Littoral mud flats and shorelines: soil-sea-ice-air and benthic life interactions

The overarching goal of this project is to develop a fundamental and comprehensive understanding of the geomechanics of littoral mud flats and shorelines towards reliable prediction of geomorphodynamics, trafficability, and navigation from satellite images and geoacoustic surveying. This 5-year study aims to:

1. Determine what environmental processes and feedbacks control the geomechanics of littoral mud flats and shorelines.
2. Measure these processes and feedbacks conjointly with geotechnical site characterization and satellite-based remote sensing.
3. Assess if climatic regimes affect and possibly change which processes and feedbacks are dominant.
4. Develop and validate a global mud flat classification framework.
5. Determine which satellite products would be most efficient for deriving the tidal flat geomechanical properties. This will be achieved through literature and data review, field and laboratory testing, cross-disciplinary fusion and data analysis.

Research will include detailed multi-disciplinary field investigations of five sites located in distinct geographic regions and environments, laboratory analysis of samples, data analyses, cross-disciplinary data fusion, and validation at new field sites.

Sponsor: Office of Naval Research (ONR, www.onr.navy.mil), N00014-25-1-2180 and N00014-24-1-2538.

Team members:

• Nina Stark (Lead PI) and Noah Evans (PhD student) (University of Florida)
• Kelly Dorgan (PI), Joleen Aulgur (Research Technician), Sunjida Alam (PhD student) (University of Texas)
• Emily Eidam (PI, Oregon State University)
• Sungyoon Jung (PI, University of Florida)
• Julie Paprocki (PI), Akshita Mavurapu (Graduate student) (University of New Hampshire)
• Zhaohui Yang (PI), Yue Zhao (Postdoc) (University of Alaska)

Geotechnical risk assessment and mitigation strategies of dune toe collapse and dune erosion

This is a Florida Sea Grant Graduate Fellowship awarded to Saurav Shrestha. The primary aim of this study is to determine the cause of dune toe collapses that frequently occur in Flagler Beach, Florida, with focus on soil mechanics and metocean conditions. More specifically, this study will address the following objectives:

1. Analyze the main geotechnical parameters influencing dune toe failure during different metocean conditions.
2. Develop a risk assessment framework for dune toe collapse under different conditions and characteristics of sediments using a probabilistic approach.
3. Develop and assess possible mitigation measures, for example, slope modification, moisture control, and change in granulometry.

Team members:

• Nina Stark (PI) and Saurav Shrestha (PhD student) (University of Florida)
• Dr. Ansley Wren-Key (Flagler County)

The impact of geotechnical properties on seabed crawler mobility in coastal environments

The purpose of this project is to (i) assess the impact of geotechnical properties on seabed crawler mobility in coastal environments of different and varying seabed conditions including in the presence of benthos and (ii) test acoustic sensing technologies for onboard rapid assessment. To achieve these goals, Co-PI Stark and her team will complete the following research tasks:

1. Develop a theoretical framework to predict crawler mobility from geotechnical seabed properties.
2. Test the framework through field testing in winter/spring 2025 in Duck, NC.
3. Contribute to the development of acoustic sensing system for rapid onboard geotechnical seabed assessment.
4. Test the performance and feasibility of the acoustic sensing system for rapid onboard geotechnical seabed assessment through field testing in winter/spring 2025 in Duck, NC.

Sponsor: U.S. Army Corps of Engineers, SERDP MR24-4562 (more info)

Team members:

• Nina Stark (PI), Stephen Adusei (PhD student), Lea Eggensberger (PhD student) (University of Florida)
• Fred Falcone (Virginia Tech)

Integration of soil mechanics in numerical models of surf zone beach processes

Soil mechanics have been related to sediment erodibility in foreshore environments. Initial and detailed recent studies documented significant variations in geotechnical sediment strength in response to changes in hydrodynamic forcing and geomorphodynamics, representing a possible hazard for the prediction of trafficability and navigation from sediment mobilization events. The variability of geotechnical seabed surface sediment properties may also lead to issues with the accurate interpretation of acoustic seabed surveying efforts. However, obtaining geotechnical properties through traditional methods of field and laboratory testing can be challenged by accessibility of sites and environmental conditions. Novel field methodologies, specifically leveraging remote sensing, offer solutions to those challenges; however, the implementation of soil mechanics in numerical modelling of geomorphodynamics has the potential to offer predictions of geotechnical properties based on geomorphological change to possibly minimize the need for field data; or to improve the prediction of geomorphodynamics by including geotechnical parameters into the modeling. While significant progress has been made to advance the modeling of the coupled hydrodynamics, sediment transport, and morphodynamics, incorporating the effects of geotechnical properties in nearshore morphodynamic modeling remains at its infancy. The planned work aims at understanding the relationship between local geomorphodynamics, beach sediment strength and textural properties, and hydrodynamic forcing conditions by analyzing existing field data, improving numerical modeling tools, and testing the improved modeling capabilities during a proof-of-concept field experiment. This will be achieved through the following five research objectives and by leveraging existing data collected by the PIs in 2023:

1. Correlate geomorphodynamic change with geotechnical  properties of beach sediments and with hydrodynamic forcing conditions observed during two field experiments in 2023.
2. Improve the performance of the morphodynamic model XBeach to simulate the geomorphological change observed during the two 2023 field experiments (including an onshore and an offshore migration event, respectively).
3. Assess the role of different geotechnical sediment properties and pore pressure behavior on sediment dynamics along cross-shore profiles with special focus on the swash and the surf zones.
4. Explore pathways to integrate relevant and measurable geotechnical properties into XBeach modeling and assess its potential impact for navigation as well as trafficability.
5. Demonstrate the performance of improved modelling capabilities.

This 2-year study will be a key step towards the prediction of rapid beach evolution and the associated variations in seabed soil strength due to storms with the aim of assisting with model calibrations for acoustic surveying and navigation, as well as with trafficability assessment from remote sensing. The work is a collaborative effort with Co-PI Hubler from Villanova University and PI Hsu from the University of Delaware.

Sponsor: Office of Naval Research (ONR, www.onr.navy.mil), N00014-24-1-2558

Team members:

• Nina Stark (PI), Stephen Adusei (PhD student), Lea Eggensberger (PhD student) (University of Florida)
• Jonathan Hubler (PI, Villanova University)
• Tian-Jian Hsu (PI, University of Delaware)
• Jiaye Zhang (PhD student, University of Delaware)

Towards an integrative understanding of near-surface seabed structure

Naval and engineering applications in the deep sea are expanding, especially in the seabed surface layer, e.g., use of smaller, unmanned submersibles for surveying strategically important areas; deployment, anchoring, and retrieval of instrumentation; burial of deep-sea cables; leveraging sediment redox conditions to power equipment. These applications require an improved, integrative understanding of the seabed that includes short-term changes driven by biological and hydrodynamic processes, as well as tools for remote sensing of seabed properties. Our interdisciplinary team proposes to test the overarching hypothesis that organic matter input to the deep sea drives biological processes that modify geotechnical and geoacoustic properties of the surface layer of sediments. In testing this hypothesis, we will explore the spatial and temporal variability and relationships among these properties subject to forcing from bottom currents within a highly productive region of the ocean, the central California continental margin. This region experiences seasonal and interannual variability in organic matter and sediment deposition to the seabed and spatial variability in the infaunal community influenced by water depth, bottom water oxygen, and lateral transport. We plan to combine seasonal sampling of geological, geotechnical, geoacoustic, biological, and biogeochemical properties along a depth gradient from continental slope to abyssal plain with high-temporal-resolution sampling of the bottom boundary layer and seabed surface. Our results will provide insight on the patterns of seabed structure and stability and the mechanisms driving those patterns, and will improve our ability to predict and remotely detect related changes in deep sea sediments.

Sponsor: Office of Naval Research (ONR, www.onr.navy.mil), N00014-24-1-2447

Team members:

• Nina Stark (PI), Lea Eggensberger (PhD student), Jack Parker (Research Technician), Charli Pezoldt (Research Coordinator) (University of Florida)
• Kelly Dorgan (Lead PI), Alexandra Sharapova (Project Coordinator), Joleen Aulgur (Research Technician), and Jenny Duncan (PhD student) (University of Texas)

RAPID: Quantification of Sediment Erosion and Deposition, Debris Accumulation, and associated Damages to the Built Environment from Storm Surge and Wave Action during Hurricane Helene

The big bend coast of Florida was recently impacted by subsequent storm events including Hurricane Idalia (Cat 3; Sept 2023), Hurricane Debbie (Cat 1: July 2024), Hurricane Helene (Cat 4; Sept 2024), and Hurricane Milton (Cat 3; Oct 2024). It represents a unique series of storms impacting the same region within a short period of time. Hurricane Helene also stood out through a rapid intensification and last moment changes in course that allowed for limited time of warnings and for evacuation and storm preparation of residents. The goal of this research effort is to collect perishable data that will enable to quantify sediment erosion and deposition, debris transport and accumulation, and resulting damages to the built environment from storm surge and wave action during Hurricanes Helene and Milton through comparison to data collected pre-storm, during-storm, and in-between storms. It will be achieved through detailed field data collection including measurements in the nearshore and in coastal environments in Cedar Key, Shired Island, and Horseshoe Beach, Florida. The findings may lead to improved understanding, prediction, and mitigation of erosion and scour and impacts thereof during severe tropical storm events from storm surge, inundation, and wave action. Specifically, the uniqueness of this opportunity lies within the fact that pre- and during-storm data was collected throughout a Cat 4 and 4m storm surge event. These observations, combined with post-storm surveys and with additional measurement during Hurricane Milton and between Hurricanes Helene and Milton will enable researchers to understand the protection (and unintended consequences) of different shoreline protection systems. The planned effort will yield a data set that will improve current predictions of tropical cyclone impacts on coastal communities and will likely serve as a benchmark data set for future research studies. Data will be shared widely through NSF NHERI DesignSafe-CI and with local communities to increase awareness and understanding of risk assessments.

Sponsor: National Science Foundation, CMMI-2501467

Team members:

• Nina Stark (PI), Jaq Mueller (PhD student) (University of Florida)

ModPen: Modular Free Fall Penetrometer System for Seabed Sediment Testing

The rapid characterization of geotechnical seabed properties is of high importance to various naval applications including sensor/effector network deployments, mine burial prediction, sonar calibration, unexploded ordnances detection and management, navigation, and trafficability. Traditionally, sediment coring and sampling or in-situ cone penetration testing are used to obtain the required geotechnical data. However, those methods are time-intensive and require access with heavy equipment and vessels, often unfeasible for naval applications. Free fall penetrometers (FFP) and particularly portable free fall penetrometers are a reliable alternative when rapid geotechnical seabed characterization is required, access is limited, and/or measurements of the uppermost meter of the seabed surface are of high importance. FFPs are typically designed to satisfy certain deployment conditions (e.g., from a small vessel, during transit, in strong current, by robotic tools). This has recently been identified as an issue creating less flexibility in deployment and restricting the collection of data in diverse ocean environments. Additionally, deployments from autonomous or remotely controlled vehicles have gained in importance, and few FFPs can currently accommodate deployment by a vehicle payload unit. This proposal requests funds to assemble a modular free fall penetrometer system (ModPen) that can accommodate different deployment settings through a modular assembly. The ModPen will focus specifically on the following deployment settings winch-based deployment from the water surface in deep-water environments. We will purchase off-the-shelf penetrometer sensors and data acquisition units, will fabricate housing units for the specific deployment settings in our machine shop and 3D printing shop, and assemble them into a modular free fall penetrometer system that can satisfy different modern deployment requirements. The planned effort will also include a demonstration in each listed deployment setting.

Sponsor: Office of Naval Research (ONR, www.onr.navy.mil), N00014-25-1-2167

Team members:

• Nina Stark (PI), Jack Parker (Research Technician), Charli Pezoldt (Research Coordinator)(University of Florida)

Rapid soil classification and integration of soil characteristics for UXO site characterization and risk assessment

The overarching goal of project is to investigate the interactions between geotechnical seabed soil properties and behavior, physical sediment dynamics, and benthic biogenic processes towards the rapid geotechnical site characterization of seabed sediments using portable free fall penetrometer for enhancement of acoustic seabed site classification, assessment of UXO mobility and remediation needs, and generally UXO risk assessment. The research objectives are to: i) develop a soil behavior classification scheme based on portable free fall penetrometer measurements; ii)  identify effects of benthic biogenic processes on geotechnical soil properties and integrate these effects in the soil classification scheme; iii) identify and quantify the impacts of the different soil classes on acoustic UXO detection and classification methods, on erodibility estimates, and on susceptibility to soil liquefaction processes; and iv) develop strategies to implement the effects of soil classes into UXO risk assessment.

Sponsor: Strategic Environmental Research and Development Program (SERDP, https://serdp-estcp.mil/), grant MR21-C1-1265

Team members:

• Nina Stark (PI), Arianna Martin (PhD student), Saurav Shrestha (PhD student) (University of Florida)
• Adrian Rodriguez-Marek (PI) and Md Rejwanur Rahman (PhD student) (both Virginia Tech)
• Grace Massey (PI) and Carl Friedrichs (PI) (both Virginia Institute of Marine Sciences)
• Kelly Dorgan (PI) and Chesna Cox (MS student) (both Dauphin Island Sea Lab)

Assessment of trafficability of coastal sediments from satellite based remote sensing

Insufficient trafficability of coastal soils represents a major uncertainty and risk to naval missions, as well as for rescue and evacuation missions in coastal environments. In most cases, on-site physical testing and in-situ determination of geotechnical properties that enable an assessment of trafficability is unfeasible due to access or timing restrictions. Thus, the long-term goal of this work is to develop relationships between geotechnical properties of coastal sediments, satellite-based remotely sensed data, and coastal processes to predict trafficability for a variety of vehicles with high confidence.

Towards this long-term goal, the objectives of the proposed study are:

1. Detect and map coastal sediment dynamics in the intertidal zone from satellite images and relate them to geotechnical properties – and the variability thereof – relevant for the assessment of trafficability, including fines content, water content, relative density, and bearing capacity.
2. Develop probability thresholds predicting the trafficability of a person, a wheeled vehicle, and a hovercraft for a wide range of typical coastal sediments and geotechnical characteristics. Apply probability thresholds to trafficability assessment based on geotechnical properties derived from satellite imagery and assess uncertainty.

Sponsor: Office of Naval Research (ONR, www.onr.navy.mil), N00014-23-1-2418

Team Members:

• Nina Stark (PI) and Stephen Adusei (PhD student) (both University of Florida)
• Fred Falcone (PhD student, Virginia Tech)
• Julie Paprocki (PI, University of New Hampshire)