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Disappearing beaches!

Published:Sunday | January 18, 2015 | 12:00 AM

Experts warn of dangerously rising sea levels around Jamaica

Petre Williams-Raynor, Contributing Editor

It may not be as dramatic as the sea covering the entire island, but from coastal flooding to beach erosion and compromised fresh water resources, sea level rise due to climate change is a clear and present danger for Jamaica.

"Under climate change, the sea levels are rising and storms are also likely to be more intense. So the vulnerability to coastal flooding increases and more people become vulnerable because the storm surge can reach further inland than they would have under a non-climate change regime, so to speak," warned Professor Michael Taylor, physicist and director of the Climate Studies Group, Mona.

"The loss of beach is significant; it is estimated at 0.26 metres per year for Jamaica with sea level rise and post-storm events. And the beach retreats at about 100 times the rate of sea level rise," he added.

Engineer Christopher Burgess' recent research on beach erosion supports Taylor's assessment.

"It is not that sea level rise is the only thing responsible for coastal erosion. There would be other factors, for example, changes in the intensity and frequency of hurricanes. However, there are some very well-used and basic models which allow us to estimate, based on sea level rise, how much erosion we can expect," Burgess told The Sunday Gleaner.

"We have looked at several beaches across Jamaica - including Palisadoes, Old Harbour Bay (and) Negril - and what was typically found is that somewhere between 40 and 70 per cent of the erosion is due to the sea level rise component," added Burgess, managing director of CEAC Solutions Company Limited.

In a 2013 paper - co-written by Carlnenus Johnson and titled 'Shoreline Change in Jamaica: Observations for the period 1968 to 2010 and projections to 2060' - Burgess found: "Long-term shoreline retreat rates were observed to vary between 0.17 and 0.76 metres per annum, with an average of 0.26 metres per annum."

Of the nine beaches looked at in the research, the fastest eroding were "Negril (Westmoreland) at 0.76 metres per annum, Old Harbour Bay (St Catherine) at 0.74 metres per annum, and Long Bay (Portland) at 0.36 metres per annum".

fresh-water security

Negril, for example, is highly dependent on its beaches to help rake in the millions in tourist dollars that it does each year.

The rising tide is also challenging for the country's fresh-water security.

"The implications of sea level rise on water resources is very acute, especially where you have karstic limestone. On the south coast of Jamaica, the limestone-producing aquifers (which supply water for wells, springs, etc) are the best producing in the island.

"These are open directly to the sea so the normal situation is for the sea to move in land a small distance, what you call a saltwater wedge ..." explained Basil Fernandez, head of the Water Resources Authority (WRA).

"You have to allow a certain outflow of fresh water underground, which maintains the saltwater wedge at a certain distance. When you have sea level rise, what is going to happen is the saltwater will move inland further naturally," he added.

"When you have climate change and with increasing temperatures, you are pumping water because you have to meet the demand for irrigation and for people, etc, and are reducing the outflow of fresh water underground. Therefore, saltwater will migrate inland even further and you are going to end up with saline intrusion miles inland," added Fernandez.

The result, the WRA boss noted, is that with sea level rise, there are areas on the island that could be without fresh water within a few decades.

"We had done a model of Clarendon, for instance, funded by the Caribbean Community Climate Change Centre, and it shows that in some instances, in like 2050 or so, and if climate change progresses with the temperatures as expected and the sea level rising, there are certain places in Clarendon where you won't be able to get to any fresh water - not even from your well," said Fernandez.

According to Taylor, the situation is one that requires careful planning around climate change, particularly for sea level rise.

"You have to plan now for what is going to happen and also for the whole importance of adaptation because some of it is actually happening. The major development projects coming in the future and which will be sited on the coast must account for sea level rise," he said.

Burgess emphasised the need for research.

"We need to look at the vulnerability of our coastline due to climate change impacts in an islandwide study. That study must include a risk assessment. It basically takes your understanding of the climate change hazards and convert them into a dollar value by looking at what is vulnerable," he said.

Fernandez said it is critical to look at improving water use and storage efficiency, including the reuse of treated waste water and artificial recharge.

"We can't allow all the rain that falls to go back out to sea. We have to allow some to get underground. We may have to channel it through sinkholes or wells underground where you can store it and pick it up back so it provides you with extra water and pushes back the saltwater wedge," he said.