"The drive will start sometime in November-December," said a senior WASA official.

Last year, Wasa had recovered 15 canals out of the 26 that can still be rescued from encroachment. Although the capital had 43 natural canals in the past, 17 do not exist anymore and can only be traced in history books. The government has constructed roads on eight of those canals by filling them up. The rest have fallen to government or private land grabbers.

"Due to lack of proper conservation of river channels and waterbodies, localities especially in Dhaka go under flood water and a little downpour creates serious waterlogging. If we can preserve the natural waterbodies, rivers and canal channels, floods would not hit major localities with the same intensity and waterlogging would be reduced," said a Wasa official.

Environmentalists believe that the already filled up natural river shores, canals and waterbodies could consume huge volumes of floodwater and protect many areas from flooding. Dhaka has 26 water reservoirs, hundreds of small and large ponds and marshy land which naturally store overflowed water. The canals distribute it to different channels.

Wasa officials said they would also conduct a follow-up drive to ensure that the recovered canals have not been occupied again. The canals that could be rescued include Kallyanpur Khal, Segunbagicha Khal, Jirani Khal in Badda, Katashur Khal, Ibrahimpur Khal and Ramchandrapur Khal in Mohammadpur. During the drive, Wasa evicted a number of canal-encroachers who had built houses, shanties and kitchen markets on filled up land.

"Some of these encroachers are trying to come back again. We are planning a fresh survey on the recovered canals," a Wasa official said.

The Local Government Engineering and Rural Development (LGERD) ministry in July this year adopted a national drainage policy to ensure a free flowing drainage system through natural canals. The policy enhanced the implications to protect and recover the rivers, canals, waterbodies and flood flow zones across the country especially in Dhaka.

It has been suggested in the policy that residential constructions will not allowed between 50 yards of a river and district commissioners will submit reports twice a year after inspecting areas on the riverbanks. Already constructed structures on the riverbanks that block free flow of water will also be removed.