The City of Charleston’s Emergency Management Division and Mayor’s Office of Resiliency and Sustainability work in tandem helping both to inform and protect the citizens of Charleston, especially on the topics of flooding and sea level rise. Communicating to citizens about coastal hazards has long been a major undertaking of the city’s Emergency Management Division. While any work involving emergency preparedness and hazard awareness comes with its difficulties, adding to that challenge is the influx of new residents to our city and region. In just 20 years, the population of Charleston has ballooned from96,650 in 2000 to 150,227 in 2020, [1] with many of the city’s new residents coming from non-coastal areas, making it all the more important that city departments are aligned in their messaging and proactive flood mitigation efforts.

To help identify where to best focus our emergency management and resiliency efforts, in 2018, the City of Charleston hired NEMAC+FernLeaf to conduct an All Hazards Vulnerability and Risk Assessment. A key finding from the Risk Assessment was the confirmation that the city’s highest level of vulnerability is related to storm surge and floodplain inundation. The report indicated that, due to a range of climate and non-climate factors, the city is susceptible to increased risk from water inundation, sea level rise, the increased severity of heavy precipitation events, and land use conversion. [2] To respond to this threat and work to protect Charleston’s peninsula in the years to come, the City of Charleston began working in coordination with the U.S. Army Corps of Engineers to develop a major surge risk mitigation plan for the downtown peninsula area.

Through this effort and others, it has become increasingly apparent that flooding and sea level rise pose an existential threat to the City of Charleston. The Charleston Harbor tide gauge has been measuring sea levels since 1922 and has reported a rise in the sea level of more than a foot. With that said, the rate of sea level rise is not linear, as nearly half of the total amount of sea level rise recorded over the past 100 years has occurred in the last 20 years. In order to most effectively confront this threat, the city proactively tracks flooding and tidal data, and is committed to putting science first. An important indicator used by the city to track the impacts of sea level rise in Charleston is the number of “minor tidal flooding” events, commonly referred to as nuisance, sunny day, or high tide flooding. Charleston uses a 7.0-foot high tide or greater as a benchmark for such flooding events. Tides from 7.0 to 7.4 feet generate minor flooding in Charleston, where water from the harbor will begin to pool on land in low lying areas, generating hazards unrelated to rain events or storm systems. The frequency of this type of flooding has increased dramatically in recent years.

Another tool designed to mitigate the impacts of flooding is the city’s Flooding and Sea Level Rise Strategy, which was updated in February 2019 and focuses on five critical components. The first, resources, included a newly created Storm water Management Department, a number of Hazard Mitigation Grants, and a National Flood Insurance Plan (NFIP) pilot project designed to reduce the number of buyouts for flooded properties.  The Dutch Dialogues™ Process is a collaborative effort with city, professional, academic and community leaders in planning, storm water management, resiliency and other interests, to bring an integrated approach, tying together numerous entities, collectively working to manage water. These tools work in tandem to increase the city’s capacity to not only respond to the effects of flooding, but to be proactive in working to mitigate and prepare for those impacts.

In the governance toolbox are initiatives like updates to Storm water Manual requirements, the All Hazards Vulnerability and Risk Assessment, an initiative in the Church Creek Drainage Basin prohibiting net fill/fill absorption, and an NFIP Community Rating Survey (CRS)score of 5, reducing citizens’ flood insurance premiums. Similar to the aforementioned resources, these governance tools represent proactive steps by city leadership to protect the citizens of Charleston from the negative effects of flooding and sea level rise.

The third component, infrastructure, includes a collection of city drainage projects totaling more than $203.8million. Among them are: Church Creek, Forest Acres, Spring/Fishburne, Calhoun West, and Market Street. As part of these infrastructure improvements citywide, a number of check valves were installed throughout the City of Charleston’s drainage system as an efficient and effective solution to tidal flooding. These check valves allow water to flow out of the peninsula and into the harbor, while preventing tidal waters from entering the drainage system and flooding city streets and sidewalks. To facilitate these ambitious projects, the city used a combination of funds, including an increased drainage fund and Storm water Management budget, general funds, tax increment finance funds, the Charleston County half cent tax, the state infrastructure bank, and more.

In terms of land use, for the first time in its history, the city has made “water first” a pillar of its newest ten-year Comprehensive Plan Update. This document will drive land use elevation and future flood risks as an instrument to better guide future development. The creation of a sustainable zoning district in elevated, dry, and connected areas will help to incentivize responsible development and community growth for years to come.

The final component, outreach, includes a number of important efforts focused on education and communication throughout the community. Through consistent outreach, the city’s Emergency Management Division is better able to inform the public on the threat of flooding and sea level rise, its range of causes, and the steps being taken by local government to mitigate its impacts. Among other efforts, the city has demonstrated its commitment to strengthening this flow of information by introducing a new website dedicated exclusively to flooding information and preparedness. The website enables citizens to report flood damage, and track flood data and changing conditions. Additionally, the city has reformatted its Resiliency &Sustainability Advisory Committee in order to enhance the opportunities for residents to collaborate with city staff on these important initiatives.

As the city continues to see throughout flooding events, successful preparation and recovery relies on the work of a number of city departments and the alignment of Emergency Management and Resiliency strategies. As recently as November of 2021, the city saw some of the highest tides in its history which resulted in a number of major road closures. Despite the disruption, however, there were no life safety issues, a direct result of the city’s robust outreach efforts and the collaboration between Emergency Management and Resiliency officials. This collaborative approach has created a framework that will continue to be critical to the success of Emergency Management now and in the future.

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[1] U.S. Census Bureau Decennial Census Counts

[2] NEMAC+FernLeaf, for the City of Charleston, SC. All Hazards Vulnerability and Risk Assessment. Asheville, NC: NEMAC+FernLeaf, November 2021.