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A woman walks by a canal linking the Kobadak River to a polder. Connecting the canal and the river causes flooding in one place that might protect land elsewhere. Downloaded from
Yet about 30 kilometers inland, farm- embankments to open the polders to ment is deposited in the beel instead of the
ers spurred an experiment to do just that. the river. The government cracked down riverbed. As the main river channel grows
on March 1, 2018
It’s much like the prescription Goodbred with arrests. Then, something unexpected deeper, water is once again draining from
offered—use controlled flooding to raise happened—exactly the outcome Goodbred nearby polders.
sunken land and drain polders—but this later saw at Polder 32. Within a few years, The endangered Ganges River dolphin
experiment began almost by accident in the land inside the inland polders had has put in appearances since the flow re-
the early 1990s. risen a meter or more. The rivers grew turned, says Jahin Shams Sakkhar, an offi-
These inland polders are designed deeper. Waterlogging eased. cial with Uttaran, a local organization that
to protect against flooding by seawater Since then, government officials have has campaigned for projects like this one.
driven far up river channels during high tried to replicate the success of those “The more open it is, the more good it is
tides. After the embankments were built, first improvised projects. The latest test for nature and for people,” he says.
those rivers, with smaller, slower currents for what’s known as “tidal river manage- Yet the filling of the beel hasn’t gone
than rivers closer to the coast, started clog- ment,” or TRM, began in 2015. A construc- entirely as planned, partly because “so far,
ging with silt that would otherwise have tion crew cut through the embankment the whole TRM process has been based
settled on land. Meanwhile, the polders of a polder lining the Kobadak River. on assumptions,” says Shah Alam Khan, a
began to sink. After monsoon rains, water Workers then dug a canal joining the civil engineer at BUET, who is helping
in the polders failed to drain through small river outside the polder to a 660-hectare lead a Dutch-funded study of the Kobadak
canals into surrounding, now sluggish, depression inside it—a wetland known as River project. The polder’s land rose
rivers. Farms and towns inside stewed in a beel. unevenly, with the area near the canal
stagnant water for months. Visit today and the experiment’s effects benefiting the most. Engineers are still PHOTO: TANMOY BHADURI
Local ingenuity and desperation are evident. Parts of the beel, called Beel deciphering sediment dynamics and
prompted farmers on two river systems Pakhimara, have gained half a meter of considering how best to direct flooding,
in southwest Bangladesh to cut gaps in fresh land. The river runs faster, as sedi- Khan says.

984 2 MARCH 2018 • VOL 359 ISSUE 6379 sciencemag.org SCIENCE
Published by AAAS

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