Integrating Mapping and Modeling to Support the Restoration of Bird Nesting Habitat at Breton Island National Wildlife Refuge

Description

The monitoring and assessment program development will focus on two major areas of interest: water quality and habitat. The basic approach, which will be similar in both areas, will include the development of comprehensive inventories of existing programs and data sets and the evaluation of existing program utility as valid metrics of restoration success. This assessment will be accomplished through the determination of the minimum monitoring program elements required to provide a quantitative basis for evaluating monitoring efficacy and/or targeted restoration benchmarks, and the identification of data gaps. The program will compile existing assessments of baseline water quality and habitat conditions; provide the basis for developing a list of critically needed, but currently non-existent, data sets and the creation of recommendations regarding the standardization of collection, analysis and data management protocols across the region. The end product is envisioned as a searchable database, accessible to the public through an interactive webmap.

This is a collaborative program, leveraging knowledge, personnel, expertise, and/or funds from a variety of sources, including federal, state, and local agencies, non-governmental organizations, academic institutions, and business and industry. This program, in coordination with the Gulf of Mexico Alliance, will engage a Community of Practice, representing many restoration partners across the region. This will ensure that these efforts fully involve stakeholders, share lessons learned, facilitate the standardization of data collection and analysis, and disseminate information across the widest possible spectrum. The program will be managed through a system of inter-related committees, including a Program Advisory Team, a Council Monitoring and Assessment Working Group, and a Monitoring Coordination Committee. The managerial system will be flexible, with informational flow, scientific analysis and decisional processes all subject to multi-directional feedback, including to/from the various working groups and stakeholders, and the Community of Practice.

Objectives

• Understand the geologic evolution of the inner shelf
• Define the evolutionary relationships between the nearsurface geology and seafloor morphology
• Identify resources for shoreline restoration
• Measure and monitor topographic and bathymetric changes through comparison of historical data to present
• Evaluate how restoration scenarios respond to various oceanographic conditions
• Determine if extraction of sand resources offshore will impact the wave climate at Breton Island
• Model natural processes, such as wave action and sediment transport, to evaluate how the island will respond to restoration

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Background

Geophysical investigations of the island platform were conducted in 2007 as part of the Louisiana Barrier Island Monitoring Project (Kindinger and others, 2014). Data collection included single-beam bathymetry, chirp subbottom profiling, lidar, and aerial photography. This information was greatly enhanced in 2014 with the collection of additional high-resolution geophysical profiles and topobathymetric lidar. Instrumentation used in 2014 included interferometric swath bathymetry, sidescan sonar, and chirp subbottom profiling. Platforms used to collect the data range from a large research vessel providing 24-hour acquisition support, to a jet-ski equipped with a single-beam bathymetric transducer for shallow water and surf zone acquisition. Sediment cores were collected to ground truth the geophysical data. Results of the investigations are reported in DeWitt and others (2015); Forde and others (2016), and; Bernier and others (2017). Data are available at https://gom.usgs.gov/doi/breton. Analysis of the shoreline and bathymetric data was used to evaluate seafloor and island area change over the past century (Terrano and others, 2016; Flocks and others, 2016).

Offshore sand resources extracted for restoration will leave a depression (borrow area) in the seafloor that may affect the wave climate in the region (e.g., Bender and Dean, 2003; Benedet and List, 2008). These perturbations to the shallow-water bathymetry can impact the wave field in a variety of ways, and may result in alterations in sediment transport resulting in new erosional or accretional patterns along the beach. A scenario-based numerical wave model was used to evaluate the impacts of proposed borrow area designs on the wave climate around Breton Island. The oceanographic scenarios are derived from a wave climatology developed for the region (Long and others, 2014). This methodology investigates the spatially variable wave climate under a range of wave conditions including both the low energy conditions that typically prevail in the northern Gulf of Mexico as well as during storm events (hurricanes and winter storms). The wave climate was compared under the current conditions (no borrow area) and with adjusted bathymetry including proposed borrow areas to determine what changes in nearshore wave height and direction may result from the utilization of offshore sand resources in this area. Results of this study are reported in Dalyander and others (2015).

The new bathymetric data and a set of potential island restoration scenarios was used to initialize a morphological model (Roelvink and others, 2009) that simulated island evolution under a variety of meteorological and oceanographic conditions. The evolution of each restoration scenario was simulated for a range of wave and water level conditions chosen from the same wave climatology used for the borrow area wave impact assessment. Simulations quantified how each of the proposed island configurations might respond to individual and repeated storm events. The combination of model scenarios and geophysical observations helped quantify sediment transport processes and erosion/accretion of the seafloor and shoreline.

Methods

In order to restore Breton Island to pre-Katrina conditions, the USFWS proposes rebuilding the shoreface, dune and back-barrier marsh. It is estimated that the proposed restoration would require upward of 10 million cubic yards of sand, to be acquired from offshore sources. Studies have shown that sediment deposits within Breton NWR suitable for shoreline nourishment are rare (Twichell and others, 2009), and are constrained to buried distributary channels, terminal spits and tidal deposits (Flocks and others, 2009). The USGS used high-resolution geophysical investigations to characterize the geologic framework of the shelf and nearshore around the island, and provided information necessary to evaluate potential restoration resources.

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Data Synthesis

• Characterize the near surface stratigraphy, island and seafloor morphology using high resolution geophysical and sedimentologic investigations
• Evaluate the influence of the geologic framework on the past and present morphology and sediment processes
• Provide geologic and morphologic information for:
  • effective restoration design and implementation
  • incorporation into morphologic models of coastal change to determine island response to construction, storms, and long-term processes
  • identification of dominant sediment transport processes, pathways, and budgets, and understand the role played by geologic processes and constraints.

References

• Bender, C.J., and Dean, R.G., 2003, Wave field modification by bathymetric anomalies and resulting shoreline changes: a review with recent results: Coastal Engineering, 49(1), 125-153, doi: 10.1016/S0378-3839(03)00061-9.
• Benedetto, L., and List, J.H., 2008, Evaluation of the physical process controlling beach changes adjacent to nearshore dredge pits: Coastal Engineering, 55(12), 1224-1236, doi: 10.1016/j.coastaleng.2008.06.008.
• Bernier, J.C., Kelso, K.W., Tuten, T.M., Stalk, C.A., and Flocks, J.G., 2017, Sediment data collected in 2014 and 2015 from around Breton and Gosier Islands, Breton National Wildlife Refuge, Louisiana: U.S. Geological Survey Data Series 1037, https://doi.org/10.3133/ds1037.
• Bernier, J.C., Kelso, K.W., Tuten, T.M., Stalk, C.A., and Flocks, J.G., 2017, Archive of Sediment Data Collected in 2014 and 2015 from around Breton and Gosier Islands, Breton National Wildlife Refuge, Louisiana: U.S. Geological Survey data release, https://doi.org/10.5066/F79C6VKF.
• Dalyander, P.S., Mickey, R.C., Long, J.W., and Flocks, James, 2015, Effects of proposed sediment borrow pits on nearshore wave climate and longshore sediment transport rate along Breton Island, Louisiana: U.S. Geological Survey Open-File Report 2015–1055, 41 p., doi:10.3133/ofr20151055.
• DeWitt, N.T., J.J. Fredericks, J.G. Flocks, J.L. Miselis, S.D. Locker, J.G. Kindinger, J.C. Bernier, K.W. Kelso, B. J. Reynolds, D.S. Wiese, and T.N. Browning. 2015. Archive of bathymetry and backscatter data collected in 2014 nearshore Breton and Gosier Islands, Breton National Wildlife Refuge, Louisiana. U.S. Geological Survey Data Series 1005. Reston, Virginia. https://pubs.er.usgs.gov/publication/ds1005; http://dx.doi.org/10.3133/ds1005.
• Flocks, J. G., and J. F. Terrano. 2016. Analysis of seafloor change at Breton Island, Gosier shoals, and surrounding waters, 1869 – 2014, Breton National Wildlife Refuge, Louisiana: U.S. Geological Survey Open-File Report. 2016–1069. Reston, Virginia. https://pubs.er.usgs.gov/publication/ofr20161069; https://dx.doi.org/10.3133/ofr20161069.
• Flocks, J., Twichell, D., Sanford, J., Pendleton, E., and Baldwin, W., 2009, Sediment sampling analysis to define quality of sand resources, in Lavoie, D., ed., Sand resources, regional geology, and coastal processes of the Chandeleur Islands coastal system – An evaluation of the Breton National Wildlife Refuge: U.S. Geological Survey Scientific Investigations Report 2009–5252, p. 197-245.
• Forde, A. S., J. G. Flocks, D. S. Wiese, and J. J. Fredericks. 2016. Archive of Digital Chirp Subbottom Profile Data Collected During USGS Cruise 14BIM05 Offshore of Breton Island, Louisiana, August 2014: U.S. Geological Survey Data Series 972. Reston, VA. https://dx.doi.org/10.3133/ds972; https://pubs.er.usgs.gov/publication/ds972.
• Kindinger, J.L., Buster, N.A., Flocks, J.G., Bernier, J.C., and Kulp, M.A., 2013, Louisiana Barrier Island Comprehensive Monitoring (BICM) Program Summary Report: Data and Analyses 2006 through 2010: U.S. Geological Survey Open-File Report 2013–1083, 86 p.
• Lavoie, D., ed., 2009, Sand resources, regional geology, and coastal processes of the Chandeleur Islands coastal system—An evaluation of the Breton National Wildlife Refuge: U.S. Geological Survey Scientific Investigations Report 2009–5252, 180 p.
• Long, J., Plant, N.G., Dalyander, P.S., and Thompson, D., 2014, A probabilistic method for constructing wave time-series at inshore locations using model scenarios: Coastal Engineering, v. 89, p. 53 - 62, doi: 10.1016/j.coastaleng.2014.03.008.
• Martinez, L., O'Brien, S., Bethel, M., Penland, S., and Kulp, M., 2009, Louisiana barrier-island comprehensive monitoring program (BICM), Volume 2: Shoreline changes and barrier-island land loss 1880s to 2005 [2.6 MB PDF]: Prepared for the Louisiana Department of Natural Resources, Coastal Restoration Division by the University of New Orleans, Pontchartrain Institute for Environmental Sciences, New Orleans, Louisiana, 32 p.
• Roelvink, D., Reniers, A., van Dongeren, A. P., van Thiel de Vries, J., McCall, R., & Skinless, J. (2009), Modeling storm impacts on beaches, dunes and barrier islands: Coastal Engineering, 56(11), 1133-1152, doi: 10.1016/j.coastaleng.2009.08.006.
• Terrano, J. F., J. G. Flocks, and K. E. L. Smith. 2016. Analysis of shoreline and geomorphic change for Breton Island, Louisiana, from 1869 to 2014. U.S. Geological Survey. U.S. Geological Survey Open-File Report 2016–1039. Reston, Virginia. 34 pp. https://pubs.er.usgs.gov/publication/ofr20161039.
• Terrano, J.F., Flocks, J.G., and Smith, K.E.L., 2016, Topobathymetric Lidar Survey of Breton and Gosier Islands, Louisiana, January 16 and 18, 2014: U.S. Geological Survey data release. https://coastal.er.usgs.gov/data-release/doi-F70G3H6G/; http://dx.doi.org/10.5066/F70G3H6G.
• Twichell, D., Pendleton, E., Baldwin, W., and Flocks, J., 2009a, Geologic mapping of distribution and volume of potential resources, in Lavoie, D., ed., Sand resources, regional geology, and coastal processes of the Chandeleur Islands coastal system – An evaluation of the Breton National Wildlife Refuge: U.S. Geological Survey Scientific Investigations Report 2009–5252, p. 150-196.