Next-generation flood control in the Lowcountry

Charleston's Water Plan Delivers Comprehensive, Integrated Framework for Long-Term Flood Resilience

Water is central to the story of Charleston – its history, culture, and environment. The city is built on an estuary in South Carolina’s Lowcountry where three rivers converge and empty into an inlet on the Atlantic Ocean.

Due to the location, inundation has long been commonplace in Charleston as flooding from rain, groundwater, storm surge, and high tide occurs naturally and regularly. To control its floodwaters, the city has implemented studies, plans, projects, and technologies since building its first seawall during colonial times in the 1760s.

Still, the water keeps coming, even more so. Threatening Charleston’s future, the sea level is rising, and the frequency and strength of wet weather events is intensifying. In response, the city is broadening its approach beyond traditional solutions focused solely on containment or drainage.

Working with Black & Veatch, Charleston has implemented a comprehensive strategy for managing flood risks and embracing water’s importance to the city. The Charleston Water Plan provides a 25-year framework for:

• Controlling flood risks from tides, sea level rise, stormwater, storm surge, and groundwater.

• Guiding safe and resilient growth while protecting ecologically sensitive areas.

• Embracing the connection between water and the city’s historic sense of place.

Intensification Prompts a New Approach

From Charleston’s waters grows marshland, spartina and sweetgrass, Spanish moss, and live oak and palmetto trees. So has grown the city, becoming South Carolina’s largest by expanding over the terrain, and mostly taking a keep-the-water-out, single-purpose-infrastructure approach to its flooding issue. Creeks and neighborhoods have been filled in. Drainage systems have been constructed. Nonetheless, communities have continued to experience frequent flooding even as the city has worked steadfastly to manage it.

Making the issue more urgent is an increase in the city’s flooding. Inundation from king tides, which can happen during sunny days when no storm is around, occurred 38 times in 2015. That was triple the amount Charleston experienced in 2000. According to the National Oceanic and Atmospheric Administration (NOAA), the city’s sea level has risen 13 inches in the past 100 years – with half of the total occurring in the most recent 20 years. NOAA estimates that the sea level in Charleston will rise another 14 inches by 2050 and tidal flooding will affect the city 180 days a year by 2045.

Addressing the intensification, Charleston has been shifting its flood control and risk mitigation approach with the help of Black & Veatch. In 2015, the city established its Flooding and Sea Level Rise Strategy, focusing on reinvestment, responsiveness, and readiness – the “3 Rs of resilience.” In 2019, the strategy was updated to name critical targets. The Charleston Water Plan builds on the prior work, providing updated data and guidance to fully address the city’s flood issues.

The plan is built on the premise that flooding is manageable, and Charleston can continue to thrive, but the city must adapt to the rising water. It seeks to build long-term sustainability and resilience through an array of goals to improve the city’s water infrastructure and protect its citizens and neighborhoods, preserving both Charleston’s economic viability and its environmental resources.

Critical components include:

• Infrastructure – prioritizing investment in drainage, tidal management, and complementary infrastructure projects. Think resilience-strengthening options such as raising the elevation of buildings, facilities, and roads, installing flood-proofing/hardening and coastal erosion measures, updating design and construction standards, and implementing green infrastructure including natural and nature-based solutions to improve local water quality, preserve biodiversity, provide community amenities as well as manage floodwater.

• Land use – directing growth away from low-lying and vulnerable areas to high, dry, connected areas. Solutions like changing the city’s zoning code, restricting the use of fill, and neighborhood adaptation can maximize project value and resilience while minimizing risk.

• Governance – establishing policies, practices, and regulations. Governance clarifies priorities, guides investment, and directs strategies.

• Resources – dedicating sufficient, reliable project funding, and proper staffing. Planning, engineering, design, zoning, watershed, building, even alternative funding expertise from a water management perspective is necessary for implementing successful projects, pursuing adaptation, and promoting resilience and sustainability.

• Outreach and partnerships – engaging stakeholders to understand Charleston’s flooding causes and impacts and participate in the process of protecting Charleston’s unique and invaluable qualities. This entails leveraging expertise and partnerships in the business, academic, scientific, educational, advocacy, and non-profit sectors. The potential for Charleston in job creation, economic resilience, and business opportunities is significant.

Driving Safety, Sustainability, Viability

Benefits anticipated from the Charleston Water Plan include the following.

• Protection of people, public spaces, neighborhoods, businesses: Maintaining safety is Charleston’s highest priority.

• Improved infrastructure: Improving Charleston’s infrastructure is essential to preserving its character while ensuring hospitals, fire stations, police stations, schools, transportation corridors, and utilities are flood-resilient now and in the future.

• Preservation of economic viability: Flood-resilient businesses, institutions, and organizations are essential to a strong economy that works for everyone.

• Environmental protection: Treat the environment as a natural and economic resource – understanding, respecting, promoting, and adapting its capacity to mitigate flooding and support Charleston’s quality of life.

• Enhanced collaboration: Flooding’s impacts resonate across boundaries of all types in Charleston and throughout the Lowcountry of South Carolina. Successful flood control and risk management requires collaboration across all these boundaries, public and private.

Principled Approach

The plan is based on a set of principles. Safety comes first. The city’s critical assets must be connected and protected. Elevation matters – value high ground for growth, connect low ground, and build with nature. Prioritize water as a foundational strategy in planning and development. Change for the good by acting now, adapting over time, and addressing environmental justice. Work collaboratively by coordinating and communicating across communities and sectors. And build value through long-term resilience and flexibility, adjusting to new information.

Charleston’s forward-looking water plan addresses the serious threats the city faces from flooding. Its adaptive, comprehensive, and integrated strategies align the city’s critical infrastructure and governmental resources to drive public safety, environmental sustainability, and economic viability for all in the community, far into the future.