Barrier Island Comprehensive Monitoring

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This research is part of the Geologic and Morphologic Evolution of Coastal Margins project.

The historical conversion of Louisiana's wetlands, cheniers, and barrier islands to open water has been well-documented in numerous studies and anecdotal observations. The goal of the State of Louisiana Barrier Island Comprehensive Monitoring (BICM) program is to provide long-term data on the barrier islands of Louisiana that could be used to plan, design, evaluate, and maintain current and future barrier-island restoration projects. The USGS has partnered with the Louisiana Coastal Protection Restoration Authority (CPRA) to help achieve these goals. The BICM program used both historical and newly acquired (2006 to 2010) data to assess and monitor changes in the aerial and subaqueous extent of islands, habitat types, sediment texture and geotechnical properties, environmental processes, and vegetation composition. BICM datasets included aerial still and video photography (multiple time series) for shoreline positions, habitat mapping, and land loss; light detection and ranging (lidar) surveys for topographic elevations; single-beam and swath bathymetry; and sediment grab samples. Products produced using BICM data and analyses included (but were not limited to) storm-impact assessments, rate of shoreline and bathymetric change, shoreline-erosion and accretion maps, high-resolution elevation maps, coastal-shoreline and barrier-island habitat-classification maps, and coastal surficial-sediment characterization maps. The methods, data, and results for each of these tasks were published in six data volumes that are summarized in Kindinger and others (2013). 

The BICM program study area encompasses the mainland shoreline of the southern Louisiana coast with special emphasis on the sandy beaches and barrier islands. For this study, the Louisiana coast was divided into four distinct regions based on geologic and physiographic setting: (1) the Pontchartrain Basin, (2) the Mississippi River Delta Plain, (3) the Acadiana Bays, and (4) the Chenier Plain. As the project developed, BICM further subdivided the coastline into eight regions: the Lakes Region; Chandeleur Islands; Modern, Lafourche, and Teche Deltas; Acadiana Bays; and the eastern and western Chenier Plain.

The Barrier Island Comprehensive Monitoring (BICM) program was implemented under the Louisiana Coastal Area Science and Technology (LCA S&T) office as a component of the System Wide Assessment and Monitoring (SWAMP) program (U.S. Army Corps of Engineers, USACE, 2004). The BICM project was developed by the state of Louisiana (CPRA, formerly Department of Natural Resources [DNR]) to complement other Louisiana coastal monitoring programs such as the Coast wide Reference Monitoring System-Wetlands (CRMS-Wetlands) and was a collaborative research effort by CPRA, University of New Orleans (UNO), and the USGS.

Objectives

• Determine the elevation, longevity, and conservation mass of the barrier islands;

• Determine major habitat types and the distribution and quantity of each habitat on the barrier islands over time;

• Determine geotechnical properties of sediments on the barrier islands and surrounding waters to access compatibility of the sediment and the sediment-dispersal pattern to evaluate fill performance;

• Relate available data on environmental forces that affect the ecology and morphology of the barrier islands to other BICM datasets;

• Determine species composition and diversity of vegetation within major habitat types on the barrier islands.

• Barrier-shoreline post-storm assessment (aerial videography and photography);

• Historical shoreline changes and barrier-island land loss;

• Bathymetry and historical seafloor change;

• Light detection and ranging (lidar) surveys for the Louisiana coast’s sandy shorelines and barrier islands;

• Habitat mapping and change analysis;

• Characterization of Louisiana coastal surface-sediment samples.

Methods

The methods, data, and results for each of these tasks were published in six data volumes that are summarized in Kindinger and others (2013).

Data Synthesis

Although the objectives of BICM were delineated into six tasks, none of them stand completely alone as single entities. Instead, the tasks are interrelated, and data from one task were commonly incorporated into analyses within other tasks. For example, while the group tasked with collecting and acquiring historical and modern shorelines created their scientific products, the bathymetry group was producing similar products in many of the same areas. Identifying the shoreline location of a barrier island is a result of using the nearshore bathymetry, aerial photography, and lidar topography. These data are also used to map the geomorphology of the area. Islands consist of sandy sediments, and the nearshore sediment texture is a reflection of the source of sediments and the energy of the area. Nearshore surficial sediments were collected as a discrete task within BICM; however, maps depicting sediment properties along with bathymetry and shoreline position provide a basis for interpreting and understanding sediment transport, sediment-source location, sediment depositional sinks, and energy of the environment. Concurrently, another group was tasked with describing habitat classification, habitat change, and land-loss trends. Changes in nearshore bathymetry and barrier-island shape are driven by sediment deposition or erosion caused by nearshore currents and changes in energy, particularly by storms. As a result of these changes, some island habitats can change dramatically while other areas may remain stable over time. Time-series analysis of data collected for all tasks is imperative to monitor these dynamic environments.

The Louisiana coast is a complex system that encompasses highly variable geomorphic and geologic settings. Regional discussions found in Kindinger and others (2013) summarize the extensive data-collection efforts and present brief interpretive analyses for four coastal Louisiana geographic regions. In addition, several coastal-wide and topical themes were selected that integrate the data and analyses within a broader coastal context: (1) barrier-shoreline evolution driven by rapid relative sea-level rise (RSLR), (2) hurricane impacts to the Chandeleur Islands and likelihood of island recovery, (3) impact of tropical storms on barrier shorelines, (4) Barataria Bay tidal-inlet management, and (5) habitat changes related to RSLR. The final theme addresses potential future goals of the BICM program, including rotational annual to semi-decadal monitoring, proposed new-data collection, how to incorporate technological advances with previous data-collection and monitoring protocols, and standardizing methods and quality-control assessments for continued coastal monitoring and restoration.