The flooding in the upper Demerara could be a result of siltation caused by the Demerara Floating Bridge

Dear Editor,

I refer to the recent flooding in the Linden Area and to state the Demerara River was a free flowing as well as a tidal river as far as up to Linden prior to the Demerara Floating Bridge being built and operational in 1978.

The pontoons that support the bridge have become silted up over a period of time resulting in the drainage flow being restricted between the pontoons causing a build-up of silt progressively under the pontoons as well as upstream of the bridge causing the river channel to move further east. This can be seen if you look east at Craig to Garden of Eden and elsewhere where the western end of the river is heavily silted and the river has changed its course. Drainage sluices are also affected by the siltation.

A similar situation is also occurring at the Berbice River Floating Bridge where recently flooding upstream of the river has been reported. This is even more serious as the bridge is located directly near the mouth of the river, which has a bar. I recall the government’s own Consultant prior to construction recommended removal of approx. 183,000 m3 of silt under the pontoons annually. This has not yet been done and the build-up under the pontoons will continue over the years creating a massive build-up of silt under the pontoons and upstream of the bridge. If the Canje Creek becomes silted up at its mouth it will be the end of Berbice as a farming community. The government’s intention to use the Berbice River as a transit point for goods from Brazil is nothing more than a pipe dream. The Berbice Bridge has compounded the problem, as the river is also well known for poor navigation.

The Hydraulics Division carried out Hydrographic Surveys of the Demerara River at Craig, Garden of Eden and at Linden during the 70’s and similar surveys should be carried out now and compared with the earlier surveys if they can be found to observe how the river has behaved since this bridge was built.

When Guyana became independent in1966 the government inherited from the British a system comprising of engineers, surveyors, competent force account workers and a hydrographic survey and hydromet sections that enabled the Hydraulics Division to carry out complicated sea defences and drainage designs and construction. The Roads Division and Transport and Harbours Department also had their own engineers and workers who built and repaired their roads and own stellings. Today, the entire system has been broken and destroyed. Engineers have no information to carry out engineering works and have to depend on guesswork. The government has no recourse now but to depend on fly-by-night contractors and engineering consultants to solve their ever-evolving engineering problems. Today, as fast as you build you have to investigate, break and repair.

A case in point is the recent flooding in the Grove/Diamond Area where the government. developed a housing scheme in an area where there was previously a sugar cane plantation. The estate initially planned and designed the area to drain as well as to re-circulate rainfall water. You cannot now develop a housing scheme without re-designing the entire area to include drainage. This is a typical unfortunate situation that exists today in Guyana- there is no engineer planning.

The sea defences are also in disastrous state where the government. has now resorted to planting courida mangrove trees to arrest the impending erosion. This is a complete waste of money. Since this government came to power they have changed the original concrete design that has worked so well over the years to a rip-rap construction, which cannot work on Guyana’s poor soft soil foundation. Over US100M has been spent to date and despite numerous failures they are still continuing with this type of construction that has a shelf life of only 10 years and requires annual maintenance that has never been carried out.

There is an election next year and if the PPP wins they will continue as they are doing now. If there is a change in government I will strongly recommend that an assessment be made of what the new government is taking over.

In my opinion it will be very costly and not easy from an engineering point of view to repair the infrastructure that has been irreversibly damaged over the last 20 years or so.

Yours faithfully,
M. Alli