Sonar to help slow Bangladesh erosion in Ganges delta

Bangladesh will start using sonar to help slow erosion of its biggest island in the Ganges Delta where climate change and rising sea levels are adding to risks, a Dutch-Bangladeshi consortium said on Tuesday.

Floods constantly reshape low-lying Bhola island, which is 130 kms (80 miles) long and home to 1.7 million people. A 1776 map showed that it was oval but it is now more banana-shaped due to erosion by the Meghna River that is part of the delta.

sonarThe consortium told Reuters that a 1.5 meter (5 ft) long sonar, similar to equipment used to search for missing Malaysia Airlines flight MH370, will be towed behind a boat to check protective sandbags off the fast-eroding eastern coast.

Monthly sonar surveys would let experts see if the bags, weighing up to about 250 kg (550 lbs), were shifting in waters that are too muddy and fast-flowing for divers. The erosion early warning system would allow damaged bags to be replaced.

“This will save a lot of money on repair work,” Jan Bron, project manager at Dutch engineering consultancy Royal HaskoningDNV, told Reuters.

If it works, the project will expand to other areas of Bangladesh, which is among the nations most vulnerable to climate change. It could also be applied to other low-lying countries.

Planning for the project will cost 1.3 million euros ($1.77 million) and the Dutch and Bangladeshi governments will each give 22 million euros to help protect a vulnerable part of Bhola’s coastline.

The consortium comprises Royal HaskoningDHV, technology firms AGT Netherlands and TechForce Innovations from the Netherlands and Bangladesh’s TigerIT, engineering group EPC and the Institute of Water Modelling.

“The system will provide a good insight into how erosion takes place,” Pieter-Christiaan van Oranje-Nassau, Chief Executive of AGT Netherlands, said in a statement.

Bhola “is just 6 feet above sea level at the highest point. Climate change will have an effect,” Bron said.

Global sea levels have risen by about 20 cms (8 inches) since 1900 and could rise by almost a meter in the worst case this century due to a melt from Greenland to Antarctica, according to a U.N. panel of climate experts.

The panel says it is at least 95 percent probable that man-made greenhouse gas emissions are causing global warming, adding to risks of floods, droughts and rising sea levels. Bangladesh is vulnerable to cyclones and shifting monsoon rains.