Bangladesh uses silt against sea rise

Bangladesh has begun to channel silt -- carried downstream from the Himalayas -- to where it is needed: to fill in shallow bowls of land prone to flooding, or to create new land off the country’s coast, the New York Times reported. Most of the silt swept to the Ganges delta washes into the Bay of Bengal.


An accidental discovery by local people may hold clues to how Bangladesh, one of the countries most vulnerable to climate change, could harness some of the dark, rich Himalayan soil to protect itself against sea-level rise, the newspaper said.


While efforts have been limited to small experimental patches, emerging evidence suggests that Bangladesh could literally raise itself up and save its people — and do so cheaply and simply, using what the mountains and tides bring.


The silt-trapping experiment has yielded tentative but visible gains in Beel Bhaina, a low-lying 245-hectare bowl of land on the banks of the Hari River, a tributary of the Ganges. Here, about 90 kilometres upstream from the Bay of Bengal, local people punched a hole through a mud embankment after a devastating flood a decade ago. The water rushed out; then the high tide began to carry in sediment, swiftly filling the bowl with silt.


A local water board engineer, Sheikh Nurul Ala, measured it and saw that, in four years, the area had risen by a metre or more near the river bank and almost as much farther inland. Today, the river flows more freely and the land is used for rice paddies and fish and shrimp cultivation.


Satellite images show that in the natural process of erosion and accretion (the return of sediment), Bangladesh actually has gained land over the last 35 years. Sceptics say it is folly to expect silt accretion to save the country, as it happens very slowly. While the simple silt-trapping engineering at Beel Bhaina was not designed as an adaptation to sea-level rise, Ala believes it can outpace the projected one-metre rise in sea levels and offer some protection.


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