Dear Editor,
I refer to the recent flooding along the East Bank and elsewhere and recent comments by Dr Luncheon reported in SN dated September 18, stating that a full review of the sea defences is underway.
In the ’60s there was some overtopping of the river dam at Craig and at Friendship which the Hydraulics Division monitored, but since the Demerara Bridge was built in 1978 the problem of overtopping has become more acute over the years, causing flooding and hardship to residents along the East Bank from Georgetown up to Friendship and beyond. The Demerara River during low tide brings down a lot of silt from the upper reaches of the river, and because of the blockage of built-up silt under the supporting pontoons of the bridge, the silt has started to back up over a period of 32 years forcing the channel to move further east and hence cause flooding. The siltation of the western bank of the river is visible with the naked eye upstream at low tide.
Downstream of the bridge has also been affected. The President recently stated that the recent high tide was measured at 3.64m, ie, some 1.2m above the tidal amplification for Georgetown, and if correct this is indeed a very serious situation facing Guyana.
The government proposes raising the sea dam to offset the overtopping. Calculations should be carried out first to ensure there is a factor of safety in the event of rotational slips in the dam at low tide. If slips occur the situation could become worse. I would recommend river training works, which can deflect the channel further west, but this is expensive and depending on the amount of siltation may not work. Digging a drain east of the dam to channel the water at low tide via the sluices may be a solution. This is also expensive since people who have encroached on the reserve will have to be removed.
There is a similar situation occurring at the recently constructed Berbice River Bridge causing overtopping on the eastern section of the sea dam and flooding out communities.
These types of bridges are not suitable near the mouths of rivers, especially when the rivers transport a lot of silt from downstream. In Bangladesh they are built in the deltas, which is a different situation. In a few years time the Berbice River will suffer the same fate as the Demerara River and together with the already dead Abary River this government will have three dead rivers on its hands.
I have written on this problem for a number of years to no avail, and unless the government carries out appropriate hydrographic surveys, compares the surveys with those carried out in the ’60s and ’70s and determines what is going on with the Demerara River then it will have no choice but to continue to live with the flooding.
A few years ago the government carried out extensive repairs to the Demerara Bridge and in my opinion has taken over responsibilityfor this bridge. Under the circumstances morally it should compensate the flood victims for their losses. Similarly, they should do so for the people in the Berbice area. The flooding is not caused by an act of God but by carelessness on the part of the government.
The sea defences are in a worse shape today, particularly in the coastal areas. Since I stopped the sea defence programme in 1975 due to shortage of funds, no sea defences were built except for some riprap at Good Hope and Mon Repos. The old concrete sea walls in the Buxton area are over 80 years old and are undermined and need to be replaced. I am surprised the people of Buxton have not called upon the President on his recent visit there to have the sea walls rebuilt. There were two massive breaches in this area during the ’60s.
In 1968 Parliament passed a law restricting construction 1000ft away from the centreline of the sea dam in several areas on the coast. Today, houses are built near to the dam with buildings even constructed on top of the sea defences. If a breach were to occur (it is long overdue) it would be disastrous for the folks on the East Coast.
The government, instead of wasting money planting trees to arrest the impending erosion, would put the money to better use if it built long-lasting concrete sea defences along the coast. It takes about 30 years for courida trees to mature and within that time the erosion will wash away all the trees.
Yours faithfully,
M. Alli
