The erosion of the Surma and Kushiara along the Sylhet border is pushing the Bangladesh border inward, already resulting in the loss of thousands of acres of land to India in last few years.
According to the 1974 Mujib-Indira Border Treaty, midstream of border rivers defines the boundaries of the two countries.
"We have been losing our land as frontier rivers Surma and Kushiara continue to change their directions due to severe erosion, changing the original border," Md Shafiqul Islam, executive engineer of Water Development Board (WDB) in Sylhet, told the Daily Star.
Official sources said more than 3000 acres of Bangladesh territory have already gone to India due to the erosion of the two rivers only. Locals, however, estimate that the loss is no less than 4,000 acres.
About a thousand acres of land in Majorgaon, Amolshid, Lakshmibazar, Sultanpur, Senapatirchak and Manikpur in Zakiganj upazila are now part of the Indian state of Assam due to the erosion of the Kushiara. Two hundred and fifty acres of land in Ballah, Uttarkul, Munshibazar, Rosulpur and Dighli on the Surma banks in the upazila have also washed away into India.
River erosion on the Bangladesh side continues unabated as dams and groynes upstream in India are causing the rivers breaking into Bangladesh territory as embankments along the Sylhet borders are mostly unprotected.
While the erosion is getting worse day by day, the Border River Protection and Development Project that plans protective works along nine kilometres on the Kushiara banks has been awaiting approval for the last three years.
The Indian side of the rivers, however, is well bulwarked against erosion.
The Indian authorities in 2005 had agreed to allow the Joint Rivers Commission to conduct study on the Surma, Kushiara and Barak.
WDB officials, however, said no headway was made for eventual Indian reluctance.
Experts fear that the Surma and the Kushiara would accelerate changing their courses along the greater Sylhet region when upstream hydroelectric dams at Tipaimukh on the Barak River in India are completed.
They also said the mega project might destroy the region's agriculture.
This correspondent saw a grim picture on Amolshid border where the Barak empties into the Surma and the Kushiara.
One farmer at Uttarbag village said his family had lost twenty acres of land and three houses to the rivers.
An official said about 25 points on the riverbanks need immediate revetment work to stop the two rivers from eroding away Bangladesh territory further.
Erosion on the Bangladesh side gives way to new chars on the other side which Indian villagers occupy in no time with the help of the BSF, locals said, adding that residents of Harinagar in India now own the land of Oligarh that was once a Bangladesh village.
A subdivisional engineer said a WDB project to protect Kushiara banks from Haidaraband to Bhuiyarmora on an emergency basis has not yet been approved.
He said if the government fails to take quick protection measures, the country would lose more land this season as the rivers, silted up upstream, are driving down volumes of rainwater into Bangladesh.