Memories of the ruinous floods in Chennai last year, partially blamed on climate change, have prompted many residents to raise the height of their houses to avoid getting inundated
If you cannot beat the flood, rise above it. This has become the mantra for some of the families with houses in the low-lying areas of Chennai that suffered severe flooding in November-December 2015.
As the string of low-pressure weather events that constitute the northeast monsoon for Chennai is beginning, the city is hoping that flooding like that of the last year does not occur this year. Communities are also working to build upon the experience gained from the last floods to prevent some of the mistakes and improve on the situation.
Even though floods of the magnitude that happened in 2015 were unprecedented, it left a scar on residents of Chennai, one that resurfaces every time rain is predicted. In November-December 2015, the city received the highest rainfall in 100 years. This – combined with the reduction of the wetlands and waterways system in the city – led to floods of the kind that left their mark on the walls of buildings and also the minds of people.
Located on the east coast of the country, Chennai receives most of its 1,400 mm annual rainfall between October and December. These rains are mostly in the form of low-pressure events in the Bay of Bengal that deliver short spurts of heavy rain over the city.
Living in a city with a flat terrain, most of the residents realise that their houses and apartments have been sinking in relative height to the adjoining roads over the years. While the ground on which their houses are built remains at the same height, the roads have been getting higher with every coat of asphalt. This means that when it rains the water flows into the housing compound from the road, adding to the flood impact.
Since residents do not have control over the rate at which the roads are laid, they have been looking at ways to increase the height of their floors, according to R.R. Krishnamurthy, professor and head, Department of Applied Geology, University of Madras. It is here that the possibility of getting specialist engineers to raise their homes has attracted the attention of the residents, and many families have opted for it, especially in the low-lying parts of the city.
“This is an example of innovative adaptation to a climate-related extreme weather event,” Krishnamurthy told indiaclimatedialogue.net. His team, in partnership with ETH University of Zurich, Switzerland, is carrying out a Climate Disaster Recovery Planning (CDRP) project in two legislative assembly constituencies of the city — Velachery and Mylapore. The aim of this project is to understand the social, economic and institutional mechanisms that came to the rescue of the residents during the 2015 floods, and the steps that can be taken to prevent trauma during future events.
“Velachery is a new part of the city which was affected badly in the 2015 floods, and Mylapore is the old part of the city that escaped heavy inundation. We chose these locations for a micro study, so that we have an idea of the resilience in different localities,” observed Krishnamurthy. This University of Madras department had earlier prepared the Climate Disaster Resilience Index (CDRI) for Chennai in 2010 for the Chennai Corporation, in collaboration with Kyoto University of Japan. They had followed it up with the Climate Action Plan for the city in 2011.
Interestingly, the building contractors who have been doing the house lifting work come from as far Yamuna Nagar in Haryana. According to Rajesh Kumar, managing director of MCMD Engineering Works Private Ltd, one of the companies in the lifting business, though they have worked in many parts of the country in 2016, it was from Chennai they got most requests. As a result, the company even opened a branch in the city.
“We had good number of enquiries from Chennai after the 2015 floods,” Kumar told indiaclimatedialogue.net. His family’s companies together carried out hundreds of renovations in Chennai during the year, which was like boom business. For instance, on one street in Madipakkam (adjacent to Velachery), the floor heights of four buildings had already been raised and one was in the process of being lifted.
The lifting operation involves placing jacks under the plinth of the house and raising the building by one foot at a time. The raised area is then filled in with masonry, before raising the building by another foot. At Chennai the highest they have raised is six feet, at Madipakkam. Kumar says that their family developed and perfected this method, starting from the time of his father in 1991.
At a three-storeyed building being lifted in Madipakkam, construction supervisor Bachan Das and his team have placed a series of jacks along the walls of the house. Their aim is to lift the floor of the building by five feet, so that it is above the water even if it floods. As a lead worker shouts out instructions, workers turn each of the jacks by a predetermined amount.
Das told indiaclimatedialogue.net that it is critically important to lift all the jacks by the same amount, so that cracks do not develop on the walls. Once the building is lifted and the new walls built, soil is filled and concreting done to build the floor of the bottom floor afresh. The rest of the floors remain as they were before the renovation.
According to Das, the idea behind such renovations is to keep buildings intact at a cost less than a quarter of what would be required to construct afresh. At present they charge Rs 250 per square foot per floor for their work. Even with the cost of material being extra, house lifting provides an opportunity to owners to keep their floors above water without having to demolish and build afresh.
“This building is only eight years old and that is the reason we opted for this renovation,” said K. Sridhar, owner of one of the three apartments in the building. “When we built this house our floor was higher than the road. Now the road is higher so we need to lift our floor.”
Madipakkam, like adjoining Velachery, is a low lying area, and was prone to water logging even before the housing colonies started developing in the 1990s. Even before the northwest monsoon has set in, the empty housing blocks have standing water and reeds growing in them.
Adapting to climate change
Chennai residents’ opting for building-lifting technologies is a kind of adaptation to climate change. Due to its flat terrain and short spells of heavy rainfall, the residents of many parts of the city are used to water logging during the rainy season. However, the floods of 2015 went beyond what the city had experienced before, and hence the residents have started resorting to this innovative adaptation technique.
The United Nations Framework Convention on Climate Change Secretariat defines adaptation as “adjustments in ecological, social, or economic systems in response to actual or expected climatic stimuli and their effects or impacts. It refers to changes in processes, practices, and structures to moderate potential damages or to benefit from opportunities associated with climate change.”
According to the Tamil Nadu State Action Plan on Climate Change, though the frequency of tropical cyclones may decrease in the future, they are likely to increase in intensity. Further, the trend in the state also shows that rainfall during the southwest monsoon has decreased whereas rainfall during the northeast monsoon has been increasing.
The combined impact could mean more events like the 2015 floods. Keeping the floor above water would be a way of dealing with it.