Guyana re-investing in groynes to bolster sea defence

After more than two decades, sea defence engineers of the Public Works Ministry are now looking to reinvest in the repairs and construction of groynes to help strengthen the coastland’s defence against rising sea level and climate change.

According to Works Minister Robeson Benn, the ministry has already started reconstruction of groynes in Essequibo at Leguan island, and has planned to start repairs to those along the Georgetown shore later this year, as funds have been allocated for these works in this year’s budget. The minister explained that, during the 1970s, the authorities stopped investing in groynes and started looking at new designs for wave walls. A decision was taken back then to replace the use of groynes with pile revetments.

However, the ministry is now reversing that decision to re-establish the infrastructure and aid the regrowth of mangroves, which he described as the first line of defence from the rising sea. Noting that Guyana has suffered significant erosion of its mangroves over the years, the minister pointed to the ongoing collaborative efforts between the Works Ministry and the National Agricultural Research and Extension Institute (NAREI) to re-plant mangroves along the shores from which they have been eroded.

A groyne is an active structure extending from shore into the sea, most often perpendicularly or in a slightly oblique angle to the shoreline. It is used to slow down erosion and stop long-shore drift. As such, re-establishment of such infrastructure along Guyana’s shore zone is expected to help slow down movement of mud shoals along the coast, thereby stabilising the soil in which mangroves flourish.

While investing in the groynes, the Works Ministry will continue maintenance, construction and upgrade of the country’s infrastructure in all of the eight sea and river defence districts. At present, the ministry is looking to reduce the cost of these works, which require enormous amounts of money.

Minister Benn reported that Public Works Ministry engineers are looking at historical structures and techniques used here and in other countries with similar environments, such as Holland, Vietnam, Bangladesh and parts of the United States.

The personnel are also reviewing newer technology, innovation and equipment available, to help lessen the high costs associated with building and maintaining the country’s sea and river defences. Most of these works are done using the ‘rip-rap’ slope design, which can last for 20 to 30 years and is the ministry’s optimal choice for sea and river defence works in Guyana.

Benn explained that, with this design, it is easier to upgrade and continuously raise the height of the sea defence structures; whereas, with other structures, such as wave walls, it is almost impossible to reuse any of the defences.