Building a flood-proofed future

With extreme weather events having become an annual affair, here is an expert-recommended architectural checklist that steps away from the conventional to keep your home safe.

Published: 17th January 2022 01:27 AM  |   Last Updated: 17th January 2022 12:46 PM   |  A+A-

Alocasia plant

Alocasia plant that purifies grey water. (Photo| EPS)

Express News Service

CHENNAI: A big kitchen, a bathroom in every room, a balcony and covered car parking'. An average middle class family's architectural aspirations look more or less like this, we find. In a city where real estate machinery has managed to maintain inflation levels at a high for several years, there are too many builders primed to make this wishlist come true. But a happy home doth that make?

Especially when it's been raining non-stop for five days, the water stagnating in the building has no place to go but the streets inundated with knee-deep water? You don't need an expert to know that there's an urgent need to redefine our priorities when it comes to building a home.  

Krithika Venkatesh of DTD Studio goes the 'first step in solving any problem is admitting there is one' way. "The Chennai floods is a manmade disaster. Since we do not have enough water penetration, watershed management is not planned properly, and - because of global warming - there is heavy downpour happening in a very short span. These are the main reasons," she notes. Addressing these lapses in a systematic manner, at the individual and community level, is the answer. But what does this mean in terms of constructing your dream house?

Essentials of the day

Redefining your checklist begins with something as simple as more open space around the house. And concreted backyards and perimeter area do not count, she adds. "The space has to have enough soil that can take in water and support plantation. Then, it can be called open space. So, when we design a space, we study the terrain and don't change it. Because rain that falls on the ground either has to penetrate or lead to a different place. We identify natural canals and make sure our building does not disturb it; also that water from the building reaches the canal," she explains, pointing out that it adds to keeping the open space ratio building at an optimal level.

Doing so can get quite challenging in the city, where maximising construction space is what drives the process. "We have a common principle - we don't construct more than 50 per cent of the space; this also includes car parking. We need to look at multiusing space," she suggests. 

"It's not about getting rid of the (stagnant) water but saving the water. Rather than avoiding the water coming into the campus by increasing the height of the plinth, we have to make sure that the land around the building is equipped to retrace the water into the ground," offers Thirupurasundari Sevvel, architect and heritage conservationist.

That can be by planting trees or - when the space is paved - using perforated stones or percolatable finishing. With the latter, your parking space can remain intact while also allowing rainwater to reach the ground. A percolation tank at the entrance of gated community or apartment complex would also help, she suggests. 

The way it drains

Another effective way of harvesting rainwater, including the water that enters the building during times of flooding or inundation, is hand dug wells, says Krithika. As these work with just the aquifer method, it does not suck out the groundwater like a borewell. This lets you manage stagnant water in the building without having to raise the plinth level. 

The next vital aspect is drainage - be it for rainwater or wastewater generated in the house. Often, we only focus on half the problem, points out Aravind Manoharan of Magizh Builders. "If rainwater enters the house, we can return to normalcy when it drains in a few days. But, the problem is when the inundation has grey water mixed into it. The effects of this problem tends to be indirect in the from of infections and diseases," he says.

To address this, we need to look at management of waste water within the house by the individual and outside the house by the corporation/government; calibrate it for normal time and flood time. Only then, can we land on a solution. Just using biotoilets can make quite the difference, even in existing constructions, he notes. 

Vishnupriya has had much experience in introducing biotoilets - made popular in the state after the 2004 tsunami - in urban and rural constructions. "Conventional toilets are either connected to septic tanks in the house or the public sewer system. A septic tank is not possible in areas with a high water table for there will be seepage and contamination of groundwater. The best part of biotoilet is that it can be used even in these areas, rocky terrain or cyclone-affected areas too," she says.

Stating that a better word for it would be eco-san (ecological sanitation) toilet, she goes on to explain that it is a three-pan model as opposed to the conventional single-pan Indian toilet. The first collects urine, the second takes feacal matter and the third is for the water shed after we wash ourselves; all three are collected in separate tanks.

The urine has urea; this can be used with water in a ratio for agricultural purposes. Feacal matter, after decomposition for six-twelve months, will look like mud in every aspect. This is achieved by adding an aerobic material (mud, dry leaves, saw dusk, ash or rice husk) to the tank that collects the waste.

The resulting manure has been proved to be an effective natural fertiliser. The third tank of grey water can be purified by just running it through plants like alocasia, which eat up the tiny feacal particles and passes clean water to the ground. 

A brave new world

As much as this seems to be an all-round solution, acceptance for this seemingly radical change doesn't come easy, finds Aravind. "People think how can we keep the toilet waste within the house; there is hesitation. Only people who are conscientious about these issues actually make the changes while others stop at thinking. It is only when they see more conversion rate will they make the switch too," he says. 

All these are solutions offered by vernacular architecture, which is often considered to be available only for the poor or the elite. But there’s always a way to find what works within your means, suggests architects in this discipline.

"This has to start from the roots, from the ideology. We can build only what is needed, have terrace gardens to grow our own food, recycle the water we have and more," suggests Krithika. Aravind adds 'limiting the number of toilets per house' to the list as well. It takes a wholesome approach to address a dynamic problem, after all. 


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