Inappropriate implementation to cause more waterlogging

"If the technical part of the project is not implemented properly then it might cause more waterlogging instead of saving the city from the flood," they said.

The seminar on analysing the feasibility of eastern bypass project was organised by the Bangladesh Paribesh Andolon (Bapa), a common forum of citizens and organisations concerned with the environment of the country at Cirdap in the city.

Bapa president Professor Muzaffer Ahmad, vice president Professor Nazrul Islam and member AMA Muhit spoke at the seminar while architect Iqbal Habib and Dr Ashraf Dewan gave presentations on the project.

After building an embankment on the western boundary of Dhaka on the left bank of the Buriganga river, the government has decided to build another embankment along the right bank of the Balu river from Tongi bridge to Demra to protect the city from flooding and water logging.

The project will make 124sq km area as flood free zone which almost close to the area of Dhaka City Corporation (145sq km) at a cost of more than Tk 2500 crore.

The basic premise of the proposed eastern bypass project is based on cordon approach, which advocated for flood control using engineering means that are designed to keep floodwaters away from the floodplain and flood flow zones of the Balu River.

The project called for dividing the eastern 124sq km of the city into three major components, each of which will be drained using a combination of existing or re-excavated canals, sluice gates and pump stations. There will be several retention ponds, totaling an area of 1895 hectors, to hold excess surface run-off during floods.

But, the flood modeling of flow simulation following the embankments show that there will be a net increase in the level of the Balu river at Demra by as much as 36 cm if the right embankment is constructed which will create a barrier to discharge water by the canals that are located with the embankment area.

Thus, continuous pumping out of water will be required. According to the plan, three pump stations with a maximum capacity of 54.6 cusecs (1927 cusecs) of water, will be established. But this will not be adequate in the face of heavy rainfall. Uninterrupted electricity supply will also be required to run these pumps, experts said.