sessions 71-80
Thursday, May 22 | 9:30 – 11:00 a.m.
Sessions
• #71 On Reste Ici – The Pointe-au-Chien Indian Tribe’s Struggle to Survive
• #72 LWI: Insights and Advancements Watershed-Based Flood Resilience
• #73 Federal Outlook on Revenue Sharing Legislation
• #74 Coastal Carbon Session 1 of 3: Advances in Blue Carbon Science
• #75 Rooting Resilience: Vegetation, Soils, and Strategies for Coastal Restoration
Thursday, May 22 | 9:30 – 11:00 a.m. | Room 286
#71 On Reste Ici – The Pointe-au-Chien Indian Tribe’s Struggle to Survive
The Pointe-au-Chien Indian Tribe is one of the oldest continuously inhabited areas in Louisiana. The Tribe has been caretakers of its land since time immemorial. This small fishing community is located in the fastest eroding basin in the U.S, the Terrebonne Basin. The Tribe is at a crossroads of unprecedented change to the natural environment caused by increased environmental disasters, including Hurricane Ida in 2021. Due to rapid changes in the environment, the Tribe is struggling to adapt to maintain its cultural heritage. This panel will discuss the Tribe’s adaptation efforts to protect its culture, environment, land, sacred sites, and tribal homes, so that it can maintain its Tribal identity and way of life for future generations. Coastal resiliency stands at the forefront of the Tribe’s focus. The panel will discuss various projects that the Tribe has developed with partners (SeaGrant, Glass Half Full, CRCL, NOAA, Lowlander, Tele Louisiane and others) to address landloss, build fortified homes, maintain Indian French, and support Tribal families. Coastal resiliency is not only important to stop further land loss but is necessary and vital to sustain our self-determination as a community.
Moderator: Patty Ferguson Bohnee – Arizona State University/Pointe-au-Chien Indian Tribe
Panelists:
• Donald Dardar – Pointe-au-Chien Indian Tribe
• Chuckie Verdin – Pointe-au-Chien Indian Tribe
• Christine Verdin – Ecole Pointe-au-Chien
Organizer: Patty Ferguson Bohnee – Arizona State University/Pointe-au-Chien Indian Tribe
Thursday, May 22 | 9:30 – 11:00 a.m. | Room 287
#72 LWI: Insights and Advancements Watershed-Based Flood Resilience
Part 1: Quick Wins in Watershed-Based Flood Resilience Planning: Insights from the Louisiana Watershed Initiative
This session will showcase the successes achieved through the Louisiana Watershed Initiative’s regional planning efforts, emphasizing effective strategies for enhancing flood resilience across LWI Regions 4,5,6 and 8 in the coastal zone. Each panelist will provide overviews of initiatives in their various regions of Louisiana that have contributed to building regional capacity and advancing flood risk management in the complex coastal Louisiana watersheds.
Each speaker will offer insights on distinct aspects of flood resilience, including early successes in stakeholder engagement, innovative, data-driven planning approaches, urban water management innovations, insights into project conceptualization and development. This session aims to inspire participants by presenting actionable insights and practical examples from watershed-based flood resilience planning in Louisiana in the coastal areas.
Moderator: Danica Adams – Arcadis
Panelists:
• Genea Lathers – Louisiana Office of Community Development
• Kelia Bingham – Acadiana Planning Commission
Organizer: Danica Adams – Arcadis
Part 2: Advancing Regional Watershed Management in Louisiana
When over 30 inches of rain fell over 2 days in August 2016, the State came to the stark realization that more must be done to manage water regionally based on watershed boundaries. In 2018, the State passed Executive Order 2018-16, promoting a regional approach to better manage, mitigate, and adapt to future flood risk, commonly referred to as the Louisiana Watershed Initiative or LWI. Between 2019 and 2021, watershed regions, steering committees, and coordinators were established to align and leverage efforts across parishes that share a watershed or drainage basin. Region 6 is supported by leadership from the South Central Planning and Development Commission (SCPDC) and a Regional Steering Committee representing 16 parishes. Together they have leveraged state H&H models in consultation with local and regional stakeholders to elevate shared water management challenges and enable an objective, science-based understanding of how projects, policies and other measures can reduce flood risk.
Region 6 will produce one of state’s first regional Watershed Plans, including the identification of high priority regional flood risk areas and recommended strategies and projects that are locally appropriate and reflect best practices in watershed and floodplain management. Join this panel to learn more about how the Plan will be utilized as both a regional land management and funding tool, discuss its status and Project Team members lessons learned to date, and better understand next steps prior to the Plan’s recommended adoption in December 2025.
Moderator: Alex Gelpi Carter – Desire Line
Panelists:
• Evelyn Campo – Desire Line
• LeeAnn Fitch – Moffat & Nichol
• Andy Sternad – Waggonner & Ball
Organizer: Alex Gelpi Carter – Desire Line
Thursday, May 22 | 9:30 – 11:00 a.m. | Room 291
#73 Federal Outlook on Revenue Sharing Legislation
With the last of Deepwater Horizon oil spill dollars coming in 2031, Louisiana’s coastal program faces a fiscal cliff. Federal funding from the Gulf of Mexico Energy Security Act (GOMESA) represents the largest source of recurring funds available. Yet federal law limits the amount of GOMESA dollars that can be received. Without changes, Louisiana will receive around $150 million from GOMESA for the foreseeable future. Fortunately, bipartisan federal legislation such as the RISEE Act and BREEZE Act propose improvements to GOMESA to increase dramatically available revenues, by increasing the percentage, removing the limiting cap, and exempting the funds from budget sequestration. These bills also could bring in a new revenue source, offshore wind, to the coastal program. Estimates indicate that these bills could provide an additional $2-3 billion to Louisiana’s coastal program over the next decade. Yet the more valuable the legislation is for Louisiana and the Gulf Producing States, the more difficult it is to advance through Congress.
With this panel, attendees will hear about the importance uses of these funds, advocacy efforts, and political challenges to passage. Neal McMillin, Director of Federal Affairs for LA DENR, will moderate. Panelists include CPRA Executive Director Glenn Ledet, Parishes Advocating for Coastal Endurance Executive Director Meg Bankston, Senator Cassidy’s Energy and Coastal Policy Advisor Sarah Alexander, and another energy policy advisor from the Louisiana delegation.
Moderator: Neal McMillin – Louisiana Department of Energy & Natural Resources
Panelists:
• Dustin Davidson – Louisiana Department of Energy & Natural Resources
• Meg Bankston – Parishes Advocating for Coastal Endurance
• Glenn Ledet – Louisiana Coastal Protection and Restoration Authority
Organizer: Neal McMillin – Louisiana Department of Energy & Natural Resources
Thursday, May 22 | 9:30 – 11:00 a.m. | Room 292
#74 Coastal Carbon Session 1 of 3: Advances in Blue Carbon Science
Coastal carbon has attracted huge management and policy interest in recent years under the banner of ‘blue carbon’ for climate change mitigation. However, management to harness the carbon benefits of coastal ecosystems will only be successful if underpinned by strong foundational understanding of carbon cycling. Louisiana is the home of coastal carbon science, with decades of research into the fundamental science of carbon stocks and flows. Today, Louisiana remains at the forefront of coastal carbon knowledge. This includes a greater understanding of ecosystems that have not normally been considered in blue carbon, such as upper estuarine systems including tidal freshwater marshes and forested wetlands. Advances are also occurring in the measurement of carbon fluxes, both laterally through the water column, and vertically between the biosphere and the atmosphere. Understanding these fluxes is key because they have the potential to offset a proportion of carbon sequestration, and are a particular issue in wetland environments. This session will showcase current advances in coastal carbon science in Louisiana, with a particular focus on fluxes. Ultimately, such information is essential to a correct understanding of the net carbon balance in coastal wetlands. This provides a strong underpinning to evidence-informed management and carbon accounting at commercial, state and federal levels.
Moderator: Ken Krauss- LUMCON
Presenters:
• Songjie He – Louisiana State University
• Luke Lamb-Wotton – Tulane University
• Rachael Hunter – Comite Resources
• Jorge Villa – University of Louisiana at Lafayette
• Brian Roberts – Louisiana Universities Marine Consortium
Organizer: Dan Friess – Tulane University
Lateral carbon flux from a saltmarsh: Implications for coastal acidification and carbon budget
Songjie He – Louisiana State University
Saltmarshes are biogeochemical hotspots storing carbon in sediments and in the ocean following lateral carbon export. This transfer of carbon and alkalinity from the land to the ocean represents an important process in the global carbon cycle. Here, we measure lateral carbon fluxes – import and export of carbon via tidal channels – in a saltmarsh in the Barataria Basin in Louisiana and evaluate the impact factors on lateral carbon fluxes. We hypothesized that porewater carbon export is an important process for blue carbon loss which contributes significantly to lateral carbon flux. To test this hypothesis, environmental parameters such as salinity, temperature, pH, dissolved oxygen, fluorescent dissolved organic matter, as well as carbon concentrations, including dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and total alkalinity (TA) concentrations were measured since 2021 for lateral carbon flux calculations. Radon concentrations were measured continuously for over 24 hours during five field trips to evaluate porewater carbon export. Our preliminary results showed that porewater carbon exports contributed significantly to lateral carbon fluxes. Lateral carbon fluxes mirrored the water flux pattern and positive (ebb-directed) lateral carbon fluxes were mostly driven by higher carbon concentrations during ebb flow associated with porewater drainage versus flood flow. Lateral flux of DIC was generally higher than TA flux, which has significant implications for coastal acidification and carbon budget. This exported TA represents a long-term carbon sink in the ocean while the ratio of TA/DIC impacts the carbonate chemistry of coastal waters.
Drivers and variability of carbon fluxes in natural and created mangrove wetlands across a barrier island in coastal Louisiana
Luke Lamb-Wotton – Tulane University
In recent decades the frequency of severe freezes in coastal Louisiana has declined, allowing for the expansion of Avicennia germinans (black mangrove) into herbaceous salt marsh. To date, no published studies in coastal Louisiana have conducted field-based investigations in mangrove sites that characterize vertical carbon exchange, in the form of net ecosystem production (NEP = GPP – ER), or soil carbon flux. Given mangrove expansion is projected to continue under intermediate and future climate change scenarios, and mangroves are often planted in wetland creation projects, understanding how mangroves are altering vertical fluxes of carbon, and their landscape-scale rates of expansion, may help better understand the long-term implications of mangrove expansion on carbon sink-source dynamics. In this ongoing study, we characterized monthly rates of NEP and soil carbon fluxes, across natural and created wetlands and investigated hydrologic and biogeochemical drivers of these fluxes. We have two specific research questions: (1) How does soil and ecosystem C fluxes vary across restored and natural wetlands and how do they differ between A. germinans and S. alterniflora? (2) What are the hydrologic and biogeochemical drivers of soil C fluxes across restored and natural wetlands? To answer these questions, we established sampling points for long-term monitoring of ER and GPP, water level and salinity, porewater biogeochemistry, and sediment physiochemical properties, across mangrove and marsh locations in natural and created wetlands on Whiskey Island, a barrier island in the Isles Dernieres Barrier Island Refuge.
Measurement of greenhouse gas flux across a hydrologic gradient in Louisiana coastal freshwater forested wetlands
Rachael Hunter – Comite Resources
Wetlands cover 3 to 8% of the global land surface but account for more than 20% of global methane emissions and store up to half of terrestrial soil carbon. Wetland carbon pools and greenhouse gas fluxes are impacted by anthropogenic activities such as changes to hydrology and sediment transport. This research focuses on quantifying greenhouse gas (GHG) emissions in freshwater forested wetlands across a range from healthy to degrading to open water or marsh. By quantifying GHG fluxes across a hydrologic and vegetation gradient in FFW, this study aims to provide critical data for the Coastal Master Plan (CMP) Integrated Compartment Model, which serves as the primary analytical tool for assessing potential CMP projects. Twelve FFW study sites were chosen at CRMS stations around Lake Maurepas, comprising four healthy wetlands, four degraded wetlands, and four transitioning to marsh or open water. Carbon dioxide, methane, and nitrous oxide emissions are measured quarterly at each of the 12 sites over two years using the static chamber method. This method involves deploying five inverted 3.5-gallon buckets on sleeve bases, either embedded in the wetland soil or positioned on floating Styrofoam rings, depending on water levels. Gas samples are collected at intervals of 0, 15 minutes, 30 minutes, one hour, and two hours after chamber deployment and gas concentrations are measured on a gas chromatograph. Preliminary data from two of the eight sampling trips will be presented.
Carbon sequestration response to chronic saltwater intrusion in a coastal marsh in Louisiana
Jorge Villa – University of Louisiana at Lafayette
As the land subsides, coastal wetlands become increasingly susceptible to flooding from storm surges during tropical cyclones. In this work, we examined differences in organic matter and carbon (C) sequestration between the upthrown and downthrown sides of a faulted wetland in southwest Louisiana that flooded during Hurricane Rita in 2005. We analyzed six soil cores (~1 meter each), collected at 2 cm intervals, for bulk density, %C, %N, δ13C, and C sequestration. The cores were paired (upthrown and downthrown) and collected from three distinct emergent vegetation patches on the upthrown side. Organic soils with low bulk densities were present up to a depth of 34 cm across all vegetation types on the upthrown side. The highest bulk densities were observed in cores from S. californicus patches, compared to those from P. australis and S. patens, suggesting that plant species influence the quantity and composition of organic matter. Additionally, discrete changes in δ13C values between the upthrown and downthrown sides indicate that organic matter from previous emergent vegetation still dominates the soil profile. While mean (SD) C sequestration rates on the upthrown side (42.6 gC m⁻² yr⁻¹ ± 19.2) were slightly higher than on the downthrown side (39.2 gC m⁻² yr⁻¹ ± 21.4), but the difference was not statistically significant. These results suggest that, despite notable changes in the organic matter pool and its sources following saltwater flooding and vegetation shifts, the wetland’s capacity for C sequestration has remained relatively stable over the past ~20 years.
Temporal dynamics in Spartina alterniflora biomass, productivity, gas fluxes and carbon stocks in Terrebonne Bay marshes
Brian Roberts – Louisiana Universities Marine Consortium
Salt marshes are highly productive blue carbon ecosystems with disproportionately high rates of carbon fixation that make them valuable in attenuating atmospheric CO2. Their productivity and complex structure provide the foundation for estuarine food webs. However, few salt marsh ecosystems have been consistently sampled over multiple years making predictions of how salt marsh primary production and carbon storage respond to environmental change challenging. To address a shortage of detailed studies of natural variation, we examined drivers of Spartina alterniflora stem allometry and productivity at three marsh islands near the Louisiana Universities Marine Consortium’s DeFelice Marine Center in northern Terrebonne Bay at least monthly since 2013. Stem density, height, aboveground biomass (stems, leaves, and flowers), belowground biomass have been sampled monthly from triplicate plots at each of three sites along with a series of soil characteristics. Light and dark plant chamber and soil chamber CO2 and CH4 gas fluxes along with porewater chemistry and soil microbial populations have been measured since 2020. The monthly sampling of marsh sites has been supplemented by weekly water sampling for inorganic nutrients, TSS, DOC/DON, CH4, phytoplankton biomass and composition. Above-and belowground production were both positively correlated with dissolved nutrient concentrations and negatively correlated to salinity. Interannual variation in water quality is sufficient to drive above-and belowground productivity. The positive relationship between nutrients and belowground production indicates that inputs of nutrients and freshwater may increase salt marsh carbon storage and ecosystem resilience to sea level rise.
Thursday, May 22 | 9:30 – 11:00 a.m. | Room 290
#75 Rooting Resilience: Vegetation, Soils, and Strategies for Coastal Restoration
This session explores how vegetation and soil processes drive coastal resilience in Louisiana. Presenters will highlight efforts to restore Live Oak Hackberry forests, a vital but underfunded habitat, and examine marsh terracing as a tool for stabilizing sediment and supporting plant communities. Research on wetland elevation and plant productivity will provide insights into how hydroperiod influences marsh resilience, while a study on carbon respiration pathways will explore how changing salinity affects soil carbon storage and plant health. A youth-led black mangrove planting initiative demonstrates the power of hands-on restoration, as students cultivate and plant thousands of trees to expand vital wetland habitats.
Moderator: Danielle DiIullo – Louisiana Sea Grant
Presenters:
• Eva Hillmann – Pontchartrain Conservancy
• Matt Salmon – Freese and Nichols
• Brandon Wolff – Stantec
• Kanchan Maiti – Louisiana State University
• Blaise Pezold – Meraux Foundation
• Dominique Seibert – Louisiana Sea Grant
• Theron Phillips – Louisiana Department of Agriculture and Forestry
Organizer: Haley Gentry – Tulane Institute on Water Resources Law & Policy
Reviving Ridges: An Initiative to Restore Louisiana’s Live Oak Hackberry Forest
Eva Hillmann – Pontchartrain Conservancy
Louisiana’s Coastal Master Plan goals include flood reduction, habitat improvement, and maintenance of our cultural heritage. Live Oak Hackberry Forest (ridge habitat) is a coastal habitat that declined >95% yet received <10% funding in the 2023 Master Plan. Ridges impact hydrology and provide habitat for >100 trans-gulf migratory bird species. The Pontchartrain Conservancy (PC) partnered with the Coastal Protection & Restoration Authority to improve remnant ridges in St. Bernard Parish. In Fall 2022-Spring 2023, PC worked with community volunteers and planted 750 trees, shrubs, and palms across two remnant ridges. Species included Live Oak (Quercus virginiana), Sycamore (Platanus occidentalis), Green Ash (Fraxinus pennsylvanica), Yaupon Holly (Ilex vomitoria), Wax Myrtle (Myrica cerifera), and Palmetto Palm (Sabal minor). We tagged a significant subset for monitoring (n=256). Tree survival was 60%. Between species, survival ranged from 51 – 66%. Yaupon survival was highest; Sycamore was lowest. Live Oak survival was 64%. The growth rate was 6 cm/yr. Between species, growth ranged from -8 to 42 cm/yr. Wax Myrtle growth was highest; Sycamore was lowest. Live Oak growth was 7.5 cm/yr. Despite a drought and heat wave (Summer 2023) likely impacting survival and growth, this work 1) increased the spatial extent of ridge habitat by 10 acres and 2) supported another regional ridge restoration project (PO-178). Further, these outcomes provide insights for land managers, including that investment in invasive species removal pre-planting is critical to ridge habitat planting success.
Marsh Terracing: One Line of Defense to Benefit the Barataria Land Bridge
Matt Salmon – Freese and Nichols
The Barataria Basin of Southern Eastern, Louisiana provides storm surge benefits to the Greater New Orleans Area. This basin has experienced the second greatest land loss of the nine coastal Louisiana basins. The Barataria Landbridge, a critical natural feature of this basin, plays a critical role in the overall resiliency of the State, its restoration and protection needs are well documented in Louisiana’s Comprehensive Master Plan and Jefferson Parish’s Coastal Strategic Action Plan.
Various state agencies have implemented numerous restoration projects to reduce land loss in this area since 1993 and to implement the overall landbridge. The Upper Barataria Terracing Project is a priority project in the 2020 Jefferson Parish Coastal Strategic Action Plan that was selected for implementation. The project location was optimized for proximity to other marsh restoration projects recommended in Louisiana’s Coastal Master Plans and to leverage the potential of the mid-barataria sediment diversion. Marsh terracing is a cost-effective technology to work in harmony with existing restoration solutions to assist with sediment capture and provide a buffer to reduce wave and storm surge attenuation.
This presentation will discuss the how this project fits into Louisiana’s multiple lines of defense storm risk reduction strategy, leveraging the Parish Coastal Plan best practices for selecting location and designing a terracing project, the iterative process to identify and successfully apply for grant funding, and how small scale projects can help achieve large goals.
Using Marsh Organs to Test How Elevation Influences Plant Productivity in Coastal Louisiana
Brandon Wolff – Stantec
Wetland marshes act as the first line of defense against the Gulf of Mexico, and wetland degradation threatens inland infrastructure and industry. In coastal Louisiana, sea level rise, subsidence, and erosion drown miles of wetlands every year, and the need for a better understanding of natural wetland land-building and preservation processes is crucial. Marsh platforms, located at the land-water interface, are highly productive due to the relationship between hydroperiod and elevation. High biomass production is a key component of wetland resilience, and elevation loss can lead to a more vulnerable coast. Understanding how elevation influences plant productivity is vital for coastal restoration and storm surge protection projects.
We hypothesize that plant growth response to flooding varies for species in brackish and saline marshes, with maximum growth at intermediate inundation levels. Using “marsh organ” mesocosms, we isolated hydroperiod as the growth factor, planting at various tidal elevations. Our data shows that both brackish and saline species are less productive at inundation extremes. We also found that wetland productivity can vary greatly over small changes in hydroperiod or elevation. This study underscores the importance of maintaining optimal marsh elevation to enhance ecosystem restoration and bolster storm surge protection efforts.
Contrasting soil organic carbon respiration pathways in coastal wetlands undergoing salinity changes
Kanchan Maiti – LSU
Carbon storage in coastal wetland soil is controlled by a complex interplay between microbial processes and porewater chemistry that are often influenced by salinity, where most of the organic carbon is mineralized to its inorganic form by various aerobic and anaerobic respiration pathways. The export of this dissolved inorganic carbon (DIC) from coastal wetlands has been recently recognized as a significant loss term for blue carbon storage in wetlands. This work estimates the relative contribution of various respiration pathways in two contrasting marshes (brackish and salt) in Barataria basin. The DIC production for the brackish and salt marshes were 34 – 36 mmol m-2 d-1 in winter and 82-133 mmol m-2 d-1 in summer. For the brackish marsh, aerobic respiration and iron reduction were found to be the primary contributors to DIC production representing 17- 35% and 61-81% of OM respiration. On the other hand, aerobic respiration and sulfate reduction were the primary contributors to DIC production in the salt marsh, accounting for 37-83% and 15-62% of OM respiration. Our study highlights the importance of iron reduction pathways under low salinity conditions. Such shift between iron reduction and sulfate reduction will impact the longer-term carbon budget in both wetland and adjacent ocean. This study represents the first attempt to concurrently estimate various respiration pathways in this region and more studies are needed to understand the trajectories of soil OM respiration pathways under changing salinities.
Branching Out: The Rise of Black Mangrove Use in Coastal Restoration
Blaise Pezold – Meraux Foundation
New strategies require collaborative efforts and interdisciplinary partnerships. The St. Bernard Parish 4-H Black Mangrove Program, initiated in 2016 to expand the reach of black mangroves (Avicennia germinans) into the Biloxi Marsh, highlights a success story in this effort. Learn about the origin of this project, how partnerships have been developed, and lessons learned from the mangrove husbandry practices.
The St. Bernard Parish 4-H Black Mangrove Program
Dominique Seibert
The St. Bernard Parish 4-H Black Mangrove Program engages youth directly in the coastal restoration effort. The project partners have been growing and then planting mangroves with high school students from Chalmette High School. Since the inception of the program, students have potted and cultivated over 6,000 black mangroves and planted approximately 4,250 mature plants in the Biloxi Marsh. This session (and the two that proceed it) cover coastal revegetation efforts, cultivation practices, and the use of innovative partnerships to foster youth stewardship.
LDAF Use of Black Mangrove
Theron Phillips
As Louisiana’s coastal climate changes, restoration strategies and techniques should be revisited. The mission of the Louisiana Department of Agriculture and Forestry’s Office of Soil & Water Conservation is to sustain and conserve water quality and soil stability in the state’s croplands, woodlands, grasslands, wetlands, and waterways. Learn how they are beginning to incorporate black mangrove (Avicennia germinans) into their efforts.
Thursday, May 22 | 9:30 – 11:00 a.m. | Room 289
#76 Climate Change and Rural Resilience: A group discussion on (un)certainty, displacement and risk
In the Anthropocene, the impacts of climate change are all too real. Communities cannot escape from these effects, and an increasing number of regions worldwide are being forced to confront the destruction caused by climate-related events. As a rapidly adapting community, people living in the rural south of Louisiana are facing many challenges: the young are moving to urban areas, stores in the neighborhood are closing due to decreasing community population, the old find it challenging to adapt to smart phones, catching shrimp is the only business many of them rely on so they cannot afford to move and so on. Building resilient communities to face the impacts of climate change, including both short-term impacts from major weather-related events and long-term impacts of more incremental climate change, remains a major challenge for rural communities going forward.
In this panel session we will share examples and invite stories on:
• Community resilience and climate change
• (Un)certainty of climatic conditions
• Rural places, vulnerability and resilience to climate change
• Displacement and dissolution of rural community as a result of climate-related events
• Risk communication and perception of risk
This panel session will be more of a group discussion with audience input welcome throughout. Both community resilience geographers and other scholars, specialists with a place-based interest in regions where climate change and rural communities are to the fore are most welcome to contribute on the day. Perspectives of rural and environmental knowledge holders and insights from other local groups, as well as undergraduate and graduate students, are very welcome.
Moderators:
Linda Bui – Department of Environmental Sciences, Louisiana State University
Kejin Wang – Department of Environmental Sciences, Louisiana State University
Panelists:
• Nina Lam – Department of Environmental Sciences, Louisiana State University & Department of Geography and Resource Management, Chinese University of Hong Kong
• Kashif Rustamani – Department of Geography and Anthropology, Louisiana State University
• Jacopo Aldrighetti – Department of Environmental Sciences, Louisiana State University
Organizer: Linda Bui – Department of Environmental Sciences, Louisiana State University
Thursday, May 22 | 9:30 – 11:00 a.m. | Room 288
#77 Observations and Numerical Modeling of Biogeomorphic and Sediment Dynamics in the Lower Mississippi River and Birdsfoot Delta Complex: a MissDelta Session
The Mississippi River Delta is shaped by river water and sediment discharge, vegetation-hydrology interactions, and coastal hydrodynamic processes, overprinted by human activities. The topic of this session is a component of the larger Mississippi River Delta Initiative (MissDelta). This session cuts across several activities of the larger MissDelta and includes four diverse presentations; a) observations of vegetation-flow interaction and implications for delta building; b) impacts of Gulf of Mexico sea-level change on the Birdsfoot Delta; c) connections between river-sediment discharge and nearshore sediment dynamics; and d) use of a coupled river-ocean model to help predict the future of the Birdsfoot Delta. MissDelta, supported by the National Academies Gulf Research Program, seeks to explore the geomorphic and human future of the Birdsfoot Delta of the Mississippi and surrounding region, and to expand the diversity of the coastal scholar community.
Moderators:
Sam Bentley – Louisiana State University
Xiaochen Zhao– Louisiana State University
Presenters:
• Sarah Brannum– Louisiana State University
• Noah Hendricks– Tulane University
• Jacob Reinhardt– Louisiana State University
• Yixuan Wang– Louisiana State University
Evaluating hydrogeomorphic evolution of the Bird’s Foot due to the presence of vegetation
Sarah Brannum– Louisiana State University
Phragmites australis is an abundant vegetation species in the Mississippi River Delta (MRD) that is experiencing widespread dieback, which threatens MRD resiliency to coastal erosion and relative sea level rise. The presence and density of Phragmites regulates the flow of water and sediment between MRD distributary channels and marsh. Quantifying channel-marsh connectivity modulated by Phragmites at various densities, life stages, spatial scales and seasons increases our ability to forecast the fate of the deltaic systems. Seasonal acoustic Doppler current profiler (ADCP) surveys along South Pass indicate that discharge decreases seaward as water is routed into smaller distributary channels and overbank flow through the marsh platform. Seasonal fluctuations due to vegetation growth periods and changing hydrologic conditions in the Mississippi river basin further influence this downstream decrease in discharge. To directly observe flow modulation from Phragmites at the patch spatial scale, a small unoccupied aerial system (sUAS) collected multi-spectral aerial photos of dye propagation near and through patches of Phragmites at varying densities. Using band ratios to distinguish between water, vegetation, and dye, the change in water velocity caused by vegetation was observed and analyzed. The less dense patches had velocity magnitude reductions, while at higher densities, the flow was completely rerouted. These results are compared to modeling efforts to test the sensitivity of transport to vegetation densities. Understanding both seasonal and climatic changes in hydrodynamics caused by Phragmites australis will inform ongoing efforts to evaluate the resiliency of the MRD.
Tide Gauges in Coastal Louisiana Reveal Long-term Trends More than Twenty Times the Global Average since 1950
Noah Hendricks– Tulane University
Coastal Louisiana, particularly the Mississippi River Delta region, faces some of the largest rates of relative sea-level rise worldwide (>9.3 mm/yr since 1947 at Grand Isle). These large rates are dominantly driven by (nonlinear) subsidence, but larger scale ocean dynamic processes in the Gulf of Mexico and the adjacent North Atlantic have also contributed to these rates, particularly over the past ~15 years (Dangendorf et al., 2023). In the past, relative sea-level rise in the region has usually been approximated by the means of the Grand Isle tide gauge record even though it is well known that local processes, such as subsidence, can vary significantly locally. Here we introduce a set of thirty-one daily tide gauge records maintained by the U.S. Army Corps of Engineers and located throughout southern Louisiana. The largely complete records extending back to the 1950s provide unique insights into the spatial and temporal trends of relative sea level throughout Coastal Louisiana. Significant spatial and temporal variability exist, and the Birdsfoot Delta region stands out with the largest multidecadal trends in the order of 35 mm/yr, more than three times the value obtained at Grand Isle and more than twenty times the value obtained from the global average. With this complete ensemble, more robust estimates of linear and nonlinear sea level trends are made for each location, and the sources and significance of these trends can now be more easily attributed to factors such as reduced sediment supply to wetlands, fluid withdrawals, and river discharge.
Hydrodynamics and sediment transport in East Bay of the retreating Mississippi River Delta
Jacob Reinhardt– Louisiana State University
The Mississippi River Delta and southeastern Louisiana have entered a stage of retrogradation due to natural and anthropogenic processes. Damming within the Mississippi Basin, subsidence, and erosion are some major factors leading to the land loss. The decreased sediment load has caused land loss of the subaerial and subaqueous environments. Coupled with high subsidence rates and decreased sediment supply, the deltaic sediment is compacting and sinking into the sea. Waves are a major factor causing subaerial land loss and subaqueous sediment transport, aiding in retrogradation of the subaqueous and subaerial environments. In coastal Louisiana waves are primarily driven by local winds. The goal of this study is to identify how wind, wind-waves, and currents interact with the Mississippi River Delta to transport sediment. The first task is to conduct a historical data analysis of wind and wave data of buoy stations, as well as historical models, to examine the spatial and temporal variations across southeast Louisiana. Next, we will be using tripod-mounted optical and acoustic sensors deployed at 5 m and 10 m depths in East Bay in Mississippi River Delta to collect wave, tide, current, and sediment concentration data. Our final task is to compare wave- and current-induced shear stresses and to calculate sediment flux and budget in the area so that the observed parameters can be used in future models to predict the morphological change in the area.
Using HAFS to Drive a Dynamically Coupled Hydrological-Ocean Model for Hurricane-Induced Compound Flooding Forecast
Yixuan Wang– Louisiana State University
Hurricane-induced compound flooding events, a significant challenge, occur when inland hydrological processes and oceanic processes, such as storm surges, coincide at the land-ocean interface. The devastating Hurricane Ida, a Category 4 hurricane, caused severe flooding in Louisiana and Mississippi, particularly in New Orleans, due to a combination of storm surge and heavy rainfall. Traditional models often operated in standalone mode or within a linking framework, where a ‘main model’ simulated compound flooding using boundary conditions from other models. We recently developed a new coupling solution and realized the seamless transition of model coverage in the land-ocean continuum. We integrated WRF-Hydro into the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) Modeling System, coupling the hydrological and ocean models (ROMS) along the land-ocean boundary. We adapted the coupled model to the Louisiana coast to assess the contributions of different processes—atmosphere, river, and surge—to the compound flooding event during Hurricane Ida in 2021, providing valuable insights for future flood management strategies. Two series of sensitivity tests were carried out driven by the atmospheric forcings of the Hurricane Analysis and Forecast System (HAFS) and Climate Forecast System Version 2 (CFSv2), respectively. The performance of the two atmospheric forcing in compound flood forecasts is diagnosed and discussed.
Thursday, May 22 | 9:30 – 11:00 a.m. | Room 285
#78 Resilient Water & Wastewater Infrastructure
Coastal communities face growing challenges in maintaining resilient water and wastewater infrastructure as climate change drives sea level rise, increased flooding, and more frequent extreme weather events. This session explores innovative approaches to safeguarding these essential systems while addressing the unique vulnerabilities of Louisiana’s coastal regions. Through assessments of sea level rise scenarios, we’ll examine the growing risks to critical infrastructure and the populations at risk. Insights from water quality improvement initiatives, such as the Bayou Folse Home Sewage Assistance Program, showcase how targeted interventions can reduce pollution and enhance environmental health. Research on decentralized wastewater treatment systems in Plaquemines Parish underscores the need for robust strategies to address system failures, exacerbated by tropical storms and power outages. Further, resilience planning for public water infrastructure demonstrates how utilities can integrate advanced flood modeling, vulnerability assessments, and adaptation strategies into long-term design and capital improvement plans. These efforts ensure continuity of service and reduce system interruptions during extreme weather events.
Moderator: Garvin Pittman – The Water Institute
Presenters:
• Juan Declet-Barreto – Union of Concerned Scientists
• Andrew Barron – Barataria-Terrebonne National Estuary Program
• Holly Fraychineaud – Pontchartrain Conservancy
• Swamy Pati – Jacobs
Sea Level Rise, Flooding, and Looming Deadlines for Coastal Infrastructure in Louisiana
Juan Declet-Barreto – Union of Concerned Scientists
As climate change-driven sea level rise progresses, disruptive flooding will put thousands of critical buildings and facilities along US coasts—including schools, power plants, and wastewater treatment plants—at risk. That flooding could interfere with the provision of essential community services and expose communities to harmful pollutants. To assess immediate, near-term, and long-term risks to this infrastructure, we characterized flooding conditions in 2020, 2030, 2050, and 2100, based on three sea level rise scenarios. For each time period and scenario, we calculated which and how many essential facilities would be flooded 2 (biannually), 12 (on average, monthly), or 26 times (on average, every other week) annually.
Louisiana ranks first in the country in number of critical infrastructure assets at risk today and in the near future. Between now and 2050, sea level rise will expose more than 300 critical infrastructure assets coastwide to disruptive flooding at least twice per year, particularly threatening public and affordable housing. This burden is borne inequitably: more than half the infrastructure at risk by 2050 is in communities at a disadvantage based on historical and ongoing racism, discrimination, and pollution. The amount of infrastructure in jeopardy late this century will depend heavily on countries’ choices and how soon they reduce global heat-trapping emissions. Policymakers and public and private decisionmakers must take immediate, science-based steps to safeguard critical infrastructure and achieve true, long-term coastal resilience.
Estuary Program Water Quality Improvement in the Bayou Folse Watershed Using Inspections and a Home Sewage Assistance Program
Andrew Barron – Barataria-Terrebonne National Estuary Program
The sustainability of communities in coastal watersheds is directly tied to the availability of dependable decentralized sewage treatment. There are ~ 4607 on site disposal systems (OSDS) in the Bayou Folse watershed, Lafourche Parish, Louisiana. The watershed is identified as impaired by the Louisiana Dept. of Environmental Quality (LDEQ). The Barataria-Terrebonne National Estuary Program utilized funds from LDEQ and Gulf of Mexico Program to conduct water monitoring, OSDS inspections, public education, and a home sewage assistance program (HSAP). An HSAP was implemented because, inspections alone would not provide enough incentive to motivate homeowners to repair their malfunctioning OSDS. The inspection-HSAP approach provided the direct education of homeowners about OSDS maitenance and reimbursed homeowners who repaired their OSDS. The HSAP reimbursement program provided monetary cost-share assistance to homeowners that might have been unable to afford the repair or replacement of their malfunctioning OSDS. FCB data for the PRE implementation phase (IP) of sampling (Oct. 2016 – Mar. 2019) were compared to POST IP data (Apr. 2019 – Dec. 2023). The HSAP repaired and replaced 176 OSDS, which included cesspool and septic tanks. Values for FCB showed an overall decrease in the number of WQ standard excursions from the PRE IP to the POST IP for both the SCR standard (-16%) and PCR standard (-44%). These decreases are attributed to the combined work of OSDS inspections, public education, and the HSAP.
Wastewater Treatment System Resilience: On-Site Sewer Systems in Plaquemines Parish
Holly Fraychineaud – Pontchartrain Conservancy
Unincorporated areas typically have decentralized wastewater treatment systems for homes and businesses, usually individual aerobic treatment units (ATUs) or septic tanks. Residential units are about 500 gallons per day (GPD) and can serve a household with ease. ATUs are used because microbial bacteria break down solids and “treat” the system, the resultant effluent is then pumped into ditches and nearby waterbodies. Pontchartrain Conservancy (PC) has conducted multiple surveys across several parishes and have found that 50% of ATUs fail. These systems pose a significant human health and ecosystem hazard and are especially vulnerable due flooding and power outages in hurricane-prone Plaquemines Parish. PC conducted 100 home and 40 commercial system inspections in Plaquemines Parish to survey the efficacy of these systems. These surveys included a visual assessment of the system and a voluntary homeowner/operator survey. The questionnaire investigated an occupant’s capabilities to maintain the system and level of expertise and interest. Results showed a 65% system failure rate, a relatively low homeowner knowledge of non-functioning systems, and a general disinterest in that fact. Most fails are from non-functioning aerators, defeating the purpose of the system. Additionally, the majority of residential and commercial operators are not chlorinating their systems. This survey implies a parish-wide problem with on-site sewer systems, both residential and commercial. Furthermore, this work highlights the need to make these systems more resilient to tropical cyclones.
Compound Flooding Risk Evaluation for System-wide Resilience Planning for Public Water Infrastructure
Swamy Pati – Jacobs
Jacobs has been a leader in providing system-wide Resilience Planning for Public Water Infrastructure. The resiliency for the major coastal urban cities depend on appropriately assessing the risk associated to compound flooding, including risk from rainfall, tidal and storm surge driven events. This presentation will delve into some of the recent examples that Jacobs has completed for various utility and public works authorities, to explain Jacobs’ resilience plan development process with compound flooding risk, which has been implemented for many other utility authorities across the nation.
To address the uncertainty of future climate, preparing a System Resilience Plan is critical to further advance its water and wastewater systems toward the goal of being a benchmark resilient utility. The System Resilience Plan will provide the enhanced design standards and forward‐looking adaptation strategies that will allow Utility to maintain a high level of service (LOS) and minimize system interruptions during extreme weather events across all of their facilities. A comprehensive adaptation plan focused on risk reduction, aggressive design standards, and forward‐looking capital improvement plan (CIP) investment is useful to develop and further advance system’s reliability and resilience.
The presentation will summarize the results of the key tasks completed in preparation of the System Resiliency Plan, including details of data collection, approaches and tools developed for Flood modeling, vulnerability and risk assessment and adaptation strategy development.
Thursday, May 22 | 9:30 – 11:00 a.m. | Room 284
#79 Using a co-production approach to inform project design, long-term monitoring, and adaptive management for restoration of the Chandeleur Islands to benefit seagrass
The Chandeleur Islands, LA are a hotspot for plant and animal diversity in the northern Gulf of Mexico. They support the only marine seagrass beds in LA, which grow along the protected side of the islands. The Chandeleur Islands are disappearing and are projected to potentially transition to submerged shoals as early as 2037, which would result in loss of the seagrass meadows protected by the islands. Planning is underway to restore the Chandeleur Islands as part of the approach to address injuries caused by the Deepwater Horizon oil spill. To optimally design, build, and maintain the restoration to benefit seagrasses, several uncertainties have been identified and prioritized by subject matter experts and managers involved in decision-making for the restoration project. These prioritized uncertainties are (1) identifying seagrass species-specific restoration criteria, composition, and condition, (2) understanding impacts of storms and other disturbances on seagrass distribution, species composition, and condition, and (3) understanding seagrass population genetic structure and resilience capacity. This session will review results of this comprehensive approach, founded in co-production, to collect and analyze data at population and landscape levels; conduct responsive sampling to determine disturbance impacts; and build on existing numerical models and remote sensing data to better connect the physical and biological systems and assess seagrass resilience capacity. This project can serve as a model for a co-production approach to inform large-scale restoration efforts.
Moderator: Michael Miner – The Water Institute
Presenters:
• Kelly Darnell – University of Southern Mississippi
• Tim Carruthers – The Water Institute
• Alicia Sendrowski – The Water Institute
• Francesca Messina – The Water Institute
• Martijn Bregman– The Water Institute
• Caitlin Young – University of Southern Mississippi
• Laura Reynolds – University of Florida
• Bingqing Liu – University of Louisiana at Lafayette
• Jon Wiebe – Louisiana Department of Wildlife and Fisheries
The role of seagrass at the Chandeleur Islands, LA as critical habitat for nearshore animals
Kelly Darnell – University of Southern Mississippi
Seagrass meadows at the Chandeleur Islands, LA are comprised of an assemblage of five morphologically distinct seagrass species that represent a hotspot of seagrass diversity in the northern Gulf of Mexico. Here we present our research over the past six years to investigate the use of these seagrass meadows as habitat by vertebrate and invertebrate species. Results document the critical role of these meadows in supporting juvenile life stages of commercially and recreationally harvested species including speckled sea trout (Cynoscion nebulosus), flounder, redfish, blue crab (Callinectes sapidus) and penaeid shrimp, and the specific role of these meadows to provide protection from predation for blue crabs. Further, we use the Chandeleur Islands, LA, as a study system to investigate the impacts of seasonal morphology changes connected to plant reproductive status and resulting changes in plant biomass for the seagrass widgeon grass (Ruppia maritima) on fish assemblages.
Co-production for providing targeted novel research to support the implementation and adaptive management of Chandeleur Islands restoration project
Tim Carruthers – The Water Institute
The Chandeleur Islands Restoration Project engineering and design is co-led by three agencies: Coastal Protection and Restoration Authority (CPRA), U.S. Fish and Wildlife Service (USFWS), and Louisiana Department of Wildlife and Fisheries (LDWF). Anticipated funding to support the project originates from the Deepwater Horizon global settlement through the Oil Pollution Act of 1990 Natural Resource Damage Assessment (NRDA) process. CPRA, USFWS, and LDWF are Trustees for injured natural resources and therefore members of the Region-Wide Trustee Implementation Group (RW TIG) along with representatives from all Gulf coast states, NOAA, USEPA, and USDA. For this planning project, decision-makers from USFWS, LDWF, and NOAA as well as the restoration project manager from CPRA and resource manager from the Breton National Wildlife Refuge worked with researchers from University of Southern Mississippi, The Water Institute, and The University of Florida. The project team’s commitment to mutual respect and engagement for a shared purpose were essential to the project success and relevance. The project team jointly scoped, designed, and developed products to inform decisions and monitoring of the restoration project, specifically to address uncertainties for seagrasses and associated communities of the Chandeleur Islands. All members of the project team shared the ownership of the process and products. The reason for this research was to produce actionable science, a summary of where this research informed management as well as some identified challenges, will be presented.
Mapping seagrass in the Chandeleur Islands over time using remote sensing and deep learning
Alicia Sendrowski – The Water Institute
The Chandeleur Islands host extensive marine seagrass beds that serve as critical habitat for several fish species. As restoration planning progresses and plans are established for long term monitoring, time and cost-efficient approaches for assessing the extent of seagrass could increase the utility of this monitoring data and minimize monitoring costs. This information is generally collected via in-water field sampling, however there is an exciting opportunity to use remote sensing to identify temporal and spatial dynamics of seagrass meadows. This talk focuses on mapping seagrass using 30m Landsat and Sentinel-2 images from the 1980’s to the present. We use field data collected between 2014 and 2023 and artificial intelligence to train a deep learning model to identify seagrass species and density. This model is then used to classify satellite imagery of the Chandeleurs over time, resulting in time series of seasonal and annual seagrass extents. Historical seagrass maps generated by hand, previous in water sampling, and aerial photography will be compared to the remote sensing / deep learning data from Landsat and Sentinel-2 imagery. We also view seagrass persistence and analyze changes in seagrass species and the potential impact of storms. These outputs can help inform restoration scenarios, management, and monitoring of the seagrass meadows of the Chandeleur Islands to inform assessment of restoration success and inform future adaptive management.
Understanding seagrass dynamics at the Chandeleur Islands using in-situ hydrodynamics, remote sensing, and modeling
Francesca Messina – The Water Institute
The Chandeleur Islands, a unique chain of deltaic barriers off the coast of eastern Louisiana, provide habitat for a variety of plant and animal species in the northern Gulf of Mexico. The islands are home to the only marine seagrass beds in Louisiana, which thrive along the shallow, leeward side of the islands, contributing to coastal biodiversity and ecosystem stability. Historically, these seagrass meadows spanned the entire chain of islands, but their extent has diminished over time. The main factors suspected to contribute to this decline are storm events and the gradual erosion of the islands, which increase hydrodynamic forces such as wave energy, flow, and sediment transport. This disruption has confined healthy seagrass meadows to the northern parts of the island chain, where conditions remain more favorable. To explore these dynamics, this study adopted a multidisciplinary methodology that includes field observations, numerical modeling, and remote sensing. The goals of the study are threefold: to understand the current interaction between seagrass meadows and hydrodynamic forces, to analyze historical trends in seagrass distribution using satellite imagery, and to model future restoration scenarios. This presentation focuses on model development and calibration, detailing how the various datasets came together to first understand seagrass dynamics and their influence on hydrodynamics, and how the datasets were incorporated into the numerical model.
Numerical modeling to inform seagrass habitat management and monitoring at the Chandeleur Islands
Martijn Bregman– The Water Institute
This study presents the analysis of model simulations using a Delft3D FM coupled flow-wave model developed for southeastern Louisiana. The model incorporates a high-resolution grid around the Chandeleur Islands to capture detailed interactions between hydrodynamics and the seagrass meadows. To realistically represent the dynamic nature of seagrass coverage, the model integrates remote sensing data from the past decade, reflecting historical changes in vegetation distribution and density. Simulations were conducted under a variety of hydrodynamic conditions, including high-energy events such as cold fronts and tropical cyclones, to evaluate the role of seagrass meadows in modifying flow patterns, wave attenuation, and sediment dynamics. By examining these factors, we aim to understand how different seagrass characteristics, such as species composition and density, influence local sediment trapping and stability. A key focus of the analysis is determining whether recent seagrass declines in the Chandeleur Islands are due to direct storm impacts, such as burial or erosion of meadows, or indirect changes in hydrodynamic and sediment transport patterns resulting from the loss of island protection. This research offers valuable insights for the restoration and management of seagrass habitat by demonstrating how seagrass meadows influence coastal processes and sediment dynamics. These insights help coastal managers develop more targeted restoration strategies that maximize the ecological benefits of seagrass meadows, particularly in shoreline stabilization and habitat support.
Changes in seagrass species distribution and cover over time at the Chandeleur Islands, LA identified through spatially explicit annual monitoring
Caitlin Young – University of Southern Mississippi
The Chandeleur Islands, LA, support the only marine seagrass beds in Louisiana and are the sole location of the climax seagrass species turtlegrass (Thalassia testudinum) across nearly 1,000 km of the Gulf Coast from west Florida to central Texas. This area is a hotspot for dynamic changes in seagrass cover, as seagrass presence relies on the protection provided by land area, which has decreased by over half during the last 150 years. Long-term monitoring of seagrass beds provides valuable information on seagrass status and trends, can inform predictions under future scenarios, and is an essential component of ecosystem-based and adaptive management. Seagrass monitoring at the Islands has been sporadic, often coinciding with a major disturbance such as a hurricane, and monitoring methodologies have not been standardized, making quantification of changes in cover and community composition difficult. In 2018, we established a long-term monitoring program of seagrasses at the Chandeleur Islands following the widely-used and recommended tiered monitoring approach. Here, we present the results of rapid-assessment in-water monitoring at ~100 stations across the distribution of seagrasses at the islands, combined with a finer-scale assessment of turtlegrass distribution and plant biomass, and frame these results in the context of previous monitoring efforts along the Islands.
Seagrass Genetic Diversity and Connectivity in the Chandeleur Islands
Laura Reynolds – University of Florida
Genotypic and genetic diversity provide the resources for populations to evolve to changing conditions over both the long and short term. Individuals vary in traits (e.g. growth rates, nutritional quality, and response to stressors) resulting in variable survival as environmental condition changes. Disturbances likely reduce overall diversity but may allow individuals that are better adapted to survive. Importantly, connectivity with nearby populations provides an influx of new genes to support that evolution as well as provide a propagule source when populations die back. The Chandeleur Islands in Louisiana support the only marine seagrasses in Louisiana (i.e. potential isolation and little connectivity) and are an example of a rapidly changing environment (i.e. high disturbance regime), making genotypic and genetic diversity of these seagrasses a management concern. With this project, we will describe the genetic makeup and diversity of four seagrass species at the Chandeleur Islands (Thalassia testudium, Syringodium filiforme, Halodule wrightii, and Ruppia maritima). Preliminary results suggest that for at least Thalassia and Halodule genotypic and genetic diversity are similar to other sites within the Gulf of Mexico, and next steps include calculating connectivity for each species.
Studying Seagrass Spatial Distribution and Density Using Daily PlanetScope Imagery at the Chandeleur Islands
Bingqing Liu – University of Louisiana at Lafayette
Seagrass meadows provide valuable services, including habitats for a myriad of marine species, and act as a vital carbon sink by sequestering CO2 from the atmosphere. Over time, these important ecosystems have been globally degraded, including at the Chandeleur Islands—a hotspot for plant and animal diversity in the northern Gulf of Mexico, which supports the only marine seagrass beds in Louisiana. To support conservation and restoration efforts, managers, governments, and scientists require high-accuracy extent maps that are essential for analyzing the conditions of both dense and sparse seagrass environments. In this study, commercial high-resolution satellites from the PlanetScope constellation, which offer daily coverage of the coastal waters of the US, are used. This frequent collection can help overcome issues previously associated with turbidity and tidal states by providing multiple images per month. PlanetScope imagery is equipped with ideal resolutions for benthic habitat and seagrass mapping, including high spatial resolution (3 meters), high radiometric resolution (12-bit), sufficient water penetration bands (visible-near infrared), and very high temporal resolution (almost daily), distinguishing it from other high spatial resolution images. This study presents the first assessment of PlanetScope imagery for retrieving the distribution and density of seagrass across years and before and after extreme events, such as Hurricanes Francine and Helene, using advanced machine learning techniques in optically shallow waters around the Chandeleur Islands. The changing distribution and density from spring through summer, including a reduction in seagrass density after the warm summer months, are initially observed, with fluctuations before and after hurricanes being detectable. It is confirmed that PlanetScope has great potential for use in monitoring seagrass and assessing potential seagrass cover under a range of conditions.
Targeted research can directly inform natural resource decision-making
Jon Wiebe – Louisiana Department of Wildlife and Fisheries
Chandeleur Islands represent one of the state’s most ecologically diverse habitats within the northern Gulf of Mexico. For its restoration, the project team is charged with addressing a diverse array of uncertainties thereby generating maximum benefits for key natural resources including seagrasses impacted by the Deepwater Horizon Incident. Natural resource managers are playing an integral role in these discussions. This stakeholder group is often best positioned towards identifying long-standing needs that remain obstacles in their ability to implement effective management decision-making (Barrett and Rodriguez 2021). Clearly, the research community have an opportunity to play an integral role here. Peer-reviewed literature remains an essential component in the evolution of natural resource management. However, relevance or the applicability of the research to directly inform natural resource management remains a challenge at times. So much so, that development of real world decision-support tools to assist resource managers with management decisions has been prioritized within NOAA’s RESTORE Science Plan. Within this presentation, I will highlight several representative examples each of which exemplify the stakeholder group’s collaborative mindset towards achieving relevance within natural resource management. Common ingredients include prioritizing intentional engagement (early and often); consistent messaging to ensure the long-standing needs are actually being met and; the forethought to ensure these efforts can evolve towards supporting future resource challenges.
Thursday, May 22 | 9:30 – 11:00 a.m. | Room 283
#80 Predicting and Evaluating Land Change in a Dynamic Coastal System
This session explores the complicated dynamics of land change in coastal Louisiana through four presentations on distinct topics that each provide insight into how the interaction of various environmental factors may impact land change, either as observed or predicted. The first presentation shows that incorporating observed interannual variability in sea-level rise can influence the timing and magnitude of predicted land loss. The second presentation examines how inundation and introduced sediment and nutrients have influenced observed land change at Davis Pond. The third presentation demonstrates wetland value assessment as a tool to evaluate indicators of habitat quality along with changes in land area. The final presentation describes modeling experiments that explore the feedback between vegetation and delta morphology, highlighting the crucial role of vegetation in land building.
Moderator: Elizabeth Jarrell – CPRA
Presenters:
• Ehab Meselhe – Tulane University
• John White – Louisiana State University
• Brandon Campo – CSRS
• Madoche Jean Louis – LSU
Interannual sea-level modulates timing of coastal land loss
Ehab Meselhe – Tulane University
Sea level rise (SLR) is a primary land loss driver for coastal regions. Recent studies have been incorporating SLR in their predictive models used for long-term research and planning activities. These analyses use land loss rates as a metric to assess the efficacy of restoration strategies to ameliorate climate change impacts. Typically, studies incorporate smooth SLR projections published by the Intergovernmental Panel on Climate Change (IPCC) that lack interannual variability. Here, we model the impact of randomly generated sea-level variability based on tide gauge observations and assess its impact on the magnitude and timing of land loss in response to SLR in coastal Louisiana. We show that periods of enhanced or reduced sea-level rise can accelerate or decelerate land loss by up to xx years relative to the smooth SLR projections. This emphasizes the importance of standardizing the inclusion of these variabilities in long-term analyses of coastal regions.
Large surface water diversions build land and increase soil carbon storage: A Davis Pond Example
John White – Louisiana State University
Coastal lands have been negatively impacted by rising sea level. Remote sensing is a powerful tool for assessing land changes, especially over large temporal and spatial scales. However, utilizing remote sensing for wetland area change can be problematic in non-tidal, precipitation-dominated wetlands. We examined the effect of wet-dry climate oscillations on land change for a primarily rain-fed wetland system prior to river reconnection and then after river reconnection. The climatic signal was lost once the river and wetland were reconnected, leading to a continuous land increase in the wetland, despite the additional flooding. A spatial model was employed using data from 140 soil samples collected and analyzed in 2007 and again in 2018 to separate the wetland into three distinct regions: area receiving 1) sediment and nutrients, 2) nutrients only and 3) no sediments or nutrients. Remote sensing tied to these areas detected significant wetland area increase in the sediment and nutrient zone, a small increase in land area in the nutrient only zone, and no wetland area change in the area receiving no sediment and nutrients over 11 years. We found river reconnection increased land building in this coastal wetland in those regions receiving river sediment and increased C in the nutrient area. These results underscores the need for spatial soil sampling efforts to be used in concert with remote sensing to assess the degree of hydrologic connectivity and impacts of restoration activities.
Addition of Wetland Value Assessment to the LA Coastal Master Plan ICM for Evaluation of Upper Basin Diversions
Brandon Campo – CSRS
In the 2023 LA Coastal Master Plan, the Coastal Protection and Restoration Authority (CPRA) outlined the intent to programmatically investigate potential diversions in the Upper Barataria and Pontchartrain Basins. The intent of this Upper Basin Diversion Program is to evaluate how diversions in the upper basin could affect local ecosystems, aid with Mississippi River flood control, as well as, interact with other diversions downstream.
In order to help answer some initial planning research question, CSRS and CPRA collaborated to add an automated Wetland Value Assessment (WVA) process to the Louisiana Coastal Master Plan Integrated Compartment Model (ICM). The ICM WVA model utilizes the CWPPRA Environmental Working Group’s WVA models, allowing for easier comparisons of operational regimes, to streamline the evaluation of ecosystem changes across the Louisiana coast. Preliminary findings suggest that operating multiple diversions along the same riverbank can lead to significant ecological outcomes—both beneficial and adverse depending on in-situ habitat—based on key indicators from the WVA models. The results underscore the importance of strategic planning in the use of river diversions to balance ecosystem health with restoration goals.
Long-Term Deltaic Morphology Shaped by Vegetation Dynamics: Insights from an Eco-Hydro-Morphodynamic Model
Madoche Jean Louis – LSU
Understanding the feedback mechanisms between water, sediment, and vegetation in deltaic systems has become increasingly important, given the pressing need to build with nature to counter ongoing land loss and sea level rise in coastal zones. Delta morphology is fundamental in shaping ecological structures and determining resilience to climate change. As sediment diversions are being implemented to address these challenges, there is an urgent need to comprehensively understand their future deltaic evolution, as the morphology of a delta directly influences its ecosystem benefits. While many studies investigating vegetation interactions in delta formation are based on flume experiments, the few numerical models are mainly for salt marshes and often treat vegetation as static over time and assume a single vegetation species. A significant gap in numerical modeling lies in incorporating the influence of dynamic vegetation life-trait histories and the simultaneous co-evolution of different vegetation types with river delta growth. This study employs numerical experiments using Delft3D Flexible Mesh (DFM) and a dynamic vegetation module in Python to explore how feedback between vegetation and delta morphology evolves in a river-dominated delta. The models account for vegetation establishment, growth, and mortality. Our findings highlight that the presence and type of vegetation play a critical role in shaping delta morphology, and vegetation seasonality shall be considered in coastal modeling. These insights are essential for informing coastal restoration strategies.