Nov 02, 2022Designing Flood Resilient Infrastructure in South Carolina

Flood Resilient Infrastructure Design & Emergency Preparedness

Helping communities recover, survive, and thrive is some of our most important work. Our South Carolina Emergency Management team is busy working on flood-resilient infrastructure design, conducting hydraulic studies to mitigate damage from past storms, preparing for future storms, and preventing the worst from happening again.

Infrastructure, as defined by Merriam-Webster, is “the system of public works of a country, state, or region.” That includes essential services and resources like water, sewer, power, transportation, and more. Often, these are utilities we rarely think about until they are unavailable, and then it’s all we think about.

Flood-resilient infrastructure design takes into account ecological, environmental, and structural elements existing on a floodplain as well as root causes and effects of potential flooding in the surrounding areas both up and downstream. The goal is to mitigate the potential impact on infrastructure and the overall community of excessive rainfall and flooding through a variety of traditional and sustainable design components, for example:

• Improving the drainage system
• Natural stormwater solutions
• Removing existing structures from the landscape to reclaim natural areas
• Adding green structures to absorb water naturally
• Redundant and diverse access to water treatment resources

Why South Carolina and Others Need Flood Resilient Infrastructure Design

Between 2015 and 2018, three hurricanes (Joaquin, Matthew, and Florence) led to Presidential declarations of federal disasters in South Carolina. It might surprise many people to learn that the bulk of the damage from all three of these storms was not the wind and storm surge, but rather it was the eventual flooding from the rain falling across the state, as well as runoff water from rivers, streams, and tributaries beyond for an extended period. That’s what can happen without flood-resilient infrastructure.

The storms caused debilitating damage throughout South Carolina. Those without the means to repair their homes were forced to either live in unsafe structures, relocate with relatives, or flee the disaster area. This strained the fabric of affected communities, some of which had experienced damage from all three storms and many of which had already been struggling with high social vulnerability as Low and Moderate Income (LMI) areas even before the storms.

Local economies continued to struggle as businesses lost customers and local government tax revenues diminished. One storm can cause destabilizing damage. Three storms in four years have left many communities on the brink of collapse. This example is an extreme case, but South Carolina is not the only state in need of flood-resilient infrastructure design. If your infrastructure is on or near a floodplain, a resilient design could be a game changer.

According to the U.S. Environmental Protection Agency (EPA), “Heavy downpours have increased in frequency and intensity worldwide in the last 50 years. They are expected to become more frequent and intense as global temperatures continue to rise. As a result, the risk of flooding is likely to increase dramatically across the United States. The average 100-year floodplain is projected to increase 45 percent by the year 2100, while the annual damages from flooding are predicted to increase by $750 million. Among the types of flooding that will likely become more frequent are localized floods and riverine floods. Localized flooding happens when rainfall overwhelms the capacity of urban drainage systems, while riverine flooding happens when river flows exceed the capacity of the river channel.”

How to Mitigate Future Flooding Disasters

The best way to mitigate future flooding disasters is to focus on the whole community to create resiliency by addressing risk and creating a culture of preparedness. That means motivating your community to protect themselves from the loss of life, property, and prosperity as a result of natural hazards. That’s not a simple, quick fix, but as you can see in the South Carolina example, it’s far superior to the alternative.

Now, South Carolina is taking the first step toward flood-resilient infrastructure design, engaging E.L. Robinson to conduct the Darlington County Hydraulic/Flood Study and Chesterfield County Hydraulic/Flood Study. The South Carolina Office of Resilience (SCOR) spearheaded the two studies funded by a U.S. Housing and Urban Development (HUD) Community Development Block Grant-Mitigation (CDBG-MIT) Grant with a focus on Low and Moderate Income (LMI) Benefit Areas and Mitigation Urgent Need in “Most Impacted and Distressed” (MID) counties.

The Darlington County Hydraulic/Flood Study and the Chesterfield County Hydraulic/Flood Study each contain multiple tasks and steps, including:

• Communication and Education for elected officials and the public in the community
• Conducting multiple public meetings to collect feedback and information and identify flooding issues throughout the county based on public meetings
• Conducting face-to-face site visits to meet residents and assess flooding issues
• Developing hydrologic and hydraulic models of the existing and proposed stormwater system for various frequencies using GIS mapping to create conceptual designs
• Prioritizing projects for construction grant submissions based on computer modeling results, including a benefit-cost analysis (result > 1) for each potential project

The SCOR will use the results of the studies to submit additional grants and identify flood-resilient infrastructure design projects to undertake based on available funding and identified priorities.

Why Work with E.L. Robinson Emergency Management Services

It takes an experienced firm familiar with these types of projects with a team that can work within the intent of the program, for example, focusing on current and future impacts on LMI and MID counties. That’s how we deliver flood studies with the highest level of credibility based on data-driven, expert analysis. It includes comprehensive data analysis and intellectual rigor that stands the test of intense public scrutiny and increases the likelihood that projects will gain funding and proceed.

Learn more about our Emergency Management Services, including flood-resilient infrastructure design and much more. Contact us with any questions or to discuss a future project.