sessions 91-100
Thursday, May 22 | 2:30 – 4:00 p.m.
Sessions
• #95 Storms and Resilience: Understanding Hurricane Impacts on Coastal Ecosystems and Infrastructure
• #96 Compound Flood Risk Assessment along the Gulf Coast – Advances in Practice and Methods
• #97 Coastal Dynamics and Restoration: Navigating Change in Gulf Landscapes
• #98 Thinking Beyond Damage Dollars: The Hidden Social and Cultural Impacts of Coastal Flooding
• #99 The Chandeleur Island Restoration Project (PO-0199) – Engineering and Design
Thursday, May 22 | 2:30 – 4:00 p.m. | Room 286
#91 Navigating Offshore Wind Development in the Gulf of Mexico: Integrating Community, Environment, and Infrastructure Solutions
This session explores the challenges and opportunities of offshore wind development in the Gulf, focusing on community engagement, environmental impacts, and infrastructure planning. Presenters will examine how proactive collaboration ensures equitable energy solutions while addressing ocean co-use concerns. Research on submarine cable installations will assess whether sediment dispersion models accurately predict environmental impacts, informing permitting and regulatory processes. Strategies for balancing wind energy development with Louisiana’s coastal restoration needs will be discussed, along with the risks posed by subsidence, sea level rise, and hurricanes. Together, these insights will guide responsible offshore wind expansion while protecting coastal resilience.
Moderator: TBC
Presenters:
• Clara Houghteling – National Renewable Energy Laboratory
• Payson Whitney – TRC Environmental Corporation
• Kristen Ampela – National Renewable Energy Laboratory
Organizer: Cameron Poole – GNO, Inc.
Ocean Co-use and Local Readiness for Gulf Coast Offshore Transmission Planning
Clara Houghteling – National Renewable Energy Laboratory
There are many users of the ocean environment along the Gulf coast, including recreational and commercial fishermen, boating, shipping, marine minerals leasing, coastal restoration, etc. The Gulf states, including Louisiana, and other stakeholders have been expressing an interest in offshore wind transmission considerations for several years and have learned from Atlantic states that this is a crucial step that needs to be addressed early in the offshore wind development process.
The Community Readiness for Gulf of Mexico Offshore Wind Transmission Planning project analyzed impacted or potentially impacted communities and other ocean users in the region including Tribal Nations, African American descendent communities, southeast Asian communities, Isleños, self-identifying “Cajuns”, and other groups who have historical and cultural ties to the coastal region. Researchers led a stakeholder mapping exercise to identify needs related to ocean co-use, solutions to mitigate any potential negative effects, and perceived benefits of offshore wind locally (e.g., air quality/health, energy outages). Researchers conducted interviews to understand stakeholder requirements and the implications of offshore wind transmission, and developed examples of inclusive energy solutions that enable coastal residents to participate in the transmission siting process, with a focus on the equitable distribution of energy benefits and burdens.
Submarine Cable Installation: Do Sediment Dispersion Predictions Match Real Environmental Effects?
Payson Whitney – TRC Environmental Corporation
Regulators and stakeholders seek reassurances about jetting impacts from submarine cable installation during the permitting stage. Often their concerns relate to effects on the environment or livelihoods and the perceived uniqueness of their waterbody. Sediment dispersion modelling has become an important aspect of assessing potential environmental impacts of submarine cable installation to provide these reassurances and secure permits. Do the models accurately predict the sediment dispersion and potential water quality impacts that occur when the cable is jetted into place? This presentation will provide an overview of typical impacts associated with cable jetting installations. It will then describe sediment dispersion modelling and monitoring techniques, typical water quality criteria imposed in permits, and results of suspended sediment/water quality monitoring performed during jetting installations. It will then provide case study examples from Northeastern US submarine cable installations that show comparisons of predictive modelling and field monitoring results. These case studies indeed demonstrate that predictive sediment dispersion modelling is conservative and provides a means for developing reasonable and achievable water quality criteria and monitoring requirements that can be applied to jetting installations of submarine cables. Understanding these effects and providing the reassurances to regulators and stakeholders will be increasingly important as the offshore wind market expands into the Gulf of Mexico, resulting in increased cable jetting operations.
Environmental Considerations for Gulf Coast Offshore Transmission Planning
Kristen Ampela – National Renewable Energy Laboratory
The U.S. Bureau of Ocean Energy Management (BOEM) awarded its first offshore wind lease in the Gulf of Mexico region to RWE Offshore US Gulf, LLC in August 2023 and in July 2024 BOEM announced that Hecate Energy Gulf Wind LLC submitted an unsolicited lease request for another area. However, to date, there has not been an assessment of siting considerations related to coordinated transmission scenarios associated with hypothetical, long-term, offshore wind energy development in the Gulf of Mexico. Environmental risks in this sub-tropical region include sensitive natural offshore and onshore habitats, barrier islands and deltaic zones, and a shoreline that is being rapidly eroded by sea level rise and hurricanes. Climate risks are a major factor along the Gulf coast with the impacts of subsidence, sea level rise, and hurricanes causing significant land loss. The Environmental Considerations for Gulf of Mexico Offshore Wind Transmission Planning project analyzed the risks to coastal habitat from climate variables to determine potential implications for future transmission cable routing. Regions of the coast that are particularly vulnerable to climate change have been identified, along with the sensitivity of points of interconnection to future climate change and implications for future transmission. Regions of the coast that are particularly sensitive to land loss have been identified, along vulnerable areas.
Thursday, May 22 | 2:30 – 4:00 p.m. | Room 287
#92 Tools of the Trade
This lightning session offer a fast-paced and entertaining introduction to a range of novel and innovative approaches related to coastal protection and restoration. The session showcases a diverse collection of quantitative tools and methods with applications ranging from data collection and analysis, modeling, design, and communication. Individual presentations touch on topics such as combining numerical models with AI and machine learning, online resources and data sharing, new ways to think about cost-benefit analysis and using human stories to contextualize modeling. Recognizing that scale of effort needed to protect and restore coastal Louisiana, and the complexity of the system, requires integrating diverse ideas to identify creative solutions, the range of tools presented here is intended to spark interdisciplinary thinking and inspire collaborative conversations.
Moderator: Elizabeth Jarrell – CPRA
Presenters:
• Chris Kees – LSU
• Jin Ikeda – LSU
• Peter Bacopoulos – LSU
• Shabnam Mirheidarian – LSU
• Linoj Vijayan – LSU
• Jason Fleming – Seahorse Coastal Consulting LLC
• Gongqiang He – Olsson
• Daoyang Bao – LSU
• Megan Poole – University of Texas at Austin
Advances in digital twins for coastal and riverine ecosystems
Chris Kees – LSU
This presentation explores the potential of digital twins in managing and preserving coastal and riverine environments. As anthropogenic and climate induced changes modify coastal ecosystems, the concept of digital twins is evolving into a powerful tool for enhancing our understanding and response strategies. By creating dynamic, virtual representations of coastal systems —integrating data from satellite imagery, sensors, and predictive models—stakeholders can simulate various scenarios, assess environmental impacts, and optimize resource management. We will discuss two case studies showcasing implementations of digital twins, one a river and the other, a coastal system influenced by flood control structure. Furthermore, we will address challenges and opportunities presented by this technology, including data integration, stakeholder engagement, and the need for interdisciplinary collaboration.
Temporal-spatial variations in salinity and water level in Louisiana coastal wetlands for 16 years
Jin Ikeda – LSU
The Mississippi River Delta is the most extensive fluvial-dominated delta system in North America, providing crucial ecosystem services. However, in 2023, Louisiana faced one of the driest summer-fall seasons in the 21st century. This study investigates the impact of the 2023 drought and decadal wetland hydrological trends in coastal Louisiana using data from the statewide Coastwide Reference Monitoring System (CRMS), which consists of over 300 monitoring stations measuring hourly hydrodynamics since 2008. We analyzed salinity and water level variations across nine coastal basins and five vegetation types using a 12-month moving average of observed data. Our findings reveal that salinity levels in 2023 recorded the highest values on saline, brackish, and intermediate marshes in the CRMS observations. Additionally, we create salinity maps of Louisiana wetlands at a resolution of 0.005 degrees (~500 m) based on monthly averaged point-based observations. The extent of the tidal freshwater zone (salinity is less than 0.5 ppt) and tidal oligohaline zone (salinity between 0.5 and 5 ppt) under extreme drought conditions in 2023 are compared to other years. We developed automated Python-based data analysis and visualization tools by leveraging the high-density network system. This visualization tool supports analysis, regional management strategies, and engineering design. Furthermore, this study will demonstrate our ongoing efforts to understand better coastal wetland responses to climate change and sea level rise in the fluvial-dominated delta.
Numerical modeling of hydrodynamics in Reach E of the Morganza-to-Gulf levee system for evaluation of ecological design in the impounded wetland
Peter Bacopoulos – LSU
A pre-existing model of the Morganza-to-Gulf levee system encompasses the Louisiana coast from Bayou Lafourche (eastern bound) to Vermilion Bay (western bound). The model mesh – i.e., geometric representation of the continuous land/waterscape – describes Houma Navigation Canal, Falgout Canal and Dularge Canal surrounding Reach E of the levee system. The mesh is employed in a year-long simulation (October 1, 2021 – September 30, 2022) with an advanced circulation (ADCIRC) model. Model results of water levels and discharges are validated near Reach E against data measured at floodgates managed by Terrebonne Levee Conservation District. The model mesh is refined in the impounded area behind Reach E to represent an ecological design consisting of mounds, each 32-m radius in size. The mounds are designed with an apex of 70 cm above datum to support a diversity in ecological function through the vertical range of supratidal, intertidal and subtidal zones provided in the design form. The mounds (589 in total) are spatially distributed along the periphery of the existing wetlands. The modified model mesh is applied in ADCIRC simulation to assess the design’s performance in stabilizing the impounded wetlands from continued degradation. Simulated water levels are diagnosed in terms of hydroperiod across the vertical range of elevation as pertinent to wetland vegetation. Simulated velocities are evaluated for peak and residual (net) as relevant to potential sediment retention and transport pathways. The hydrodynamic analysis is adaptable for performance evaluation of the ecological design under management strategies like freshwater flow diversions.
Wetland evolution and accretion dynamics in coastal Louisiana: Beyond vegetation equilibrium models
Shabnam Mirheidarian – LSU
This study leverages CRMS data to investigate the complex dynamics of wetland accretion in coastal Louisiana, moving beyond traditional vegetation equilibrium models. By examining aboveground and belowground biomass, along with soil properties such as bulk density (BD), organic matter (OM), and vertical accretion rate (VAR), we incorporate the impacts of episodic deposition, erosion, belowground compaction, swelling, and hydrogeomorphic species zonation. Our analysis of organic loading (Morg) and aboveground biomass (AGB) across the Louisiana coast, categorized by basin and salinity type, reveals non-linear relationships that challenge the assumptions of the Marsh Equilibrium Model (MEM). In microtidal environments, these dynamics suggest that equilibrium solutions based solely on hydroperiod and biomass productivity are insufficient. This study highlights the need for more advanced models that integrate episodic events, geomorphic processes, and subsurface dynamics to better predict vegetation resilience and wetland sustainability. Additionally, species-specific biomass correlations have been refined, and ongoing efforts are focused on investigating the role of species to improve predictive capabilities for wetland restoration and management in coastal Louisiana
Digital Twin for a Riverine Environment
Linoj Vijayan – LSU
Digital twins (DT) are virtual representations that mirror real-world systems (physical twin), existing in the digital realm. Research and development on digital twins for natural environments like rivers and the coast is still in its infancy. A numerical model that forms the basis of a riverine digital twin is presented here. Virtual representations of dynamic environments like a river require coupling of hydrodynamic and sedimentation models, potentially resolving a wide range of spatio-temporal scales. Process fidelity in numerical models is particularly sensitive to surface features like bathymetry. In this work, multilevel unstructured meshes generated that are adaptively refined to resolve critical structures that strongly impact the flow and transport. This ensures an optimal scalable virtual representation of the DT in terms of quality and size. This digital twin is developed using a very high-resolution bathymetric dataset from US Army Corps of Engineers surveys. Dynamic process variables are assimilated into the twin from stations within the domain, for calibration and validation of the DT. The digital twin requires a solution of coupled hydro- and morpho-dynamic equations, including accurate and dynamic representations of the topography and bathymetry. A dynamic wetting and drying process occurring along the banks and flood plains of the river modeling of which can be sensitive to mesh quality. A depth-averaged two-dimensional model and a full three-dimensional model are being developed to support varying degrees of fidelity to the hydrodynamic processes that occur in the physical twin.
Real Time Model Guidance and Decision Support for Operators of the Hurricane Protection System
Jason Fleming – Seahorse Coastal Consulting LLC
The ADCIRC coastal ocean model has been used extensively over the last twenty years for offline design and risk analysis studies for the hurricane protection system. Starting in 2006, our team has used this same model along with forecast/advisories from the National Hurricane Center (NHC) to produce model guidance for wind and water levels in real time as hurricanes are bearing down. This information is used by decision makers to understand the impacts they are facing under different scenarios of how a storm may play out. In 2008, the Coastal Emergency Risks Assessment (CERA) web mapping application was used for the first time to deliver an easy-to-use interactive data exploration and dissemination for these model results. This information is used by CPRA and the New Orleans District of the US Army Corps of Engineers as well as US public sector agencies including NOAA, FEMA, the Coast Guard, and other Corps Districts, among many others. The underlying technologies are described, and examples of the value of our real time storm surge model guidance to protect life and property over the last eighteen years are provided, including Hurricanes Gustav (2008), Isaac (2012), Laura (2020), Beta (2020), Delta (2020), Ida (2021), Beryl (2024), and Francine (2024).
Flor 3-D Modeling of Hydraulic Design for the Grand Pass Salinity Control Structure
Gongqiang He – Olsson
The Bayou Dularge Ridge, Marsh, and Hydrologic Restoration project aims to mitigate salinity intrusion into Lake Mechant by controlling water flow through Grand Pass. As part of the project, a salinity control structure is proposed for Grand Pass, a critical feature intended to regulate the exchange of water between Caillou Lake and Lake Mechant. The study evaluates multiple design alternatives for the structure to ensure effective salinity control while maintaining boater safety and structural stability in this dynamic environment.
To achieve this, a calibrated FLOW-3D model was developed to simulate the complex three-dimensional hydrodynamics in the vicinity of the proposed structure. FLOW-3D is a computational fluid dynamics (CFD) software that solves the complete 3D Reynolds-Averaged Navier-Stokes (RANS) equations with turbulence closure. It is inherently non-hydrostatic and gives more accurate vertical flow profiles than models that are based on hydrostatic shallow water equations.
Three structure designs were evaluated: a broad-crested rock weir, a sheet pile wall, and a stepped rock weir. Each design was analyzed under different flow conditions to assess velocity profiles, bed shear stresses, and potential erosion risks. The FLOW-3D model results revealed differences in flow distribution, particularly how the designs impacted flow velocities near the banks and within the channel. These findings are critical for the placement of scour protection and ensuring the structure’s long-term stability.
A Hybrid Numerical and Machine Learning Model Framework for Rapid and Accurate Spatial Flood Prediction
Daoyang Bao – LSU
Flood prediction is essential for decision-making and risk mitigation against flood hazards. Traditional prediction approaches, including process-based numerical models and data-driven machine learning (ML) models, each have their strengths and limitations. Numerical models provide accurate spatial predictions but are computationally intensive, while ML models offer faster predictions but are limited by data availability.
To address these challenges, we developed a novel framework that combines numerical models with ML models for rapid and accurate spatial flood prediction. This framework includes a prediction model, a numerical model, and a mapping model. The prediction model, based on Long Short-Term Memory (LSTM) networks, is trained on time series data of water depth, discharge, and wind. The numerical model, a dynamically two-way coupled hydrological-ocean model, integrates WRF-Hydro and ROMS via COAWST, capturing the complex interactions between hydrological and oceanic processes. The mapping model utilizes ML to map spatial flood depth distributions.
When applied near Galveston Bay, TX, our hybrid approach demonstrated highly accurate flood predictions with a remarkable level of computational efficiency. It produced flood maps with average differences of 0.2 m compared to traditional numerical simulations, and did so in just 4 seconds using a single core, as opposed to 16 minutes with 480 cores in conventional models.
This hybrid approach exemplifies the potential for rapid, accurate spatial flood predictions. As part of the Gulf of Mexico Coastal Hazards Forecast.
Archiving Loss: Capturing Residents’ Relation to Louisiana’s Eroding Coast
Megan Poole – University of Texas at Austin
Scholars and decision makers consult archives to gather what will help us give an account—we consider the archive a place for finding what will help us reason out or make sense of something. When it comes to consulting archives that capture climate change’s effects on the Louisiana coastline, we are often caught up in models and figures: projections of ocean temperature, surface temperature, sea level rise. Born and raised in Southwest Louisiana, I know these models. I know the flood maps that change after each major hurricane because damaged marsh no longer holds storm surges at bay. I know the Google Earth time lapse showing coastal erosion eating our shoreline. I know federal resilience indexes, which say that we are hardier than almost anyone else in the nation—no fine print saying that there are few left to measure.
And I’m starting to worry that—decades from now—those models will be the primary archive of my hometown, the definitive tale of what became of that place, a panoply of existences reduced to lines on charts, colors on maps. This presentation asks, then: When models are our primary way of bearing witness, what do we miss? Likewise, when we need facts and numerical data to consider testimony “credible,” whose accounts do we dismiss? Climate models, I argue, are too far removed from place, too disconnected from all the experiences therein, to offer a full archive for witnessing loss on the Louisiana coast. In turn, I propose a method for contextualizing models with human stories that capture the memories that tie land to culture.
Thursday, May 22 | 2:30 – 4:00 p.m. | Room 292
#94 Coastal Carbon Session 3 of 3: Opportunities and Constraints for Crediting Coastal Wetland Carbon in the State of Louisiana
The State of Louisiana is investigating the potential of developing carbon credits from coastal restoration and risk-reduction projects, to sell on the voluntary market as an additional revenue source for the overall coastal program. Achieving financially-viable accreditation of these restoration and risk-reduction projects will require updates to existing carbon-crediting methodologies or creating additional methodologies (and/or standards) that would include addressing some of the known uncertainties and challenges specific to the coastal zone of Louisiana. Unlike most US states, some 85% of coastal Louisiana is under private ownership. Although state legislation addresses aspects of carbon credit ownership from coastal restoration, legal uncertainty remains. For example, whether carbon credits are considered within the bundle of rights associated with property or are considered real property. Another challenge is the highly-dynamic ecology and geomorphology of the Mississippi Delta, which is challenging in terms of current definitions of sequestered carbon permanence and additionality, both of which are primary requirements for accreditation. However, there is ongoing demand from industry and other private landowners to either generate carbon offsets and / or to generate revenue from carbon sequestered due to funded restoration on their land. This panel discussion will consider multidisciplinary aspects of the opportunities and constraints of coastal carbon accreditation in coastal Louisiana.
Moderator: Dan Friess – Tulane University
Panelists:
• Jim Bergan – Delta Land Services, LLC
• Tim Carruthers – The Water Institute
• Claude Griffin – US Business Council for Sustainable Development
• James Pahl – CPRA
Organizer: Dan Friess – Tulane University
Thursday, May 22 | 2:30 – 4:00 p.m. | Room 290
#95 Storms and Resilience: Understanding Hurricane Impacts on Coastal Ecosystems and Infrastructure
This session will focus on the transformative effects of hurricanes on coastal landscapes, ecosystems, and resilience strategies. It will bring together research on hurricane-induced changes, from salinity variations and sediment exchange to the survival of wetland vegetation and the performance of engineered coastal defenses. Presentations will explore how storm dynamics influence sediment deposition and soil characteristics, revealing their role in wetland elevation changes and long-term ecosystem stability. Speakers will highlight the interplay between natural processes and engineered solutions, such as nature-based breakwaters and marsh creation projects, which serve as both ecological habitats and storm mitigation measures. Presenters will explore the importance of understanding salinity dynamics and storm-driven sediment transport to inform restoration efforts and enhance coastal resilience against rising sea levels and increasing storm intensity. By examining case studies like Hurricane Ida and leveraging long-term monitoring systems, the session provides actionable insights into designing adaptive strategies for coastal infrastructure and ecosystems.
Moderator: Denise Reed – UNO
Presenters:
• Xiaochen Zhao – LSU
• George Washburn – Pontchartrain Conservancy
• Glen Curole – CPRA
• Ryan Waldron – Stantec
• Stephanie Procopio – LSU
• Kayla Willis – Tulane
• Ioannis Georgiou – The Water Institute
• Rob Howard
Investigating Hurricane-induced Salt Variation across the Land-Estuary-Ocean Continuum Using A Dynamically Coupled Hydrological-Ocean Model
Xiaochen Zhao – LSU
Salinity variations across the Land-Estuary-Ocean (LEO) continuum are critical for coastal ecosystems and provide socio-economic benefits to nearby communities. However, evaluating these variations is challenging due to the complex interactions of terrestrial and oceanic processes, including river discharge, winds, tides, sea level rise, and storms. This study incorporates a salinity module into a newly developed, dynamically coupled hydrological-ocean model using the COAWST platform. Hurricane Florence (2018) serves as a case study to examine how various physical processes influence salinity dynamics and freshwater plume development in the Cape Fear River Estuary, North Carolina. The model simulated saltwater intrusion into freshwater wetlands upstream of the estuary and demonstrated that salinity in the estuary was initially regulated by wind-driven water level gradients, followed by a dominant influence from significant river runoff. In the coastal ocean, runoff created a large freshwater plume that moved westward, driven by the interplay between runoff, winds, and the estuary’s geomorphology. This study demonstrates that the coupled model is a valuable tool for representing saltwater intrusion, tracking coastal pollutants, and understanding water and material exchange across the LEO continuum.
Hurricane Ida’s Effect on Recently Planted Forested Wetland Saplings
George Washburn – Pontchartrain Conservancy
Forested wetlands are essential to Coastal Louisiana for their ecological services, particularly their aid in mitigating hurricane-force winds and storm surges. As more named hurricanes hit the Gulf Coast, the role of these wetlands is becoming more critical. While these forests help to act as defenses for our communities, they also suffer massive losses of mature trees when high-level storms land. Pontchartrain Conservancy (PC) has planted over 100,000 trees in 15 years across 5 locations in Southeast Louisiana, including the LaBranche Wetlands, the Central Wetland Unit (CWU), and forested wetlands near Madisonville. PC planted Baldcypress (Taxodium distichum), Water Tupelo (Nyssa aquatica), and Green Ash (Fraxinus pennsylvanica) in all three locations in the 6-12 months before category 4 Hurricane Ida. PC has shown that survival in Madisonville is the highest at ~90%, while over 80% in LaBranche and ~75% in the CWU. Less than two years old when the storm hit, these trees almost fully recovered, showing only a stalling height change for their first year and growing thicker in diameter. The CWU has the most stagnated hydrology and highest salinity of the three sites, which may explain poorer survival.
This work implies that while mature trees suffer instability during category 3+ hurricanes, and some may question the efficacy of planting new trees when named storms are becoming more common along the Gulf Coast, freshly planted trees can weather these storms. When planting locations are carefully chosen, high survival and growth rates can be seen despite large storms.
Measuring the Settlement and Shoreline Change of a Large Marsh Creation and Foreshore Rock Dike Project Over Time and Hurricane Disturbance
Glen Curole – CPRA
The Little Lake Shoreline Protection/Dedicated Dredging Near Round Lake (BA-37) project is large marsh creation (920 acres) and shoreline protection (25,976 ft rock dike) project. The marshes constructed in 2006 are intermediate marshes that are surrounded by highly organic marshes. Elevation grid models were created using topographic survey data to determine volume changes in the marsh creation area. Marsh creation mean elevations over eight surveys and a sixteen year time period were compared to estimated values derived from consolidation curves to gauge settlement in the created marsh. Pre and post-construction shoreline position data were analyzed to estimate shoreline changes along the marsh creation area and the lake rim shorelines.
Pre Hurricane Ida (2006-2016), the elevation data shows that the constructed intermediate marshes were settling at a slightly slower rate than the anticipated consolidation curve and have suffered only minor acreage losses since construction. Surprisingly, elevation data (2022) collected in the aftermath of this category 4 hurricane reveals that these marshes are still settling at a slower rate than the predicted curve although edge marshes incurred erosion. The pre Hurricane Ida shoreline erosion rates in the marsh creation and lake rim areas have been reduced since construction. Subsequent shoreline data (2021) displays increased transgressions in the marsh creation and subaerial land loss in the lake rim areas. The marshes surrounding the project experienced unprecedented land loss following the passage of Hurricane Ida.
A Resilient Nature-Based Breakwater for SAV Restoration in the Barataria Basin Estuary
Ryan Waldron – Stantec
Prior to the Deepwater Horizon spill, SAV thrived along the shorelines of Lakes Salvador, but the spill and subsequent stresses caused significant loss.
This project aims to restore SAV habitat by constructing a nature-based breakwater system, to reduce bed shear stresses. Through rigorous modeling, the breakwater was designed to withstand high wave energy and water levels while providing suitable habitat for SAV to thrive. Construction occurred from December 2023 to October 2024, with post-construction monitoring underway to evaluate effectiveness in creating over 100 acres of suitable habitat for the goal of establishing 50 acres of SAV.
As construction was nearing completion, Hurricane Francine’s eastern eyewall passed over the lake. The breakwater withstood the storm with no damage, although flotant marsh detached from nearby shores and accumulated on the lee of the breakwater. Though it was not intended to perform in this way, the breakwater was resilient to the storm and prevented the flotant from washing into open water.
The project highlights the importance of interdisciplinary collaboration between ecology and engineering in addressing coastal challenges. By combining natural and engineered solutions, this approach offers valuable insights for future restoration efforts, balancing ecosystem health with shoreline protection.
Restoring SAV also provides significant economic and environmental benefits to coastal communities. By re-establishing SAV habitats, the project strengthens both the coastal ecosystem and the livelihoods of those who depend on it.
Weather Event Impacts on Soil Characteristics of a Salt Marsh in the Barataria Basin, Louisiana
Stephanie Procopio – LSU
Hurricanes and other storms can greatly affect salt marsh soil characteristics. Thus, marsh soil characteristics can be used to determine when different weather events occurred. Elements in the soil are proxies for marine vs terrestrial factors. Marine indicators are more typical of storm surges than terrestrial indicators are. A salt marsh near the Coastwide Reference Monitoring System (CRMS) 0224 station in the Barataria Basin was chosen as our study site. Three cores were taken at 1 m (core ID: M1), 5 m (M5), and 30 m (M30) from the marsh edge. Each core was 4 meters long and taken in 50 cm increments using a Russian peat Borer with twenty-four 50 cm cores in total. Back in the laboratory, X-Ray Fluorescent Spectroscopy (XRF) was used to measure elemental composition of all cores in 1 cm increments. The XRF data projected elemental concentration changes with depth in each core. Potential storm layers and fluvial flooding correlated across all three cores. Each core showed 2 or 3 storm surges in recent history and a transition zone with fluvial flooding leading to several more storm surges. To further identify storm surge events, the cores were sliced into 5 cm or 10 cm layers and analyzed for water content, bulk density, loss on ignition, grain size, as well as carbon and nitrogen content. The continued research will focus on groundwater exchange along with soil characteristics in relation to weather dynamics.
Unveiling the impact of tropical cyclone frequency on coastal wetland surface-elevation change: a 14-year comparative analysis
Kayla Willis – Tulane
Wetlands are highly valuable yet vulnerable landscapes within coastal regions, increasingly subject to both natural and anthropogenic pressures such as sea-level rise, subsidence, and diminished sediment supply. Furthermore, the potential for tropical cyclones to pass through these regions adds a layer of complexity, potentially exacerbating the challenges faced by these vulnerable ecosystems. Previous studies have suggested the possibility of increased vertical accretion on the wetland surface during major storms, which could counterbalance rising sea level. However, the relationship between storm frequency and the resilience of coastal areas remains unclear, particularly considering wetland subsidence that makes surface-elevation gain less than the vertical accretion. We have investigated how changes in tropical cyclone frequency between two 7-year periods (2009 to 2015 and 2016 to 2022) influence wetland responses in coastal Louisiana, with the larger number of tropical cyclones in the more recent period shedding light on how increased storm frequency impacts surface-elevation change. Utilizing a comprehensive coastal monitoring system and hurricane data from NOAA, we observe that more frequent hurricane passages correlate with enhanced surface-elevation change. We also examine storm-surge data, which can provide further insight into the complex interactions between coastal wetland surface-elevation change and hurricane passages.
Storm Dynamics Control Sedimentation and Shelf-Bay-Marsh Sediment Exchange along the Louisiana Coast
Ioannis Georgiou – The Water Institute
Hurricanes can benefit wetland accretion by augmenting the delivery of mineral sediment, an essential process allowing marshes to offset submergence during rising sea levels. Using Hurricane Gustav (2008, Louisiana) as a control, we examined eight synthetic storms with varying characteristics (track, speed, intensity, size) to evaluate sediment exchange between the inner shelf and bay and bay-to-marsh interfaces. All storms showed net landward sediment exchange from the inner shelf to the bay to the marsh—storms with closer proximity, higher intensity, and slower forward speed positively correlated with net sediment exchange; storm size had little impact. Except for slow-moving storms (½ speed of Gustav), our analyses suggest that most hurricane scenarios cause net bay erosion, because more sediment is conveyed to landward wetlands than is replenished from erosion of the inner shelf. Our results suggest that the ongoing deepening of the bay will likely worsen because of rising sea levels.
Analysis of Ground-Truth Data Collected from Hurricanes at Landfall and Its Relationship to Coastal Resilience
Rob Howard
Co-authors: James Rob(ert) Howard, Ph. D., Meteorologist, Ponchatoula, LA, Stephanie M. Wingo, Ph. D., UAH / NASA Interagency Implementation and Advanced Concepts Team (IMPACT), Huntsville, AL, Scott F. Blair, Science Operations Officer, National Weather Service, Topeka, KS, Sara W. Mayberry, Geographic Information Systems Consultant, Hoschton, GA, Donald R. Jones, Meteorologist, National Weather Service, Lake Charles, LA, Charley Kelly, Forecaster, National Weather Service El Paso, TX Forecast Office, Santa Teresa, NM, Christopher Cupp, Navy Liaison in the Alaskan Command Joint Operations Staff, Anchorage, AK, Michael Efferson, Lead Forecaster, National Weather Service, New Orleans/Baton Rouge Forecast Office, Slidell, LA
Collection of direct surface meteorological and hydrologic data from coastal regions during hurricane landfall events remains somewhat problematic and data scarce even with the advent of new technologies. Still, real-time weather data has been safely collected in coastal areas within tropical cyclones at landfall over the past 30 years, including events such as Hurricanes Katrina and Rita (2005). These data are vital to accurately documenting what transpires during these devastating events. Equally if not more important is the application of research conducted using these data to the forecast of wind, surge, and freshwater flooding impacts in future events, the potential design of structures and landscapes for coastal resilience in the face of future impacts, and the potential development of both onshore and offshore wind energy structures and the design of these systems to resist impacts from future storms.
Observations and analysis of high-resolution (1 Hz) meteorological data, primarily wind data, from four hurricanes in 2004 and 2005, collected in a joint effort between students, staff, and faculty from academia with the aid of the general public, emergency management personnel, and officials from other government agencies, will be presented and directly related to each of the applications described above. Specifically, surface data recorded from at or near the landfall locations of Hurricanes Katrina and Rita (2005) in Louisiana, the only data of its kind successfully collected from each of these events in real-time at or within a few kilometers of the coastline and within the inner-core and eye-wall of each hurricane, will be used in the analysis, with supplemental information provided from data recorded in Hurricane Frances (2004) in Florida and/or Hurricane Ivan (2004) in Alabama. The presentation will demonstrate the need for continued coastal surface data collection and study within future tropical cyclones, will show the need to provide more complete and uniform datasets, and will demonstrate how natural and structural mitigation efforts can lessen the impacts of these events or how the lack thereof leads to worsening impacts over time. This should help society improve recovery efforts and resistance to future hurricane impacts.
Thursday, May 22 | 2:30 – 4:00 p.m. | Room 289
#96 Compound Flood Risk Assessment along the Gulf Coast – Advances in Practice and Methods
Coastal areas in the Gulf of Mexico and along the Mid-Atlantic are frequently threatened by the combined flood hazards driven by interacting fluvial, pluvial, and coastal hydrodynamics. The combined occurrence of these flood drivers, referred to as coastal compound flooding, can be more severe than can be accounted for by single-mechanism analysis exercises while also posing a greater analytical challenge to quantify.
Existing guidance documents on design and analysis methods, at both state and federal levels as well as in academia, lack consistent direction on quantification and incorporation of compound flood risk and can frequently lead to under-designing and over-designing of structures leading to cost inefficiencies and increased risk to people and property. Developing efficient modeling tools that can quantify compounding flood depths during real time events will greatly improve efficiency and decision making during real time events. These modeling tools in conjunction with effective probabilistic frameworks can be leveraged to develop improved data on current and future flood risk that can improve planning and design initiatives.
The panel will bring together experts from Gulf Coast states to discuss the state of the science of tools and methods and lessons learned from implementation.
Moderator: Mark Bartlett – The Water Institute
Panelists:
• Thomas Wahl – University of Central Florida
• Amin Kiaghadi – Coastal Modeling Team Lead, Texas Water Development Board
• Anne Coglianese – City of Jacksonville
• Muthu Narayanaswami – Water Institute
• Lauren Schmied – Baird
Organizer: Brett McMann – The Water Institute
Thursday, May 22 | 2:30 – 4:00 p.m. | Room 288
#97 Coastal Dynamics and Restoration: Navigating Change in Gulf Landscapes
This session explores land loss driven by tidal erosion, the geological evolution of unique marsh ecosystems, and the performance of, and impacts to, restoration and shoreline protection efforts in response to recent storms. From accelerating elevation gains signaling vulnerability to erosion, to the restoration of Mermentau micro-bayhead delta marshes, presenters will consider how historical and geological contexts inform contemporary challenges. Louisiana’s extensive shoreline mapping efforts reveal how storms like Hurricanes Zeta, Ida, Laura, and Delta have shaped the coast and tested restoration projects. Insights into shoreline protection strategies demonstrate how targeted efforts can bolster resilience in high-risk areas.
Moderator: Alisha Renfro – National Wildlife Federation
Presenters:
• Leigh Anne Sharp – Coastal Protection and Restoration Authority
• Juan Moya – Stantec
• Mark Byrnes – Applied Coastal
• Benjamin Beasley – Applied Coastal
Accelerating Elevation Gain Indicates Land Loss Associated with Tidal Erosion at Coastwide Reference Monitoring System Sites
Leigh Anne Sharp – Coastal Protection and Restoration Authority
Coastwide Reference Monitoring System (CRMS) sites were initially established in vegetated marsh at least 10 m from the water’s edge between 2006 and 2008. Prior to Hurricane Ida, ten CRMS sites had seen all vegetation converted to open water at the boardwalk where elevation and accretion are measured. Seven of the ten were gaining elevation as they lost land. Further, we observed an acceleration in elevation gain that preceded the conversion from vegetated marsh to open water. Surface elevation trajectories at most CRMS sites are positive. A sudden acceleration in elevation gain in the absence of delta formation or a new sediment source indicates increasing vulnerability to tidal erosion in lower deltaic plain marshes.
A Geological Perspective of the Mermentau Marshes In East Texas and Western Louisiana: The Restoration of Micro Bayhead River Deltas
Juan Moya – Stantec
Between 18k and 75k years ago, the Gulf landscape was dominated by incised streams responding to low sea levels sea levels. The shorelines were up to >300 feet below its present location. The landscape was dominated by incised streams responding to the low sea levels. About 4k-5k years, he coastal plain watersheds started to inundate the incised channels as the response to the last the sea level rise event. The channel fills are now called the Mermentau Alloformation (MA) (Heinrich et al. 2020). MA is a geologic indicator of valley fill, the accumulation of thick organic deposits, and catastrophic flooding. The MA is still active today (Mermentau flooding), feeding coastal lowlands with fine sediments and the recent marsh-hydric soils. Texas data shows that almost 100% of the Mermentau deposits are the substrate of many coastal wetlands bordering the bays (out of the barrier islands). We are calling these unique ecosystems Mermentau marshes.
The geologic and geomorphologic analysis of 20 sites of Texas Mermentau marshes show that they behave as micro-bay head deltas, expressing specific processes of disintegration of the hydric soils and substrates. A comparison of the evolution of these Mermentau micro-bayhead delta marshes with the large bayhead river deltas is presented. The results show similar trends in the way the marshes disintegrate. We also compared the Mermentau marshes from central Texas and western Louisiana, which show significant differences. After this analysis, we suggest key restoration concepts for these unique Mermentau micro-bayhead delta marshes.
Louisiana Shoreline Mapping and Change Assessment, 1800s to 2021: Impacts of Recent Storms and Barrier Island Restoration
Mark Byrnes – Applied Coastal
The Barrier Island Comprehensive Monitoring Program (BICM) provides comprehensive data on Louisiana coastal environments that support planning, design, maintenance, and evaluation of the coast. In 2018, existing BICM historical shoreline change data were revised, augmented, and updated, resulting in coastwide shoreline datasets for the mid-1800s to 2015. Assessment of long-term regional shoreline change trends highlights areas of large and chronic loss that have been the primary focus of shoreline restoration. This database has been updated with a 2021 shoreline, and shoreline change analysis is being performed for the periods 1880s to 2021, 1998 to 2021, and 2015 to 2021 to provide net change trends for the long-term, era of restoration, and near-term, respectively.
Initial results highlight impacts from Hurricanes Zeta and Ida for the barrier island shoreline between Raccoon Island and Sandy Point, as well as benefits of restoration activities. Passage of Hurricanes Zeta in 2020 and Ida in 2021 resulted in extensive shoreline recession along many Gulf and bayside shoreline reaches. Most of the Caminada and West Grand Terre restoration projects illustrated net shoreline stability between 2015 and 2021, indicating restoration efforts counteracted at least 6 years of erosional processes. For the Whiskey Island restoration project, net gain of 300 to 1,000 ft was documented for this period. The BICM shoreline change database enables assessment of the efficacy of sand placement for barrier shoreline restoration projects within the context of long-term and regional trends.
Regional Evaluation of Recent Storms and Shoreline Protection Along the Southwestern Louisiana Coast, 1880s to 2021
Benjamin Beasley – Applied Coastal
The Barrier Island Comprehensive Monitoring Program (BICM) was implemented to support planning, design, maintenance, and evaluation of restoration and protection projects in coastal Louisiana. In 2018, BICM historical shoreline change data were revised, augmented, and updated, resulting in coastwide shoreline datasets for the mid-1800s to 2015. Assessment of long-term regional shoreline change trends highlights areas of large and chronic loss that have been the primary focus of shoreline restoration and protection. A 2021 shoreline was added to the existing database to document recent changes and allow an evaluation of potential storm damage reduction associated with restoration/protection projects.
Comparison of recent erosion trends with historical shoreline changes for the southwestern Louisiana coast highlights shoreline impacts from Hurricanes Laura and Delta between Calcasieu Pass and Freshwater Bayou, as well as the influence of shoreline protection structures along the coast of Rockefeller Refuge. Passage of Hurricanes Laura and Delta in 2020 resulted in extensive shoreline recession and washover deposition along most of the southwestern Louisiana shoreline, similar to Hurricanes Rita (2005) and Ike (2009). Shoreline protection, constructed along a portion of the Rockefeller Refuge coast between 2015 and 2021, appeared to sustain less erosion and washover than adjacent coastal reaches. Spatial and temporal changes for this section of coast were quantified to evaluate the resilience of downdrift beaches to limited natural sediment transport from protected areas.
Thursday, May 22 | 2:30 – 4:00 p.m. | Room 285
#98 Thinking Beyond Damage Dollars: The Hidden Social and Cultural Impacts of Coastal Flooding
Coastal planning is heavily reliant on technical, science-based tools such as predictive models, risk indicators, ecosystem services calculations, and benefit-cost analyses to assess the impacts of natural hazards on communities. While these tools are important, they often overlook the social factors that influence a community’s ability to respond to or recover from disaster events. The research presented in this session highlights different approaches to improving flood mitigation, enhancing community resilience, addressing coastal adaptation strategies, and discussing post-disaster recovery. Each of the presenters emphasizes unique community vulnerabilities, underscoring the importance of accounting for social systems in flood risk management and disaster preparedness.
Moderator: Scott Hemmerling – The Water Institute
Presenters:
• Fahmida Akhter – LSU
• Christine Halling – UNO
• Allie Olsonoski – Environmental Defense Fund
• Utkuhan Genc – Purdue University
Introducing Socially Adjusted Vulnerability Assessment for Flood Mitigation
Fahmida Akhter – LSU
Federal agencies select the best flood mitigation project based on Benefit-Costs analysis (BCA). These BCAs’ calculations of costs and benefits often focus on property values and ignore the distribution of damages across different populations and how this might lead to different outcomes on total social welfare. For effective flood risk management that considers social vulnerability, assessing the property’s value at risk and the social factors that influence an affected community’s ability to respond to or recover from it is essential. A major driver of this is the income and wealth of at-risk populations. Thus, to address the distributional impacts (i.e., equity), it is important that BCAs are based on social welfare, where individual social vulnerability is considered through relative impacts on income. One of the ways to address equity is through diminishing marginal utility of income, which explains that welfare increases more when $100 goes to low-income people compared to high-income people. This paper aims to use this concept to produce vulnerability-weighted damage impacts for households living in single-family dwellings that make income-informed, tenure-informed estimates of marginal utilities to flood damage. We present a methodology to integrate equity into BCAs with a case study based on Jefferson Parish in Louisiana. This approach will help federal agencies decide who to target while investing and how to put different weightage for low-income communities.
The Rising Dead: The Fallout from Hazardous Flooding
Christine Halling – UNO
Louisiana has long been famed for its floating caskets after substantial weather events. Between 2020 and 2021 alone, Louisiana experienced damage to nearly 4,000 graves from Hurricanes Laura, Delta, Zeta, and Ida. In every case, each one of these people had groups of descendants who were forced to re-mourn their loved-ones while also reeling from the after-effects of a disaster on their own lives. Recovery is slow, but methodical. Requiring the mobilization of teams of air support, heavy equipment operators, anthropologists, lawyers, and funeral directors, often relying on nontechnological recovery strategies, respect of and sensitivity to the impacted communities is key. In addition, constant communication through direct community engagement and assisting the navigation of the complexities of the Federal Emergency Management Agency’s disaster relief process is essential to ensuring that the communities have agency in the rebuilding (or evacuation) of their mortuary communities. Navigating this system can be complex and challenges even the most hardened “last-responder.” Because Louisiana is not the only place experiencing these problems—recent severe weather has resulted in cemetery damage and destruction from South Carolina to Puerto Rico and from Florida to New Mexico—developing community-inclusive cemetery response plans (as opposed to mass fatality plans) is essential. This presentation is a “post-mortem” of Louisiana’s experiences from 2016-2024 being on the forefront of such hazard impacts and, until recently, also being the vanguard in its ability to respond to such events.
Integrating Community Insights: Rethinking Nonstructural Flood Risk Reduction for Resilient Coastal Protection in Louisiana
Allie Olsonoski – Environmental Defense Fund
This presentation will delve into the critical role of nonstructural flood risk reduction measures in Louisiana’s Southwest Coastal Study, emphasizing the need for a social science approach to resilience planning. The discussion will center on how communities in Cameron, Vermilion, and Calcasieu parishes perceive nonstructural strategies like home elevation and floodproofing, and their importance in the broader context of coastal protection. Drawing from the Restore the Mississippi River Delta Coalition’s ongoing research, this discussion will present qualitative data on community responses to nonstructural initiatives, exploring the challenges and opportunities in fostering engagement and participation including building trust with residents and community leaders. Additionally, it will address the gap between state and federal programs and local needs, offering recommendations on improving communication, trust, and support for nonstructural measures. By incorporating community perspectives into resilience planning, the panel will highlight strategies and recommendations to better reform nonstructural policies at the national level that meet the needs of residents today.
Using Equitable Access to Essential Services as Guidance for Investments in Coastal Adaptation
Utkuhan Genc – Purdue University
Tropical cyclones and coastal flooding are among the costliest and deadliest natural hazards in the U.S., with coastal Louisiana particularly vulnerable. Access to essential services like healthcare, utilities, and food is critical for community resilience, but population decline due to severe storm events often leads to reduced service availability in rural areas. As populations decline, businesses providing these services find fewer incentives to stay operational or to repair and reopen them if damaged in a flood event. Thus, identifying areas most vulnerable to losing access and determining which services are critical for community resilience becomes crucial to prevent further deterioration of living conditions.
In this presentation we will present an evaluation of drive-times to essential services under disruption scenarios and the criticality of each service based on population served, availability of alternative options within critical service times, and marginal drive-time for those without alternatives.
We also assess equity issues regarding access to services across sociodemographic groups among entire coastal Louisiana. Our criticality metric identifies key facilities requiring protection based on service coverage and redundancy.
These metrics highlight the vulnerability of certain populations and regions, guiding policymakers. This research can contribute to managing the effects of population decline and ensuring equitable access to services, aligning with national efforts to improve equity in climate adaptation.
Thursday, May 22 | 2:30 – 4:00 p.m. | Room 284
#99 The Chandeleur Island Restoration Project (PO-0199) – Engineering and Design
The Chandeleur Island Restoration Project is located in St. Bernard Parish, Louisiana within the Breton National Wildlife Refuge. The Project Area is comprised of restoration areas on North Chandeleur and New Harbor Island. The Project sediment borrow area is located at Hewes Point, just to the north of North Chandeleur Island. The purpose of the Project is to engineer and design a restoration project benefitting the Chandeleur Islands with a particular focus on bird and sea turtle habitat, enhancement of submerged aquatic vegetation habitat, and creation/restoration of barrier islands and coastal headlands. Proposed project restoration features include beach/dune/marsh fill, isolated (pocket) marsh construction, back-barrier sand reservoir construction, and the construction of a feeder beach on the Gulf-facing shore of North Chandeleur Island. A total of five (5) alternatives were evaluated on the basis of habitat construction, project longevity, and benefits to the area ecology and economy. The construction and monitoring cost of the project is estimated at approximately $350 million. An extensive data collection effort was undertaken to describe the current island topography/bathymetry, infrastructure, and existing geotechnical parameters over the entire 13-mile island. This session will provide a geomorphological history of the island and it is evolution over time, discuss the intensive borrow area and island survey efforts, findings of the geotechnical investigations, and describe the restoration engineering process, alternatives development, and project design.
Moderator: Michael Poff – Coastal Engineering Consultants, Inc.
Presenters:
• Michael Miner – The Water Institute
• Brett Borne – Coastal Engineering Consultants, Inc.
• Jennifer Aguettant – GeoEngineers, Inc.
• Steve Dartez – Coastal Engineering Consultants, Inc.
Sediment Dynamics and Geomorphic Evolution of the Chandeleur Islands to Inform Restoration Strategies
Michael Miner – The Water Institute
An analysis of the Chandeleur Islands evolution was conducted to inform restoration strategies. A large volume of sand lost from the active littoral system has accumulated north of the islands, providing a unique restoration opportunity to reintroduce this sand to updrift locations. Much of the northern island overlies thick sand deposits (>20ft) that are liberated by shoreface erosion, naturally nourishing the island. The backbarrier marshes here are more resilient during storms than the beaches and dunes, serving as nucleation sites for post-storm sand deposition and facilitating recovery of beach/dune habitat and island integrity critical to protecting seagrasses. Once the Gulf shoreline erodes to meet the backbarrier shoreline, a threshold is crossed that ultimately results in island conversion to submerged shoals. The benefit of restoration can be maximized by sand placement in a central location for natural processes to redistribute it to build backbarrier marsh, dunes, and a continuous sandy shoreline. Sand placed in the backbarrier as vegetated, shore-perpendicular platforms (mimicking the natural backbarrier marshes) can serve as long-term sand reserves as the island migrates and erodes into them as part of a design that includes dune restoration to create habitat for species reliant on higher elevations. An approach that increases island resiliency through greater retention of sediment in the system during storms is likely to benefit habitat such as seagrass that rely on the integrity of the island to attenuate wave energy over the long term.
Surveys for the Chandeleur Island Restoration Project : A Monumental Effort
Brett Borne – Coastal Engineering Consultants, Inc.
The Chandeleur Island Restoration Project is located in St. Bernard Parish, Louisiana within the Breton National Wildlife Refuge. The Project Area is comprised of restoration areas on North Chandeleur and New Harbor Island. The Project sediment borrow area is located at Hewes Point, just to the north of North Chandeleur Island. An extensive data collection effort was undertaken to describe the current island topography/bathymetry over the entire 13-mile island, map potential infrastructure, and perform a geophysical/cultural resources survey of the borrow area. The topographic/bathymetric surveys consisting of survey control monument installation along with topographic, bathymetric, and magnetometer surveys for North Chandeleur and New Harbor Islands. The survey transects consisted of 1,000 feet (ft) spaced transects along the entire length of North Chandeleur Island for a total survey transect length is approximately 332 nautical mile (NM). A full geophysical survey was conducted including data collection for bathymetry, marine magnetometer, side-scan sonar, and subbottom profiling. Primary survey transect spacing was 65 feet (20 meters) to meet current cultural resource investigation guidelines. Tie lines-oriented perpendicular to the primary lines were also investigated at a spacing of approximately 984 feet (300 meters). In total, approximately 149 NM of survey tracklines are conducted for the Hewes Point Borrow Area investigation An offshore pump-out area and conveyance corridor location was identified and a geophysical survey consistent with that done for the Hewes Point Borrow Area was conducted. Primary survey transects spacing of 65 feet (20 meters) resulted in an additional 76 NM of survey data collection.
“What? Like it’s Hard?” Collecting Geotechnical Data for the Chandeleur Island Restoration Project 30 Miles Offshore
Jennifer Aguettant – GeoEngineers, Inc.
The Chandeleur Island Restoration (PO-0199) Project presented several unique challenges regarding geotechnical exploration. Located approximately 30 miles south of Gulfport, MS, traditional means of accessing the island with shallow-water geotechnical drilling equipment were not feasible. In addition, the variety of site conditions where subsurface data was needed (beach, to seagrass, to deeper water) required multiple pieces of drilling and support equipment to collect the data. On top of all that, the lack of available lodging within a relatively close proximity to the site also presented a problem, not to mention working against a shrinking window of time in hurricane season, turtle nesting season, lack of cellular communication, and vessel availability. In short, this project required some creativity. Laboratory testing efforts for the island borings focused on index, strength, and consolidation testing. While testing on vibracore samples collected in the Hewes Point borrow area focused on grain size distribution. Test results were used to identify variation or trends in subsurface stratigraphy looking at the island from north to south and east to west. Three design alternatives for the island were selected for evaluation, each of which included beach, dune, and marsh features for the project with subtle differences. Based on survey data provided by the Project Team, specific cross-sections were selected for engineering analyses which included settlement and slope stability. Cross-sections were selected based on the existing topography and the proposed fill to be placed. In addition, enhancements to New Harbor Island, located southwest of Chandeleur Island, were also considered. The New Harbor Island project features included breakwaters surrounding the island and marsh creation.
Chandeleur Island Restoration Project (PO-0199) Engineering and Design, Go Big or Go Home
Steve Dartez – Coastal Engineering Consultants, Inc.
North Chandeleur Island is approximately 13 miles in length with an average width of 0.5 miles. Its topography varies from north to south with the northern expanses being bare sandy beaches at or near intertidal elevations. As the island progresses to the south, the beaches become narrower with broken vegetated dunes, spartina marshes, and black mangrove stands expanding to the west side. New Harbor Island is a small, intertidal island located on the southwest side of North Chandeleur Island. The Chandeleur Islands have long been known for their diverse assemblages of both colonial nesting birds and migratory shorebirds. Additionally, The beaches of the Chandeleur Islands have historically been utilized by various species of sea turtles as nesting habitat for egg laying while the expansive seagrass beds on the west side are valuable sea turtle foraging grounds. The three main species of sea turtle that have been observed on and around North Chandeleur Island include the Loggerhead sea turtle, the Green sea turtle, and the Kemp’s Ridley sea turtle. With the focus of the project centering on restoration of the bird and sea turtle habitats, selection of project restoration features focused on creating or restoring these essential habitats. The presentation will illustrate the restoration features and their function, the combination of features that were used to formulate different restoration alternatives, the selection criteria and how each alternative ranked, and the details of the recommended design. The presentation will also highlight the restoration strategy for New Harbor Island. Potential construction methods, the estimated project cost, and schedule will also be outlined.