Hundreds of families along the West Coast of Demerara have been affected by the recent high tides, overtopping and breached sea defences. Following this most recent tidal surge, there should be no lingering doubts as to whether rising sea levels, caused by climate change, are threatening Guyana’s coastal communities.
Despite the presence of defensive walls, Guyana’s coast is still highly vulnerable to flooding and now, more than ever, coastal residents are facing the reality that sea level rise is changing their communities and their lives. There have been stronger tidal surges, more frequent flooding, and saltwater intrusion into farmlands.
While the Civil Defence Commission (CDC) and other local authorities battle to cope with the aftermath, they are advising residents against erecting structures that block drainage networks or are near sea defences, even as calls are being made to move the capital city and other densely populated areas away from the coast.
Apart from the existing sea defence structures, mangroves are also considered as a primary sea defence. The role of coastal mangroves in Guyana is to dissipate or reduce wave energy along the coastline. They not only complement existing structures but help with environmental conservation and the cost of maintaining hard structures. As in many coastal regions around the world, mangroves also provide a natural defence against the raging tide and rising sea levels.
As recent as last month, the National Agricultural Research and Extension Institute’s Mangrove Department issued a statement acknowledging that this unique ecosystem was threatened by the cyclic erosion/accretion that occurred along Guyana’s coastline. The erosion process, which occurs in 20 to 30-year cycles, is impacting several naturally regenerated and planted restoration sites at Hope Beach, Wellington Park, Greenfield and several villages along the West Coast of Demerara.
NAREI also pointed to a study completed by Professors Antony and Gardel in 2013, which indicated that the dynamics of the Guyana coastline were strongly hinged on pulses of mud abundance or scarcity embedded in multi-year cycles of mud-bank activity and inter-bank phases. The cyclic mud-bank phases regulate mangrove regeneration by providing a substrate for extremely rapid and large-scale colonisation from older mangrove colonies and vigorous tree growth. Erosion, therefore, can be caused by this natural process and by human or man-made interventions. For example, building structures beyond the seawall/within the sea defence area alters or disrupts the natural movement of sediments, hence, resulting in erosion.
While mangroves are subjected to cyclic erosion, studies conducted on Guyana’s coastal mangroves have proven that a mangrove bandwidth of 50 metres to 80 metres is required to reduce a 3-metre high wave to approximately 0.01 metre. In the areas where mangroves are not present, severe overtopping occurs (along Kingston and Sheriff Streets) which results in increased cost for maintenance works over a period of time.
According to Ranata Robertson, Coastal Engineer at the University of Guyana, it is important for Guyana to conduct ongoing research to determine the movement of these mud banks and the associated erosion cycle. Studies to map and model coastline retreat and advance are critical areas of research that need to be integrated into a long-term coastal zone management programme. Collaborative studies have been ongoing with the University of Guyana Civil Engineering Department, NAREI’s Mangrove Restoration Programme and Sea & River Defence Division to better understand and model this cyclic process.
The Mangrove Action Committee, a volunteer group under NAREI, identified a number of interventions to be implemented during 2018 that will seek to address these issues. They include public awareness and education programmes on the importance of mangroves, targeting youths through environmental clubs, and engaging the relevant Government agencies such as the Environmental Protection Agency (EPA).
It should be noted that mangroves are protected under the Forestry Act, and as such, it is illegal to destroy mangroves without permission from the Guyana Forestry Commission.
While coastal flooding is by no means isolated to Guyana, ignoring scientific evidence and failing to adapt and prepare will mean lives and livelihoods will continue to be at risk.
