Floating floors could help Bangladesh residents during floods

    Dec. 16, 2022
    While amphibious homes could be an ideal solution for Bangladesh residents’ flood problems, Zahrun Zannat suggests that floating floors could provide a quick and more immediately affordable solution.
    Photos by Zahrun Zannat, courtesy American Geophysical Union.
    The fully amphibious house comprises a concrete base filled with low-density foam, with a traditional house constructed on top.
    The fully amphibious house comprises a concrete base filled with low-density foam, with a traditional house constructed on top.

    Amphibious houses and houses retrofitted with floating floors have the promise to save people in Bangladesh substantial time and money during the monsoon flood months, according to a press release by the American Geophysical Union.

    New research presented at AGU’s Fall Meeting in Chicago compared the feasibility of both fully amphibious homes and retrofitted homes. The research found that homes in Bangladesh can be affordably retrofitted with floating floors made from locally available materials, such as plastic bottles and PVC pipes. But fully amphibious houses — like those in the Netherlands that rise with floodwaters thanks to foam-filled, buoyant concrete — remain too expensive for many people in Bangladesh.

    To lower costs, the low-density foam could be made in Bangladesh instead of being imported from the Netherlands, says Zahrun Zannat, a graduate student in urban planning at the Bangladesh University of Technology and Engineering (BUET) who presented the work.

    “The retrofitted floor is low cost, it’s inspired by traditional practices, and it’s something the local people can build on their own,” says Zannat.

    For the amphibious house with the foam base, she found that while the cost is “quite higher,” the long-term financial benefits of not losing possessions, livestock, or weaving materials help balance the high up-front cost of building the amphibious house.
    The retrofitted floating floor can be made affordably and with local materials, making it an accessible option for people living in flood-prone regions in Bangladesh.
    The retrofitted floating floor can be made affordably and with local materials, making it an accessible option for people living in flood-prone regions in Bangladesh.

    Flood Hazards

    Zannat’s work is in the Sirajganj District of Bangladesh, about 30 miles (50 kilometers) northwest of Dhaka, the capital city. The Brahmaputra River flows through the district, which is home to over 3 million people, and every monsoon season (June to August) the river floods for three to four months. Over the past several years, floodwaters have reached peaks of around 50 feet (15 meters), typically flooding about two-thirds of the houses in the region.

    “The floodwaters are getting more intense day by day, year by year, with climate change issues,” says Zannat.

    People who live in the flood zones can either pack up and leave — a costly option not open to everyone — or attempt to stay.

    Some houses are built on raised beds of soil, clay or concrete — but, as flooding intensifies, these are often not raised enough. Those who stay may be forced out of their homes and lose possessions when floodwaters get too high. For weavers who make up a substantial portion of the economy in this area, losing their loom can be devastating.

    Hygiene is an additional concern during the flood season, especially for women and people who menstruate and need privacy to safely practice hygiene, Zannat says.

    Float on Floods

    In 2016, Zannat’s institution, the Institute of Water and Flood Management at BUET, collaborated with IHE Delft University, Netherlands to retrofit one family’s home with a floating floor, and another was provided with an amphibious house and outhouse. Both families were happy with the units, she said, but for different purposes.

    The floating floor worked very well for living until the floodwaters got too high, reducing the ceiling height and access to living space. But they were able to keep personal possessions, including a handloom, safe and dry, saving them from significant financial loss.

    Retrofitted sanitation units provide a flood-resistant space for menstruating women to have access to clean spaces.
    Retrofitted sanitation units provide a flood-resistant space for menstruating women to have access to clean spaces.
    The amphibious house remained habitable throughout the flood season, and that family was able to keep livestock safe inside, too, Zannat reports. But the whole community benefitted from the floating outhouse.

    “When the area is inundated, the women get to have access to a hygienic station that can help reduce skin diseases and other types of disease,” says Zannat. “Having the sanitation unit really helped them.”

    While retrofitting floating floors is relatively accessible, amphibious buildings are expensive because the foam used to construct the floating base is expensive and produced in the Netherlands. Producing the foam in Bangladesh could drastically cut costs and help make amphibious buildings more affordable, Zannat says. Having construction subsidized by local governments could also help.

    Even if building whole communities with floating houses is a distant goal, providing communities with floating hygiene buildings and communal shelters could be accomplished more quickly and could help many families.

    Despite hurdles to increasing access, Zannat is optimistic about bringing this technology to Bangladesh.

    “I’m hopeful,” she says. “There are some challenges, but the benefits quite outweigh the negatives. And all these challenges? We can solve them.”

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