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Dune Management Challenges on Developed Coasts

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Dune Management Challenges on Developed Coasts Dune management challenges on developed coasts By Nicole Elko, Kate Brodie, Hilary Stockdon, Karl Nordstrom, Chris Houser, Kim McKenna, Laura Moore, Julie Rosati, Peter Ruggiero, Roberta Thuman, and Ian Walker Lillian Street in, Kitty Hawk, NC, October 2015. (Photo credit: North Carolina DOT, used with permission.) Shore & Beach Vol. 84, No. 1 Winter 2016 Page 15 and dunes are large coastal features by systematic, accurate monitoring. This dunes, a request made by managers who typically formed when wind- type of approach requires effective com- were in attendance. blown sand is trapped and stabi- munication of reliable and accessible S MANAGEMENT CHALLENGES lized by vegetation. Located between information across complex stakeholder The inherent uncertainties of beach the backbeach and inland features, they networks, which can be challenging. and dune evolution, competing interests are an essential component of the coastal An adaptive management approach to among stakeholders, and multi-scale sediment budget and a primary control dune restoration and coastal protection physical, environmental, and socio- on the backshore ecosystem. In this role, is enhanced when all stakeholders have economic forces complicate the manage- coastal dunes provide essential ecosys- a basic understanding of the problem. ment of developed coasts. Management tem services, including habitat for en- The problem-solving process actually de- challenges discussed at the workshop dangered species such as piping plovers, pends on individual and societal attitudes focused on how to: (1) balance natural sites of high tourism value, groundwater and perceptions, whose inclusion can and human-use values when determining recharge zones, and protection of coastal improve the ability of coastal managers dune functions and needs; (2) sustain dy- infrastructure and properties from wave to achieve solutions that ensure a resilient namic dunes given spatial and temporal erosion and storm surge flooding. Fore- coastal system. For example, high dunes constraints from static human develop- dunes that back many sandy beaches can in some areas, which offer greater storm ment; (3) address long-term physical be maintained naturally by the interac- protection, can be a point of contention process challenges such as sediment tions between littoral processes (sand for residents and visitors who wish to supply, sea level rise, and chronic ero- supply delivered to the beach by waves), have easy access and a clear view of sion; (4) manage stakeholder expecta- aeolian processes (sand transport by wind beaches for recreation purposes. tions and interests over both short and over the sub-aerial beach), and critical This paper represents a synthesis of long time-scales; (5) provide improved ecological processes (sand trapping and ideas generated by nearly 100 members education and outreach programs to sup- vertical accretion by plants). Recent sci- of the coastal science and management port appropriate dune construction and entific research has focused on sediment community who participated in the management; (6) improve management movement between the beach and dune, American Shore and Beach Preservation planning and policies; and (7) prioritize including interactions between ecology Association’s (ASBPA) “Dune Manage- funding challenges. The need to better and morphology (e.g. Sherman et al. ment Challenges on Developed Coasts” incorporate input from social science 1998; Lancaster et al. 2013). workshop in Kitty Hawk, North Carolina, was also identified as an emerging and Dunes protect low-lying, developed 26-28 October 2015, to identify ways to important theme across the listed man- coastal areas from elevated water lev- overcome the perceived gap between the agement challenges. els and wave erosion associated with research of scientists and engineers and Balance dune functions coastal storms (Sallenger 2000). The the needs of management practitioners Sand dunes provide protection against value of dunes has been recognized for and other stakeholders. The purposes wave run-up and inundation during decades (USACE 1962), but dunes have of the workshop were to (1) identify the storms, a niche for plants adapted to only recently been included as a “design challenges involved in managing, restor- dynamic coastal conditions, habitable feature” in shore-protection projects ing and/or building dunes on developed substrate for invertebrates, feeding ar- (USACE 1995). Today, coastal dunes coasts; (2) determine the highest priority eas for primary consumers, and higher are recognized as a cost-effective method research needs for managing dunes on trophic levels, nesting sites, refuge areas of protecting community infrastructure developed coasts; and (3) identify ap- and corridors for migration (Peterson and from storm damage (NRC 2014). The proaches to help bridge the gap between Lipcius 2003; Everard et al. 2010). The expanded use of beach nourishment scientific knowledge and management greatest economic value of dunes is the facilitates dune building by providing a implementation. The workshop aimed protection they can provide for human sand source, accommodation space for to promote a non-technical dialogue infrastructure (Costanza et al. 2006). The dunes to form, and potential reduction in and information sharing between re- value in reducing storm risks is related wave-induced erosion. Despite the value searchers and managers/policy makers to dune elevation relative to prevailing of dunes for shore protection and envi- to collaboratively identify ways the storms, which determines susceptibility ronmental benefits (Everardet al. 2010), technical community could provide and to wave overwash and flooding as well as their basic function as “dynamic” land- communicate solutions for design, natu- sediment volume, which dictates the abil- forms and their role in providing these ral evolution, and maintenance of dunes ity of the dune to withstand storms and benefits isn’t always well understood or for consideration by practitioners. The maintain the integrity of the crest height appreciated by coastal landowners and consensus of the workshop participants (NRC 2014). Additional factors affect- beach users, and therefore sometimes not was that successful dune management re- ing the capacity of the dune to withstand incorporated into design specifications. quires an adaptive and flexible approach storm hazards include sedimentary com- that is: (1) locally-specific, educational, Because of uncertainty in the forces position (Palmsten and Holman 2012), and engaging to stakeholders and (2) that form and maintain dunes, manag- topographic complexity (Houser 2013), systems-based, considering the combined ing a dynamic dune system at a range interaction with the built environment aspects of social, ecological, and morpho- of spatial and temporal scales requires (Nordstrom et al. 2012), and vegetation dynamic processes. This paper aims to an adaptive management approach that (Feagin et al. 2015) — including inva- summarize not only the workshop discus- is based on sound, scientific knowledge sive beach grass dynamics (Seabloom sions but also recent research on coastal of coastal dune processes and grounded et al. 2013). Page 16 Shore & Beach Vol. 84, No. 1 Winter 2016 As discussed during the workshop, as fences in trapping sand (Miller et al. the USACE reviewed the performance he factors influencing 2001). The longer-term evolution and of several federal storm damage reduc- Ttemporal and spatial maintenance of dunes created by humans, tion projects following Hurricane Sandy scales of dune erosion however, depends on the positioning and found that projects backed by dunes and recovery differ on and morphology of the incipient dune, generally performed better than those undeveloped and developed the sediment budget of the beach-dune without dunes (USACE 2013). How- coastlines. Humans can system, and their maintenance by aeolian ever, the benefits of engineered dunes processes. Dunes that form by natural for reducing coastal flood risks are not affect the likelihood for dunes processes allow spatially-dependent dune sufficiently quantified to predict their to form or grow, ultimately plant communities to keep pace with damage reduction potential. Increasing impacting the benefits dunes topographic changes, thereby provid- human pressure to develop the shorefront provide. Buildings, roads and ing surface cover and root structure that through time, and risk from coastal haz- shore protection structures maintains sand accretion and contributes ards associated with rising sea levels and can restrict the quantity of to erosion resistance. Despite the advan- possible changes in storminess accentu- sediment and the space tages of building a dune using vegeta- ate the need to find ways to maximize the tion alone, the vulnerability of landward resource value of dunes in limited space. available for dunes to form; facilities in the initial years following whereas, beach nourishment major storms often encourages human Sand dunes also have direct human projects can re-establish intervention to accelerate the process of benefits beyond shore protection, includ- sediment budgets and space dune growth. ing consumptive (mining, harvesting, waste disposal, extraction, and recharge for dunes. Spatial constraints on dune evolution of water) and passive (aesthetic, psy- Beaches and dunes are part of a linked chological, cultural and environmental veloped coastlines. Humans can affect sediment exchange system that spans
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