For thousands of years, the delta of Bengal has been defined by its intricate relationship with water. This was never a purely natural phenomenon; it was a sophisticated feat of hydraulic engineering. Ancient “overflow irrigation” systems, influenced by Egyptian water engineering techniques, once allowed our ancestors to manage the rhythmic pulse of the delta. These engineered waterways—such as the Mathabhanga, often mistaken for a natural river—were designed to manure the fields with nutrient-rich silt while providing a dependable lifeline for rural settlements.
For nearly three millennia, these waterways provided dependable water supplies, boosted agricultural productivity, and supported rural livelihoods. In recent decades, however, rapid population growth, lack of maintenance, and unplanned development have pushed many rivers and canals in Bangladesh into severe decline. As channels silt up, dry out, or become encroached upon, the country’s environmental stability falls increasingly at risk. Our own research using satellite-based night-light data shows how the loss of floodplains is directly linked to rising flood vulnerability across the country.
This concern is not new. In the late 1970s, the then President Ziaur Rahman recognised the danger posed by deteriorating waterways and launched a nationwide canal restoration programme. Between 1977 and 1981, nearly 2,000 miles of canals (an estimated 1,500 of them) were excavated or re-excavated, revitalising rural economies and strengthening food security.
Today, the proposal to excavate 20,000 km of canals has brought the issue back to the centre of national debate. The scale is ambitious, and understandably so. The real question, however, is not whether canals should be restored, but how this can be done in a way that delivers lasting environmental and economic benefits.
Bangladesh has already experienced the consequences of poorly planned water management. The Flood Action Plan relied heavily on embankments and structural interventions that disrupted natural water flow and damaged wetlands. Dhaka once had one of the most effective gravity-based drainage systems in the world, supported by an intricate network of canals and low-lying retention areas. Much of that system has been lost to unplanned urbanisation and embankments.
Even recent excavation projects have sometimes produced disappointing results. Canals dug without understanding how water and sediment move across the delta quickly silt up again, causing erosion, worsening floods, and wastage of public resources. Without a scientific framework and long-term maintenance, excavation alone cannot solve a hydrological problem.
Meanwhile, the dry season is becoming longer. Farmers are increasingly dependent on groundwater for irrigation, even as climate change makes rainfall more erratic. Arable land is shrinking—from nearly 73 percent of the country in 1990 to about 60 percent in 2023—while the population continues to grow. The pressure on water, food, and ecosystems is intensifying over time and space.
This is why science and long-term planning must guide the new canal initiative. The country already has such a framework in the Bangladesh Delta Plan 2100, which calls for reconnecting rivers, canals, wetlands, and floodplains so that the landscape can store, move, and release water in a controlled way. Aligning canal restoration with this vision makes it part of a national climate resilience strategy, rather than a series of isolated projects.
It also answers a practical question: does every kilometre need to be excavated? The answer is no. A three-tiered approach makes far more sense, but it must follow the natural flow of the catchment, working upstream to downstream so that newly cleared channels do not silt up again. Some waterways are fully silted and require complete restoration. Others still hold water but need their banks stabilised through the ambitious Green Shield planting pledged by the ruling party in its election manifesto, and protected from encroachment. Many are already functioning and would survive with maintenance, plantation and community monitoring in parallel. Thinking in these tiers turns the 20,000-km target from a large excavation drive into a realistic and cost-effective national water management programme.
Modern technology makes this approach possible. High-resolution digital elevation models created from Light Detection and Ranging (LiDAR) data can reveal the true shape of the land. With such tools, planners can identify lost canals, understand natural flow paths, and decide where excavation is necessary and where protection is enough. We need to understand local geography as well, including soil type and composition. Without this knowledge, we risk repeating past mistakes.
Bangladesh is not short of water, but rather poor in water management. With proper planning, transparent implementation, and strong scientific guidance, canal restoration could deliver multiple benefits: reduced waterlogging, improved flood management, more reliable surface water for irrigation, enhanced groundwater recharge, stronger fisheries and biodiversity, and renewed inland navigation. Countries such as the Netherlands have shown that long-term prosperity in a delta depends on working with water, rather than against it. Bangladesh, with its vast floodplains and dense river network, has even greater natural potential.
A scientifically grounded canal restoration programme can reconnect the country’s blue and green landscapes and create a more liveable environment for millions. Done properly, canal excavation is not about digging soil. It is about restoring the hydraulic logic that once made this delta one of the most productive and resilient regions in the world.
Dr Ashraf Dewan serves as the director of research at the School of Earth and Planetary Sciences, Curtin University in Australia. He can be reached at [email protected].
Dr Mo Hoque is senior lecturer in hydrogeology and environmental geoscience at the University of Portsmouth in the UK. He can be reached at [email protected].
Views expressed in this article are the author's own.
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