Threat to Padma Bridge posed by river erosion

The embankment built to protect the Padma Bridge project area is under severe threat, according to a report carried in a contemporary. A two-kilometre segment of the embankment at Jajira point of Shariatpur has started experiencing river erosion. The river has become deeper closer to the Padma Bridge and at the same time the erosion is approaching the bridge. Given the treacherous nature of the river Padma, a hydro-meteorological disaster cannot be ruled out if measures are not taken immediately to protect the river-line embankment at that point. The problem of this river is particularly treacherous because of the fast shifting soil of its bed. This is exactly happening to one-kilometre segment of the embankment and the rest one kilometre length is actually experiencing erosion.

This is not the first time that alarm bell has been sounded. Months before another report came up with the danger posed to the embankment and the bridge. But the authorities failed to respond to the call the way it should have done. Following the landslide of 100 metre of the embankment at Naodoba zero point in November last year, the Bangladesh Water Development Board (BWDB) and the Bangladesh Bridge Authority (BBA) jointly carried out a study. The study found that the depth of the river along one-kilometre stretch is greater than in the surrounding areas. What was of particular concern is that the soil of the river bed continued to move away from that segment. The river moved closer to the other segment of one-kilometre length. Erosion happened there too.

The BWDB has undertaken repair works of the 100-metre embankment that gave in last year in November. The repair consists of putting in place sand-laden geo-textile (geo) bags and cement concrete (CC) blocks at a cost of Tk27 million. Isn't it too little too late? Tortuous and treacherous, the Padma cannot be restrained by such patch works. Even in the lean season, it can break through the defence of strong embankment. The least said about its power in the monsoon the better.

An extensive and comprehensive study was well in order to see if there was any error or defect when the river training was done. The bridge authority constructed an embankment two kilometres to the east in order to protect the project area of the Padma Bridge. After the river training, the bank-line embankment reportedly was aligned to the one constructed earlier.

This is somewhat confusing. Without river training, the feasibility of a bridge is questionable. When a bridge of the order on a mighty river like the Padma is concerned, not just river training but river engineering should be conducted meticulously beforehand to determine the vulnerability or not of the structure to river erosion or shifting of the channel.

Any attempt to prevent erosion of the river by piling geo bags and cc blocks is most likely to prove a child's play. It is better to act on the basis of findings of river training and even river engineering. If needed, experts in hydro-meteorology from abroad can be hired to find out how grave the situation is and how it can be arrested sustainably. After all, this bridge has to be protected at any cost.

Early detection of any defect in the embankment will give better chance for obviating the threat effectively. There is also the need for analysing the anthropogenic impacts on the river. Sand extraction within the vicinity of the bridge was also reported a few times in the past. The bridge authority and the BWDB did not swing into action against the culprits to let such drives to act as a deterrent to the illegal and destructive practice. Before the worst happens, necessary remedial measures must be devised to save the bridge and the locality under threat.

nilratanhalder2000@yahoo.com