Geo Spatial analysis of climate change, its impact and path to resilience of Greater Mumbai

Each year, Mumbai, the ‘unstoppable’ city, is brought to a grinding halt by the monsoons. Originally seven islands, Greater Mumbai today, largely sits on land reclaimed over drainage patterns of rivers such as Mithi, Dahisar, Poiser and Oshiwara. Hence, the city riddled with low-lying areas is susceptible to water-logging. Add to this, our storm water drainage system is over a hundred years old, not designed to deal with the large amounts of rainfall and surface run-offs that we have witnessed over the past two decades. In 2005, Mumbai witnessed the worst bout of flooding where over a metre of rain fell within 12 hours, causing considerable loss to life and property, the city took a week to return to some form of normalcy. This year on year flooding has not receded, in fact, it encompasses a larger area each year with several parts of the MMR facing severe flooding for the past decade.

Each year, the flooding greatly impacts Greater Mumbai’s suburban railway network, the city’s main lifeline. The working of the financial capital is disrupted for cumulatively a week, and witnesses enormous economic losses. Equally ritual are the stories of people staying back in their offices, stranded in trains and railway stations, wading through waist-deep waters and amidst floating cars. However, there are hardly any planning intiatives taken to mitigate the impact or to start building resilience. We need to answer questions such as Which areas are impacted? What are the pre-conditions for flooding? How much area is flooded with related quantum of rainfall? how much rain will cause flooding? what is the year on year increase in flooding? Do we even have scenarios for intensity of rainfall vs the tides levels?

Global warming, climate change, and rising sea levels are already becoming a reality, not just conjecture. World over people have been coming up with apocalyptic scenarios of the earth being taken over by water and coastal cities becoming completely submerged under water. This research is not trying to advocate such fear-mongering. The New Jersey-based Climate Central, a non-profit, has suggested that all of Mumbai is likely to go under the high tide level by 2050, but what does this really mean? The research will be looking at level rises and which areas in Greater Mumbai will be affected. Using geo-spatial analysis, it will show very crisp patterns of which areas of the city will be severely impacted. This kind of projected data will offer the city time and pace to intervene. If the whole city is to go under water, then building a wall is not the solution. The change will be incremental and the city will have to build resilience incrementally.

If the sea level goes up by 50mm, then the relative flooding in the city could be up to a metre, for example. The research will look at scenarios such as the impact of a 100mm increase would lead to which areas go under water and what would be the respective flooding? What are the DCRs, flood mitigation measures and proposals which the city will have to start working on to alleviate such rising sea levels?

Statutes and by-laws that are put in place to regulate development in areas which are eco-sensitive, and those that act like buffers for the storm surges and tidal action have been severely diluted in due to the enormous pressure on the land and vested interests (DCPRs, EIA and the CRZ). The local fishing community, fauna and flora, salt marshes, mudflats and the mangrove forests are under threat. Changes in construction pattern & legislation will have to be enforced to make Mumbai robust and face the impact of global and local climate change.

There is a lack of empirical models/scenarios to show the impact of rising sea levels on the flooding levels within the city. The objective of this UDRI research rubric is to study in detail what is the impact of rise in sea levels on different parts of the city and what measures can the city incorporate to mitigate the impact and build resilience. It is a multiple year, multi-disciplinarian initiative, spanning across several layers of urbanism, and comprising several tools for examination. It is an overarching umbrella for a number of research projects, programs and publications, undertaken in parallel, on Mumbai and the Metropolitan Region.