intertwined.
• In every state there is multiplicity of agencies and therefore municipality has become one of the agency and not the agency. It is time that all the agencies dealing with developmental activities and governance framework are integrated with municipalities concerned. But this will take a while as for 70 years there have gone bypassing the local government. It was because of programmes like BRGF and JNNURM and now AMRUT that municipalities are coming back to some position.
• The long term and medium term resolution lies in putting integrated coordinated governance framework for cities.
• Mumbai has problem of high tides. When there are high tides and rain water comes into it, it results in problem of back flow. A simple solution suggested so many times is that there should be gates which take water back to the sea. Only two places have such gates and 100 places don’t have it to prevent the back flow. By saying that such infrastructure is expensive shows the inability to truly analyse the cost-benefit ratio when high damage is done to infrastructure and lives post the flood.
• Along with drainage, the rivers are not kept clean. People should be taught not to put garbage in rivers, plastics shouldn’t be thrown in rivers. Strong actions should be taken against those who do it. Other countries don’t see this problem of plastics being put in the drainage system and choking it. So there is a need to take action before the flood occurs.
• There is little participation by the communities. Only state and central government cannot deal with such a big problem. If communities are involved, given the task, responsibilities and resources including finance beforehand, then there will be prompt action.
• There is a need for a water centric approach which has been missing completely. To develop cities, water is not taken into account as a factor for development. There are courses in architecture, special universities about urban planning but drainage channel is not taken into consideration while building infrastructure. So until unless urban development becomes water centric, this problem is bound to come.
• There is no linkage between the forecast of rain and forecast of flood. There is no system of flood forecasting or flood warning for cities. The elaborate system of flood forecasting in central water commission is for rivers. What is required is the model of linking flooding with rainfall. This model is developed internationally in academic institutions but not in India.

Conclusion:

Rains in the city are not in control of single agency. The cities handle last part of drains, i.e. tertiary drains. Before it there is state highway and national highway within the city and because the roads and drains are intertwined, the drains are not independent of the roads. So when national highways are made, there is least botheration about the drainage system. So there is a need to revisit the planning on one hand and governance as far as cities are concerned.