Opposition questions necessity of US$18M Hope Canal

Jun 08, 2010 News

The multibillion-dollar Hope Canal project came under the scrutiny of the National Assembly last Thursday as the Minister of Agriculture was questioned on the need for a relief channel to the East Demerara Water Conservancy (EDWC).
One of the first issues raised was whether or not there had been a feasibility study of the project. Minister of Agriculture, Robert Persaud, in his response contended that there had been no such study. He said on the matter, “… a feasibility study would stand only to re-confirm the deficiencies in flood relief capacity of the EDWC.”
He highlighted a number of problems with the conservancy which is basically a reservoir that holds some 582 square kilometers of fresh water and is dammed by an earthen embankment.
The conservancy was studied intensively in the wake of the 2005 floods, with investigations being undertaken by the United Nations Disaster Assessment and Co-ordination (UNDAC) Team as well as by a number of local bodies.
One of the results of this study was the Conservancy Flood Management Modeling Report 2005. According to Persaud, all of the reporting on the conditions of the conservancy delivered the same verdict – that there needed to be “an additional outlet to address the drainage problems of the conservancy.”
Persaud also noted that there were also hydrological studies done on the EDWC where it was discovered that the conservancy was not a level pool. There were some places where the water level was higher than in others and this, Persaud noted, contributed to the overtopping experienced in a number of areas, especially in 2005.
This condition which usually sees the eastern water levels exceeding the maximum safe level for breach prevention requires the opening of the flood relief gates on that end, namely the Lama and Maduni sluices.
This tends to aggravate the flood conditions in the Mahaica/Mahaicony areas.
According to Persaud, every year since 2005, we have seen the recorded levels of water at the conservancy exceeding the maximum safe limit of 58.50 GD. He noted that in 2005, ten percent of the dam overtopped despite having open flood gates.
Estimates are that another 60mm of water would have caused a breach in the conservancy, resulting in damages far in excess of what was reported in 2005.
Persaud went on to lay out the options for providing a relief structure for the conservancy. These options included the Hope/Dochfour channel discharging into the Atlantic Ocean with either one of two discharge options or another relief channel that drains from the conservancy into the Mahaica River.
The relief channel that drains into the Mahaica River will provide a 3.5 km relief channel linking the Conservancy to the Mahaica River, but according to Persaud, studies indicate that the river has a reverse gradient caused by sedimentation and a bar across its mouth which prevents it from draining completely at the low tides.
He noted that there also needs to be a further study to ascertain what will happen under severe flooding conditions when the runoff levels will be considerably higher.
The other option – the Hope Canal — will be a 10.3 km long relief channel that has to be cut right out to the Atlantic Ocean where it will discharge either as a high outfall weir or as a deep foreshore discharge channel which will have to be dredged almost 2.5km out on the foreshore. According to Persaud, the weir option was chosen since it was the most feasible possibility at the moment.
Another area that the Minister addressed was whether the discharge sluices were performing at their full capacities.
Persaud noted that in the case of the Kofi, Cunha and Spill Weir at Land of Canaan, the maximum discharge capacity was not being achieved as a result of the hydraulic gradient of the conservancy.