BanglaBhoot
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Study reveals 1,790sq km landmass emerges out of Bay for incredible rate of sedimentation
The Daily Star - April 23, 2010
Even as many worry Bangladesh will shrink in size because of global warming, a new study shows that the country has actually grown in landmass equal to five times the size of Dhaka city.
The new land has emerged in the Meghna estuary, where sediments flow down from the Himlayas and collect into charlands. The study found that the 8.5-magnitude 1950 Assam Earthquake increased the sediment flow and has added a net increase of 1,790 square kilometers to the country's land mass.
More charlands have emerged than we have lost due to river erosion over the years, said Dr. Maminul Haq Sarker, a geo-morphologist who conducted the study at the Center for Environment and Geographical Information System (CEGIS).
The new land, which emerged mostly in Noakhali, was discovered when Sarker and his research team analyzed satellite pictures and other data from 1943 to 2008 tracking sediments coming from the Himalayas and flowing down the Padma (Ganges in India) and Jamuna (Brahmaputra) rivers. The rivers deliver about one billion tons of silt a year from India, Nepal, China , and Bhutan to the Megnha estuary within the Bay of Bengal.
The study found that the 1950 earthquake accelerated the sediment flow by causing huge landslides in the Himalayas, dumping an estimate 45 billion cubic meters of earth into the rivers. Within a few years after the 1950 earthquake, silt and clay began to rapidly accumulate in the estuary. In all, the sediment added 2970 square kilometers in new charland while 1180 square kilometers were erodeda net gain of nearly 1800 square kilometers.
Beside Noakhali, new land has accumulated at the Patuakhali, Shariatpur, Barisal and Chittagong districts.
The findings, formally released yesterday, shines a ray of hope on otherwise dire predictions by groups such as the International Panel on Climate Change (IPCC) that Bangladesh will lose about 17 percent of its land area because melting polar ice daps will increase sea levels.
But Sarker cautioned more research is needed.
This is an indicative study, he said. We need to continue our research to say something concrete.
Now we might think to battle the climate change challenge in different way if we can use the sediment in planned way, he said. We can recover certain amount of our land mass from the aggression of rising sea level.
Citing a recent study of two American scientists, Saker said that the research suggests that one-third of this sediment is deposited on the floodplain and tidal plain of Bangladesh, thus continuously raising the land. One-third of the sediment is deposited on the estuary thus building new islands. The final third is lost in the deep ocean, he said.
The research also found the main reason behind the erosion of 230 square kilometers at Bhola Island, which many regard as an victim of rising sea levels due to climate change, was instead caused by the shifting flow of the Meghna channel. The shift also eroded a total of 195 square kilometers of land from Sandwip and Hatiya islands.
Country gets new land
The Daily Star - April 23, 2010
Even as many worry Bangladesh will shrink in size because of global warming, a new study shows that the country has actually grown in landmass equal to five times the size of Dhaka city.
The new land has emerged in the Meghna estuary, where sediments flow down from the Himlayas and collect into charlands. The study found that the 8.5-magnitude 1950 Assam Earthquake increased the sediment flow and has added a net increase of 1,790 square kilometers to the country's land mass.
More charlands have emerged than we have lost due to river erosion over the years, said Dr. Maminul Haq Sarker, a geo-morphologist who conducted the study at the Center for Environment and Geographical Information System (CEGIS).
The new land, which emerged mostly in Noakhali, was discovered when Sarker and his research team analyzed satellite pictures and other data from 1943 to 2008 tracking sediments coming from the Himalayas and flowing down the Padma (Ganges in India) and Jamuna (Brahmaputra) rivers. The rivers deliver about one billion tons of silt a year from India, Nepal, China , and Bhutan to the Megnha estuary within the Bay of Bengal.
The study found that the 1950 earthquake accelerated the sediment flow by causing huge landslides in the Himalayas, dumping an estimate 45 billion cubic meters of earth into the rivers. Within a few years after the 1950 earthquake, silt and clay began to rapidly accumulate in the estuary. In all, the sediment added 2970 square kilometers in new charland while 1180 square kilometers were erodeda net gain of nearly 1800 square kilometers.
Beside Noakhali, new land has accumulated at the Patuakhali, Shariatpur, Barisal and Chittagong districts.
The findings, formally released yesterday, shines a ray of hope on otherwise dire predictions by groups such as the International Panel on Climate Change (IPCC) that Bangladesh will lose about 17 percent of its land area because melting polar ice daps will increase sea levels.
But Sarker cautioned more research is needed.
This is an indicative study, he said. We need to continue our research to say something concrete.
Now we might think to battle the climate change challenge in different way if we can use the sediment in planned way, he said. We can recover certain amount of our land mass from the aggression of rising sea level.
Citing a recent study of two American scientists, Saker said that the research suggests that one-third of this sediment is deposited on the floodplain and tidal plain of Bangladesh, thus continuously raising the land. One-third of the sediment is deposited on the estuary thus building new islands. The final third is lost in the deep ocean, he said.
The research also found the main reason behind the erosion of 230 square kilometers at Bhola Island, which many regard as an victim of rising sea levels due to climate change, was instead caused by the shifting flow of the Meghna channel. The shift also eroded a total of 195 square kilometers of land from Sandwip and Hatiya islands.
Country gets new land
