2019 National Coastal Conference Abstracts – Poster Session

Morphological and Sedimentological Impacts of Hurricane Michael along the North-West Florida Coast

Jacob Adam, University of South Florida

In October 2018 Michael, an energetic category 5 hurricane, made landfall in Mexico Beach, North-West Florida. It is the third most intense Atlantic hurricane to make landfall in the United States in terms of center pressure and the strongest storm in terms of maximum sustained wind speed since Hurricane Andrew in 1992. The hurricane generated a storm surge of 2.5m which is more than 7 times the average tidal range in this area, which is 0.34m, and thus provided an opportunity to study the response of a variety of coastal environments to an extreme storm.

Morphology changes induced by Hurricane Michael along the Barrier Islands were quantified through analysis of pre & post storm LiDAR surveys, as well as aerial photos. Sedimentological characteristics of storm deposits along barrier islands, within Apalachicola Bay and surrounding coastal marsh were examined with 116 sediment cores and 40 sediment samples. This poster will present 1) the morphological characteristics and spatial variation of dune scarping and beach erosion; and 2) the sedimentological characteristics of overwash deposits in various environments including: ocean facing and bay facing barrier beach, within the Apalachicola Bay, and the coastal marsh along the Bay.

Presenter Bio: Jacob Adam is a M.S. Student in Coastal Geology at the University of South Florida. He started his Master’s Program at USF in Fall 2019 after receiving a B.S. in Geology in Spring 2019 also at the University of South Florida.

Jacob is currently participating in the field measurement and numerical modelling as part of the Tampa Bay National Estuary Program’s Fort De Soto Back Bay recirculation project. He is also involved in the monitoring & studying of the beach nourishment projects along the coast of Pinellas County.

 

Tools for Sedimentological Restoration

Jeff Andrews, APTIM

There are some great lessons to be learned from the sinking of major deltas specifically the Mississippi River Delta, as to how human intervention can complicate the ecosystem by interrupting natural processes and exacerbating degradation. Central to this issue is mostly “sediment”.  Human activities have impaired sediment availability to support sustainable coasts. Globally, degrading shorelines need frequent infusion/emplacement of sediment.  Ecological restoration can only be undertaken on a stabilized coastline where sedimentological restoration has occurred. The main challenges for restoration and restoring a healthy sediment budget are to understand sources and sinks of sediment and predicting the rate of land growth under various restoration strategies, including river/sediment diversions, marsh creation and barrier island restoration. Important to this issue is the understanding that sediment, its dynamics and its availability, is not haphazard, but related to the underlying/subsurface geology. This complex problem cannot be fixed until there is a good understanding of the underlying geology. Thus, the remedy to the problem is to take a holistic approach and develop a robust sediment management plan for the entire region. Sediment is critical to the sustainability of coastal Louisiana, and being sediment-limited, proper management of sediment resources is critical.  Louisiana’s Coastal Master Plan (CMP) prescribes billions of dollars in sediment diversion, barrier island restoration and marsh creation projects.  To meet the sediment needs of this ambitious plan, Louisiana has developed a comprehensive Louisiana Sediment Management Plan (LASMP) which facilitates the inventory of sediment resources, management of relevant datasets, and provides tools for project planners and managers to efficiently manage fluvial and offshore sediment resources.  LASMP is crucial to the success of any regional strategy employing large-scale sedimentological restoration because sediment management is a key element of sedimentological restoration.  Four primary components of this plan that direct State efforts toward a more formal Regional Sediment Management (RSM) approach include: 1) regional approach to sediment management 2); borrow area considerations; 3) implementation of appropriate policy and regulations; and 4) communication and coordination with Federal, State, and other stakeholders.

This presentation will review the various sediment management tools developed to mitigate the severe landloss, mainly due to sediment deficit in coastal Louisiana, and will emphasize the need of a regional approach for managing sediment. These tools include: Delta Sand Search Model (DSSM) or “Guidelines/Protocol for exploration for sediment”; the Louisiana Sediment Resource Database (LASARD) for archiving/populating related geoscientific data; and a Surficial Sediment Distribution (SSD) Map identifying known surficial sediment resources in offshore, coastal waters and the Lower Mississippi River. The latest tool is the Louisiana Sediment Availability and Allocation Program (LASAAP). The tool’s primary goal is to link the sediment-needs for the State’s marsh, barrier island and ridge creation/restoration projects to the coast-wide potential sediment sources within state and federal waters.  The long-term goal for these tools is to enhance State planning capabilities to optimize sediment resource utilization, capitalize on synergistic project opportunities, reduce project costs, maximize land-building potential, and ensure projects have the necessary sediment available for 50-yr planning horizon of the CMP.

 

Break On Through (To The Other Side): sound-side overwash along the NC Outer Banks

Patrick Barrineau, Coastal Science & Engineering, Inc.

The North Carolina Outer Banks are (in)famous for their susceptibility to  overwash from tropical storms and hurricanes as well as nor’easters and strong low-pressure systems. Much of the Outer Banks are micro-tidal barrier islands with a continuous foredune ridge and low back-barrier flats sloping into shallow lagoons (eg Pamlico Sound). These lagoons are tens of miles wide and separate the islands from the mainland. Along most of the shoreline, a lack of tidal inlets or consolidated headlands means nearshore processes are dominated by wind and wave energy. The lagoons provide a considerable fetch distance for winds to travel unimpeded before arriving on the landward side of the back-barrier shorelines. During Hurricanes Irene (2011) and Dorian (2019), the Outer Banks experienced overwash in some locations. Channel drainage patterns and other qualitative observations suggest the flood waters were flowing from Pamlico Sound into the Atlantic Ocean. This is the opposite of traditional conceptual models of overwash, wherein storm surge and waves erode the foredune to provide an outlet for ocean water to flow landward. Both Irene and Dorian followed similar tracks to the west of the barrier islands, which led to multiple days of onshore flow followed by a sudden shift in winds over Pamlico Sound. Water levels on the landward side of the Sound were already high due to heavy rains and onshore winds. As the storms moved to the north and northeast, the winds shifted and rapidly drained the mainland shorelines. Because there are only a handful of tidal inlets over >100 km of shoreline along the Outer Banks, water levels increased on the back barrier of the Outer Banks and eventually led to seaward drainage of the flood.

Prevailing conceptual models of barrier island evolution today suggest overwash is an important element in sea level rise adaptation; transporting sand from the beachface to the back barrier allows the island to move landward with a transgression. However, observations following Irene and Dorian suggest sound-side overwash is not exceedingly rare along the Outer Banks – these two overwash events were separated by only eight years and both occurred following Category 1 storms. So, incorporating this possibility into our conceptual models of barrier island response to sea level changes is a useful endeavor if we wish to accurately predict the islands’ response to sea level rise this century.

Presenter Bio: Dr. Barrineau serves as a coastal scientist and project manager for CSE, performing work in the field, laboratory, and office. He holds a BA from Auburn University, an MS from the University of South Carolina, and a PhD from Texas A&M University. Dr. Barrineau studies coastal processes and landforms through field-based research on sediment transport and barrier-lagoon evolution. He has organized and led field studies in South Carolina, Texas, New Mexico, California, Brazil, and Israel. In addition to his work at CSE, Dr. Barrineau teaches a graduate-level course in Coastal Zone Management at the University of South Carolina.

 

Elucidating Factors of Variable Marsh Accretion Rates in South Slough Estuary, OR

Madison Bowe, South Slough National Estuary Research Reserve

Tidal marshes, which provide valuable ecosystem services including carbon sequestration and flood protection, are being threatened by sea level rise induced by climate change. A principal predictor of whether a marsh will survive this phenomenon is its accretion rate, a parameter for which marsh Sentinel Sites in South Slough National Estuarine Research Reserve (South Slough NERR) show significant variability. Current and historic accretion rates were measured in six Sentinel Site marshes using marker horizon cores (feldspar and cesium-137). Current rates were compared with marsh elevation, location along the salinity gradient, species richness, historical diking, sediment deposition and organic content, mean inundation period, and marsh area-to-edge ratio and distance across adjacent mudflat. Historic accretion rates, though generally higher, showed the same approximate trend as current rates. Sediment deposition, organic content of sediment, inundation period, area-to-edge ratio and mudflat size did not show high correlation with accretion rate. Location along the salinity gradient was excluded due to limited sample size. Marsh elevation and species richness are both negatively correlated with current accretion rates in a final ridge regression model with R2=0.7934. Historical diking or lack thereof may help explain elevation variation within South Slough. This work leverages the NERR system’s Sentinel Site Program, which is important for providing information to coastal and resource managers as coastal communities face increased pressure from sea level rise.

Presenter Bio: Madison is a senior studying Environmental Biology at the SUNY College of Environmental Science and Forestry. As a NOAA Hollings scholar in summer of 2019, she studied marsh accretion rates in South Slough Estuary, OR. She is currently working on a senior thesis, using demethylation drugs to study male gametophyte development in Wollemi pine. After obtaining her Bachelor’s she plans to thru-hike the Appalachian Trail before attending graduate school to study plant ecology.

 

The Spatiotemporal Evolution of the Mid to Lower Shoreface, Grand Strand region, SC.

Christina Boyce, Coastal Carolina University

A four-year time-series of high resolution multibeam surveys has documented the behavior of the shoreface-to-shelf transition zone in northeastern South Carolina during a period of unusually frequent large storm events. The character of modification of the lower shoreface varies along the coast and has continuously highlighted rhythmic cuspate features with wavelengths of 50-200 meters found throughout the Grand Strand region. These features appear to align with stratigraphic boundaries within the geologic framework and have little to no moment over time. A textural component within the features was noted by backscatter imagery and may provide a mechanism to be a self-maintained feedback system, possibly contributing to the growth of transverse bedforms on the nearby shelf (Murray and Thieler,2004).  These features within the geological framework are being exhumed and serving as a significant source of sediment to the modern beach environment in an otherwise sediment-starved system. This sediment source may challenge some definitions of “closure” on the interannual to decadal scales. With an increase in large storm events in the Grand Strand Region, the inter-annual behavior of the shoreface to shelf transition zone may become more apparent and provide insight into cross-shore exchange of sediment that might typically only be active on decadal scales.

Presenter Bio: Christina is currently attending Coastal Carolina University where she  is working towards her Master’s degree in Coastal Marine and Wetland Studies. Her primary focus is looking at inter-annual to decadal scales of nearshore processes using geophysical methods. Christina received her BS in Geology from Lake Superior State University and plans to further her education after her time at Coastal.

 

Tools and Technology of the USACE National Regional Sediment Management Program

Brandon Boyd, US Army Engineer Research and Development Center

The National Regional Sediment (RSM) Program assists in identifying sustainable, cost-effective, environmentally acceptable solutions for managing sediments. The first phase in the RSM process is to develop an understanding of the region. Key tools and technologies to understand the region include regional sediment budgets as well as application of regional hydrodynamic, hydrologic, sediment transport, and ecological numerical models. Utilizing Geographic Information System (GIS) capabilities, enterprise databases, and web-based visualization tools greatly enhances the ability to understand and share information on regional scales. Relationships with stakeholders and partners as well as documentation of best practices are non-traditional tools that are also essential for implementing RSM practices. We present an overview of the coastal-focused tools and technology of RSM and the goals they support. These goals include keeping sediment in the littoral system, reducing problematic sedimentation, mimicking natural sediment processes, environmental enhancement, and protecting infrastructure. Recent cases where these RSM tools were use are also presented.

Presenter Bio: Dr. Brandon Boyd’s research is focused on better describing wetland and estuarine processes and the feedbacks between those processes and navigation and restoration efforts. Dr. Boyd also serves as the Coastal Deputy Program Manager for the Regional Sediment Management Program along with Dr. Katherine Brutsché, Program Manager, and David May, Inland Deputy Program Manager.

 

Drivers of nutrient and sediment loading vary in coastal sub-watersheds

Andrew Brainard, Ramboll

Nutrient and sediment loading from coastal sub-watersheds can reveal patterns of anthropogenic drivers of near shore coastal zone pollution, particularly as these sub-watersheds are highly populated and altered through various land use changes. Increased developed and agricultural land uses have been demonstrated to result in greater nutrient and sediment export from watersheds, in addition to the length of a watersheds stream network that runs through these land use types. I modeled nutrient and sediment export rates, using a web-based application of GWLF-E, in near shore coastal sub-watersheds of Long Island Sound (n = 19), Delaware Bay (n = 13), and Chesapeake Bay (n = 41) to determine if different watershed land uses and stream networks were correlated with increased nutrient (total nitrogen, total phosphorus) and sediment export rates. Across all sub-watersheds from each of the coastal zones, decreased total phosphorus was correlated with increased length of stream networks in non-agricultural settings; total nitrogen and sediment loading rates were not significantly correlated with developed or agricultural land use. This pattern of significantly decreased total phosphorus export rates in sub-watersheds with greater stream length in a non-agricultural setting was observed for Chesapeake Bay sub-watersheds. For Long Island Sound sub-watersheds, increased total phosphorus and nitrogen were significantly correlated with increased developed land use, while in Delaware Bay sub-watersheds increased total phosphorus and nitrogen increased significantly with greater agricultural land use. Documenting specific land use practices and landscape conditions that contribute to increased nutrient and sediment loading rates in near shore sub-watersheds can provide resource managers and planners insight into how best to reduce future coastal pollution through targeted restoration and management.

Presenter Bio: Dr. Brainard is project scientist in the Environment & Health practice at Ramboll, and has authored multiple publications in the field of aquatic ecology and water resource related issues, including watershed and landscape influences on water quality, aquatic invasive species, and Harmful Algal Blooms (HABs). He received his doctorate in Ecology from the SUNY College of Environmental Science and Forestry (SUNY ESF) in 2018.

 

Post-Hurricane Michael Damage Assessment Using ADCIRC Storm Surge Hindcast, Image Classification, and LiDAR

Ty Briggs, Florida Atlantic University

Remote sensing data collected in the aftermath of a disaster can play a vital role in identifying badly damaged areas where homes and infrastructure have been destroyed, prioritizing emergency assistance needs, locating survivors, and providing restoration guidance. In this study, we use NOAA’s National Geodetic Survey Emergency Response Imagery database, LIDAR, and tax appraiser data to assess storm damage after Hurricane Michael in Mexico Beach, FL. Post-Michael imagery was classified as debris, roofs, vegetation, sand, roads, and water. Pre-storm LiDAR-derived building footprints in the impacted area were overlaid on the reclassified post-storm imagery to quantify the extent of structural damage to residential areas. The extent of the damage was also examined using maximum wave height and depth of storm surge inundation derived from the output of the ADCIRC modeling system. Over 700 buildings were classified as considerably damaged or completely destroyed. The 2017 tax appraiser data were used to estimate the economic value of the storm impact. Results of this study may help in reconsidering existing building code requirements to protect people and property and reduce future storm damages.

Presenter Bio: Ty was born and raised in the United States Virgin Islands and moved to Florida as a teenager to explore the many opportunities available here in the contiguous United States. In his spare time Ty is an avid angler and enjoys volunteering.

 

Spatial Variability of Sediment on a Nourished and Non-Nourished Beach in Southeast Florida

Nicholas Brown, Florida Atlantic University

Sediment placement on Florida’s beaches is a common strategy for increasing storm resilience, providing habitat, and supporting the tourist economy. Sediment borrow sites include inlets (typically for navigational maintenance), offshore, and upland mines. State regulations require that sediment closely match the native grain size distribution and composition. However, sediment characteristics can vary alongshore, cross-shore, and with depth. The objective of this study is to quantify sediment properties on a frequently nourished barrier island beach and an adjacent non-nourished beach, located south of the Jupiter Inlet, in Palm Beach County, Florida. Six transects were sampled at the surface and at 75 cm depth at the dune toe, mid-beach, and mean high water line. Sediment samples were analyzed for Munsell color, bulk grain size distribution and statistics (using the Moment Method), percent carbonate, and non-carbonate grain size distribution and statistics. The mineralogy of both the bulk and non-carbonate fraction were evaluated with a standard binocular microscope. The 3D spatial variability of sediment characteristics on the nourished and non-nourished beach will be presented and discussed, including influence of inlet proximity and selective transport patterns. Results of this study should provide information on the spatiotemporal variability of sediment placed on beaches and help determine best management practices for coastal projects.

Presenter Bio: Nick is a Ph.D. student in Dr. Tiffany Roberts Briggs’ Coastal Studied Lab at Florida Atlantic University in Boca Raton studying coastal geomorphology and sedimentology. Nick’s undergraduate degree is a B.S. in Geology from Grand Valley State University in Allendale, Michigan where his researched was primarily focused on biogeochemistry.

 

A collaborative effort with a diverse group of stakeholders to cooperatively address coastal storm risks.

Pamela Castens, US Army Corps of Engineers

The U.S. Army Corps of Engineers (Corps) has initiated the first stages of study coordination and collaboration on the South Atlantic Coastal Study (SACS). The SACS was authorized by Section 1204 of the Water Resources Development Act (WRDA) of 2016 to proactively address coastal storm risks of vulnerable coastal populations, infrastructure, ecosystems, and economies within the Corps’ South Atlantic Division (SAD). The study includes tidally influenced shorelines subject to damages from coastal storms and sea level rise within North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, Puerto Rico, and the U.S. Virgin Islands. The study will conduct regional analyses of coastal risk throughout SAD and identify measures to address vulnerabilities, which are a combination of infrastructure/population, environmental and cultural resources, and social vulnerability. Coastal risk reduction is a responsibility shared by all stakeholders including coastal communities, local and state governments, tribes, Federal agencies, and others.  This study, with stakeholder input, will allow for the development of a long-term strategy to address increased hurricane/storm damage to vulnerable resources resulting from sea-level rise and identify opportunities to enhance resiliency and lower risks.

Presenter Bio: Ms. Castens is currently a senior Project Manager with the US Army Corps of Engineers Wilmington District.  She has over 29 years of professional project management, planning, and environmental compliance experience spanning multiple Federal agencies as well as the private sector.  Formerly Chief of South Coast Section (Planning Division) in Los Angeles District, she has a wealth of experience in plan formulation and execution of planning, design and construction of coastal projects spanning the deep draft navigation, coastal storm damage reduction, and ecosystem restoration mission areas.  Now with the Wilmington District, her accomplishments include legacy study program closeout, deep draft navigation program management, Quality Assurance environmental review, and oversight of the Hurricane Sandy Agency Technical Review program for North Atlantic Division; she is currently functioning as regional project manager for the South Atlantic Coastal Study on behalf of the Corps’ South Atlantic Division.  Accredited as a Project Management Professional by the Project Management Institute since 2012, her education includes a BA in Physical Geography from Bucknell University in Lewisburg, PA, and a Masters’ degree in Coastal Geomorphology from the University of California, Los Angeles.

 

Reconstructing a Centennial-scale History of Extreme Floods using Oxbow Lake Sediments of the Pee Dee River, SC

Nicholas Conway, Coastal Carolina University

Extreme river floods are the key force shaping floodplain landscape and a major process delivering sediment, pollutants, and nutrients to coasts. These devastating natural hazards pose concerns about potential change of extreme flood occurrence in the face of climate change. However, accurately assessing the impact of anthropogenic climate change and natural climate modes on the intensity and frequency of extreme flooding relies on multi-century discharge records. Unfortunately, instrumental records are relatively short (often <100 years) and overlap with times of dam and reservoir construction. Oxbow lakes, ubiquitous in the floodplains of alluvial rivers, may preserve an archive of extreme flood at centennial timescales as they capture coarser channel sediments transported by intensified river flows. This study aims to identify signals of extreme floods in oxbow lake sediments and establish a timeline of past flooding events to evaluate possible change(s) in flood hazard near the Pee Dee River (PDR), South Carolina.

Laser diffraction grain-size analysis and X-ray computed tomography (CT) scanning were performed on a a 2-m long piston core (SBL2) to identify event layers of extreme floods. CT images reveal high-density laminations and corresponding coarser shifts of grain size are interpreted as flood event layers. A robust age-depth model was established for SBL2 using multiple independent age controls (14C, optically stimulated luminescence, 210Pb/137Cs, and historical event tie-points). End-member modelling analysis was performed to identify a coarse component of the grain-size data used as a proxy of extreme flood. A linear relationship between end-member modelling results and measured discharge was established for the last ~80 years and applied to the older part of the core yielding peak discharge estimates back to ca. AD 1800.

Our analysis identifies abrupt shifts in grain-size resulting from dam construction, droughts, and local geomorphic changes to the river system. Preliminary interpretations reveal that inter-decadal and multi-decadal trends in the frequency of extreme floods may be present in the PDR system, likely controlled by climate mode variability. Overall, peak annual discharges of the PDR seem to have decreased through time since flood control damming was completed in AD 1962. Further flood frequency analysis of this dataset may lead to an understanding of the effects of climate change and natural variability on extreme flooding in this region.

Presenter Bio: I am a second year graduate student pursuing a master’s degree in Coastal Marine & Wetland Studies at Coastal Carolina University. My key research interests are in fluvial sedimentology, paleoflood hydrology, coastal plain geomorphology, and paleoclimate. I am interested in the climate phenomena that drive extreme storms and there impacts on coastal communities and shorelines.

 

Influences of flooding and sediment on Loggerhead sea turtle reproduction success

Ali Courtemanche, Florida Atlantic University

The beaches of the east coast of Florida are critical nesting habitat for the Northwestern Atlantic loggerhead sea turtle (Caretta caretta) population. Palm Beach County experiences some of the highest nesting densities in the state. Boca Raton is located within Palm Beach County and encompasses 4.8 miles of beach classified as a medium density beach due to coastal urbanization. One mile of beach was selected for a spatially dense investigation of the role of morphology, flooding, and sediment characteristics on the nesting, hatching, and emergence success of loggerhead sea turtles during the 2019 nesting season. Flood pipes were installed across seven cross-shore transects between the foredune and mean high water line (upper foreshore). Sediment samples at each pipe were taken at the surface, 45 cm depth, and 80 cm depth in May and July of 2019, with the latter two intended to represent average nest depths. Nesting, hatching, and emergent success of the loggerheads within ~60 m of each transect were compared to temporal variability of sediment composition during the incubation duration. Success was also evaluated with morphology trends cross-shore and alongshore. During the study period, Hurricane Dorian washed out 128 sea turtle nests of the 446 remaining nests on Boca Raton’s beach, 14 of which were loggerhead nests within the transect region. Understanding the role of sediment variability with nesting, hatching, and emergent success has potential implications for other abiotic factors known to affect the initial nest site selection, incubation, and emergent processes associated with sea turtle reproduction.

Presenter Bio: Ali Courtemanche is a graduate student in the Environmental Science Program at Florida Atlantic University. She earned her Bachelor of Science degree in Biology at Florida Atlantic University in Spring 2014. She is currently employed at Gumbo Limbo Nature Center as a Marine Turtle Specialist and at Florida Atlantic University as a teaching assistant.

 

The impact of physical and mineralogical properties of intertidal sands and resultant microbial ecology on the use and modification of land derived substances

Kaitlin Dick, Coastal Carolina Univeristy

The impact of physical and mineralogical properties of intertidal sands and resultant microbial ecology on the use and modification of land derived substances

Kaitlin L. Dick1, and Angelos K. Hannides2

(1)          Department of Coastal and Marine System Science and (2) Department of Marine Science

School of the Coastal Environment, Coastal Carolina University

Beaches are an economic and ecological resource with immeasurable value to coastal communities around the world. Among the many ecological services it provides, sand at the coastal intertidal zone acts as a filter between the land and the ocean, trapping dissolved and particulate substances which microorganisms can use and modify. Sand particles also provide a medium on and in which microbes can live and utilize dissolved and particulate substances. Grain size properties, mineralogy, porosity, and permeability of these sands influence how the filtration system of the beaches acts through the exchange of chemicals between the sand and water column and the microbial ecology and function of the beach.

This raises the question: what are the geophysical controls on the biogeochemical engine of the sandy beach environment, especially in relation to the overall microbial abundance and transformation of substances? My thesis work focuses on the partnership of space and the organism, that is, the relationship between the physical and mineralogic composition of beach sediment and the microbial growth and productivity.

I plan on testing beach sites in Long Bay, South and North Carolina, for geophysical features including permeability, porosity, grain size, mineralogic composition and microbial aspects including microbial abundance, activity and uptake. I then plan on examining the relationship between the sand and the microbial ecology to better understand this association.

I hypothesize that there will be a measurable, statistically significant difference between the sands of different silicate and carbonate ratios along Long Shore Bay. Furthermore, based on physiologic properties of carbonate sands, i.e. cracks, fissures, pits and other surface abnormalities, the resulting increased surface area will provide more surface area for microbes to grow. This would lead to the increase in microbial abundance, activity and uptake and ultimately cycling within the biogeochemical engine of the sandy beach environment.

Rapid changes in the physiochemical properties of beach sand, such as a nourishment project, will affect the microbial function within the sand. I, therefore, plan to apply my findings on the interplay between geophysical characteristics and microbial ecology on a beach both before and after a nourishment project and examine how the beach microbiology changes through this event. While it is recommended that borrow sites should have sand of similar grain size composition to that of the native sands, the other properties dictated by sand grains may not be measured or controlled, and they may result in substantial shifts in microbial function.

In summary, my research will result in a better understanding of what happens after a beach nourishment project in regards to the microbial ecology and subsequent biogeochemical engine of the beach sediment. It will add to the growing body of knowledge regarding the beaches of Long Bay.

Presenter Bio: Kaitlin Dick is a graduate student at Coastal Carolina University studying under the direction of Dr. Angelos K. Hannides.

 

Numerical Modeling and Field Study to Determine Capacity of Vegetated Coasts for Flood Prevention and Erosion Protection

Yan Ding, U.S. Army Corps of Engineer Engineer Research & Development Center, Coastal & Hydraulics Lab

Vegetation in coasts, marsh, and wetland provides storm protection benefit by attenuating wave energy, reducing wave setup/runup and inundation due to waves and surges. Wave attenuation effect has been studied in terms of field observation and numerical simulation modeling.  However, high-energy waves and surge currents during storms possibly cause erosion on shoreline and retreat of marsh edge, and damage vegetation. It is lacking of observation data on storm damage among vegetation and methodology for quantifying ability of vegetation and marsh to recover from storm. To understand benefits of vegetation and marsh on coastal protection, it is necessary not only to quantify wave energy dissipation due to vegetation species, but also to evaluate capability of vegetation resistance against dynamic forcing by wave and current. In this study, we implement new capabilities into an existing USACE coastal process model, CSHORE, to simulate wave attenuation, setup, and runup change in vegetated coasts. The new capabilities on assessment of vegetation benefits has been validated by using laboratory data and field observation in the south Louisiana coast and the north shore of Chesapeake Bay. In addition, through field observation in the south Louisiana coast, we have continued on collecting the data on vegetation property changes, marsh edge retreat, and wave conditions. The correlation between vegetation damage due marsh erosion and wave energy has been studied.  This relationship enables to develop a new process model to predict temporal variation of vegetation benefits by considering seasonal changes of vegetation properties.

Presenter Bio: Yan Ding is Research Civil Engineer in the Coastal and Hydraulics Laboratory, U.S. Army Engineer Research & Development Center, Vicksburg, MS. His expertise lies on hydraulics and river dynamics, wave dynamics, sediment transport, integrated coastal process modeling, storm-surge modeling, dam-break flow modeling, and numerical simulation.

 

Estuarine shoreline erosion driven by flood channel proximity at Pea Island, NC

Michael Dunn, North Carolina State University

Tidal inlet channels are complex geographical systems that are constantly adjusting to their surrounding environment, primarily in response to human activities and climatic conditions. When a channel is in proximity to a barrier island shoreline, accelerated erosion in localized areas is likely to occur threatening infrastructure on the island. Despite extensive studies done along the barrier islands of the Outer Banks, the interactions between the southernmost tidal inlet channel at Oregon Inlet, storm forcings and estuarine shoreline erosion of the immediately adjacent Pea Island have not been studied in detail. The aim of this project is to develop theoretical and applied knowledge of the processes driving estuarine shoreline erosion at Pea Island. Aerial photography from 2003-2019, bathymetric survey data and measured wave, wind and water level data were used to investigate changes in the estuarine shoreline and establish the interaction with the nearby tidal inlet channel. Results indicated that there were approximately 70 meters of estuarine erosion as well as 320 meters of channel migration with the orientation and depth of the channel directly intersecting the section of shoreline with maximal erosion. These findings demonstrate a relationship between tidal inlet channel orientation and increased shoreline erosion. The results will be used in a broader coastal monitoring program investigating the vulnerabilities along the NC 12 highway. A compilation of these findings will be provided to NCDOT for proper mitigation techniques to be employed where necessary and to support transportation planning along the NC 12 corridor.

Presenter Bio: Michael Dunn is a soon to be graduate from North Carolina State University, where he will be receiving his B.S. in Civil Engineering. His research experience is primarily focused on geospatial analysis of the  barrier islands of North Carolina and investigation of accelerated estuarine shoreline erosion at Pea Island, NC.

 

Arctic Coastal Erosion: Coupled Modeling System for Coastal Hazards Evaluation

Chris Flanary, Integral Consulting Inc.

Permafrost coastline, present along Alaska’s North Slope, comprises 34% of the world’s coastlines and is rapidly eroding due to heightened wave activity and increased temperatures. For example, erosion of the permafrost coastline around Drew Point, AK can exceed 10 m/year and is expected to increase. However, existing tools for predicting coastal erosion were developed for temperate areas and noncohesive sediments, which is not applicabile for permafrost coastlines. Integral Consulting has teamed with Sandia National Laboratories, the U.S. Geological Survey, University of Alaska Fairbanks, and University of Texas at Austin to develop monitoring and modeling tools to accurately predict Arctic coastal erosion. Integral led the development of a coupled oceanographic modeling system for arctic erosion that will integrate with a terrestrial processes model. These modeling tools allow for the accurate prediction of permanent coastal land loss that is important to evaluating adaptation strategies for Arctic infrastructure.

Characterization of discrete coastal erosion events, occurring during storm conditions, requires high temporal fidelity predictions of hydrodynamic and wave parameters along the Alaskan coast through the application of site specific numerical models. To evaluate coastal erosion, a three-model system was developed to simulate nearshore conditions around Drew Point on the North Slope of Alaska. Two spectral wave models, WAVEWATCH III (WW3) and Simulating Waves Nearshore (SWAN), provide wave field information at varying spatial and temporal resolutions in the region of interest. The third is a hydrodynamic model, Delft3D-FLOW, used to simulate nearshore circulation including water level, currents, and temperature in the region of interest. The coupled WW3, SWAN, and DELFT3D models incorporate atmospheric and hydrodynamic factors such as sea ice coverage, winds, currents, and regional water levels to predict relevant parameters such as water levels and wave heights along the region of interest. In addition, multiple atmospheric reanalysis data were used to force the WW3 simulations and the results were compared with measured wave height data within the Beaufort Sea to evaluate the effect of climate change on ocean conditions. This provided an assessment of model performance for Arctic Ocean WW3 simulations using multiple reanalysis datasets. Overall, the ERAI-WRF and ASR atmospheric reanalysis data sets best predicted significant wave height and peak wave period at the selected measurement locations relative to the other reanalysis data used.

The coupled model with the inclusion of atmospheric reanalysis data was used to evaluate coastal erosion around Drew Point. The predicted water level and significant wave height were combined to compute the dynamic pressure forces due to waves at varying heights along a vertical coastal structures, representative of the bluff face, to evaluate erosion potential. These modeling tools allow for characterization of permafrost coastline erosion due to discrete wave events.  Accurate prediction of Arctic coastal erosion rates will allow for better prediction of coastal hazards, thereby informing management decisions for communities and infrastructure that are built on the permafrost. These innovative tools can be applied to the assessment of coastal hazards worldwide in an effort to protect communities and infrastructure.

Presenter Bio: Dr. Chris Flanary is a physical oceanographer with more than 10 years of experience working with 3-dimensional numerical ocean and coastal models in multiple programming languages and computer architectures. He has 15 years of field experience specializing in oceanographic instrumentation deployments in coastal and open ocean environments. Dr. Flanary has conducted topographic and hydrographic surveys operating RTK-GPS, total station, and side-scan sonar systems and has 20 years of experience as a boat operator and deck hand on larger vessels.

 

Combining beach nourishment with habitat creation: An under-explored opportunity.

Robert Grover, Greenman-Pedersen, Inc.

Smith Point County Park is located on the ocean shoreline of Suffolk County, New York, on the barrier Island known as Fire Island. This County-owned park occupies approximately the easternmost five miles of the island, which terminates at Moriches Inlet, one of seven tidal inlets on the Long Island barrier Island system. Moriches Inlet is an historic ephemeral inlet that was stabilized with stone jetties in the early 1950’s.
The inlet acts as a partial littoral barrier to the net westward littoral transport system, resulting in chronic erosion of the County Park. The inlet is periodically dredged, as part of a Federal navigation project, and the spoil is placed to the west of the inlet. In the early 2000’s, GPI was retained by Suffolk County, in conjunction with CSE, to design an erosion control project using sand dredged from the inlet and placed, more strategically, on the park beaches and dunes. The project was successful, but the combination of sand starvation due to the inlet and a series of coastal storms in the early 2000’s prompted the County to explore other alternatives, preferably avoiding the $10+ million cost of mobilizing an ocean-going dredge.
As with most tidal inlets, Moriches has a complex system of shoals and bars, both inside and outside, known as the ebb tidal and flood tidal deltas. These features sequester enormous quantities of sediment. In the case of the Moriches ebb tidal delta, this sand deposit causes ocean waves refract around the shoals, causing a very localized reversal in the net littoral transport direction. The result is an accumulation of sediment immediately west of the inlet, which is unavailable for down coast transport. This shoal bypass zone, as it is called, formed a large dune field, consisting of up to four rows of high, vegetated dunes. The County’s idea was to mine this deposit for beach nourishment, but the regulatory hurdles were considerable. With some brainstorming, we conceived of a project, consisting of mining the first two rows of dunes, and constructing a series of tidally influenced washover ponds to provide habitat for marine fish and invertebrates, as well as migratory shorebirds, waders and waterfowl. The project was met with rave reviews by wildlife agencies, but mixed reviews by coastal erosion regulators.
Before the project was able to be brought to construction, however, the park, with the rest of the South Shore was hit with Hurricane Irene in 2010. The County was busy formulating a response to the damage from Irene, along with FEMA, when Hurricane Sandy struck in 2012. As a result of Sandy, and an increased pressure to protect endangered Piping Plovers, The Corps of Engineers, in conjunction with the State, County, and GPI, formulated the Fire Island to Moriches Inlet or FIMI project, incorporating many of the elements of our earlier design. Since construction, this area has hosted Piping Plovers and other assorted wildlife.
This can serve as a model for dual-purpose coastal management.

Presenter Bio: Bob Grover is Director of Environmental and Coastal Sciences at GPI, in Babylon, NY, and   a coastal scientist with 47 years experience.  Most of his projects have been located on Long Island, but others have been in Massachusetts, Maryland, and others.  He has served as the coastal expert for Suffolk County, Long Island, on ocean coastal issues for 20 years.

 

Engineering Application of the Beach-fx Model for Carolina Beach in New Hanover County, North Carolina

Alison Grzegorzewski, US Army Corps of Engineers

Carolina Beach, located in New Hanover County in southeastern North Carolina, experienced 21 hurricanes and 29 tropical storms within a 50-mile radius prior to 1964, including the devastating Hurricane Hazel in 1954, a Category 4 storm event.  Since construction of the berm and dune project in 1964, there have been 10 hurricanes and 14 tropical storms that have passed within 50 miles of Carolina Beach, averaging a storm every 2.4 years.  The significant damage resulting from Hurricane Hazel was a key factor in the authorization and construction of the Federal berm and dune project.  In recognition of the need to manage storm risk to Carolina Beach, a partnership was undertaken between the Town of Carolina Beach and the US Army Corps of Engineers to construct a berm and dune project and to provide periodic nourishment.

 

Beach-fx is an event-driven life-cycle model that incorporates risk and uncertainty throughout the modeling process.  Over the project life-cycle, the model estimates shoreline response to a series of historically based storm events applied for each of three USACE sea level change scenarios as required by Engineering Regulation, ER 110-2-8162 (USACE, 2013).   The storms are randomly generated using a Monte Carlo simulation.  The corresponding shoreline evolution includes not only erosion due to the storms, but also allows for storm recovery, post-storm emergency dune and/or shore construction, and planned nourishment events throughout the life of the project.  Risk based damages to structures are estimated based on the shoreline response in combination with pre-determined damage functions for all structure types within the project area.    Uncertainty is incorporated not only within the input data (storm occurrence and intensity, structural parameters, structure and contents valuations, and damage functions), but also in the applied methodologies (probabilistic seasonal storm generation and multiple iteration, life cycle analysis).  Results from the multiple iterations of the life cycle are averaged over a range of possible values.

The predominant driving force for coastal morphology and associated damages within the Beach-fx model is the historically based set of storms that is applied to the life-cycle simulation.  Because the eastern coast of North Carolina is subject to seasonal storms, tropical storms (hurricanes) in the summer months and extratropical storms (Northeasters) in the winter and fall months, the storms dataset for Carolina Beach is made up of both types. These storms were derived from hindcast data obtained from Oceanweather, Inc.  The shoreline of Carolina Beach is influenced predominantly by tropical systems which occur during the summer and fall.  Northeasters during the late fall, winter, and spring do have an effect, but to a lesser degree due to shielding effects of the coastal geography north of the project site. Although hurricanes typically generate larger waves and storm surge, Northeasters also impact the shoreline because of their longer duration and higher frequency of occurrence.

While beaches may recover post-storm, extreme storm events may cause sediment to leave the beach system entirely.  Therefore, a portion of shoreline recession due to intense storms may never fully recover.

Presenter Bio: Alison Sleath Grzegorzewski is a Coastal Engineer at the Wilmington District of the US Army Corps of Engineers.  Prior to joining the Wilmington District, Alison was a Research Hydraulic Engineer at the US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory.  Alison is a graduate of the Massachusetts Institute of Technology; graduate thesis: “Simple Models for Turbulent Wave-Current Bottom Boundary Layer Flow: Theoretical Formulations and Applications” under Dr. Ole Madsen.  Alison is currently a doctoral graduate student in the Coastal and Environmental Hydrodynamics Laboratory at the University of New Orleans studying barrier island morphology under Dr. Ioannis Georgiou.

 

Morphology Change Modeling for Crab Bank, South Carolina Using the Coastal Modeling System (CMS)

Alison Grzegorzewski, US Army Corps of Engineers

The Coastal Modeling System (CMS) is an integrated suite of numerical models for simulating water-surface elevation, current, waves, sediment transport, and morphology change in coastal and inlet applications.  The CMS-Wave model (Lin et al., 2008) simulates wave transformation. The CMS-Flow model (Sanchez et al., 2011) calculates time-dependent water surface elevations, current velocities, sediment transport, and morphology changes.  The models have been developed and are currently supported under the Coastal Inlets Research Program (CIRP) at the U.S. Army Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory (CHL).

The primary objective of this study was to evaluate the potential impacts of increasing the footprint of Crab Bank on the morphology changes within the Crab Bank and Shem Creek entrance areas using coupled CMS-Flow and CMS-Wave models.  The present study employed the use of field data collected during a previous Charleston Harbor numerical modeling study (USACE, 2013), which included nearshore bathymetry, current and wave measurements.  Astronomical tide, measured river flows, and wave data were used to force the CMS-Flow and CMS-Wave models. Morphology changes in the Crab Bank and Shem Creek entrance areas were simulated and investigated for without-project and with-project conditions during two representative weather conditions; one month of active winter conditions (December 2012) and one extreme storm event (Tropical Storm Andrea June 2013).

Located just south of the geographical midpoint of the South Carolina coastline, Charleston Harbor is positioned on a natural tidal estuary formed around the confluence of the Cooper, Ashley, and Wando Rivers.  Charleston Harbor includes approximately 14 square miles of open water.  Crab Bank is an island within the lower Charleston Harbor.  Crab Bank is an important bird habitat area and has been experiencing erosion/changing shorelines over several decades.  Erosion trends for Crab Bank show that the size of the island has been reduced from approximately 23 acres in 2000 to an approximate current size of 0.68 acres (USACE, 2018).

Overtopping is a primary transport mechanism of Crab Bank, and the associated sediment transport to the leeward side of the island has resulted in migration of the island to the north.  Using available Lidar, the northern and leeward migration of Crab Bank was examined by USACE (2018).  Larger erosion rates were indicated in areas that experienced frequent overwash; similarly, lower erosion rates were indicated in areas that did not experience frequent overwash.  The Crab Bank footprint modeled in this study takes into account the past migration patterns of the island and historical sediment transport trends.  Once Crab Bank is elevated with the proposed USACE federal project footprint, the sediment transport dynamics of the island will change with a reduced overwash impact.  However, the Coastal Modeling System showed negligible changes in Shem Creek or at adjacent shorelines as a result of increasing the footprint of Crab Bank at the end of either simulation time period modeled in this study.

Presenter Bio: Alison Sleath Grzegorzewski is a Coastal Engineer at the Wilmington District of the US Army Corps of Engineers.  Prior to joining the Wilmington District, Alison was a Research Hydraulic Engineer at the US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory.  Alison is a graduate of the Massachusetts Institute of Technology; graduate thesis: “Simple Models for Turbulent Wave-Current Bottom Boundary Layer Flow: Theoretical Formulations and Applications” under Dr. Ole Madsen.  Alison is currently a doctoral graduate student in the Coastal and Environmental Hydrodynamics Laboratory at the University of New Orleans studying barrier island morphology under Dr. Ioannis Georgiou.

 

Smith Island,Maryland: Shore Protection Using Headland Control: Design, Construction and Early Performance

Caswell Hardaway, Virginia Institute of Marine Science

Smith Island is part of an archipelago that extends from the north end of Bloodsworth Island to the south end of Tangier Island, approximately 25 nautical miles. These include the main islands of Bloodsworth, South Marsh, Smith, and Tangier. Chesapeake Bay borders the west coasts and Tangier Sound the east coasts of the archipelago. The islands are very low and mostly marsh with cheniers, low elongated uplands, where Smith Island communities of Ewell and Tyllerton were established in the 17th century and the community of Rhodes Point in the 18th century. With sea level rise shoreline recession has proceeded through time with significant land loss particularly along the west coast with fetch exposures of over 30 miles across Chesapeake Bay. Some parts of the island are eroding at over 20 feet/yr.

Recently two extensive shoreline protection projects have been installed along the west coast of Smith Island in order to abate the rapid loss of marsh coast. The first project, along about 20,000 feet of shoreline, on the north coast of Smith Island was installed in 2015. This part of the island is called the Martin National Wildlife Refuge (NWR) which includes about 4,800 acres of mostly wetland habitat and extensive submerged aquatic vegetation (SAV) beds in the creeks and lagoons. The second project was installed in 2016 along about 6,000 feet of shoreline that fronts the island community of Rhodes Point.  Both projects utilized the concept of Headland Control where strategically placed headland breakwaters were installed that allows the adjacent unprotected eroding shorelines to evolve toward a state of dynamic and eventually static equilibrium. Headland Control is a living shoreline approach that involves the use of breakwaters, sand nourishment, and wetland plantings to establish or maintain headland features that will control shore erosion along the project coast.

The Martin NWR project consists of 22 headland breakwaters from 180 to 270 feet in length.  Additionally about 2,280 feet of continuous structure was needed to maintain hydrologic control  across the fragmented landscape and prevent breeching into Lighting Knot Cove.  Another 950 feet of continuous structure was needed to maintain wave sheltering integrity along the distal end of Fishing Point thereby protecting vast expanse of SAV beds.

The Rhodes Point project consist of 19 headland breakwaters ranging from 180 ft to 300 ft in length. This was built along on Hog Neck, a marsh peninsula protecting the community of Rhodes Point that was narrowing to less than 300 feet in some places. With an erosion rate of over 10ft/yr, Rhodes Point would be open to the Chesapeake Bay in less than 20 years.

All material and construction had to be done by and from barge. Where the water was too shallow for breakwater construction by barge a separate barge port was used at the closest deep water access. A sand access path was created along shore to not only supply the rock but to create a protective sand berm alongshore. The rock breakwaters were then built from land.

1. Scott Hardaway, Jr.

Coastal Geologist

VIMS

William & Mary

Gloucester Point, VA 23062

James R. Gunn

President

Coastal Design and Construction, Inc.

Gloucester, VA 23061

Presenter Bio: Mr. Hardaway has maintained a research position with the Virginia Institute of Marine Science, Gloucester Point, Virginia for 40 years where he conducts studies on wave climate analysis, sediment transport processes, coastal plain geology/geomorphology and the long-term effectiveness of breakwaters and beach nourishment for shore protection.  Mr. Hardaway has developed empirical relationships for shoreline parameters in the Chesapeake Bay for breakwater and sill systems and has been involved in the design and implementation of more than 80 shore protection systems  (headland breakwaters and sills, aka Living Shorelines).

 

Revisiting the Delaware Beach Regulatory Building Line

Jesse Hayden, Delaware Department of Natural Resources and Environmental Control

The Delaware coastal regulatory building line was first set in effect in 1979 under the authority of the Delaware Beach Preservation Act. The goal of the building line is to regulate construction occurring along the coastline of Delaware. Construction on beaches and dunes can hinder their ability to undergo natural processes and puts development at greater risk to damage. By establishing a determinate line along the coast to control development, the Delaware Beach Regulatory Building Line has provided protection to the coastal dunes and has ultimately helped preserve the shape and integrity of the beaches allowing them to serve their protective function. The original building line was drawn in 1979 and has not been officially revised statewide. In 2019 a new coastal construction evaluation line was mapped to assess the ever-changing nature of the coast. At a time when sea-level rise is becoming a critical threat to the sustainability of natural resources, protecting and preserving shorelines is crucial. The importance of the beaches lies in many factors such as tourism, public natural resources, and protection to infrastructure from coastal storm damage.

The 1979 regulatory building line was mapped using an offset distance from particular contour elevation lines. The Delaware Beach Preservation Act defines these elevations and distances as follows: Along the Atlantic Ocean coast beaches between the Delaware and Maryland border to the tip of Cape Henlopen, the building line was drawn 100 feet landward of the seaward-most 9-foot elevation contour; along beaches between the tip of Cape Henlopen to Prime Hook Beach, 100 feet landward of the seaward-most 6-foot elevation contour; and along the beaches between Prime Hook Beach to the Old Marina Canal north of Pickering Beach, 75 feet landward of the seaward-most 6-foot elevation contour. Exceptions to these rules call for the line to be drawn at the landward limit of the beach only if it is more seaward than the regulatory elevation and the line is drawn long the landward edge of the boardwalk within corporate limits of Rehoboth and Bethany Beach. Recreating these guides for the new coastal construction evaluation line, the most recent elevation data from 2014 was overlaid on 2017 LiDAR imagery using GIS and through GIS tools, the new line was drawn digitally. The drawing of an updated building line proposes an idea and tells a story of the effects that regulatory changes could have by measuring the amount of buildings and tax parcels moved seaward, landward, or bisected by the building line.

A poster presentation of the building line can visually demonstrate the changes in position of the 2019 line in comparison with the original line from 1979, as well as changes in development during the same period. The poster will also visually communicate the effectiveness of beach nourishment projects that have undergone through the Department of Natural Resources and Environmental Control in areas where beach nourishment has been the primary shoreline management strategy.

Presenter Bio: Stephen Perrin is a senior in the Department of Geography at the University of Delaware. Work on the Revisiting the Delaware Beach Regulatory Building Line project was performed during a summer internship with the Delaware Department of Natural Resources and Environmental Control.

 

A Decision Maker’s Guide to Valuating Coastal Resiliency

Mariah McBride, Coastal Systems Internatioal

As the climate changes and many coastal communities become more acquainted with the binding relationship between sea level rise and erosion rates, local decision makers are becoming progressively responsible for communicating the most advantageous plans of action. A solution that has effectively become known as standard practice for many seaside constituencies is that of beach nourishment, or the replenishment of sand in locations that have become deficient in natural sand source supply. There have been approximately 1.5 billion cubic yards of sand placed on the coastal United States through an accumulation of roughly 400 beach nourishment projects (NOAA, 2018). The sustainability of beach nourishment projects, the practicality of such projects in comparison to those less feasible, the aesthetic appeal of a broader beach, and the net benefit available to local property owners are among the many features that have proven the feasibility of beach nourishment. Yet, it is still imperative in many cases that decision makers aim to effectively communicate and present the cost-benefit of beach nourishment to local communities even when considering its many demonstrated successes. This could be attributed to factors including the sense of uncharted territory felt by communities that have only recently been faced with confronting the effects of beach erosion or the feeling of reluctance amongst community members that are uncertain of the prospective return on investment. Regional administrators who encourage this form of coastal zone management, including those experienced with the outcomes of beach nourishment and those who are not, are continually tasked with generating comprehensive material that accurately communicates the regional benefits of such an endeavor. Quantifying the economic benefits of beach nourishment is a topic that many economists have explored and several models have been accepted into practice. As many local decision-makers are aware of these recognized economic models, the variance between data outcomes based on the model selected for application is a topic less explored. For example, the hedonic model can be utilized to calculate the value of independent variables (ie varying beach widths adjacent to proportional single family homes) against a dependent variable (ie the total market price of each single family home) to determine property value enhancement of a wider beach in real-time. Alternatively, historic data can be adjusted for inflation and used for a comparative model in order to explain the economic implications of beach nourishment in a particular location over a period of time. A cost-benefit analysis model can be applied to rationalize the cost of beach nourishment and may be used as a tool to justify upfront costs. Understanding the variety of messages that can be generated by utilizing these economic models might be essential to effectively communicating the economic benefits associated with beach nourishment based on the values of a particular audience. The purpose of this report is to provide coastal zone managers with a framework that assists in distinguishing the various data outcomes that are accessible through the application of individual economic models and determining which methodology might be most relevant and impactful given the circumstances or ethics of a given audience.

Presenter Bio: Graduated valedictorian from Texas A&M University in 2018 with a Bachelor of Science in Maritime Public Policy and Communication and a double minor in Ocean & Coastal Resources and Geology. Awarded the Student Research Poster Presentation Award at the 2018 ASBPA Conference in Galveston, TX and was selected for the Academic Achievement Award at the 71st Annual Gulf and Caribbean Fisheries Institute Conference (2018) in San Andres, Columbia.

 

Web tools for visualizing and analyzing coastal inundation impacts

John McCombs, Lynker at NOAA Office for Coastal Management

The NOAA Office for Coastal Management has developed multiple tools for visualizing and analyzing coastal flooding and its impacts.  The Sea Level Rise Viewer and Coastal Flood Exposure Mapper are two such tools which allow users to quickly and easily view, interpret, and tell stories related to coastal flooding from a variety of causes.

The NOAA Sea Level Rise Viewer was developed over six years ago and remains a powerful teaching and planning aid that enables communities to visualize potential impacts from sea level rise or coastal flooding. Many NOAA partners and customers are successful in addressing a variety of coastal management issues—public education, resilience planning, and ecosystem restoration, to name a few—when they use the viewer and leverage its underlying data for spatial analysis. Partners and customers value the tool’s ability to communicate the potential impacts of various sea level rise and high tide flooding scenarios. They also value how the spatial data can inform climate-related planning activities.

The Coastal Flood Exposure Mapper is an easy-to-use web-based tool that allows users to create a collection maps that show the people, places, and natural resources exposed to coastal flooding. The maps can be saved, downloaded, or shared to communicate flood exposure and potential impacts. In addition, the tool provides guidance for using these maps to engage community members and stakeholders. The current geography includes the East Coast, West Coast, Gulf of Mexico, and islands in the Pacific and Caribbean.

This poster will highlight the available data sets and scenarios within these tools which can be used by coastal managers, and the coastal community at-large, to become better informed about potential risks and hazards from coastal flooding.

Presenter Bio: John McCombs has been at the NOAA Office for Coastal Management for 16 years as a remote sensing specialist.  He has been involved in producing NOAA’s Coastal Change Analysis Program land cover data, developing the Sea Level Rise Viewer, and is now serving as the Southeast and Caribbean Regional Geospatial Coordinator.

 

Comparing spatial variability of post-nourishment sediment characteristics with loggerhead sea turtle nesting and hatching success

Andrew Medhurst, Florida Atlantic University

Widespread variation of nesting density, nesting success, hatching success, and emergence success of loggerhead sea turtles exists along Florida’s beaches.  Some studies suggest that these variations are influenced by coastal development and anthropogenic activities such as beach nourishment.  Beach nourishment helps maintain habitat, promotes tourism, and provides protection against storms.  These projects place sediment with similar characteristics as the native sand but can still exhibit variability that may impact nesting sea turtles.  This study compares spatial variability of loggerhead sea turtle nesting, hatching, and emergence success with sediment characteristics used in a 2017 nourishment project in Boca Raton, Florida. A total of 53 nests in both nourished and natural areas of the beach from the 2018 nesting season were compared with sediment composition, grain size, and sorting at each nesting site.  Comparisons of nesting data between nourished and natural areas of the beach indicate sedimentary characteristics contribute to increased variability in loggerhead nesting.

Presenter Bio: Andrew Medhurst is graduate student in the Environmental Science program at Florida Atlantic University.  Andrew’s research interests focus on human-environmental interactions in coastal ecosystems and conservation development.  Andrew attended Florida Gulf Coast University and received undergraduate degrees in Biology and Environmental Studies.  He is a Returned United States Peace Corps Volunteer, having served 2 years in the Philippines as a Coastal Resource Management Volunteer.

 

Coastal tourism and its influence on wastewater inputs: anthropogenic transport of nitrogen to a barrier island

Michael O’Driscoll, East Carolina University

Barrier islands are dynamic and sensitive ecosystems that fringe shorelines in many densely populated coastal regions across the globe. They provide a range of important ecosystem services including habitat, flood protection, fisheries, recreational opportunities, and nutrient cycling. Coastal tourism can affect these services by altering the local water and biogeochemical cycles. On barrier islands and in other coastal settings, onsite wastewater disposal is facilitated by sandy soils, however shallow water tables and proximity to vulnerable surface waters increase the risk of contaminant migration to surface waters. This study estimated the influence of coastal tourism on water use, wastewater generation, and nitrogen (N) inputs to a barrier island (Bogue Banks, North Carolina). The island is served entirely by onsite wastewater treatment and a growing number of package treatment plants (PTPs), facilities designed to treat wastewater onsite for small commercial and residential developments. N exports were estimated for a group of seven PTPs that treated wastewater from vacation properties using a range of technologies: extended aeration; sequencing batch reactor; and advanced media filtration. Influent and effluent wastewater samples were collected monthly from February 2014-January 2015 and analyzed for particulate and dissolved N. Increased summer visitation associated with coastal tourism resulted in an increase in water use, wastewater inputs, and PTP N loading to the surficial aquifer. However, extended aeration systems did not have significantly elevated TN loads during the summer months because their treatment efficiency increased. It was estimated that N inputs associated with coastal tourism made up approximately one-half of the annual wastewater N load. Onsite wastewater N loading to the surficial aquifer appeared to be the dominant source of N loading on the island. Water quality data indicated that these N inputs have resulted in increased groundwater nitrate concentrations. Overall, wastewater inputs added approximately 5 cm of groundwater recharge annually to the island. The results suggested that coastal tourism can measurably alter the water and nitrogen cycles of a barrier island by increasing wastewater N loading, groundwater N concentrations, and groundwater recharge.

Presenter Bio: Dr. O’Driscoll is a first-generation college student and a US Navy Veteran. Currently, he is an Associate Professor in the Department of Coastal Studies at East Carolina University and an adjunct faculty member in the Dept. of Geological Sciences and the Nicholas School of the Environment at Duke University. He has earned graduate degrees in Geology, Environmental Pollution Control, and Forest Resources (Penn State University). His research focuses on utilizing tracers and other hydrogeological, geochemical, and geophysical techniques to develop insights into the geological controls and land-use effects on surface water-groundwater interactions and contaminant transport, particularly in nutrient-sensitive coastal watersheds.

 

TEMPERATURE AND SEDIMENT VARIABILITY FOLLOWING BEACH PLACEMENT USING DIFFERENT BORROW SOURCES

Jyothirmayi Palaparthi, Florida Atlantic University

Florida beaches are important economic resources and are also home to thousands of nesting sea turtles every year. Beach-dune systems are periodically restored (beach nourishment) to mitigate erosion, enhance coastal habitat, protect from storms, and attract tourism. We hypothesize that different borrow sources with slight variability in their characteristics could affect temperatures within the placed sediment. Temperatures encountered during egg incubation will determine the gender of the sea turtle hatchlings, but can also exceed a critical threshold resulting in embryonic mortality. This study evaluates the sediment characteristics of three different borrow sources placed on beaches in Jupiter, FL two years after their placement in 2014-2015. Characteristics evaluated include grain size, sorting, color, and carbonate content at two depths (mimicking average sea turtle chamber depths). Sediment sources were from an upland mine, offshore, and a nearby inlet. Differences in sediment characteristics are compared to differences in temperature change at the two depths. The results of this study are important for determining sediment suitability for coastal restoration projects that will continue to promote healthy ecosystems in the face of increasingly warmer summers.

Presenter Bio: I am Jyothirmayi Palaparthi, 1st year PhD student in Florida Atlantic University working with Dr. Tiffany Roberts Briggs. My research includes evaluating the role of post-nourishment sediment properties on temperature and morphology change and the potential influences on sea turtle nesting habitat.

 

Mosaic 3D Mapping of Coral Reefs and Hardbottom Ecosystems: Visualization, Characterization, and Quantification with Permanent, Virtual Data Sets

William Precht, Dial Cordy and Associates, Inc.

3D mapping of coral reef and hardbottom ecosystems provides a unique virtual record of the spatial relationships between habitat complexity and its related biota.  Imagery is collected using digital still photography and ultra-high definition (4K) videography.  Multiple camera arrays can be mounted on dive scooters, ROVs, or AUV platforms depending upon depth, site conditions and project needs.  The camera array is “flown” at a height of 1-2 above the sea bottom in a series of multiple overlapping swaths that cover the entire study site.  Photographic sequences taken over each portion of the reef provide multiple perspectives of most sessile benthic organisms and reef topographic structure   The application of computer algorithms use 100s to 100,000s of these photos, for each site to create a 3D point cloud data that accurately records site topography and position and structure of such organisms.  Point clouds or derived polygonal mesh models can be analyzed as “virtual” models of reef site.  These models can be used to determine detailed dimensions of organisms and abiotic features. Incorporating 3D mapping in reef monitoring improves precision and accuracy of field surveys, while reducing time spent underwater.  2D images created from the 3D data provides an exceptional tool for visual characterization of the reef and its components.  This computer-based approach captures a permanent record with sufficient detail to perform statistically robust desk-top analysis of complex ecological data.  This permanent, “virtual” record also allows the user to employ various ecological integrated methods integrated both on this permanent record to answer hypothesis-driven, project specific questions. Importantly, if the questions change in time – so can the resultant, subsequent analysis without the need to acquire additional data.

Presenter Bio: Since completing his graduate degree from the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, Mr. Precht has specialized in the assessment, monitoring, restoration, and rehabilitation of various coastal resources, especially coral reef, seagrass, and mangrove systems. His contributions to the professional and academic ecological sciences community are nationally and internationally recognized, particularly in regard to historical ecology and the application of ecological principals to coastal restoration. Bill’s work draws upon significant, state-of-the-art research experience in field studies and theoretical analysis.  Mr. Precht has demonstrated success in creating long-term partnerships, team building, and coordinating multidisciplinary scientific programs. Mr. Precht has been a certified SCUBA diver since 1974. To date, he has logged over 4,000 scientific dives with >3,750 of these dives on coral reefs and associated ecosystems.  Mr. Precht also serves as an Adjunct Faculty to Northeastern University’s Three Seas – East/West Marine Biology Program where he teaches a course in coral reef ecology every winter quarter (on-going, annually since 1988). Through this program, Bill has trained many of the world’s premiere coral reef scientists. To date, he has published over 300 peer-reviewed scientific journal articles and abstracts and has presented over 150 invited lectures to universities, professional societies and organizations. In 2006 he completed the first-ever book on coral reef restoration, entitled Coral Reef Restoration Handbook – The Rehabilitation of an Ecosystem under Siege published by CRC Press, Boca Raton, FL. Bill has also been featured in two award winning nationally broadcast documentaries on coral reefs.

 

Intra-storm Erosion Processes on Steep Beaches and Dunes

Jack Puleo, University of Delaware

The largest population centers tend to be located near the coast with 40% of the global population living within 100 km of the shore. Coastal areas are economic gateways for commerce, environments that encourage and support tourism, contain a high level of biodiversity, and support worldwide fisheries. However, coasts are inherently vulnerable to extreme events and increased water levels. The topography and bathymetry of the coast provides protection from extreme event forcing for beaches and the landward infrastructure. The berm and dune are primary elevated features of coastal morphology that dissipate oceanic energy. Extreme event energy dissipation on the beach profile results in sacrificial volume loss through erosion. Volume loss following an extreme event is perhaps most apparent at the dune where calmer oceanic conditions do not have the capacity for natural recovery at that location. Many dune fields along the US coast are unnatural and engineered by state/federal agencies. So, dunes provide the “last line of defense” for landward coastal properties, civil infrastructure, ecosystems, and people against flooding waters. Understanding how berms and dunes evolve under extreme events was identified as a major research need during the Storm Processes and Impacts Workshop; 2018, is necessary for proper management strategy (ASBPA, 2015), and for predictive model development and validation. Few data sets of beach processes collected during an extreme event exist leading to weak scientific and engineering progress.

Our recent work, supported by the US Coastal Research Program aims to collect data during extreme events. We have developed a photocell array (PCA) for identifying the bed level variability during the event and have tested the sensor in bench top tests. The sensor was used to collect berm and dune elevation changes during simulated extreme events in the Large Wave Flume at Oregon State University as part of the DUNE3 project. The project occurred over bare and vegetated dunes to assess the importance of vegetation in mitigating erosion. Field data have also been collected on the Delaware coast during extreme events using other rapidly-deployable sensors. Data streams include water levels, bed levels and fluid velocity at multiple locations on a cross-shore transect. Data from the field efforts showing large velocities (> 3 m/s) and bed level elevation changes (> 0.5 m) will be shown. Preliminary results from the PCA during the DUNE3 study will also be provided.

Presenter Bio: Jack A. Puleo is a Professor and Associate Chair in the Department of Civil and Environmental Engineering at the University of Delaware. He is also the Director of the Center for Applied Coastal Research. He received the B.Sc. degree in oceanography and mathematics from Humboldt State University in 1996, the M.Sc. degree in oceanography from Oregon State University in 1998 and the Ph.D. degree in coastal engineering from the University of Florida in 2004. His primary areas of interest are swash-zone hydrodynamics and sediment transport and remote sensing of the coastal environment. His recent efforts involve intra-storm hydrodynamic and erosion processes and developing low-cost sensors for rapid deployment prior to extreme events.

 

Real-Time Downscaling of ADCIRC Storm Surge Predictions

Carter Rucker, NC State University

During major storm events such as hurricanes, emergency managers rely on fast and accurate forecasting models in order to make important decisions concerning public safety. These models are typically computationally heavy and cannot quickly make predictions at high resolution. However, model output can be post-processed to mimic high resolution results at minimal computational cost. This research proposes methods for improvement in the accuracy of downscaling a real-time storm surge forecasting model. Such improvements to the model include 1) expansion in its spatial applicability, 2) potential accuracy increase using water surface slope extrapolation, and 3) potential accuracy increase using friction loss across the ground surface.

This research builds upon a model which uses maximum water elevation output from the Advanced Circulation (ADCIRC) model and downscales these results to a finer resolution by extrapolating the water levels to a Digital Elevation Model (DEM). The downscaling model was formerly hard-wired to run only in North Carolina using a specific ADCIRC mesh extrapolated to a 50-foot resolution DEM; it is currently used to provide extra guidance to emergency managers and decision makers during hurricanes. This research has expanded upon the applicability of this model by joining with an ADCIRC output visualization tool called Kalpana. The downscaling model is now able to run faster with the same level of accuracy and can run on any mesh using any DEM at any given resolution.

Improvements are also being made to the accuracy of the downscaling model by adding measures of basic physics. The first measure focuses on the slopes of the water levels produced by ADCIRC. The previous downscaling model only extrapolates water levels horizontally, so extrapolating using this water surface slope will produce different results. The second measure focuses on adding friction loss due to variations in the ground surface based on National Land Cover Dataset (NLCD) Manning’s n values. Horizontal extrapolation tends to over-estimate water level extents during flooding, so addition of head loss would theoretically increase the accuracy of the model. If seen fit, both extrapolation by slopes and head loss from friction can be implemented simultaneously to improve the model’s accuracy. If the accuracy of this downscaling model can be improved upon without increasing its run time, this model can be used by emergency managers to provide a better estimation of flooding extents.

Presenter Bio: I am a second-year graduate student at NC State University. I am from Raleigh and grew up going to North Carolina beaches. These beaches have driven my interest toward barrier island dynamics, coastal hazards, and forecasting effects of major storm systems. I received my undergraduate degree from NC State in civil engineering, where I focused my courses in water resources and coastal engineering. Continuing my education with a master’s degree, I am working with Dr. Casey Dietrich to create a model which outputs predictions for high-energy storms. Aside from research, I am in Engineers Without Borders and COPRI (ASCE).

 

Hurricane-induced extreme flood unprecedented over the past 4000 years in the Waccamaw River basin, South Carolina

Zhixiong Shen, Coastal Carolina University

Heavy rainfall and inland flooding are among the major coastal hazards associated with hurricanes. Total local hurricane rainfall is proportional to rate and duration of rainfall while the latter is inversely related to the translation speed of hurricane. A latest study demonstrates that the tropical cyclone translation speed over land area affected by North Atlantic tropical cyclones has been reduced by 20% between 1949-2016 due to global warming (Kossin, 2018), suggesting that local hurricane rainfall is related to global temperature. This idea can be tested by investigating the magnitude of inland flooding due to hurricane during the mid-Holocene when global temperature was the warmest during the preindustrial Holocene. Here we present evidence of extreme mid-Holocene flood from oxbow lake deposits of the Waccamaw River in South Carolina for this purpose.

A vibracore from an oxbow lake near Longs, SC shows several prominent layers of fine to medium sand, interpreted as caused by extreme flood of the Waccamaw River, sandwiched between organic-rich mud. Historical extreme flood of the Waccamaw River is almost unanimously caused by hurricanes and the top few sand layers can be correlated with recent hurricanes, including Matthew and Florence. Therefore, a massive sand layer at 1.27 to 2.57 m depth is interpreted as caused by extreme floods due to hurricanes. Radiocarbon dating constrains the age of this sand to 3898±63 to 4188±98 cal yr BP during the warmest mid-Holocene. Our interpretation suggests that (1) the recent hurricane-induced extreme floods of the Waccamaw River may be unprecedented over the past 4000 years; and (2) the most extreme hurricane-induced floods correlate with warm temperature, supporting the idea that local hurricane rainfall is related to global temperature. This means that recent heavy rainfall and extreme inland flooding due to hurricane can be further intensified by future warming, which can cause profound geomorphic response in coastal floodplain and changes in sedimentation in coastal waters, posing challenges to coastal management.

Presenter Bio: Dr. Zhixiong Shen is a geologist at the Department of Marine Science at Coastal Carolina University. He obtained a BSc degree in Geography from Peking University in China, and a PhD degree in Physical Geography from the University of Liverpool in UK. Dr. Shen worked as a research scientist at Tulane University.

 

Correlating synthetic storm characteristics with morphological changes on a developed barrier island

Scott Spurgeon, University of South Alabama

Coastal communities continue to grow in population and infrastructure development, while the threat from major storms and sea level rise is also increasing. This study focuses on the impacts of several storms on Bay Head, a town located on a developed barrier island in New Jersey. Bay Head features a seawall buried beneath its nourished dunes that helped protect the area during Hurricane Sandy in 2012. Previous research simulated morphological changes due to Hurricane Sandy, but did not consider impacts due to other storms of varying intensity. In this study, the morphodynamic numerical model XBeach was used to simulate the morphological response of Bay Head to several synthetic storms. Leveraging the North Atlantic Coast Comprehensive Study (NACCS) dataset, several hurricanes were extracted based on their maximum wave height to determine a correlation, or if one exists, between maximum wave height and the morphological change. Three storms out of the NACCS dataset with the largest wave heights (7.83 m, 7.49 m, and 7.45 m) were simulated first, and other storms with lower maximum wave heights (6.54 m, 6.04 m, 6.00 m) similar to Hurricane Sandy (6.5 m) were simulated for comparison purposes. By comparing the final cross-shore topographies between storms, the analysis showed that storms with a maximum wave height over 7 m were able to overcome the seawall and resulted in severe impacts on the final height of the nourished dunes that mitigate damage to the structures in Bay Head. Whenever these nourished dunes are overwashed, the structures behind them are exposed to the full force of the storm. In comparison, energy of storms with a maximum wave height similar to Hurricane Sandy was dissipated by the dunes and seawall. These data and simulations of additional storm impacts will be used to calculate the correlation between storm characteristics, such as maximum wave height, and morphological change on the developed barrier island.

Presenter Bio: Scott Spurgeon is an undergraduate mechanical engineering student at the University of South Alabama. Scott moved from his hometown of Denver, Colorado to Mobile, AL about one year ago and has since gained a love for the ocean and coastal communities. After taking a fluid dynamics course with Dr. Stephanie Smallegan last fall, Scott became interested in coastal engineering and the research that she conducts. Scott was awarded a summer undergraduate research fellowship from the University of South Alabama in 2019, and he simulated morphological impacts due to synthetic hurricanes in Bay Head, NJ using XBeach.

 

Coastal Communities Coping with Climate Change: the Deal Island Community Shoreline Restoration and Enhancement Project

Rebecca Swerida, Maryland Department of Natural Resources- CBNERR

Deal Island, Maryland is a small, environmentally and socially vulnerable rural community in Somerset County. Families are closely tied to the local salt marshes and open water habitat as a part of their heritage and fishing and crabbing based livelihood. With an average elevation of only 3 feet above sea level, this area has been stricken with noticeable flooding and erosion issues which are only expected to worsen as sea levels rise. Over the last 100 years, mean sea level in the Chesapeake Bay has risen by 1 ft and by the year 2050 it is predicted to rise up to an additional 2 ft. Roads, property and vital community infrastructure are regularly impacted by flooding.

The Deal Island Peninsula Project was created by the Coastal Zoning and Management program (CZM), Maryland Chesapeake Bay National Estuarine Research Reserve (hereafter: Reserve), University of Maryland, and Deal Island community. The Project brings together residents, watermen, resources managers, local governments and scientists to better understand vulnerability and maintain the community’s cultural heritage.

The Deal Island Community Shoreline Restoration and Enhancement Project was identified as a top priority and funded through DNR’s Community Resilience Grant Program. The project site has lost an extensive dune system and approximately 234 feet of shoreline since the 1970s. Should the shoreline breach, a marsh complex would quickly wash out and directly expose a locally important road to erosion. A 1,200 linear feet dune restoration project with offshore breakwaters will demonstrate how nature-based practices can help address flooding and erosion to protect people, infrastructure, and ecosystems.  The project will prevent a shoreline breach, enhance a marsh migration corridor, restore dune habitat, and enhance shoreline resiliency to coastal storm events and other climate impacts.

In addition to local benefits, the shoreline stabilization project will allow the Reserve system to study and refine shoreline restoration methods. Reserve and CZM staff developed a “Before, After, Control, Impact (BACI) design monitoring framework to be adapted and applied to individual resiliency projects, including the Deal Island Shoreline Project. Pre-construction monitoring is currently underway with plans to monitor the site twice a year for at least 3 years post construction. The goals of the project were identified as 1) erosion control 2) enhancement of marsh integrity 3) conservation of wildlife habitat. In order to understand how well the project supports those goals, the following metrics are being observed: marsh, shoreline and stone structure elevation, vegetation diversity and density, rates of accretion and changes in sediment characteristics. A similar, adjacent shoreline area, not to be impacted by construction, will also be observed as a control site. Community engagement remains a priority for the long term monitoring. A local volunteer base will assist in photo monitoring, vegetation planting and long term maintenance.

Most importantly, the monitoring data will be used to understand how this and similar projects impact specific habitat parameters and may or may not achieve their resiliency goals. The results of monitoring data analysis will be used to improve restoration methodologies. Ideally, all monitoring data and case study information will be made publicly available in a database to be accessed by restoration practitioners.

Presenter Bio: Becky Swerida is the Reserve Biologist for the Chesapeake Bay National Estuarine Research Reserve in Maryland. Her primary research interests are in estuarine ecology and restoration science, specializing in emergent and submerged aquatic vegetation and sediment dynamics. Becky grew up on the New Jersey shore and studied environmental studies, specifically marine and aquatic ecology, and biology at Gettysburg College. Later, she earned a Master’s of Science in the Marine, Estuarine and Environmental Science (MEES) graduate program through the University of Maryland at the Horn Point Laboratory in Cambridge, MD. Before transferring to the CBNERR program, Becky was a part of the Shoreline Conservation Service group within MD DNR working with Living Shorelines and wetland restoration projects.

 

Integration of FILSIM Probabilistic Planning Tool with Physical Depth Damage Functions

Tori Tomiczek, United States Naval Academy

Rising seas and intensifying storms generate shoreline erosion and property damage, threatening the resiliency of coastal communities across the United States and around the globe. Beach nourishment is a well-known coastal engineering solution that both enhances recreation and mitigates storm impacts inland. However, it is important for engineers to identify optimal beach nourishment dimensions and to predict the expected performance of a project so that re-nourishment intervals can be optimized while maintaining a community’s robustness.

FILSIM is a simple probabilistic tool that simulates the evolution of a beach nourishment project over its life-cycle based on analytical solutions and probabilistic Monte Carlo simulations. Inputs to the model include geometric parameters of the fill and means and standard deviations of a region’s expected annual wave climate. The model monitors the evolution of the beach nourishment over its N year design life to determine the number of emergency re-nourishments triggered by erosion of the berm and dune. The tool is being coupled with a simple economics module that leverages a library of depth-damage curves published in the U.S. Army Corps of Engineers’ (USACE) North Atlantic Coast Comprehensive study (NACCS).

The economics module is an efficient module to predict order of magnitude damage estimates due to any storm event that causes erosion beyond the dune into the upland area. Storm surge flooding and wave action may also result due to dune breaching or overtopping. For each row of structures within one block inland of a defined shoreline expanse (termed “reach”), structures of similar archetypes are aggregated into “synthetic structures” based on the 12 building archetypes defined in the NACCS. Based on the erosion extent, inundation depth, and wave crest elevation above a structure’s first floor elevation (FFE), probabilistic damages are predicted to synthetic structures within the bounds of the most likely, minimum, and maximum damage curves presented in NACCS. Damage is then translated from a percentage of the structure to a monetary value based on aggregated economic data found in publicly available databases including county data, the National Structures Inventory (NSI), and common real-estate databases. Consistent with the framework of the FILSIM model, rather than compute parcel-scale damage for each structure in a reach, synthetic structures are assigned a mean and standard deviation of value and damage due to inundation, wave action, and erosion.

The FILSIM and accompanying economics model can be applied as an efficient, first order comparison of alternatives to identify options that maximize benefit and minimize costs and damages. These options may be further investigated in higher resolution hazard and damage models such as Beach-fx. The framework of the coupled FILSIM-economics model is illustrated for an idealized coastal community, and a case study of the model and resulting damage to structures in St. Johns County, FL, USA is shown for two beach nourishment alternatives.

Presenter Bio: Tori Tomiczek is an Assistant Professor at the U.S. Naval Academy. She earned her B.S. at the University of Florida and PhD at the University of Notre Dame. She completed a post-doctoral fellowship at Oregon State University before joining the Ocean Engineering faculty at USNA in 2017. She has participated in field reconnaissance surveys evaluating damage and recovery and has enjoyed working on physical model experiments at USNA, OSU, and Kyoto University. She is interested in better understanding wave-induced forces on coastal structures to inform design guidance and finding sustainable, resilient solutions that mitigate damage due to coastal hazards.

 

Creating Community Conversation to Encourage Resilient Communities

Michelle Vieira, Taylor Engineering

As more coastal communities struggle with the effects of sea level rise, it is imperative that these municipalities identify their level of exposure, focus on vulnerable structures and populations, and then develop strategies to adapt to these changes climate conditions.

This presentation will highlight our work with the Northeast Florida Regional Council (NEFRC) to create a data-driven exposure analysis for the seven counties of Baker, Clay, Duval, Flagler, Nassau, Putnam, and St. Johns that they serve.

The purpose of this work is the creation of community education tools for NEFRC and the counties that they support in order to aid in future resiliency work within coastal communities.  The end result of his work will be the development of ‘community conversations’ and possible ‘resilience road shows’ that are informed by the data analysis that is performed on the region and a Northeast Florida region-wide survey that focuses on climate change, sea level rise, and building resilient communities.

In order to create a foundation for these conversations, we created an Exposure Analysis utilizing data from the 2019 NatureServe and NFWF Coastal Resilience Assessment of the St. John’s River Watershed combined with four FEMA depth grids of varying storm frequency.  This data was then used to inform the creation of a GIS web-based online resilience tool to simulate sea level rise conditions within the focus region while identifying critical infrastructure, vulnerable populations, and vulnerable species.  A region-wide survey was also developed and launched to the entire Northeast Florida focus area to capture present stakeholder levels of education, concern, and engagement.  The results of this survey will be analyzed to inform the ‘community conversations’ at both the local and regional level.

Since stakeholder acceptance and funding opportunities are the most common reasons that projects fail to succeed, creating data-based education tools for communities may be the first step in successful campaigns for resiliency planning and building projects.

Presenter Bio: Ms. Vieira’s graduate education at the University of North Florida emphasized port and harbor engineering, coastal and estuarine hydrodynamics, and water wave mechanics. Her thesis focused on the proposal and prototype of an innovative tidal power generation system.  This graduate work resulted in both U.S. and international patents granted. Upon graduation, she joined Taylor Engineering’s coastal engineering group where she has gained experience with coastal engineering analyses in support of climate adaptation strategies for coastal communities, resilience planning,  shore protection economic benefits, remote sensing, beach nourishment design and permitting, and other issues.

 

FILSIM: A Probabilistic Planning Tool for the Management of Beach Nourishments

Anna Wargula, US Naval Academy

The vulnerability of coastal communities to episodic storms and long-term erosion and sea level rise is closely tied to the temporal evolution of beaches owing to natural processes and management practices. FILSIM is a computational planning-level tool, currently in development, to determine optimal beach re-nourishment intervals based on analytical solutions that minimize costs associated with scheduled and emergency beach fills as well as predict inland damage owing to overland surge and waves during significant storms. The intended application of FILSIM is as a first-level, rapid investigation into multiple scenarios in order to narrow down “best practices” that can be developed further using in-depth models, such as the U.S. Army Corps of Engineers’ (USACE) Beach-fx. This study presents the analytical theory behind the tool, its integration with the USACE Coastal Hazards System (CHS), and a proof-of-concept investigation into the tool’s recommendations.

FILSIM uses analytical equations, probabilistic input, and Monte Carlo simulations to model the temporal evolution of berm-dune-upland beach profiles over a 50-year planning cycle. The simulation begins with initial design fill(s) along one or more reaches of a shoreline, where a reach may be an area with similar berm widths and/or similar inland structural archetypes. Each fill is defined by an alongshore location, project length, and berm width with a mean value and a standard deviation that represents realistic construction variability. Although berm width can vary between reaches, all fills are assumed to have the same equilibrium beach profile, berm elevation, dune elevation and width, and upland elevation, all defined with a mean and standard deviation to capture reasonable variability for the region. Each time the initial beach fill is re-nourished within a simulation or re-established for a new simulation, the fill geometry is somewhat different, depending on the probability distributions of the various parameters.

The model steps through 4 seasonal time steps per year modeling the evolution of the beach owing to natural processes and scheduled/emergency re-nourishments. Natural beach evolution processes include longshore spreading of a fill, background erosion (e.g., owing to longshore transport processes and/or sea level rise), seasonal fluctuations of the berm width owing to storms with less than 1 year return periods, and beach erosion and recovery following large storms (more than 1 year return periods). Storm characteristics can be defined by a mean and standard deviation using local hydrodynamic datasets or by integration with the USACE CHS model outputs of storm characteristics at the site. Whether or not a scheduled or emergency re-nourishment of the beach will take place is determined at the end of each time step, depending on user-defined “failure criteria” of the beach (e.g., the berm has diminished to 10% of its design width), similar to those used in the USACE Beach-fx model.

Records of beach nourishment practices and datasets will be compared with FILSIM model outputs to evaluate the performance of FILSIM as a tool for decision-making. This simple, analytical, and probabilistic approach is anticipated to become a useful tool for guiding sustainable management decisions that enhance resilience in coastal communities.

Presenter Bio: Anna Wargula, Ph.D., is an Assistant Professor of Ocean Engineering at the United States Naval Academy in Annapolis, MD. She holds a Ph.D. in Ocean Engineering from the MIT/WHOI Joint Program. Her current projects include probabilistic modeling of beach fill evolution for operational planning, field observations to determine drivers of estuarine marsh erosion, field and laboratory studies quantifying the role of mangroves in reducing waves and surge, and observations of wave impacts on inlet circulation.

 

Alongshore Spatial Scales of Hypoxia in Long Bay, SC: 2012-2017

Sarah Wessinger, Coastal Carolina University

Seasonal hypoxia (low dissolved oxygen) frequently occurs in summer in Long Bay, South Carolina. Hypoxia is typically observed in enclosed embayments, such as estuaries, where mixing with the open ocean is limited. In an open embayment like Long Bay, physical mixing processes should prevent the development of hypoxia; thus, the occurrence of hypoxia in Long Bay is unexpected. Hypoxia is detrimental to coastal ecosystems by weakening the fauna’s immune systems, growth, and reproduction as well as causing species migration and even mortality. Past studies suggest multiple mechanisms could drive hypoxia in Long Bay, including entrapment of nearshore waters resulting in eutrophication, coastal upwelling, and groundwater discharge. The characteristic scale of these different mechanisms can vary greatly. For example, coastal upwelling is a large-scale shelf-wide process whereas groundwater discharge is likely to be associated with more localized water masses.  The purpose of this study is to examine the spatial scales of hypoxia and its frequency of occurrence over a 5-year period in Long Bay.

Dissolved oxygen (DO) was continuously monitored from 2012-2017 at three piers within central Long Bay: Apache, Second Avenue, and Cherry Grove. The piers are spaced approximately 15 km apart, with Cherry Grove being the northernmost pier and Second Avenue the southernmost pier. Summertime DO concentrations were recorded at each of the piers every 15 minutes and low pass filtered over 24-hour time scales to remove diurnal and semidiurnal variations.  In this study, we define low DO events as DO concentrations below 4 mg/L.  Low DO events were observed 66 times at individual piers over the 5-year time frame. The majority of low DO events were observed at the southernmost pier; whereas the least amount of low DO events were observed at the northernmost pier. Low DO events that occur over one or more piers simultaneously are representative of a low DO episode. Twelve episodes were observed to span two of the three piers (24 events at individual piers), representing an alongshore spatial scale between 13-29 km, whereas eight episodes were observed to span over all three piers (24 individual pier events), representing an alongshore spatial scale larger than 29 km. Eighteen episodes occurred at one pier (18 events), representative of a spatial scale less than 13 km. The finding that the largest number of episodes spans only one pier indicates low DO occurrences are most frequently relatively small in scale. Low DO episodes with larger spatial scales (i.e., multi-pier events) generally occur for longer durations suggesting sustained low DO occurrences are larger-scale and therefore may be related to different driving mechanisms than shorter duration occurrences that are more frequent. The majority of two pier episodes were first observed at Second Avenue pier. This result could suggest that low DO waters originate from the south and are advected to the north; however, time delays between events at adjacent piers suggest advection is unlikely to transport the low DO waters alongshore. Therefore cross-shore advection or local conditions could be more likely to drive multi-pier large-scale occurrences of low DO.

Presenter Bio: Sarah Wessinger is an undergraduate student at Coastal Carolina University (CCU).  She is an SAF and Coastal Research Fellow at CCU under the mentorship of Assoc. Prof. Erin E. Hackett in the Department of Coastal and Marine Systems Science.

 

Improving Predictions of Coastal Flooding via Sub-Mesh Corrections

Johnathan Woodruff, North Carolina State University

To better predict coastal water levels and circulation, especially the extreme water levels caused by hurricanes and other coastal flooding events, the ADvanced CIRCulation (ADCIRC) hydrodynamic model has been developed extensively over the last 30 years. ADCIRC has been used for predictions over large domains, but its accuracy depends on the use of high levels of resolution in its unstructured mesh describing the coastal region.  This high resolution can increase the computational cost and delay the prediction. This study aims to implement sub-mesh-scale correction factors into ADCIRC, which will allow it to decrease the  mesh resolution (and thus its cost) while maintaining the same level of accuracy. These factors are used to represent hydrodynamic features not resolved by the coarsened mesh, thus allowing for predictions of realistic water levels at a fraction of the cost.

A one-dimensional (1D) version of ADCIRC was used to prove that adding correction factors to the governing equations within the model was possible. In question was where changes needed to be made in the shallow water equations, and how the wetting and drying algorithm would need to be adapted to account for the modifications. Also in question was how the altered code would perform, and how different the results would be from an unaltered model run on an identical domain. A simple diurnal tidal signal was used as a boundary condition, run over a plane sloping beach. This was done to analyze the simplest case possible for a hydrodynamic model such as ADCIRC. The result of this numerical experiment was a stable 1D routine with a new wetting and drying algorithm that mimicked the results produced by the traditional ADCIRC model. With what was learned in this initial step, a systematic alteration of the two-dimensional ADCIRC model is underway. Further developments with more complex scenarios are soon to come.

Presenter Bio: Johnathan Woodruff is a second-year Ph.D. student in the Coastal and Computational Hydraulics Team within the Civil, Construction, and Environmental Engineering Department at NC State. He obtained his B.S. degree in Agricultural and Biological Engineering at the University of Florida, and his M.S. in Civil Engineering at Georgia Tech. He specializes in using and enhancing the ADvanced CIRCulation (ADCIRC) hydrodynamic model. Johnathan is currently working on incorporating sub-mesh scale correction factors into ADCIRC to improve the performance and accuracy of the model as part of NSF project “Subgrid-Scale Corrections to Increase the Accuracy and Efficiency of Storm Surge Models”.