Young Coastal Scientists and Engineers Conference – Americas

Young Coastal Scientists and Engineers Conference – Americas

CONFERENCE AGENDA

Dauphin Island Sea Lab, Alabama, USA August 21­23, 2017

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, Alabama, USA, August 21­23, 2017

Arrival: Sunday August 20 Check in AFTER 4PM at Dauphin Island Sea Lab Faculty House #1 (on map: 18.1 ­ Greeters House) Campus map: http://www.disl.org/images/uploads/Facilities_Map_2016.pdf 7:00 pm – Informal gathering under Horizon Hall ______Day 1: Monday, August 21 (All conference talks are held in the Shelby Auditorium)

8:00 am – Continental breakfast in Auditorium Atrium

8:30 am – Opening remarks Kelly Dorgan, Dauphin Island Sea Lab Allison Penko, U.S. Naval Research Laboratory Meg Palmsten, U.S. Naval Research Laboratory

8:50 am – Keynote Lecture Hilary Stockdon, U.S. Geological Survey Today’s Scientists Solving Tomorrow’s Problems

9:30 am – Session 1 – Estuaries and tidal environments Jeff Coogan, Role of wind forcing on estuary length and circulation in a river­dominated, microtidal estuary, Mobile Bay Braulio Juarez, Wind­driven flow in a coastal plain estuary Steven L. Dykstra, Spatial Variability of Tides due to Discharge Gisselle E. Guerra, Saltwater intrusion in a subtropical estuary, as predicted by a Markov­chain model 10:30 am – Break 10:45 am – Session 2 – Estuaries and waves Katherine M. Haynes, Field measurements of boat wake attenuation in coastal salt marshes Jin Young Kim, Retreat of Galveston Bay Wetlands by Wind Induced Waves Aaron Kenny, A Laboratory Study on Mangrove Forest Wave Attenuation for use in Living Shorelines William J. Pringle, Large scale tidal dynamics modelling in the Indian and Western Pacific Ocean Basins 12:00 pm – Lunch at May’s Café and eclipse watching

2 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, Alabama, USA, August 21­23, 2017 2:00 pm – Session 3 – Structures and restoration

Lila J. Lasecki, D’Olive Creek restoration

Caleb Barth, Incorporation of Structural reliability assessment into upgrade and renewal decisions for port and marine structures Justin A. Bartusek, Barbours Cut Dock Expansion & San Jacinto Marsh Restoration Project Victoria Curto, Mobile Bay Bridge storm surge impact analysis 3:00 pm – Break 3:15 pm – Session 4 – Beach nourishment and living shorelines Katie Finegan, Town of Oak Island Feasibility Study: A Case for Combining Beach and Inlet Issues Into an Overall Management Program Brittany E. McMillan, Life cycle cost analyses of beach nourishment on Dauphin Island, AL Joshua Todd, Living Shoreline Demonstration Project – Recent Experience on Design and Construction 4:00 pm – Industry Talk Kevin Frost, Nortek USA, Boston, USA 5:00 pm – Icebreaker, under DISL classrooms 6:30 pm – Shrimp boil at May’s Café and beach party ______Day 2: Tuesday, August 22 8:00 am – Continental breakfast in Auditorium Atrium

8:45 am – Keynote Lecture Stephanie Smallegan, University of South Alabama Engineering the pathway to a resilient barrier island under sea level rise 9:30 am – Session 5 ­ Sediment transport Yeulwoo Kim, An Eulerian three­phase model for sheet flow under breaking waves Meagan E. Wengrove, University of New Hampshire, Do sand ripples matter to larger coastal change? Ryan S. Mieras, Large­scale experimental observations of wave­induced sediment transport over a surf zone sandbar

3 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, Alabama, USA, August 21­23, 2017 Tynon Briggs, Calculating aeolian sediment dynamics relative to varying concentrations of the gravel lag 10:30 am – Break 10:45 am – Session 6 – Sediment transport Tongtong Xu, Exploring the influence of obliquely oriented shoreface­connected ridges on alongshore sediment transport and shoreline change Huidi Liang, Influence of land reclamation projects on sediment transport process of channel­shoal system Munitions Mobility Demetra Cristaudo, Preliminary results of a munition mobility study in the swash Stephanie E. Gilooly, Resolving the Role of the Dynamic Pressure in the Burial, Exposure, Scour, and Mobility of Underwater Munitions 12:00 pm – Lunch at May’s Café 2:00 pm – Professional Development Activity Allison Penko, U.S. Naval Research Laboratory Communicating Science: The Elevator Pitch and Speed Networking 3:15 pm – Session 7 ­ Beach morphology Cody L. Johnson, Morphological Modeling of Low­Dune Barrier System Changes due to Hurricane Forcing Youn­Kyung Song, Numerical Simulation of Ridge Evolution based on Field Data from a Steep Meso­Tidal Engineered Beach Jose C. Tuz­Pech, Impact of a permeable groyne field on littoral transport: an experimental study 4:00 pm – Break 4:15 pm – Session 8 – Coastal geology Robert Hollis, Constraining Holocene evolution of the Petit Bois Island System Nina Schulze, Holocene evolution and sediment provenance of Horn Island, Mississippi Clayton Dike, Late Quarternary paleochannels and deltas along the Mississippi­Alabama shelf 5:00 pm – Industry Talk Doug Shillinger, RBR Limited, Ottawa, Canada 6:00 pm – Dinner at The Estuarium

4 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, Alabama, USA, August 21­23, 2017 ______Day 3: Wednesday, August 23 8:00 am – Continental breakfast in Auditorium Atrium

8:30 am – Keynote Lecture Brian Dzwonkowski, Dauphin Island Sea Lab Impacts of river discharge on the coastal environment: Perspectives from a long­term mooring system in the Mississippi Bight 9:15 am – Session 9 – Waves & Turbulence Liangyi Yue, University of Delaware, A high performance pseudo­spectral solver for turbulent flow Ling Zhu, Louisiana State University, Attenuation of nonlinear waves by rigid vegetation: Comparison of different wave theories Byoungjoon Na, Effect of void fraction to energy dissipation in deep water plunging breaking waves Rafael Mezo­Padilla, Hydrodynamic circulation on the western gulf of mexico using self­organizing maps 10:15 am – Break 10:30 am – Session 10 – Waves Ramy Y. Marmoush, Laboratory experiments of wave energy dissipation and longshore current generation on a sandy beach Dylan Sanderson, Use of a Probabilistic Storm Database in Monte Carlo Lifecycle Modeling Seongho Ahn, Wave energy resource assessments and a preliminary classification for US coastal waters Sarah M. Trimble, New possibilities for predicting and mitigation deadly rip currents 11:30 am – Lunch at May’s Café 1:00 pm – Group photo 1:30 pm – Session 11 – Tsunamis Wei­Liang Chuang, Pressure, force, and fluid velocity distributions due to tsunami bore impact on a simplified coastal building at various headings India Woodruff, Developing a model of the 2013 U.S. East Coast Meteotsunami 2:00 pm – Keynote speaker Scott Douglass – South Coast Engineers

5 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, Alabama, USA, August 21­23, 2017

2:45 pm – Closing remarks Jack Puleo, University of Delaware

3:30 pm – Dauphin Island geomorphology walk

6:00 pm – Dinner at Islanders

THANK YOU to our 2017 sponsors!!

http://www.gldd.com https://rbr­global.com

http://www.nortekusa.com http://www.vtisl.com

https://www.mottmac.com http://www.baird.com

http://www.mbakerintl.com

6 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

ROLE OF WIND FORCING ON ESTUARY LENGTH AND CIRCULATION IN A RIVER-DOMINATED, MICROTIDAL ESTUARY, MOBILE BAY, AL.

Jeff Coogan, University of South Alabama, [email protected] Brian Dzwonkowski, University of South Alabama, [email protected]

Using long-term records (~10 years) of salinity and 300 days of ADCP data, aspects of the estuary length and salinity flux were evaluated in Mobile Bay under a range of river discharge, tidal, and wind conditions. The temporal variability in the salinity structure was represented by 1/7 the estuary length, and showed a strong relationship to river forcing of �� , similar to values reported in San Francisco Bay. In addition, local wind forcing was observed to play a significant 1/7 role in modifying this �� relationship. Estuary length responded asymmetrical to local wind with up-estuary (down-estuary) wind reducing (increasing) salinity intrusion. This system wide response was consistent with local subtidal circulation exchange flow measured by the ADCP. During down-estuary wind conditions the flow was strongly sheared, which would enhance salt intrusion. During up-estuary wind conditions, two-layer flow was reduced (and inhibited under high winds) which would impede exchange and shorten the estuary length. To further explore potential salinity transport changes associated with the wind, a 1D salinity flux was calculated using the ADCP and salinity profile data. The results suggest that the wind forcing is not changing the salt storage within the bay, but instead wind is straining the density field through lengthening and shortening the overall estuary length. These results indicate that in a shallow microtidal system, wind can play a large role in modifying the estuary length and intrusion.

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Wind-driven flow in a coastal plain estuary Braulio Juarez, University of Florida, [email protected] Arnoldo Valle-Levinson, University of Florida, [email protected] Wind is one of the main drivers of estuarine circulation. Despite its importance, wind-induced flows in estuaries have been described essentially with analytical and numerical models, but with limited observational data. The aim of this work is to investigate the lateral structure of wind- induced flow in a coastal plain estuary, the James River, Virginia. Such structure is explored with the first Empirical Orthogonal Function mode derived from month-long moored ADCPs deployed at an estuarine cross-section. Mode 1 explained 60% of the variance and was highly coherent with the wind stress. The lateral structure of mode 1 consisted of upwind flow centered at the channel and at middle depth, and downwind flow over the shoals. Wavelet coherence analysis showed that the wind is highly coherent with mode 1 (coherence > 0.85), especially in the period band between 2 and 4 days. The wind stress and the temporal variation of mode 1 were out of phase by 90 degrees with the wind stress leading mode 1 during all the time series. These results yield the conclusion that the lateral structure described by mode 1 was induced by the wind stress and helps to corroborate analytical and numerical results.

th 4 ​ Young Coastal Scientists and Engineers Conference – Americas ​ Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Spatial Variability of Tides due to Discharge Steven L. Dykstra, Dauphin Island Sea Lab/University of South Alabama, [email protected] Brian Dzwonkowski, University of South Alabama/Dauphin Island Sea Lab, [email protected]

The propagation of tides is important process in estuaries and coastal streams. Water level, velocity and discharge measurements from 20 stations in coastal Alabama are used to show how discharge damps the tide and can force the extent of the tidal regime over 100km seaward. As discharge increases, it first damps the velocity amplitude setting up a convergence with the result of an increased tidal range. As this occurs, the barotropic fluvial force compresses and shortens the tidal wave. The results show standing wave environments transition to progressive waves before dissipating. This occurs because the tidal pulse in the velocity measurements damp first followed by the water level. The result of this transition is a spatially complex coastal environment with large annually changes dependent on freshwater discharge.

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Saltwater intrusion in a subtropical estuary, as predicted by a Markov-chain model.

Gisselle E. Guerra, Department of Civil and Coastal Engineering, University of Florida, Gainesville, FL 32611, USA, [email protected] Miguel Á. Reyes-Merlo, Instituto Interuniversitario de Investigación del Sistema Tierra en Andalucía (IISTA). Universidad de Granada, Avda. del Mediterráneo, s/n, E-18006, Granada, Spain, [email protected] Manuel Diéz-Minguito, Instituto Interuniversitario de Investigación del Sistema Tierra en Andalucía (IISTA). Universidad de Granada, Avda. del Mediterráneo, s/n, E-18006, Granada, Spain, [email protected] Arnoldo Valle-Levinson, Department of Civil and Coastal Engineering, University of Florida, Gainesville, FL 32611, USA, [email protected]

River discharge, tidal elevations and salinity measurements were collected from November 2014 to November 2015 to investigate saltwater intrusion in a subtropical estuary. The limit of saltwater intrusion was defined by the position of the 2 g/kg (X2) isohaline as it changed each tidal cycle. Observations were obtained along the Suwannee River, at the Florida’s Big Bend. The X2 position has been used as a habitat indicator for biological communities because of its relationship with the abundance of species at different trophic levels, and with the freshwater input. Observations were used to construct a first-order autoregressive Markov-chain model, with Monte Carlo simulations, and predict X2. The model relates the X2 position of the previous tidal cycle to the tidally averaged river discharge and tidal elevation. In order to capture the seasonality of the Suwannee River discharge, the analysis was done separately for high and low river discharge regimes. The high discharge regime coincided with the cold season and had a mean flow of 348 m3/s. The low 3 discharge regime overlapped with the warm season and had a mean flow of 165 m /s. The X2 location was influenced by anomalously large river discharge related to El Niño. As expected, saltwater intrusion was inversely related to river discharge. Values of X2 were 0.4 km for a discharge of 383m3/s, and 6 km for a discharge of 168 m3/s. The autoregressive model showed close agreement with observed values and followed the trend of the salinity distribution, which is restricted to the river discharge.

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

FIELD MEASUREMENTS OF BOAT WAKE ATTENUATION IN COASTAL SALT MARSHES Katherine M. Haynes, University of South Alabama, [email protected] Bret M. Webb, University of South Alabama, [email protected]

In many locations along the Gulf Coast, boat wakes are recognized as a contributor to coastal erosion and their impact is of continued concern to property owners. To counteract this, land owners have historically armored their shorelines as a means of protection. Now with increasing attention being given to the negative impacts associated with some forms of shoreline modification, many have begun shifting to the use of living shorelines for protection. Often composed of marsh vegetation and a supporting nature-based feature, living shorelines are a more natural approach to erosion reduction along sheltered shorelines. Though at this time, research regarding the ability of marsh systems to attenuate the energy of boat wakes is lacking. Therefore, our ability to design or restore a marsh with that specific goal in mind is currently in question. This conference presentation will describe the methodology and results of a novel study on boat wake attenuation by coastal marshes. Energy reduction will be measured using wave gauges (N=4) distributed along a transect through established marshes in the micro-tidal estuary of Mobile Bay. Factors such as vegetation species and marsh density will be addressed by repeating the study in multiple locations. The results of this study may be utilized as a component of living shoreline guidance for the area, providing engineers and ecologists with the best available science to determine appropriate marsh widths for the reduction of boat wakes. 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Retreat of Galveston Bay Wetlands by Wind Induced Waves Jin Young Kim, Texas A&M University, [email protected] James Kaihatu, Texas A&M University, [email protected]

Salt marshes are an important ecosystem resource. Marsh vegetation has a significant role in inland protections as a barrier from storm-driven waves. The retreat of the wetlands is mainly caused by wave forces from storm surge, sea level-rise, and human/natural activity. The wetlands of Galveston Bay play a several important ecological roles in protecting and maintaining the health and productivity of the estuary. They also have significant role in inland protections as a barrier from the attenuating waves. However, Galveston Bay salt marshes have been eroding since the 1990s at a rate of 0.3 percent per year. This research predicted retreat rates of the wetlands in Galveston Bay by using hindcast waves in the Delft3D flow + Swan models, and monitoring the response. Influence of the wave propagation to the wetlands is parameterized with wave height - erosion rate relationships derived from a series of laboratory experiments. Model results indicate that wave height trends are similar between simulated and recorded wave data at the offshore side of Galveston Bay by NDBC Buoy. The tide level trends are also matched with the recorded tide gauge. Significant wave height typically did not exceed 0.5m due to the shoaling effect at the wetlands area in the Galveston Bay. The winds caused by passage of cold fronts did not make any notable change to significant wave height but they increased significant wave height about the order of 0.1 m. In addition, it is confirmed that continuous cold front wind decreased the water level throughout the coastal areas of Galveston Bay. Because of the decrease in water depth, submerged area of the wetlands in the Galveston bay will decrease regardless of the tide condition. This physical phenomenon can possibly change the condition of wave-wetlands interaction, and requires further study.

Figure 1: Significant wave height in the Galveston Bay 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

A Laboratory Study on Mangrove Forest Wave Attenuation for use in Living Shorelines

Aaron Kenny, Indian River Lagoon Research Institute at Florida Institute of Technology, [email protected] Robert J. Weaver, [email protected] Abigail Stehno, [email protected] Andrew Sager, asager2013@my .fit.edu

In today’s world, we experience a wide variety of shoreline evolution. Caused by large storm events, seasonal changes, and climate change, shorelines undergo both constructive and destructive forces. Thus, the means to remediate these forces is of extreme importance. The question then lies in the manner of how to counteract these effects. In the Indian River Lagoon (IRL) of Florida’s Space Coast, we are looking into using nature to serve as the shoreline protection measures to protect our delicate shorelines. The use of using living shorelines, such as oyster reefs or mangroves, is being promoted as a means to protect a shoreline instead of hardened structures like seawalls. This study focuses specifically on how mangroves are used as part of stabilizing a shoreline, as well as how mangrove prop roots are able to attenuate different wave conditions. Using a parameterized physical mangrove model, different wave conditions can be tested to better understand how mangrove forests can affect varying site conditions. This research can be used further in the development for site-specific modeling for the implementation of a living shoreline. Simulated and actual live mangroves are tested in the wave flume to determine the effectiveness of using simulated mangroves to predict the effects of a live mangrove fringe on attenuating wave conditions

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

LARGE SCALE TIDAL DYNAMICS MODELLING IN THE INDIAN AND WESTERN PACIFIC OCEAN BASINS William J. Pringle, University of Notre Dame, [email protected] Joannes J. Westerink, University of Notre Dame, [email protected]

In this study we present results from the modelling of the dynamics of tides in the Indian Ocean, Southern Ocean, Western Pacific, and the connected marginal seas using a fully hydrodynamic unstructured grid finite-element based model (Fig. 1 shows study area). The study falls within a project concerned with the development of a comprehensive high resolution circulation model driven by tides, winds, and wind waves for the region. We aim to advance wave, surge and current forecasting abilities so that wave and circulation models are on par with recently developed capabilities in US waters. In general, data-assimilation based on satellite altimetry is required to obtain global deep water solutions within 1 cm for the M2 tidal wave. Here, we investigate the accuracy of our high resolution hydrodynamic model solutions in deep water, and more importantly from our aspect, in coastal waters. Parameterizations of internal tide and bottom stress dissipation, grid and bathymetric data resolution, and boundary condition types are varied in order to tests the effects on the solution. We find that the semi-diurnal tide is especially sensitive to boundary conditions in the Southern Ocean, and internal tide dissipation in the Indian Ocean and connected marginal seas. In shallow basins with large tidal energy such as the Yellow Sea the parameterization of bottom stress can be very important. Diurnal tides are less sensitive to our changes in general, but the bottom stress coefficient can be important in certain areas around e.g. the Indonesian seas. The resolution of the grid and bathymetry is mostly locally important in nearshore areas. We formulate a combination of suitable grid resolution (Fig. 1), dissipation parameters and boundary conditions that give us dissipation and energy fluxes close to global data-assimilated models. The resulting solution is also compared with tide gauge measurements in deep and coastal waters. The validated model will be used to model wind-driven circulation and surge events for the regions such as the Yellow Sea, East and South China Seas through to the Arafura Sea, Bay of Bengal, and the Arabian Sea.

Figure 1: Grid resolution and study area 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

D’OLIVE CREEK RESTORATION Lila J. Lasecki, EI, Mott MacDonald, [email protected] Victoria Curto, PE, Mott MacDonald, [email protected]

The purpose of this project is to design a restoration plan for two sections of D’Olive Creek (DAF and DAF-1) in Daphne, AL. D’Olive Creek is in the Lake Forest watershed which deposits into Mobile Bay. Increased rainfall-runoff discharge due to urbanization and extreme rain events has caused a change in the flow regime in the Lake Forest watershed, resulting in degraded streams that are eroding and developing headcuts. The Alabama Geological Survey completed a watershed assessment and found that erosion was occurring at over 1,000 times the natural rates in this watershed. The eroded material is currently being deposited into Mobile Bay. Funding for restoration was provided through the Mobile National Estuary Program, the National Fish and Wildlife Federation, and the BP settlement. The design team proposed a restoration approach that will satisfy several goals, including: reduction of turbidity, increased habitat for native flora and fauna, and improved aesthetics for the local area. The design of the D’Olive Creek DAF and DAF-1 restorations were developed using reference reach and regional data, in-stream structures, and hydraulic analysis to restore and maintain a stable channel that is capable of handling flows unique to this watershed. The stream plan, profile, and dimension reflect what would exist in a natural, unimpaired setting in this region. Proposed boulder riffle structures provide rigidness that will sustain the channel and floodplain during 100-yr rain events. The proposed stream restoration widens the floodplain to reduce shear stresses while armoring the channel to increase the roughness, thus, reducing velocity and, in turn, reducing sediment deposits in Mobile Bay. The design consists of shifting the channel bed profile upwards and cutting a new floodplain that is easily accessed by the channel. Floodplain access reduces the flow depth and the applied shear stress of the stream. The design team found this approach to be the most cost- effective solution, while still meeting goals for a “natural” design.

Figure 1: Arrow pointing to sediment leaving Lake Forest and entering Mobile Bay (al.com) 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

INCORPORATION OF STRUCTURAL RELIABILITY ASSESSMENT APPROACH INTO UPGRADE AND RENEWAL DECISIONS FOR PORT AND MARINE STRUCTURES David Taylor, Baird Australia Pty Ltd, [email protected] Dara McDonnell, Arup Pty Ltd, [email protected] David Dack, Arup Pty Ltd, [email protected] Dave Anglin, W.F. Baird & Associates Coastal Engineers Ltd, [email protected] Caleb Barth, W.F. Baird & Associates, [email protected]

Aged port and other marine structures can be vulnerable to failure due to materials degradation, and are often shown to be under-designed when assessed using modern standards and updated marine loading conditions. Increasingly, port and marine infrastructure is being operated for longer than the intended design life, and reliability methods can provide owners with the information required to better plan upgrades and renewals while maintaining an acceptable risk profile. Reliability assessment is particularly well suited to looking at the effect of changes to environmental conditions at a site, for example from sea level rise, or changes to the capacity of the structure over time from corrosion and degradation. The conventional approach for undertaking a structural assessment of an existing port or marine structure has been deterministic, whereby uncertainties in the load and resistance component estimates are accounted for using factors of safety defined in published codes and standards. However, reliability assessment methods that consider site-specific data and detailed knowledge of load and structural resistance parameters can be an effective way to more accurately quantify the risk of failure and to better inform asset management decision making. The output of the reliability assessment can be expressed as an effective probability of failure which can then be weighed against a set of defined criteria for acceptability. The acceptability of risk will depend on a number of factors, such as the quality of the available data, the consequences of failure, and the risk strategies and systems of the asset owner(s). The purpose of this presentation is to demonstrate the potential benefits that a reliability assessment approach can provide. To this end, the presentation includes a summary of the background of reliability assessment, a discussion on the typical methodologies used to undertake such an assessment, and examples comparing code-based and reliability assessment approaches. Under the right circumstances, a robust reliability assessment can significantly benefit owners with the asset management of their port and marine structures, specifically providing optimization of capital expenditures.

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Barbours Cut Dock Expansion & San Jacinto Marsh Restoration Project Justin A. Bartusek, Atkins, [email protected]

Barbours Cut Terminal, located along the Houston Shipping Channel (HSC), has grown to become a leader in container handling facilities. Atkins was hired by a private client to expand one of the dock facilities within Barbours Cut as well as seized a unique opportunity that brought together the dock expansion project with an environmental restoration project. The dock expansion called for the dredging of 475,000 yd3 of material to connect the slip with the existing federal channel. Dredged material was transported approximately 9.5 miles inbound along the HSC to the San Jacinto Historical Battleground (BU) site. San Jacinto marsh is a 350-acre tidal wetland complex at the confluence of the HSC and San Jacinto River. The site is preserved by the Texas Parks and Wildlife Department (TPWD) as the location of the Battle of San Jacinto, which is credited as the pivotal event that won Texas independence from Mexico in 1836. It is also designated as a National Historical Landmark and stands as one of the few functioning tidal wetlands among the heavy industries of Houston. The site has undergone a series of changes through the years associated with coastal erosion and subsidence. The primary goals of the fill project were to: 1. Restore San Jacinto marsh to a historically accurate condition, helping visitors visualize the events that took place during the 1836 battle. 2. Create an inter-tidal habitat that promotes native marsh grass growth and is tolerant of varying water elevations and salinity levels. The project faced a host of challenges that Atkins helped the client overcome including fast-track scheduling, transport distance, material type, and abundant cultural resources. Atkins completed the design and permitting work took place from March to September 2015 and the project was constructed by Weeks Marine Inc. from January to June 2016. The final product was a navigational dredging project that included restoration of 150 acres of inter-tidal marsh habitat at the San Jacinto Battleground which mimics the conditions of the battlefield in 1836. The project was awarded an Environmental Excellence Award for Navigational Dredging from the Western Dredging Association (WEDA) in June 2017.

Figure 1: New dock dredging site. 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

MOBILE BAY BAYWAY BRIDGE STORM SURGE IMPACT ANALYSIS Victoria Curto, PE, Mott MacDonald, [email protected] Josh Carter, PE, D.CE, Mott MacDonald, [email protected] Josh Todd, EI, Mott MacDonald, [email protected] Katie Walling, Mott MacDonald, [email protected]

The primary goal of this report is to describe the risk associated with loads from tropical storms and hurricanes on the Mobile Bay Bayway Bridge (MBBB). This study presents a discussion of coastal processes associated with extreme storm events at the MBBB, an evaluation of changes to those coastal processes due to climate change over the project lifetime, and computation of loads from a range of the extreme storms on the existing MBBB. Hurricane storm surge may subject the MBBB to high wave loads which have the potential to cause severe damage to the bridge structure. These extreme loads will increase over time due to increasing water elevations expected to occur as a result of climate change and associated sea level rise. The Federal Highways Administration (FHWA) and American Association of State Highway and Transportation Officials (AASHTO) have developed analysis guidelines and design guide specifications to assist in evaluating loads from extreme hurricanes at coastal bridges. This analysis evaluates the loads with a modified Level I effort according to the AASHTO standards. The primary source used to determine the environmental forcing conditions of wind and storm surge associated with increasing levels of risk is existing data. The AASHTO guide specifications and the FHWA require consideration of climate change over the project lifetime in the assessment of a large project. The primary impact of climate change to the MBBB is sea level rise. The storm surge and associated sea level rise were combined with hurricane wind fields to develop wave conditions along the bridge using numerical wave modeling associated with storms with a 10, 25, 50, 100, and 500 year return interval at present (2017), and in 2067 and 2117. These wave results were further modified to account for the nonlinearity of wave crest asymmetry that occurs with large waves in shallow water to determine the maximum wave crest elevation. The wave results were used as input to the AASHTO guide specification calculations to evaluate loads on the bridge superstructure (deck) and substructure (piles). The additional sea level that is expected to occur over the project lifetime has a large impact on the deck loads, as the force increases proportionally to the rise in sea level due to increase exposure of the deck to waves with higher water, along with the proportionally increased wave heights that occur with the deeper water.

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Town of Oak Island Feasibility Study: A Case for Combining Beach and Inlet Issues Into an Overall Management Program Katie Finegan, EI, [email protected] Brandon Grant, EI, [email protected] Johnny Martin, PE, [email protected]

The Town of Oak Island is seeking to provide long-term, sustaining management of its beaches. While beneficial use projects from the USACE had met Town objectives in the past, significant initiatives for shoreline protection have not occurred in the last 15 years. Recent storms such as Hurricane Matthew have shown that a long-term plan is needed to meet Town goals and protect infrastructure. The Town of Oak Island intends to maintain its beaches via implementation of a proposed Master Beach Nourishment Plan (MBNP) which is the next step after completion of this feasibility study.

The Town of Oak Island is specifically seeking federal and state permits to allow implementation of this feasibility study and the follow-on MBNP as a non-federal shoreline protection and inlet management project over a multi-decadal period to preserve the Town’s tax base, infrastructure, and tourist oriented economy.

The proposed program incorporates actions to nourish recipient beaches within the Town, via use of multiple sand sources, over a multi-decadal timeline with revolving nourishment-project events. The overall plan identifies engineering design elements including: sand volumes required to yield the desired level of protection throughout the Town; triggers expected to prompt future nourishment events; sand borrow sources, volumes, quality, and viability; the expected capacity of the recipient beaches for nourishment; and the projected timing of nourishment events. The plan also integrates inlet management for protection of adjacent infrastructure by use of a demarcated “safe box” or corridor for the inlet to migrate within. Once the inlet reaches the edge of the box, an inlet relocation project would be initiated to return the inlet to a more stable location. Lastly, the plan also investigates the use of cost-effective analytical (statistical) design procedures versus complex modeling to determine initial and maintenance needs of sediment over the life of the project.

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21­23, 2017

LIFE CYCLE COST ANALYSES OF BEACH NOURISHMENT ON DAUPHIN ISLAND, AL Brittany E. McMillan, University of South Alabama, [email protected]

The vulnerability of barrier islands to hurricanes increases as sea levels rise. During hurricanes, large volumes of sediment may be transported from beaches, dunes, and back barrier regions, which results in severe damage of the island. These extreme morphological events are expected to become more severe as sea levels rise and storm surge and waves are able to further inundate barrier islands. Dauphin Island is a developed barrier island located near Mobile, Alabama, where approximately 1,250 permanent residents reside. It is known to have been severely damaged during past hurricanes and is subject to SLR rates of 3.3 mm/yr based on data from 1966 to 2015. In 2016, a nourishment project that required 300,000 yd 3 of dredged sediment and cost $7 million (USD) was completed on the east end of the island. Although there were no major storms from 2010 to 2013, approximately 50,000 yd 3 of sediment was eroded. During storm events and as sea levels rise, erosion rates will increase and alternative strategies that sustainably improve the resiliency of barrier islands compared to beach nourishment alone will become necessary to implement. During a conceptual design phase, these strategies are assessed for sustainability; however, the analyses often do not consider future climate changes and the design may not be a sustainable option when the temporal behavior of the system is considered. In order to determine the sustainability of beach nourishment to increased erosion rates by sea level rise alone, 100­year life cycle cost analyses were conducted for non­linear sea level rise trends. According to IPCC projections, a nonlinear rise in sea level is expected over the next century. The 100 year life cycle cost analyses for a nonlinear rise in sea level from present day sea level to 1m and 2m were determined to be $147 million and $231 million, respectively. These cost analyses reveal that the cumulative costs of future beach nourishment projects are not sustainable for Dauphin Island and that alternative strategies should be considered to increase barrier island resiliency.

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Living Shoreline Demonstration Project – Recent Experience on Design and Construction Joshua Todd, Mott MacDonald, [email protected] Josh Carter, Mott MacDonald, [email protected]

The goal of the projects is to establish a living shoreline that will help prevent erosion along coastal fringe marshes by using the living shoreline products to attenuate the wave energy that reaches the shore, while stimulating oyster growth and thereby increase the biodiversity in the immediate vicinity of the project site. The first project is off Bayou La Loutre in St. Bernard Parish, Louisiana. The second project is near Grand Isle, Louisiana in Jefferson Parish. The projects are also intended to provide the Louisiana Coastal Protection and Restoration Authority (CPRA) experience and data on living shoreline products and their performance in order to design more effective living shoreline projects in the future. The proposed solution will also provide a sustainable wave protection system to adapt to climate change and rising sea levels: oyster reefs in the Gulf of Mexico tend to grow to the water surface. As sea levels rise, the oysters will grow vertically providing a breakwater that dynamically adjusts to the water level providing consistent wave protection for the marsh edge into the future. A set of 8 artificial oyster reef products were proposed for use in an erosion control project in coastal Louisiana. A successful living shoreline project will reduce the shoreline erosion and provide ecosystem benefits. Engineering performance characteristics of available living shoreline products, such as wave energy reduction and stability under storm conditions, are limited due to the experimental nature of the products. This presentation discusses the project design and experience from construction using artificial oyster reef projects. Design focused on using the artificial oyster reef products must reduce wave energy transmitted past the designed structure to levels below the marsh erosion tolerance limit to successfully control shoreline erosion. However, known performance characteristics of available living shoreline products are generally limited due to the experimental nature of the products. Therefore, the ability of each product to reduce wave energy transmitted past the designed structure was evaluated along with the hydraulic loading on the structures using 2D-V and 3D computational fluid dynamics modeling tools. Construction utilized precast concrete units. A review is provided on lessons learned applicable to more efficient design, project layout to improve constructability, as well as a variety of installation procedures.

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

AN EULERIAN THREE-PHASE MODEL FOR SHEET FLOW UNDER BREAKING WAVES Yeulwoo Kim, University of Delaware, [email protected] Ryan S. Mieras, University of Delaware, [email protected] Zhen Cheng, Woods Hole Oceanographic Institution, [email protected] Tian-Jian Hsu, University of Delaware, [email protected] Jack A. Puleo, University of Delaware, [email protected]

Wave-driven sediment transport is of major importance in driving beach morphology. However, a comprehensive understanding has not been achieved due to complex mechanisms associated with unsteadiness and free-surface effects. Particularly for highly non-linear and asymmetric-skewed breaking waves, the boundary layer approximation (i.e., assuming horizontal pressure gradient via local acceleration), often used in many analyses and models, becomes questionable. Moreover, wave breaking induced turbulence may approach the bed and enhance sediment transport. Thus, a numerical model which can resolve the entire water column from the bottom boundary layer to the free surface can be a powerful tool to understand wave-driven sediment transport. In this study, an Eulerian two-phase flow model, SedFoam (Cheng et al., 2017, Coastal Eng.) is fully coupled with a volume-of-fluid solver, interFoam/waves2Foam (Berberovic ́ et al., 2009, Phys. Rev.; Jacobsen et al., 2011, Int. J. Numer. Methods Fluids). The fully coupled model, named SedWaveFoam, regards the air and water phases as two immiscible fluids with the interfaces evolution resolved, and the sediment particles as dispersed phase. By merging a wave generation toolbox waves2Foam, SedWaveFoam can also generate/absorb various type of surface waves. The full profile of sediment transport driven by surface waves is resolved using Reynolds-averaged Eulerian two-phase flow equations with closures of inter-granular stresses and a k-ε turbulence model. With a full capability of resolving wave surface and sheet flow processes in the bottom boundary layer, the effect of wave-induced bottom shear stress, pressure gradient, boundary layer streaming, and wave-breaking-induced turbulence on sediment transport under waves can be investigated. SedWaveFoam has been validated with the large wave flume experiment for sheet flow driven by monochromic waves reported by Dohmen-Janssen and Hanes (2002, J. Geophys. Res.). SedWaveFoam is further applied to the sandBAR SEDiment transport experiment data (BARSED; Anderson et al., 2017, J. Geophys. Res.; Mieras et al., 2017, J. Geophys. Res.). Specifically, SedWaveFOAM will be used to simulate BARSED experiments to reveal the role of wave velocity skewness and asymmetry and boundary layer streaming under steep breaking waves on sheet flow processes.

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

DO SAND RIPPLES MATTER TO LARGER COASTAL CHANGE? Meagan E. Wengrove, University of New Hampshire, [email protected] Diane L. Foster, University of New Hampshire, [email protected] Matthieu A. de Schipper, Technical University Delft, [email protected] Tom C. Lippmann, University of New Hampshire, [email protected]

Do sand ripples actually matter to larger coastal change? Sand ripples are formed as waves and currents move through coastal zones. This research works to answer this question by monitoring ripple dynamics in coincidence with larger coastal morphology in the nearshore of the Sand Engine, a mega-coastal nourishment in the Netherlands (Figure 1a). During the 1.5 month long field deployment a local shore attached sandbar migrated 50 m and gained 600 m3 of sand (Figure 1b). During that same period ripples in the nearshore (between the offshore sandbar and the shoreline) were responsible for transporting 1500 m3 of sand (that’s 600 wheelbarrows full of sand every single day!), with 300 m3 of that sand being moved in the alongshore direction toward the shore attached sandbar (Figure 1c). This means that sand ripples transported half of the sand that was gained by this local sandbar system. These observations are evidence that ripples may be significantly contributing to large coastal change.

Figure 1: A look into scales of coastal change from kilometer scale to centimeter scale. a) Sand Engine mega- nourishment, change over 3 years of time, blue box in bottom panel indicates local survey area in b. b) Local bathymetric change over a 3 week period, top two panels are surveys taken at week 0 and week 3, where yellows are dry beach, green is the shoreline, and blues are water with light blue indicating shallower sandbars. The bottom panel indicates change between surveys W3 and W0. Blue indicates erosion and yellow is accretion of sand, note the region just below the two red dots is a shore attached sandbar that moved 50 m during the deployment and gained sand. The red dots indicate sonar sampling locations to observe sand ripples over time with example images shown in c. c) Images showing ripple dynamics over a 3 hour period, ripple crests are in yellow and troughs are in black, ripples can change shape dramatically and can transport a lot of sand by migration. d) Example instantaneous underwater image of sand ripples; image shows sediment shedding off ripple crests, showing how they are dynamic features. 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

LARGE-SCALE EXPERIMENTAL OBSERVATIONS OF WAVE-INDUCED SEDIMENT TRANSPORT OVER A SURF ZONE SANDBAR

Ryan S. Mieras, University of Delaware, Center for Applied Coastal Research, [email protected] Jack A. Puleo, University of Delaware, Center for Applied Coastal Research, [email protected] Dylan Anderson, Oregon State University, Coastal and Ocean Engineering Program, [email protected] Daniel T. Cox, Oregon State University, Coastal and Ocean Engineering Program, [email protected] Tian-Jian Hsu, University of Delaware, Center for Applied Coastal Research, [email protected]

A large-scale laboratory experiment was conducted to evaluate cross-shore sediment transport and bed response over a surf zone sandbar under field-scale wave conditions. Results from 11 different wave cases were analyzed, spanning wave periods from 5.0 to 9.0 s, and wave heights over the sandbar from 0.49 to 0.94 m, using a well-sorted sand with median grain diameter, �50 = 0.17 mm. Observations on the sandbar crest of intra-wave sediment mass flux, transport rates and net volume of sediment transport on the crest of a sandbar were used to quantify the relative contributions of suspended sediment transport and sheet flow to net sediment transport rates (Figure 1). The ensemble-averaged gross volume of sediment transported per wave in the suspended load layer, |���|, was of the same order of magnitude as the gross volume transported in the sheet flow layer, |���|. The net volume transported via sheet flow was positive (onshore-directed) for all 11 test conditions (Figure 1). In the extreme case of sheet flow dominance, 82% of the gross volume of mobilized sediment (per wave) was transported in the sheet layer, while in the extreme case of suspended load dominance, only 14% was transported in the sheet layer. In the cases where suspended sediment transport dominated sheet flow (4 of 11 cases), the net transported volume of sediment was always offshore-directed, whereas, when sheet flow dominated suspended sediment transport (7 of 11 cases), the net volume of sediment transport was always onshore-directed.

Figure 1: Ensemble-averaged net volume (per meter flume width) of sediment transported via sheet flow, ���, and suspended sediment, ���, per wave, for the 11 test cases. The grey error bars show one standard deviation from the mean. Negative values signify offshore-directed sediment transport. 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Calculating aeolian sediment dynamics relative to varying concentrations of the gravel lag Tynon Briggs, University of West Florida, [email protected] Phillip P. Schmutz, University of West Florida, [email protected]

In beach-dune systems the size and texture of sand grains can impact and alter the fluid threshold necessary for movement of sand. Therefore, intrusive sediments such as high concentrations of gravel can heavily influence the rate of sediment transport and subsequently coastal dune development. Scattered throughout Santa Rosa Island, Florida there is extensive concentrations of gravel within the back barrier system, which is a product of hurricanes transporting the road pavement gravel base via wave storm surge. This human introduced gravel is an intrusive sediment and holds potentially negative implications for aeolian sedimentary transport and coastal dune development. The primary goal of this research is to evaluate how this intrusive gravel lag inhibits aeolian sediment transport activity and if the removal of the gravel lag facilitates an increase in sediment transport. The study site is located on the University of West Florida’s property on Santa Rosa Island and consists of multiple five-meter by five-meter survey plots. Each survey plot contains varying concentrations of the gravel lag, with one of the plots cleared of all lag deposits. Wind speeds and sediment transport dynamics are measured via a vertical array of anemometers and Wenglor sediment particle counters. Data collection occurred from March through May 2017. The mean grain size for each plot was determined to be 0.4 mm (no lag plot) and 0.47 mm (lag plot). This corresponded to a calculated threshold shear velocity (u∗t) of 0.29 (no lag plot) and 0.33 (lag plot) m/s, which is equivalent to a wind speed at a height of 2 m of 6.7 m/s (15 mph) and 7.4 m/s (16.5 mph), respectively. Data analysis is only in its infancy; however, preliminary findings appear to validate our research hypothesis that intrusive gravel lag does indeed inhibit aeolian sediment transport activity and that the removal of said gravel will promote an increase in sediment transport (Figure 1).

Figure 1: Sediment transport activity in correlation to wind speed within the No Lag and Lag plots ! 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Exploring the Influence of Obliquely Oriented Shoreface-connected Ridges on Alongshore Sediment Transport and Shoreline Change Tongtong Xu, Georgia Institute of Technology, [email protected] Kevin Haas, Georgia Institute of Technology, [email protected]

Shoreface-connected ridges (SFCR) are series of ridges and troughs obliquely oriented towards the shore in the inner-continental shelf. They exist sporadically from Long Island to Florida on North American Atlantic Shelf with maximum expression on the Delmarva peninsula, including the western half of Fire Island, NY. The long-term historic shoreline record of Fire Island shows persistent undulations in shoreline shape at an alongshore scale similar to the alongshore scale of the ridges (Figure 1). To study the effect of ridges without the other complexities in the bathymetry and forcing, SWAN (Simulating WAves Nearshore) is configured to simulate wave transformation on a simplified, synthetic bathymetry replicating the scales of the SFCR on Fire Island, forced with realistic wave parameters based on wave observations collected by the National Data Buoy Center. ROMS (Regional Ocean Modeling System) is then coupled with SWAN along with the sediment module to obtain the alongshore sediment transport driven by alongshore currents. The inherent SSW bottom boundary layer (BBL) formulation in ROMS yields an unrealistically small magnitude of current. A new BBL formulation is implemented in ROMS to increase the current magnitude. In the alongshore momentum balance, the pressure gradient, although small, compared with the bottom stress and wave breaking force, is the driving mechanism behind the alongshore hydrodynamic variation and sediment transport. The alongshore pressure gradient is generated by the wave focusing and defocusing, leading to the alongshore variations in the shoreline change guided by the SFCR. When the incoming wave direction is aligned with the orientation of the SFCR, the alongshore variability of the wave field is maximized. A wave ray tracing analysis is used to interpret the evolution of the spectra due to the refraction of the waves and illustrates the process of the ridges acting as wave guides, trapping energy on the crests.

Figure 1: Color shading marks the region and recent bathymetry of Fire Island showing the SFCR on the western side and a more planar shelf on the eastern side. The total length of Fire Island is around 50 km. The exaggerated persistent shoreline undulation (orange) shows the scale similarities to the SFCR. 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

INFLUENCE OF RECLAMATION PROJECTS ON THE SEDIMENT TRANSPORT PROCESS OF CHANNEL-SHOAL SYSTEM Huidi Liang, 1. College of Civil Engineering, Tongji University, Shanghai, 200092, China 2. Department of Civil and Coastal Engineering, University of Florida, Gainesville, FL 32611, USA, [email protected] Maitane Olabarrieta, Department of Civil and Coastal Engineering, University of Florida, Gainesville, FL 32611, USA, [email protected] Channel-shoal system, found in global estuaries, coastal bays and tidal inlets, is a highly dynamic structure, which is determined by local driving forces and variant sediment supply. The system is typical in regions and can be easily changed because of the geography changes caused by reclamation projects. Caofeidian, one of the largest barrier island in Bohai Bay China, was experienced vast land reclamation projects since 2003. The changes in the channel-shoal system are significant and critical to sediment transport. Using a process-based model, responses in hydrodynamic variables to the reclamation project and their impacts on the sediment transport are investigated. Numerical modeling indicates that wave condition is the dominated factor in sediment transport processes. Generally the high sediment transport area exists in deep channel, where is flood current dominated, while sediment transports in tidal flat toward ebb current direction. While after the tidal flat is reclaimed, the magnitude of sediment transport decreases in the study domain, even in certain areas with increased velocities. The decreases are caused by the weaken sediment exchanges between channel- shoal system by lack of the tidal flat area and the changes of the local current through breakwater construction. The block of the wave propagating from east is also one of the reasons. We conclude to absence of tidal flat reducing the sediment supply after reclamation that will lead to erosion in channels.

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

PRELIMINARY RESULTS OF A MUNITION MOBILITY STUDY IN THE SWASH ZONE Demetra Cristaudo, Center for Applied Coastal Research, University of Delaware, [email protected] Brittany Bruder, Field Research Facility, USACE, [email protected] Jack A. Puleo, Center for Applied Coastal Research, University of Delaware, [email protected]

Some past military activities have resulted in the presence of unexploded ordnance (UXO) in the nearshore environment. UXO, also referred to as munitions, lying on the seabed, may be mobilized due to wave-current conditions and can be found on the foreshore. The foreshore, also called swash zone, is the wet part of the beach covered and uncovered by successive waves. The presence of munitions on the foreshore constitutes a danger for the public motivating the present study. Two large-scale laboratory studies and a field experiment were conducted to investigate munition transport under different forcing and beach conditions. These tests were carried out using in-house designed surrogate munitions (ranging from spherical cluster bombs to 155 mm High Explosive Howitzers), equipped with instrumentation to measure different components of motion. The surrogates are realistic replicates of real munitions in terms of shape and physical characteristics Internal munitions sensors include: inertial motion units (to measure acceleration, angular velocity, orientation); a shock sensor (to measure high frequency acceleration detecting wave impact on the surrogate); pressure transducers (to measure the water level above the surrogate); and an array of optical sensors (to measure burial/exposure and rolling). In addition, instrumentation to measure forcing conditions and cameras to track munitions trajectories were deployed. Preliminary results will be discussed. In particular, munitions sensor response will be compared with GPS measurements of position and camera imagery as well as comparisons of same measurements from different sensors will be highlighted.

Figure 1: Large-scale laboratory study, experimental setup (Littoral Wave Environment at Aberdeen Test Center, Maryland, USA). Scaffolding frame and instrumentation viewed from the beach (A). Surrogates deployment and instrumentation viewed from the side of the flume (B). 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Resolving the Role of the Dynamic Pressure in the Burial, Exposure, Scour, and Mobility of Underwater Munitions Stephanie E. Gilooly, University of New Hampshire, [email protected] Diane L. Foster, University of New Hampshire, [email protected]

The primary goal of this research is to resolve the burial, exposure, and mobility of munitions commonly present in nearshore and inlet underwater test sites. The burial and exposure of munitions result from an amalgamation of the sediment transport processes including sheet flow, scour, bedform migration, and momentary liquefaction. It has been stated that incipient motion for both a munition and the surrounding sea bed can be caused by disruptive shear stresses and pressure gradients, which can be parameterized by the Shields and Sleath parameters, θ and S, respectively (Shields 1936, Sleath 1990). Foster et al. (2006) proposed a generalized incipient motion formulation due to both the pressure gradient and shear stress as a function of bed state parameters. This research looks to advance this combined parameter to include near and far field shear stresses and pressure gradients, especially dynamic pressure gradients created by the flow interacting with munitions or other boundaries. To do so, pressure-mapped model munitions are being developed that can measure the orientation, rotation, and surface pressure surrounding munitions during threshold events leading to a new positional state. These munitions will be deployed for multiple days in inner surf zone and estuary environments along with acoustic Doppler velocimeters (ADVs), pore water pressure sensors, a laser grid, and an IMAGENEX pencil beam sonar with an azimuth drive. These instruments allow for near bed and far field water column and sediment bed sampling. Currently preliminary assessments of various pressure sensors and munition designs are underway. The pressure sensors being analyzed are the FlexiForce A201 and the TE Connectivity MS5837-30BA diaphragm sensors. The FlexiForce sensors are 0.203 mm thin and can be mounted on the surface of the munition without greatly disrupting the flow field. The diaphragm sensors will be used to understand changes in surrounding pore water pressure as the munition begins to bury/unbury, while the FlexiForce sensors will be used to indicate munition rolling during threshold events. Both sensors are expected to give quantitative measurements of dynamic pressure gradients in the flow field surrounding the munition.

Figure 1: Diaphragm (left) and FlexiForce (right) Pressure Sensors Currently under Investigation 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Morphological Modeling of Low-Dune Barrier System Changes due to Hurricane Forcing Cody L. Johnson, Louisiana State University, [email protected] Dr. Qin Jim Chen, Louisiana State University, [email protected]

Coastal barrier island systems serve as the first line of defense against ocean born waves and storm surge. Without these barriers, oceanic hydrodynamic forcing would cause significantly more damage to landward infrastructure and ecosystems. Widespread recognition of this crucial function has prompted coastal managers to adopt systematic restoration programs. Louisiana, for example, has, in response to its critically eroding shorelines, implemented 30 barrier island restoration projects over the past two and half decades. One contemporary project, the Caminada Headlands Beach and Dune Restoration Project (phase I and II) will cost an estimated 220 million dollars and restore ~13.25 miles of coastline. Design optimizations for such costly endeavors are of paramount importance and are fraught with many challenges. For example, coastal managers and engineers must consider the scarcity of restoration material (economically viable sand of sufficient quality) and the response/feedbacks of the coastal system as a whole. Process based morphological models, which simulate the complex hydrodynamics and sediment dynamics of the nearshore environment, can be employed to inform such design processes and suggest avenues for innovation. XBeach (eXtreme Beach behavior) is a high-resolution, process based numerical model used to simulate the morphodynamics of beach/dune systems over the passage of a storm. It solves the non-linear shallow water equations at the wave-group time-scale coupled with a phase-averaged short-wave model. This allows XBeach to drive a nearshore sediment transport model, which resolves the important infra-gravity wave forcing, in a computationally feasible manner. A bed-updating avalanching algorithm realistically accounts for changes in dune slope due to erosion. In this work, XBeach is used to hindcast the effects of hurricane Isaac (2012), as well as other contemporary high-energy storm events, on the Caminada-Moreau headlands. Hurricane Isaac made landfall just prior to the Caminada restoration and is thus ideal to employ as validation for a model of the system. The model makes use of an extensive data set which includes high frequency, high resolution topo-bathymetric surveys, pre- and post-storm lidar surveys, and the hydrodynamic forcing due to hurricane Isaac. Much of the employed data was collected during the design and construction process of the Caminada Headlands Restoration Project. As such, it is directly applicable and well-suited to the research. The model is then employed to forecast the effect of storm events of the post-restoration Caminada-Moreau headlands. 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Numerical Simulation of Ridge Evolution based on Field Data from a Steep Meso-Tidal Engineered Beach Youn-Kyung Song, Department of Ocean Engineering, College of Engineering, Texas A&M University, Galveston, TX 77553 USA, [email protected] Jens Figlus, Department of Ocean Engineering, College of Engineering, Texas A&M University, Galveston, TX 77553 USA, [email protected] Patricia Chardón-Maldonado, UPRM Center for Applied Ocean Science and Engineering, University of Puerto Rico, PR-108, Mayagüez, 00682, Puerto Rico, [email protected] Jack A. Puleo, Department of Civil Engineering, Center for Applied Coastal Research, University of Delaware, Newark, DE 19716 USA, [email protected]

Ridge and runnel (RR) systems are comprised of an intertidal bar with a pronounced shore- parallel berm crest followed by a landward slip-face and depression, often filled with ponded water. The formation and onshore migration of such a slip-face ridge during calm wave conditions after a storm are studied to better understand the complex feedback mechanisms between wave dynamics, sediment transport and profile evolution as these systems provide a natural way of recovery for an eroded beach. In this study, the overall beach dynamics are simulated using the numerical process-based morphodynamic model CSHORE in order to reproduce the accreting slip-faced RR system observed during a 3-week field experiment on a steep meso-tidal engineered beach at South Bethany Beach, Delaware. In the beginning of this field campaign, a Nor’easter eroded significant portions of the beach and formed a pronounced RR system that then evolved during the less energetic conditions after the storm. Detailed measurements of wading depth beach profiles and near-bed flow velocities were obtained including the inner surf and swash zones along with offshore wave and current records. Once properly calibrated, CSHORE was able to accurately predict the evolution of the crest location and elevation (e.g., root-mean-square differences between the measured and modeled profile elevations of 0.22 m), and seafront slope of the accreting ridge using only a few seconds of simulation time (an order of 10−3 of the measurement duration for over 28 tidal cycles): The modeled profile matched the measured crest elevation closely with only about 4 cm error and the measured seafront slope with lower than 6 % error . However, the model predicted a longer period of recovery (about 9 additional tidal cycles) compared to the measured data. The CSHORE predictions on swash inundation depth, cross-shore extension of runup, and associated cross-shore mean water velocity reasonably represent the field measurements and are discussed in light of the model calibration strategy and future modifications. This presentation anticipates to be resourceful for engineers and coastal management agencies who seek for a rapid numerical assessment of beach recovery rates and profile shapes for emergency nourishment activities on engineered and natural beaches affected by erosion during storms.

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

IMPACT OF A PERMEABLE GROYNE FIELD ON LITORAL TRANSPORT: A EXPERIMENTAL STUDY Jose C. Tuz-Pech, Programa de Maestría y Doctorado en Ingeniería, Universidad Nacional Autónoma de México, [email protected] David Gracia-Barrera, Instituto de Ingeniería, Universidad Nacional Autónoma de México, [email protected] Alec Torres-Freyermuth, Instituto de Ingeniería, Universidad Nacional Autónoma de México, [email protected]

The beach morphodynamics in the northern Yucatan coast are very sensitive to the presence of coastal structures. The study area is characterized by high-angle short waves associated to intense sea-breeze conditions, driving significant sediment transport along the coast. In this work, we study the impact that a permeable groyne field has on beach morphology during both mean wave conditions (sea breezes) and a storm event that took place on May 5th. Two 12-m long permeable groynes, made with 65 kg hexapods (BARI) concrete elements, were deployed separated by 30 m in Sisal beach. Beach morphology was measured using GPS RTK surveys conducted every three days to investigate the beach sensitivity during the deployment of one and two groynes. Moreover, offshore wave conditions were measured at 10 m water depth to correlate the observed morphology changes. Therefore, the impact of the groyn field on adjacent beaches can be evaluated. The structures will be remove on June 30th and hence subsequent surveys will allow us to evaluated the speed of the natural recovery (i.e, beach resilience).

Figure 1 Topo-bathymetric surveys conducted: (a) before structures deployment (02/MAY/2017), (b) 43-day after deployment of a single groyne (14/JUNE/2017), (c) 5-day after deployment of a second groyne (19/JUNE/2017).

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

CONSTRAINING HOLOCENE EVOLUTION OF THE PETIT BOIS ISLAND SYSTEM Robert Hollis, Division of Marine Science, University of Southern Mississippi, Stennis Space Center, MS, 39529, [email protected] Davin Wallace, Division of Marine Science, University of Southern Mississippi, Stennis Space Center, MS, 39529, [email protected]

Barrier islands are critical for habitat, tourism, and sheltering populated mainland areas from storm events. However, these systems are especially vulnerable to limited sediment delivery, accelerated sea level rise, and storm impacts, particularly in the Gulf of Mexico. Current monitoring studies do not provide records long enough to fully capture barrier evolutionary processes in response to rapid sea level rise and storm impacts. Without sufficient data it is difficult to produce accurate models to predict the future fate of the modern islands. Examining barrier island response to these forcing mechanisms using the geologic record can extend our understanding of these vulnerable systems. However, as transgressive coastal processes redistribute barrier sediments, original barrier island stratigraphy and sedimentary structures are rarely preserved. Based on sediment cores and geophysical data, previous studies suggest that portions of barrier island stratigraphy and remnant shoreline deposits may be preserved under large sand ridges on the inner shelf seaward of Petit Bois Island, Mississippi. Four radiocarbon dates on the inner shelf near the base of the Holocene ranged from 6,300-8,800 (uncorrected) years ago. This provides a low-resolution foundation for our hypothesis that these estuarine and tidal deposits are Holocene in age and can potentially be associated with an ancient shoreline position. However, these studies lack a robust number of radiocarbon dates and the identified depositional environments have yet to be validated by microfossils. Furthermore, these currently flooded environments remain enigmatic with respect to the coevolution of nearby Petit Bois Island. Here we will present a broad regional context of the Petit Bois system consisting of previously collected geophysical and sediment core data from the literature as well as the United States Geological Survey, the United States Army Corps of Engineers and Mississippi Department of Environmental Quality. Seismic boomer and CHIRP sub bottom data were used to delineate Holocene paleofluvial channels as well as the Holocene Pleistocene contact. The Pleistocene surface appears to be dipping to the southwest and is much shallower in the Mississippi Sound. Core data show variable facies extent throughout the study site. New sediment cores will target estuarine and tidal deposits on the shelf as well as barrier island facies. These cores will be examined in detail using micro and macrofossil assemblage distributions to validate paleoenvironments. Woody and carbonate material will be radiocarbon dated for both the marine ridges and Petit Bois Island. Correlating these ages with previously published high-resolution sea level curves would be an immense resource towards predicting future barrier responses with accelerated sea level rise in the Gulf of Mexico by understanding the Holocene evolution. 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

HOLOCENE EVOLUTION AND SEDIMENT PROVENANCE OF HORN ISLAND, MISSISSIPPI Nina Schulze, Division of Marine Science, University of Southern Mississippi, Stennis Space Center, MS, 39529, [email protected] Davin Wallace, Division of Marine Science, University of Southern Mississippi, Stennis Space Center, MS, 39529, [email protected]

As the largest, most stable island along the Mississippi-Alabama barrier island chain, Horn Island is a vital sand resource, provides a refuge for wildlife and protection against storms for the mainland. Understanding the past response of this important barrier to sea-level rise, storm impacts, and sediment supply is critical towards our understanding of its future evolution. Given the historic record of geomorphic changes is relatively short, the geologic record can effectively bridge our knowledge gap. However, the origin of sediments on Horn Islands is largely unknown, and the sediment provenance throughout its evolution is similarly obscure. The present theory of Horn Island’s formation is that the island chain was initiated by a sand bar that grew westwards from Dauphin Island. Decelerating sea level rise 4,000 to 5,000 years ago created optimal conditions for the island’s formation. This is supported by a lone radiocarbon date from below Horn Island, which suggests that the system formed after 4,615 ± 215 years BP. However, these hypotheses are based on sparse microfossil and radiocarbon data, and no data currently exist concerning the source of material through time. Rivers potentially supplying sediment include the Mississippi, Pascagoula, Mobile and Apalachicola, but the oscillating nature of their paths and sediment supply means that Horn Island could have received variable amounts of sediment from these rivers throughout the Holocene. To further understand the geomorphology, we first examine nine drill cores that were previously collected across Horn Island in the late seventies through the Department of Environmental Quality. New cores will be collected to target previously described facies such as barrier island sand and lagoonal mud. We will conduct x-ray diffraction (XRD) and x-ray fluorescence (XRF) analyses down core to identify mineralogical and chemical differences in the sediments that correspond directly to potentially different riverine sources. In addition, we will examine microfossils preserved in these sediments to understand the various depositional environments at Horn Island. To provide a regional chronostratigraphic context, additional radiocarbon ages will be collected from woody and carbonate material, and results will be correlated with seismic boomer and CHIRP sub bottom data previously published by the United States Geological Survey (USGS). In particular, these geophysical datasets will show existing paleochannels that can be tied to island evolution. These data presented will serve to determine the Holocene evolution of Horn Island environments in response to sea-level rise and variable sediment sources, which will shed light towards long-term sustainability. 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

LATE QUATERNARY PALEOCHANNELS AND DELTAS ALONG THE MISSISSIPPI- ALABAMA SHELF Clayton Dike, Division of Marine Science, University of Southern Mississippi, Stennis Space Center, MS, 39529, [email protected] Davin Wallace, Division of Marine Science, University of Southern Mississippi, Stennis Space Center, MS, 39529, [email protected]

Throughout the Late Quaternary, river channels have migrated landward in accordance with sea level rise along the Mississippi-Alabama Shelf, changing the transport terminus of coarse grained sediment. Modern river mouth positions between the Mississippi River and DeSoto Canyon may be part of a transgressive procession from the shelf edge, the shoreline during the Last Glacial Maximum. However, little is known about the paleopositions of the Pearl, Jourdan, Wolf, Biloxi, Pascagoula, Escatawpa, and Mobile Rivers on the shelf. Determining the positions of these rivers as they moved up the shelf in response to sea level rise will identify sandy channels and associated deltas. To aid in the determination, seismic data from seven surveys hosted by the United States Geological Survey (Figure 1) will be discussed. Over 450 channel interpretations have thus far been made in the inner and middle shelf ranging in depth below sea level from 2 to 84 m. After channels from the outer shelf have been plotted, inferred rivers may be traced to the inner shelf and identified. The goal of this project is to interpret paleochannels and deltas along the Northern Gulf of Mexico in a quantitative source to sink framework, thereby understanding the response to sea-level changes over the Late Quaternary.

Figure 1: Cruise track lines of previously collected seismic data hosted by the United States Geological Survey. 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

A HIGH PERFORMANCE PSEUDO-SPECTRAL SOLVER FOR TURBULENT FLOW OVER COMPLEX BATHYMETRY Liangyi Yue, University of Delaware, [email protected] Tian-Jian Hsu, University of Delaware, [email protected]

Direct numerical simulation (DNS) has been widely used in the investigation of turbulent flows. With application of the pseudo-spectral method, the numerical modeling system was designed with a framework (Figure 1) aiming at high scalability computing, high numerical accuracy and portability. Consisting of three different levels, the code was written in C++ based on the object- oriented programming (OOP) language and parallelized with the Message Passing Interface (MPI) technique. Components in LevelOne and LevelTwo are common elements in a counterpart. Class Field offers fundamental matrix operations, such as multiplication and discrete Fourier transform, which was built based on the well-known libraries P3DFFT and Armadillo. Within this numerical framework, the dimensionless Navier-Stokes equations were solved directly, which are integrated in time using a third-order low-storage Runge-Kutta method first. For spatial discretization, the discrete Fourier expansion was adopted in the streamwise and spanwise direction, while the Chebyshev expansion was used in the wall-normal direction. Several benchmarking cases in laminar and turbulent flow were carried out to verify/validate the numerical model and very good agreements are achieved. Ongoing efforts focused on solving turbulent flow over complex bathymetry (e.g., bedforms) by implementing a coordinate transformation (similar to sigma-coordinate) technique into the existing pseudo-spectral solver.

System

LevelTwo

Domain Phase Stepper

Variable Boundary

LevelOne

Field

P3DFFT Armadillo LevelBase

Figure 1: Framework of the numerical modeling system.

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

ATTENUATION OF NONLIENAR WAVES BY RIGID VEGETATION: COMPARISON OF DIFFERENT WAVE THEORIES

Ling Zhu, Louisiana State University, Baton Rouge, LA, USA. [email protected] Qin Chen, Louisiana State University, Baton Rouge, LA, USA. [email protected]

Vegetation plays a significant role in coastal zones due to its capability of damping storm surges and waves, and protecting coastal infrastructures. This study investigates the performances of theoretical wave attenuation models in predicting vegetation-induced wave height decay. The existing theoretical models are all based on linear wave theory, which cannot accurately describe the surface elevation and velocity field of highly nonlinear waves. The objective of this study is to understand the effect of wave nonlinearity on the performance of theoretical wave attenuation models under both emergent and submerged vegetation conditions. This study applies two nonlinear wave theories, Stokes’ second-order and cnoidal wave theories, to solve the energy balance equation for wave height evolution. Results from a well-validated non-hydrostatic phase- resolving numerical wave model serve as reference solutions. The differences between theoretical and numerical model results are denoted by !", and the difference between linear and nonlinear based theoretical model results are denoted by ∆$. !" reflects the accuracy of theoretical models; whereas ∆$ indicates the effects of nonlinear wave theories on the prediction of wave height attenuation.

A total of 30 tests are devised for shallow-intermediate water waves (0.37 ≤ *ℎ ≤ 1.48, where *ℎ is the relative water depth) through emergent and submerged vegetation. The Ursell number (Ur), indicating the wave nonlinearity, ranges from 4.4 to 142. The test results show that for wave propagation through emergent vegetation, ∆$ and !" are quite small (≤ 6% and ≤ 5%, respectively); whereas over submerged vegetation, ∆$ and !" both increase with Ur. For waves with Ur = 142, the !" of the linear-based theoretical model reaches as large as 25%. With a 5% tolerance of !", linear-based theoretical models remain valid for emergent cases and submerged cases with a small Ur (≤ 30 for the vegetation and wave conditions given in this study). The inability of theoretical models to simulate the in-canopy velocity reduction and nonlinear wave- wave triad interactions is found to contribute to the large !" in submerged vegetation cases. Detailed results will be presented at the conference. Financial support for this research is provided by the US National Science Foundation.

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Effect of void fraction to energy dissipation in deep water plunging breaking waves

Byoungjoon Na, Ocean Engineering Department, Texas A&M University, [email protected] Kuang-An Chang, Civil Engineering Department, Texas A&M University, [email protected] Zhi-Cheng Huang, Institute of Hydrological and Oceanic Sciences, National Central University, Taiwan, [email protected] Ho-Joon Lim, Offshore Technology Services (OTS), TechnipFMC, [email protected]

This paper presents laboratory measurements of velocity fields and void fraction in deep-water plunging breaking waves using imaging and optical fiber techniques. Bubble size distributions are also determined based on combined measurements of velocity and bubble residence time. The number of bubbles with a chord length less than 2 mm demonstrates good correlation with the swirling strength. The power law scaling and Hinze scale of bubbles that are determined from the bubble chord length distribution are compared favorably with existing measurements. The turbulent dissipation rate accounting for void fraction is estimated using mixture theory. When void fraction is not considered, the turbulent dissipation rate is underestimated by more than 70% in the violent first splash-up roller. A significant discrepancy of approximately 67% between the total energy dissipation rate and the turbulence dissipation rate is found. Of which uncounted dissipation, 23% is caused by bubble-induced dissipation.

Figure 1: Normalized (by ETL ) total energy dissipation rate dE dt , turbulent dissipation rate with and * * without considering void fraction εα and ε , and bubble induced energy dissipation rate Sbε . The vertical dashed lines indicate the locations of the three fiber optics reflectometry stations. 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

HYDRODYNAMIC CIRCULATION ON THE WESTERN GULF OF MEXICO USING SELF-ORGANIZING MAPS Rafael Meza-Padilla, Laboratorio de Ingeniería y Procesos Costeros, Instituto de Ingeniería UNAM, [email protected] Christian M. Appendini, Laboratorio de Ingeniería y Procesos Costeros, Instituto de Ingeniería UNAM, [email protected] Cecilia E. Enríquez O., Facultad de Ciencias, UNAM, [email protected]

Remote sensing and high-resolution models have allowed us to study data scarce regions such as the Mexican side of the Western Gulf of Mexico (WGoM). The lack of in situ measurements for long periods is evident from the number of buoys and moorings deployed in US waters compared to Mexico. Hence, its characterization is based on relatively short periods, such as Rivas et al. [2008] who used sixteen months of observations from surface-to-bottom mooring in the central GoM to study vertical velocities and vertical heat fluxes within Loop Current Eddies (LCE). Also, most of the studies focus individually on specific processes/regions leaving behind an integrated approach of the along/across-shelf circulation dynamics of the LCE that enter the WGoM and travel westward until its impact in Mexico. To deepen on the complex and random dynamics of the LCE, advanced techniques for feature extraction and pattern recognition in large datasets are required to reveal the underlying physics of hydrodynamic processes that have been overseen by other traditional methods, particularly those including temporal averaging. For this, we apply the Self-Organizing Maps (SOM) to the output variables (salinity, temperature, and current fields at 200 m depth) of HYCOM experiments 50.1, 31.0 and 32.5, covering a total period of 24 years from January 1993 to December 2016. SOM is an unsupervised learning technique that involves artificial neural networks. Its major strength is providing a non-linear cluster analysis by mapping high dimensional input data onto a two- dimensional space while preserving the topological relationships between the input vectors (i.e. HYCOM outputs). We employed the dual SOM analysis which involves studying patterns along space and regions of variability along time. Our results show a very consistent behavior that shows a new approach to understand and characterize the metrics of the LCE traveling westward and its influence along the Mexican GoM. They are also in accordance with altimetry and field measurements realized during the JS0515 campaign in may 2016.

Keywords: Self-Organizing Maps, LCE propagation, Western Gulf of Mexico, cross-shelf ocean circulation. 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

LABORATORY EXPERIMENTS OF WAVE ENERGY DISSIPATION AND LONGSHORE CURRENT GENERATION ON A SANDY BEACH Ramy Y. Marmoush, Queen’s University, [email protected] Ryan P. Mulligan, Queen’s University, [email protected]

A three dimensional (3D) physical model is constructed in a 26.0 m by 20.5 m wave basin to observe nearshore hydrodynamics induced by wave breaking on a sloping beach. The beach is 18.7 m long, 3.9 m wide, and 0.8 m high with a 1:5 slope made from a concrete base and a thick layer of fine silica sand. Waves are generated using a 10.5 m wide, piston-type unidirectional wave paddle that can produce irregular wave signals for given wave spectrum. In these experiments, four wave signals with different bulk properties and incident wave angle α= 25˚ are tested in 0.6 m water depth. Measurements are collected every 0.1 m along a cross-shore beach transect (Fig. 1a). Instruments include five 16 Hz pressure sensors, two 50 Hz capacitance wave gauges, two 25 Hz acoustic Doppler velocity profilers that are moved to each station, and one 8 Hz acoustic Doppler profiler. Wave statistics (Fig. 1b and 1c) along a cross-shore profile are computed over the last 5 minutes of each 9 minute experiment to ensure steady state conditions. The significant wave height (Hs) profile (Fig. 1b) indicates the increase in height during propagation towards shoreline due to wave shoaling. For the same peak wave period (Tp) signals, the highest offshore wave signal shows the earliest and strongest increase in wave energy. The difference in significant wave height at the break point between the biggest and smallest wave signals is 2.4 cm, and the difference in cross-shore location is 0.4 m, indicating higher wave energy dissipation and a wider surf zone for the larger incident waves compared with other signals of the same peak period. Fig. 1c plots the wave energy dissipation (εwb) profile indicating where wave shoaling (-ve) and breaking (+ve) occurs along the beach profile. Increasing Tp increases shoaling, Hs at breaking, the width of the surf zone from the shoreline and rate of energy dissipation.

Fig. 1: Cross-shore profiles along the beach transect for all tests: a) bed elevation and instrument locations; b) significant wave height; c) wave energy dissipation. Incident wave conditions (Hs, Tp) at the paddle (xr= 11.2m) are indicated in the legend, and the still water level (SWL) shoreline is located at xr= 0.0 . 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Use of a Probabilistic Storm Database in Monte Carlo Lifecycle Modeling Dylan Sanderson, [email protected]

Probabilistic Lifecycle Cost Analysis (PLCA) tools such as Beach-fx and G2CRM implement Monte-Carlo methods to predict the evolution and estimate uncertainty of a project's physical behavior and economic benefits over the project's lifecycle. These PLCA models are data-driven models and rely on a pre-populated relational database that is accessed from the model’s computational kernel and contains storm/response information. In recent years, large probabilistic storm databases, such as the Coastal Hazards System (https://chs.erdc.dren.mil/default.aspx), have become available using high-fidelity numerical models. These storm databases can contain on the order of 300-500 relevant synthetic storm events for a single project location. Because the relational databases in Beach-fx and G2CRM need to contain all of the expected responses to any available storm event, it is computationally unfeasible to populate the databases using all of the storms available on the Coastal Hazards System. Therefore, a representative storm suite with 12-36 storms is developed that effectively characterizes the entire probabilistic space. The use of a representative storm suite reduces the number of storm/response computations from upwards of 10 million to somewhere between 90 and 810 thousand. Comparing the use of a representative storm suite and the full probabilistic storm data base results in stage-frequency curves that are nearly identical (Figure 1).

Figure 1: Stage-Frequency curves comparing the use of a representative vs. full storm suite in G2CRM 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Wave energy resource assessments and a preliminary classification for US coastal waters

Seongho Ahn, School of Civil & Environmental Eng., Georgia Tech, [email protected] Kevin Haas, School of Civil & Environmental Eng., Georgia Tech, [email protected] Vincent Neary, Sandia National Laboratories, Albuquerque, NM, [email protected]

The wave energy resource for the US coastal waters is assessed and classified. Partitioned bulk wave parameters of a 30-year hindcast at the 70,386 sites obtained from the WaveWatch III spectral wave model are used in order to estimate the wave power density (J, KW/m) and an annual available energy (AAE, MWhr/m) which is the annual energy production (AEP) without considering the energy conversion losses. As wave energy converter (WEC) technologies absorb the energy by resonating at the same period as incident waves, the AAE / power density is quantified as a function of partition peak period and wave direction. In order to show the energy distribution, percent contribution of the wave resources in terms of partition peak period is described for the total US coastal waters as well as five sub-regions. To classify how much energy is available specifically for WEC devices that operate within its operating period band, four wave period bands are defined and the AAE / power density is constrained by different period bands. Finally, the preliminary outline of four wave resource classes is defined in terms of AAE / power density and each location is classified into the different classes based on the total AAE / power density as well as each period band. The wave energy assessments and classification developed herein would provide significant benefits to the WEC industry, from data reduction for site characterization and assessment. Figure 1 shows the geographic distribution of the wave energy resource classes for the total AAE density along the US coastal waters.

Figure 1: Geographic distribution of the wave energy resource classes for the total AAE density. Class 0 sites are locations which have consistently low power and would not facilitate utility scale wave energy development. Class 1 sites are generally low power that might support small, localized applications. Class 2 and 3 sites are associated with progressively higher power and are able to support utility scale applications. 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

New possibilities for predicting and mitigation deadly rip currents Sarah M. Trimble, Texas A&M University, [email protected] Chris A. Houser, University of Windsor, [email protected] Rob Brander, University of New South Wales, [email protected]

Rip currents are concentrated seaward flows of water originating in the surf zone of beaches that cause hundreds of fatal drownings annually worldwide. Calculating the exact number of deaths is hindered by logistical difficulties in collecting accurate incident reports, but the estimated annual average is about 59 in the United States (US), 53 in Costa Rica, and 21 in Australia. Previous research shows rip drownings are caused by a combination of personal and group behaviors interacting with the physical environment. The co-incidence of a rip and swimmers, the ‘hazard,’ results from gaps in knowledge and in communication: we do not know how to accurately predict rips, and existing scientific understanding hasn’t fully infiltrated the practiced knowledge of the general public or policy makers designing beach access. This dissertation presents four papers examining the geophysical and social causes of rip-related deaths. Paper 1 demonstrates a novel method for mapping bathymetry within rip channels – topographic low spots in the nearshore resulting from feedback amongst waves, substrate, and antecedent bathymetry. The location and orientation of rip channels are investigated in Paper 2, which analyzes bathymetric inter-scalar anisotropy. Paper 3 builds on rip detection by evaluating beachgoer knowledge alongside rip presence to evaluate physical environment control on swimmer exposure. Altogether, the project presents new methods to improve prediction and warning systems with the geocomputation and provides mitigation practices for increasing safety by designing and building geomorphologically informed beach access. As a whole, the dissertation evaluates both human and physical geographies of rip currents, a naturally occurring phenomenon which becomes hazardous when entered by vulnerable individuals. Results can inform policy makers of a range of rip fatality mitigation methods: developing frequent nearshore maps to observe rip channel behavior, automating the detection of rip channels, and designing beach access controls informed by morphology.

Figure 1: The dark gap of a rip current flowing seaward cuts the breaking waves at Bondi Beach, Australia. 4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Pressure, force, and fluid velocity distributions due to tsunami bore impact on a simplified coastal building at various headings Wei-Liang Chuang* & Kuang-An Chang Zachry Department of Civil Engineering, Texas A&M University, College Station, Texas, USA *[email protected]

Abstract The present study investigates the tsunami bore impingement on a simplified, rectangular costal building sitting on a 1/10 sloping beach in a laboratory. Four different orientations, 0°, 15°, 30° and 45°, were tested under the same wave condition. A tsunami-like wave of high run-up inland intrusion type was generated in a shallow wave basin. The tsunami wave broke on the sloping beach before reaching the coastal building while the bore became highly aerated upon the impact. The aerated flow was quantified by using the bubble image velocimetry (BIV) technique, and a sample result is shown in Fig. 1. Synchronized measurements of pressures, free surface elevations, fluid velocities, and surge forces were repeated 20 times for each test condition, and ensemble averaged values were used in the quantification. A comparison of the flow velocity profile between the measurements and a dam break flow solution was performed. Furthermore, the impact surge forces were calculated with the use of the measured local pressures and the results were compared with the measured forces.

Figure 1: Mean fluid velocity maps for different structure headings upon the bore impact.

4th Young Coastal Scientists and Engineers Conference – Americas Dauphin Island Sea Lab, University of South Alabama, August 21-23, 2017

Developing a model of the 2013 U.S. East Coast Meteotsunami India Woodruff, University of Delaware, [email protected] James Kirby, University of Delaware, [email protected] Fengyan Shi, University of Delaware, [email protected]

Meteotsunamis, also called meteorological tsunamis, are significant ocean waves generated by atmospheric forcing. The East Coast of the United States is highly susceptible to meteotsunamis. However, the significance of their impacts on coastal regions has only recently been recognized. There is no warning system yet developed to predict meteotsunami events in the U.S. Better understanding the mechanisms of meteotsunami generation on the East Coast can aid in developing a warning system. The objective of the project is to model the June 13th, 2013 Meteotsunami that occurred along the East Coast of the United States. The 2013 event was examined by the National Oceanic and Atmospheric Administration (NOAA) in 2014 which found the event origin to be a mesoscale convective system traveling from the Great Lakes region to the Mid-Atlantic coastline. The centerline of the storm traveled through New Jersey and across the continental shelf, whereupon it reached the mid-Atlantic shelf break and was reflected back to shore. Proudman resonance amplified wave heights, thus increasing the severity of the meteotsunami. Tide gauges from North Carolina to Massachusetts recorded the event. Data was collected from NOAA about the pressure jump, speed of the system and wave amplitudes of the event. In this study, the bathymetry data will be used to analyze the resonance phase speeds over the interested domain in order to locate areas where Proudman resonance occurs. Using FUNWAVE-TVD, a fully nonlinear Boussinesq wave model initially developed by Shi et al. (2012), the storm event will be modeled to investigate the generation mechanisms of the meteotsunami. Time series of wave heights will be compared to the data from NOAA to examine the model performance. The effect of frequency dispersion on meteotsunami characteristics and propagation will be discussed. The case study will serve as one of the benchmarks used in developing a probabilistic analysis of meteotsunami hazards along the East Coast.