Beach erosion along Grand Cayman’s Seven Mile Beach has become an increasingly critical issue for the Cayman Islands, prompting responses from public and private sectors alike. Recent studies and expert reports offer insights into the causes of the erosion and outline potential interventions to preserve this natural asset, widely considered one of the best beaches in the world.
Dart, a major investor in the Cayman Islands, has been proactive in funding and supporting scientific studies to understand and mitigate Seven Mile Beach’s erosion. Its involvement in commissioning studies and in exploring innovative science-based solutions reflects a commitment to environmental stewardship. Dart’s efforts complement government initiatives, underscoring the value of public-private partnerships in addressing complex environmental issues.
Key stakeholders, including Dart, the Cayman Islands Government, property owners and others are increasingly aligned in their commitment to address this issue through science-based solutions.
Understanding the drivers of erosion
Seven Mile Beach’s erosion is driven by both natural and human-induced factors, as outlined in a comprehensive report by Danish water engineering consultancy firm, DHI.
The study analysed 30km of shoreline, including Seven Mile Beach, identifying the balance — or imbalance — of sand as a critical factor in erosion. It found sand along the beach is constantly in motion, affected by waves, storms and natural currents.
“There’s a balance between what’s going up to the north and to the south. If that balance is disturbed, then suddenly sand is disappearing from the beach, DHI senior engineer Berry Elfrink said. “When it tips over the reef, then it’s lost forever.”
Recent shifts in weather patterns further impact sand movement. Hurricanes often push sand northward, while nor’westers drive it south, but the frequency and intensity of these storms have left Seven Mile Beach with a net sand deficit.
“Sand is a very difficult thing to get in that area; it is produced biologically … and transported by coastal currents,” Elfrink said.
Without intervention, the shoreline’s natural sand buffer may continue to erode, exacerbating the issue and threatening the integrity of Seven Mile Beach.
Sand traps and sand engines: A nature-based solution
To counteract the erosion, DHI recommends a nature-based intervention known as a sand engine as one of several measures to be used collectively. A sand engine uses natural wave energy to distribute sand across the beach, avoiding the need for heavy machinery or intrusive construction on the beach.
The DHI study found that storm-induced currents transport sand, especially from the southern section of the beach to waters located off the north of Seven Mile Beach. The study notes that it is likely that these sand pockets will be lost irretrievably to deeper waters and hence recommends their recovery by creating ‘sand traps’ at those locations. The sand harvested from the traps is proposed to be placed at strategic locations to be gradually distributed by wave action (‘sand engine’) along the shoreline, thereby creating a circular sand economy. This approach has been successfully implemented in other coastal areas and have proven to be environmentally friendly and effective.
“[A] recycling system of sand,” Elfrink said. “[Sand will] gradually be transported from the place where you put it … along the entire shore, but in a natural way.”
The goal is to use this approach as a low-impact intervention to support Seven Mile Beach’s natural resilience against erosion.
Building a multi-phase shoreline management strategy
While sand engines offer a practical solution for mitigating erosion, they are only one part of a comprehensive strategy recommended for Seven Mile Beach, according to the DHI study and a peer review of the study from Coastal Systems Development, Inc., a US-based coastal engineering firm.
Both studies emphasise that addressing Seven Mile Beach’s erosion comprehensively will require a combination of ongoing sand recycling, shoreline monitoring and proactive policies.
In a cost-benefit analysis, economist Marla Dukharan underscores the importance of early intervention, warning that erosion is likely to spread and affect the northern parts of Seven Mile Beach if left unaddressed.
“The cost of beach renourishment (as currently estimated) pales in comparison to the potential losses associated with a do-nothing scenario,” Dukharan stated, highlighting the importance of preventive steps over reactive measures. “We therefore recommend that beach renourishment be conducted at Seven Mile Beach with urgency.”
Economic stakes: The cost of inaction
While the science reveals the urgency of intervention, the economic stakes underscore the importance of a rapid, sustainable solution. Seven Mile Beach’s contributions to the Cayman Islands economy are substantial, with an estimated impact of US$1 billion annually, according to Dukharan’s 2024 report.
Properties along Seven Mile Beach are valued at approximately US$6 billion and their decline could have far-reaching effects on government revenue, employment and real estate investment.
Dukharan notes that short-term rental income in South Seven Mile Beach has been particularly impacted, with an average annual loss of about US$13,000 per unit since 2019.
Establishing a true cost of beach renourishment requires additional data like a survey and other estimates, however the Cayman Islands Government in 2021 approved CI$21 million for renourishment. The Cayman Islands Government has not suggested a policy of directly passing these costs along to visitors, but Dukharan’s report outlines how it could be done. The initial cost equates to roughly US$20 per cruise tourist and US$59 per stayover visitor, using current visitor numbers. The ongoing maintenance costs would amount to US$.94 per cruise visitor per year and US$2.80 per stay-over visitor per year.
“These costs are small relative to the overall property values on Seven Mile Beach and the potential for losses in the absence of renourishment,” she said.
Dart’s commitment to collaborative solutions
As a major stakeholder, Dart has been proactive in funding and supporting scientific studies to understand and mitigate Seven Mile Beach’s erosion. According to Elfrink, Dart’s support was rooted in a broad commitment to find sustainable solutions, rather than focusing narrowly on localized erosion control. He emphasised that Dart’s objective was to “provide [stakeholders] with a set of options … to preserve the coast and the beaches without causing negative impacts.”
An integrated strategy for long-term resilience
A sustainable future for Seven Mile Beach will require coordinated efforts across multiple fronts. The science behind sand engines and shoreline management points to a multi-step strategy that combines both short- and long-term measures:
The urgency of beach erosion on Seven Mile Beach calls for a science-based, multi-layered approach. Sand engines, regular renourishment and public-private partnerships form a comprehensive path forward, allowing Seven Mile Beach to continue thriving as a world-class destination and cultural and economic cornerstone for the Cayman Islands.
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