COASTAL FLOODING & SOLUTIONS, Workshop Case Studies
Flood Mitigation, KICA Water Management Task Force
Kiawah Island, South Carolina
Jon Lucas Hernandez
Water is one of Kiawah’s greatest assets - the ocean, marsh, river and ponds. The island’s natural abundance is a big reason why people are drawn to the island and why they stay, but living with water requires continuous data collection, monitoring, and forecasting.
In 2019, The Kiawah Island Community Association (KICA) established the Water Management Task Force to evaluate and refine KICA’s approach to water management, and determine a comprehensive solution to address Kiawah’s commonly recurring flooding issues. This included a deep dive into state, federal, and local databases to collect and understand both current and past conditions on the island. Sea level trends, rainfall totals, impervious cover percentages, existing infrastructure and elevation data made up the majority of components that went into the modeling and predictions for this project. There were two models that came out of the study that included a validated-current model of flooding on the island and a predicted model of flooding with the proposed changes in infrastructure.
Ultimately, the task force determined that six strategic infrastructure improvement projects would optimize Kiawah’s drainage system, allowing water to more efficiently exit the system. This would eliminate hazardous flooding in significant portions of the island during heavy rainfall events and position Kiawah to recover more quickly from storm surge.
At present, a severe rainfall at Mean Higher High Water can flood Kiawah’s main roads, limiting access to and from the island. This occurred five times in the last five years, and is a public safety issue. According the modeling that was completed, in the same rainfall scenario, with improvements to Kiawah’s infrastructure, main roads would remain open to traffic and hazardous flooding on common property throughout many neighborhoods would be resolved.
In the spring of 2020 the community voted to approve a special assessment to fund these critical drainage infrastructure improvements. KICA expects that these improvements will provide for safe travel on and off the island during the most intense rainfall events.
In efforts to increase coastal resilience, Kiawah Island as a whole has been making an effort to increase in situ monitoring of weather, changes in groundwater dynamics, and tidal stage. The Town has recently established a tide gauge on the Kiawah River Bridge and KICA has partnered with SC Beach Advocates to add an additional gauge in Ocean Park. The two gauges will help fill data gaps in the NOAA CO-OPS NWLON of tide gauges and will improve modeling predictions, tide predictions, and allow the island to monitoring the rate of relative sea level change. As the weather stations, groundwater monitoring, and tide gauges continue to collect information, Kiawah Island will be able to improve data-driven decision making and further its adaptive approach to planning for a resilient community for decades to come.
Our project managed to get enough community support to call for a special assessment to fund the work. We are scheduled to have everything completed by 2021. Since the projects passed, all entities on the island have pushed for more monitoring efforts and ways to gather data on indicators for future planning and projects.
We are hoping to develop an adaptive management strategy for the island to follow as a whole. This will involve community engagement to decide what concerns the community has in regard to changes in climate and relative sea level. From this information and our monitoring efforts, we will be able to develop a set of thresholds and trigger points to monitor. As a threshold is reached, we will have outlined plans on how to proceed with creating solutions and what entities on the island will be involved in those decisions.