Climate crisis: The link between urbanisation, increased flooding, economic loss

Over the years, visual imagery around floods in India has undergone a change. From submerged fields and marooned villages in states such as Bihar and Assam, floods now bring pictures of floating cars, submerged subways and floodwater in living rooms within cities.

This is not just an anecdotal observation. The climate crisis is beginning to alter rainfall patterns. With a massive surge in urbanisation — an increase in built-up area undermines natural drainage systems – without compensating for the loss of natural drainage systems with man-made ones, floods are bound to cause more damage, at least in monetary terms, in India.

All natural disasters, including floods extract heavy human costs. The poor live at subsistence levels and such shocks are always very harsh on them. But the prospect of greater wealth destruction during natural disasters is also worse news for the Indian economy.

A simple comparison illustrates the point. From 2008 to 2014, houses were damaged in both Bihar and Kerala every year because of floods and heavy rains. A 2018 Central Water Commission (CWC) report shows that the value lost per damaged house was almost four times in Kerala as in Bihar: ₹2,857 in Bihar and ₹10,906 in Kerala. More than the intensity of floods, this numbers reflects the fact that Kerala houses are better-built than Bihar, because the former has higher per capita income.

Richer states and non-farm sector are suffering more damage in floods now

A 2018 CWS report gives state-wise value of damages caused by floods from 1953 to 2016. Sorting these states by per capita GSDP shows that the share of the bottom one-third of states in flood related damages has reduced from more than 50% to just above one-third between 1961-2000 and 2001-2016. This means that India’s more affluent states are suffering a higher damage in floods.

Floods are now increasingly affecting the non-farm sector in India. In the 1961 to 2000 period, an average of 58% of the damage caused by floods annually was from the damage to crops while 27% was from public utilities. This pattern has now reversed. From 2001 to 2016, crop loss accounted for an average 29.7% of the damage, while public utilities accounted for 58.6% of monetary losses due to floods. What explains these two changes? Both the climate crisis and the nature of urbanisation are to blame.

Intense rainfall is increasing in districts with more affluence

While floods affect all, they seem to affect some more than others. Counterintuitive as it sounds, floods cause more monetary damage if they affect an area with a greater share of rich. This is due to the simple reason that richer dwellings have more valuable items than their poorer counterparts. A joint reading of an HT analysis of rainfall patterns and a Mint database of district-wise wealth tracker shows that India’s richer districts are becoming more vulnerable to floods now.

Mint’s wealth tracker uses the 2015-16 National Family and Health Survey (NFHS) to rank districts on the basis of assets and amenities (pucca house, electricity connection, phone, television, AC/cooler, refrigerator, washing machine, and motorised vehicle) owned by households. A household is described as affluent if it owns at least six of the eight assets listed here. HT has used the India Meteorological Department’s gridded rainfall database to look at the increase in heavy and extreme rainfall in comparison to the long period average (LPA).

The median share of the affluent in districts where heavy and extreme rainfall – when a lot of rain happens in very little time or over a very small area – has increased the most during the 2015 to 2020 period is 20.73%. This share becomes smaller as we move to districts where such rainfall has increased by lesser degrees. In districts where heavy and extreme rainfall has increased the least, the median share of the affluent was 15.4%.

It should be kept in mind that the district-wise increase in heavy/extreme rainfall is a relative measure as it is being tracked against past rainfall (1961-2010) in the same district.

Concrete jungles without drains are bound to get flooded

Almost every time Kerala faces serious floods, the Cochin airport has to suspend operations, as the runway gets flooded. This should not be surprising. Where the airport has been built, there used to be paddy fields at one point of time, where flooding was a boon rather than a bane.

Where the airport has been built, there used to be paddy fields at one point of time, where flooding was a boon rather than a bane.

A similar case is of the Santacruz airport in Mumbai built on the floodplains of the Mithi River. During heavy rains in July, Mumbai airport has had to temporarily suspend operations due to waterlogging on either the runways or tarmac in 2017 and in 2021. However, disruptions due to turbulence following heavy rainfall events are more common, recurring every year since 2017. In 2019, a passenger aircraft overshot the main runway while landing in heavy rains on July 2. The main runway remained shut for close to four days. It is common for operations to become restricted to a single runway during heavy rains. Expansion of the airport has squeezed the Mithi river into a small stream, and the construction of a second runway in 1970 created a right-angle bend in the river which has worsened flooding.

The cases of these airports are symptomatic of a larger problem with India’s changing land-use pattern. The National Statistical Office (NSO) gives remote sensing-based land-use statistics in India. Built up area increased from 118,998 square kilometres in 2011-12 to 121,848 square kilometres in 2015-16. Of the 3,609 square kilometres added from other sources, 73% came from agriculture, 5.7% from forest land, and 3.3% from grass or grazing land. These numbers capture the rapid surge in concretisation in India in the recent past. An increase in concretised area also means that rainwater does not seep into the ground. In the short-term, this means waterlogging and, in the long-term, it means a fall in replenishment rate of ground water tables.

Agricultural land was most used for creating builtup space

What makes the concretisation problem even worse, at least from the point of view of flooding, is the fact that most Indian cities have built houses but not drains. A government survey carried out in 2010-11 in 104 municipal corporations/Nagar Nigams in large cities found that 56 of them had 50% roads not covered by storm water drainage. Similarly, 745 of 1,383 other urban local bodies (ULB) had less than 50% coverage, and 1,142 ULBs had less than 75% coverage. This is apart from the everyday sight of drains choked with waste or silt where they do exist.

When these problems fester in big cities, it can lead to huge losses. Mumbai’s 2005 flooding — when the city received over 900mm of rain in a single day — caused an estimated insurance loss of $0.9 billion, according to a report by Swiss Re Institute. A more recent study by the United States Trade and Development Agency (USTDA) and accounting firm KPMG, submitted to the Maharashtra government in September 2019, pegged Mumbai’s financial losses as a direct consequence of flooding to be ₹14,000 crore between 2005 and 2015.

Experts fear that the financial damage in Mumbai is only going to increase as the city’s natural drainage continues to be subsumed by concrete. In 2019, for example, a plush residential township built on the floodplains of the Mothali river in Dombivali, was flooded with water entering the homes of even those living on the first floor, while similar projects built on the floodplains of the Waldhuni and Ulhas rivers have also experienced similar distress in between 2018 and 2021.

The Brihanmumbai Municipal Corporation (BMC) has also noticed that the Mithi River took longer to drain its water into the sea this year than during past seasons, leading to apprehension that Mumbai is staring at more floods in the coming years. Officials and experts attributed this to a combination of factors, including heavy rains coinciding with high-tide, and clogging up of drainage channels with muck and garbage. The BMC this year spent a total of ₹150 crore on its monsoon flood management plan, which showed little to no improvement at fixing the underlying problem.

In fact, rapid development of infrastructure may be creating problems in places where they did not exist earlier. For example, residents reported unprecedented waterlogging in 2020 along the strip of South Mumbai that runs from Worli to Girgaum Chowpatty, allegedly due to the Coastal Road project that has buried about 5km of the intertidal zone along the shore, thus preventing water from draining into the sea.