Catch & Release: Coastal Resilience & Water Inundation in the Southeast

Catch and Release: Coastal Resilience and Water Inundation in the Southeast

Author: Nicholas Bilgri

Catch and Release: Coastal Resilience and Water Inundation in the Southeast

Author: Nicholas Bilgri

Abstract

Resilience has become the overarching topic impacting the architecture and urban planning fields today. This paper will define resilience in the context of design; explore its role in urbanity; and examine strategies that architects, urban designers, and planners can integrate into their practice.

An organism is resilient when it can withstand adversity repeatedly yet continue to ward off extinction. Environmental resilience is cyclical in nature. An organism must then regenerate and repopulate itself and adapt to its ever-changing surroundings.

What is Resilience?

In qualitative terms, a resilience mindset strengthens one’s ability to withstand adverse elements, both immediate and enduring; to overcome detrimental experiences and thrive. Something that is resilient bends, but never truly breaks. Its assets can wear away but are never fully erased.

Resilience can be broken down into two distinct categories: engineered and ecological resilience.

Engineered resilience is an object or system’s ability to absorb or avoid damage, without suffering complete failure. The object or system rectifies itself and attempts to return to equilibrium. The system is linear in nature and cannot be regenerated. For example, a framed steel structure bolstered by moments within the system can shift but returns to place without collapse.

Environmental resilience can be thought of in terms of biology.

In the context of architecture and urban planning, resilience is not a product that can be specified, or a certificate that can be achieved with a checklist. Guidelines are helpful, but to achieve truly resilient communities, designers must go beyond that binding framework. Architects and urban designers are faced with the difficult task of merging the need to both withstand adversity and return to equilibrium as quickly as possible, while also taking

that momentum and creating a world that can evolve through cycles of economic, environmental, and social disruption.

Context: Home

Architecture, interiors, and planning firm LS3P is proudly rooted in the American Southeast, with projects covering with eight offices across three states and an international reach, each of the firm’s locales face unique challenges while sharing the same nagging environmental distresses including sprawl, threat of forest fires, and seismic events. For coastal cities, one issue has remained dominant for decades: water inundation. From tidal flooding in Charleston, SC to raging rivers in Greenville, SC, flooding has intruded on urban life, even on sunny days.

Urban centers have expanded rapidly, leading to sprawl and the disruption of natural hydrological conditions. Poor planning is one cause. Greenfield development on Johns Island, SC removes the efficiently drained mud and replaces it with a cap for slabon-grade housing. Sprawl in Myrtle Beach places homes in flood plains, altering the natural tidal flow. The ever-rising tide levels in Charleston Harbor regularly inundate major arterial roadways and submerge critical infrastructure, such as healthcare facilities the Medical District.

The outdated policies that form development and the market factors associated with them create an ongoing struggle for architects, planners, and engineers. These policies and the existing regulatory framework create difficult scenarios in which designers struggle to make resilient design decisions due to lack of financial incentive for investors and developers. However, this

mindset can easily be overcome and can adapt to present-day processes to accomplish environmental, social, and economic resilience.

Architects and planners must consider an incredibly wide range of factors when designing for resilience. For those practicing in the Southeast, water is a primary concern.

Hydrology: Flowing together

To better understand the needs of our communities, architects and planners must first understand how the Southeast is linked through water. Every city falls into at least one of these watersheds, with every creek, pond, river, and lake flowing into these drainage areas:

The Yadkin-Pee

Dee watershed runs north of WinstonSalem, down near the Charlotte metropolitan area, and empties into the ocean in Georgetown, SC, north of Charleston. As of 2010, 39% of the North Caroline section of the watershed failed to meet state water quality standards. This is likely due to soil runoff and erosion caused by suburban sprawl.

Figure 1

The Cape Fear watershed comprises blackwater rivers, slow moving and swamp-like, running from Greensboro, NC down through Willington. The basin ends just south of Raleigh but carries directly through Fayetteville. In 2018, Hurricane Florence caused the failure of a dam, leading to coal ash leaking into the watershed just five miles north of Wilmington.

The Santee watershed is the most expansive of the three. It is the second largest river basin on the East Coast. Its head is located north of Charlotte in distant Hickory, NC and empties south of Georgetown.

The river basin encompasses Greenville, Charlotte, and Columbia and is home to protected wetlands and old growth forests like Congaree National Forest. It culminates in Lake Marion, providing hydroelectric power for the Piedmont region. Major flooding could be seen in these metropolitans in 2015 after Hurricane Joaquin.

The Cooper River and Charleston Harbor have their own unique relationship with these watersheds. The harbor is formed by the confluence of the Ashley, Cooper, Wando, and Stono

Rivers. This creates an inlet and forms the land mass on which the city of Charleston is located. This is part of the “drowned coastline” that runs along the Carolina’s eastern border. The term “drowned” is used to describe the inundation that occurs naturally due to tidal changes. In locales like Charleston, Myrtle Beach, and Wilmington, these tides are exacerbated by rising sea levels and increased drainage of river basins.

The Southeast’s geographic relationship with water is evident, as well as the quantifiable effects of its attractiveness and risk.

Economics: Risk vs Reward

A simple truth drives the connection between geography and development: people love water. People want to live near it, recreate in it, industrialize it, and commercialize it. This trend is not exclusive to Georgia or the Carolinas. According to the U.S. Census Bureau, the population of counties along the Gulf of Mexico soared by 150 percent. 41 million Americans lived along the Atlantic coastline today. In 1960, 47 million lived in coastline counties throughout the entire United States. The Atlantic and Gulf coasts are also home to 4 of the top 10 most populous counties. This an enormous amount of real estate at risk to hurricanes, coastal flooding, and tidal flooding. Weather events in the United States that resulted in more than $1 billion in damage an astounding 28 times in 2018 and 2019. Globally, 40 of these $1 billion events occurred in 2019 alone (ULI). The increase in risk and the volatility of local conditions have begun to concern investors, lenders, and insurers alike.

Figure 2

Besides the obvious physical risks posed by an increase in climate events, investors are also at risk for the soft costs of resilience. With an increased awareness of the adverse effects of climate change come policy changes, technology innovations, resource scarcity, and evolving markets. These natural progressions to a more resilient future can be mitigated in the design process by creating structures and spaces that are adaptable, capable of withstanding climate events, and progressive in their approach. However, even initial investments in resilience will eventually become obsolete. Architects will need to express to clients that the life of a structure must evolve with its environment, which adds maintenance and upkeep costs and the potential for renovation and retrofitting.

saved taxpayers $4 for every $1 spent. Further, designing to the 2018 IBC instead of the National Flood Insurance Program standards can lead to a savings of $11 for every $1 spent. Given this accounting, it’s important to draw the comparison to cities with active and planned resilience infrastructure improvements and the cost of insuring developments. Cities and municipalities actively working to mitigate risks will assist in providing lower insurance premiums to investors. This, paired with updated zoning codes and development requirements, can push more sustainable and resilient urban development.

Equity: Community-centric Infrastructure

The National Institute of Building Sciences predicts that every $1 spent on hazard mitigation infrastructure leads to a savings of $6 in recovery from Federal relief funding. Retrofitting existing building stock can save the private-sector $4 for every $1 spent. Designing above the required code, in this case the 2015 IBC,

There is a real opportunity for designers to take a progressive step forward in creating an urbanity that is both resilient and socially uplifting. While every city has its unique urban challenges, issues of equity permeate urbanities at all scales. The type of infrastructure needed to serve our locales and mitigate environmental adversities can also serve as parks and trails, increasing mobility options and creating a more woven urban fabric. These interventions can create and restore local ecologies that have been decimated due to over development and resource pollution. Architectural solutions can include green roofs that act as community gardens and urban agriculture, or greywater systems that lower the utility costs for residents. Designers need to think outside the realm of just a park or just a building or just a shoreline. This infrastructure needs to serve our communities in their total capacity.

Historically, communities most impacted by environmental events are in economically distressed areas. As municipalities recognize

these areas for redevelopment and infrastructural improvements, it is important to maintain the communities and cultures that have grown there.

Strategies: Planning for Resilience

With a higher level of planning, architects and planners can take many actions to both immediately mitigate the effects of coastal flooding and sea level rise and set the region up for more favorable outcomes in more adverse events. Municipalities can create, or incorporate into their existing masterplans, visionary ideas for their jurisdictions that account for hydrology and resilience. Most municipalities already have these plans in place, but too often issues of economic or environmental resilience lose out to growth.

Planners can begin by allowing for higher density development on higher ground and developed areas currently being underutilized. This strategy, in combination with an urban growth boundary, will focus development energy on constrained, purposeful sites while accomplishing other important goals such as housing and mobility affordability, issues of equity through more economically diverse urban centers, and the goal of moving growing populations out of much-needed natural flood infrastructure and endangered ecologies.

Architects and planners can advocate for zoning code reform which coincides with the goals set forth by visionary masterplans. Allowing for a mix of building programs while incentivizing high density, walkable development will help accomplish goals of low-carbon emissions, a cleaner public health environment, and

a heightened sense of community “place” and identity. This reform will create communities that are more resilient to changing environmental conditions and allow communities to weather economic storms through built in redundancies and better worklive-play relationships.

Discussions of density can be uncomfortable for some communities, as the term may have unintended associations with gentrification, displacement, or sprawl. A lower-density area like Charleston may reject the notion of greater density associated with a city like Atlanta. However, it is important to note that even sprawling cities have followed similar American planning ideals as smaller-scale, more suburban cities like Charleston. Conversely, a city like Amsterdam, though large, still maintains its charm and intimacy while having a density ratio far higher (4x the size)

than both Charleston and Atlanta, with Atlanta being only slightly denser than sprawling Charleston.

Planning can also dictate the form and scale of development to better equip designers with the tools necessary to build more resilient architecture. Strategies can include requirements for elevation above dangerous flood levels greater than recommended by FEMA, limits on building footprint, or dictation of building materials to meet certain energy standards.

Strategies: Designing for Resilience

Designers have the opportunity and responsibility to make decisions that will greatly reduce the risks clients face with coastal flooding and sea level rise. Architects must adhere to local requirements and codes but can also advocate for more advanced measures of resilience. These measures tend to accrue cost at the initial stages of development and are often rejected by developers and investors. Conscious designers must be increasingly proficient at explaining the benefits of increased initial costs versus the reduced risk to stakeholders. As a rule of thumb, these decisions fall into three different flooding control strategies: reduce, retain, and release.

Reducing the amount of rainwater runoff into local water systems, both natural and mand-made, can drastically increase the effectiveness of those systems. Reduction can be achieved by slowing the rate of water flow into the system via means that filter and feed relative ecosystems. The strategies can include incorporating swales adjacent to porous hardscapes, creating green roofs and elevated parks, or simply choosing site plantings

that retain more volume. In the event of a 100-year rainfall, these decisions could be the difference between flooded streets and parking lots with contaminated runoff, or useable hardscapes with cleaner and controlled flow into local creeks and rivers.

Retaining water on site is a more expensive method of mitigation, but a necessary one in denser urban environments. Combined with reduction methods, water retention can be an asset and a resource to a site. Water retention can be achieved via cisterns and ponds, at ground level or at the roof. Subgrade retention becomes difficult in many locales, such as Charleston, due to the higher water table. Collected water can serve practical uses, from watering gardens and creating urban agriculture to flushing toilets and washing laundry via greywater system. Harvesting rainwater can be a cost-effective way to sustainably live and reduce strain on storm water systems at scale.

Lastly, designers must determine the most advantageous time to release water back into the system once it has been slowed and cleaned, utilized for practical needs, or even just stored. In a city like Charleston, this release might occur at low tide, when

the gravity-based stormwater system has maximum capacity. In a city like Charlotte, timing might not be a huge issue, and the advantages of reducing and retaining water do not dictate the success of the releasing it. In an urban condition such as Greenville or Columbia, the release might be subjected to the recession of river levels or the height of assets such as local lakes and reservoirs. No matter the situation, the relationship of reduce, retain, and release is adjustable at scale and available to all types of urbanities.

Conclusion

While architects and planners face the daunting task of designing and building better cities in the face of climate change and sea level rise, LS3P is well situated to understand the needs and adversaries of a wide range of municipalities in the region. Southeastern cities may vary in scale and environmental context, but they are closely related both hydrologically and in policy. Designers have the responsibility to push for higher outcomes in policy and planning, and to take further steps into more environmentally friendly and equitable design.

References

Figure 1:

Pee Dee River. (2020, December 23). In Wikipedia. https://en.wikipedia. org/wiki/Pee_Dee_River

Figure 2:

Santee River. (2021, January 24). In Wikipedia. https://simple.wikipedia. org/wiki/Santee_River