Sundarganj Delta City: Flood Risk and Inclusive Housing
Sundarganj is a delta city of 6.5 million people, growing at 4.2% per year. About 38% of residents live in informal settlements. Sixty per cent of the built-up area lies on a floodplain below 2 m, and drainage was designed for a city of 1.2 million. In 2019, floods reached 1.1 m in parts of the city for nine days. A 90 ha landfill sits beside a wetland, and a new expressway has been built on reclaimed marsh. The government proposes a satellite township 15 km inland, linked by rail, with 200,000 homes, at a cost of $1.4 billion. Residents’ groups fear displacement; developers want to build on the floodplain; conservationists say the wetland is a Ramsar site. The city must decide how to reduce flood risk while housing newcomers.
1. Evaluate the satellite township proposal against alternative ways of reducing flood risk and meeting housing need.
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The satellite township is attractive because it moves new growth off the floodplain and could be engineered above flood level. But at $1.4 billion it would consume most capital, take years, and may become a dormitory town that does not house the poorest, who depend on central-city livelihoods. It also risks displacement if existing informal settlements are cleared. A stronger package is to upgrade drainage and raise embankments in the existing city, relocate only the most exposed households, and build the satellite township in phases with affordable housing and rail. Preserving the wetland and stopping further building on reclaimed marsh is essential because the wetland stores floodwater. The township should therefore be part of a portfolio, not the single solution.
2. Explain how rapid urbanisation has altered the hydrological cycle in Sundarganj.
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Urbanisation replaces vegetation and soil with roofs, roads and concrete, reducing infiltration and evapotranspiration. It increases surface runoff and shortens lag time, so peak discharge rises. Drainage channels and embankments speed water to low-lying areas, while landfill and reclaimed marsh remove flood storage. Groundwater recharge falls, lowering baseflow between storms. In Sundarganj, drainage built for 1.2 million cannot cope with a city of 6.5 million, so even moderate rainfall produces 1.1 m flooding. The expressway on reclaimed marsh further reduces storage and can block flows.
3. Discuss why flood risk in Sundarganj is unevenly distributed.
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Flood risk is uneven because exposure and vulnerability differ. Informal settlements are often on the lowest, most flood-prone land, with weak housing, no drainage and insecure tenure; 38% of residents live there. Wealthier groups can afford raised buildings, insurance and relocation. The landfill and expressway may protect or benefit some areas while displacing water onto others. During the 2019 flood, the nine-day duration would hit daily-wage workers hardest because they lose income. Risk is therefore a product of physical hazard plus social inequality; a city-wide drainage scheme that ignores tenure and income may reduce risk for some and reproduce it for others.