known to affect the pace of many infrastructure and developmental projects implemented in the city.

The total population of Mumbai has grown steadily from 3 million in 1951 to 8 million in 1981 to 12.43 million in 2011 with population density of 28,404 persons per sq. km. (MCGM, 2014). About 55‐60% of the population resides in informal settlements or hutments known as slums, which occupy 33% of the total residential area (MCGM, 2014a) and almost all the population increase in the city over time has been absorbed in these settlements (Annez et al., 2010). The majority of the people living in slums belong to low‐income segments of the population. Yet, Mumbai is the economic powerhouse of the country, contributing 33% of income tax collections nationwide, 60% of customs duties collection and 40% of foreign trade (MCGM, 2014a). The per capita income at current prices has increased from USD1,089 (1USD=INR60)<sup>6</sup> in 2006‐07 (GoM, 2007) to USD4,058 in 2013‐14 (GoM, 2014). However, the household income distribution shows acute inequalities with 20% earning less than USD167 per month, 50% below USD330 per month and top 10% earning USD2,000 per month (Annez et al., 2010). These acute inequalities in income distribution reveal acute poverty in the city and also explain more than 50% population living in informal slum settlements.

On the weather front, the city experiences a heavy southwest monsoon rainfall and is also prone to cyclones and gusty winds. Historically, Mumbai has been receiving an annual rainfall of about 2,200 millimeters (mm) during the monsoon season between June and September. Since 2004, the average annual rainfall has been more than 2,400mm, with variations in rainfall from the lowest of 1,274mm recorded at Colaba weather station in 2002 to a maximum of 3,378mm recorded at Santacruz weather station in 2010<sup>7</sup> (MCGM, 2014). There are a number of days every year when rainfall exceeds 65mm or 135mm per day. Rainfall of 200mm or more per day is also not uncommon during the onset of monsoon. Heavy precipitation and resultant flash floods are, therefore, a regular event in Mumbai.

Flooding is a chronic and recurrent problem during monsoon. The key reasons for flooding are tidal variations, flat gradients and mud flats causing excessive siltation (MCGM, 2014a). Many low‐lying and reclaimed areas across the city get flooded, especially when heavy rains combine with high tide or storm surges, with the added difficulties due to unsanitary methods of solid waste and sewage disposal and problems with the drainage systems (Sherbinin et al., 2007). Other contributing factors to flooding are manmade inappropriate levels of outfalls, loss of holding ponds due to land development, increase in the run‐off coefficient, encroachments on drains and obstructions due to crossing utility lines (MCGM, 2014a). Mumbai’s vulnerability to extreme precipitation was demonstrated on **_26 July 2005_** when **_944mm_** rainfall occurred in the suburban district in the 24‐hour period. About 200km of road length and the airport was submerged in flood water. Local train services, bus services and air traffic came to a complete standstill. Around 2 million people were

> 6 The conversion rate of **1US Dollar = Indian Rupees 60** used throughout this paper.

> 7 Floods occurred in 2010 after this maximum rainfall and have occurred every year since the 2005 event.

5