Southwest Washington Erosion Study

The Issue

How the USGS is addressing this issue

• Quantify historical and current regional coastal sediment budget and transport rates. Predict the future sediment budget in the Columbia River cell, between Tillamook Head, OR and Point Grenville, WA.
• Determine regional bathymetric and shoreline change trends. Develop a model and a methodology to predict short-term and long-term shoreline evolution and hazard areas with regard to existing and future sediment budgets.
• Determine natural and anthropogenic influences (extent and timing) on the dominant sediment sources ( e.g., Columbia River ) and littoral system.
• Establish baseline conditions and quantitatively monitor future coastal changes.
• Assist State and local planners in identifying options to reduce hazards and impacts to natural resources and the economy. Provide information to assist in developing management measures to prevent shoreline development crises.

1998 Activities

• Conduct a comprehensive literature search.
• Compilation of literature and other scientific reports.
• Review of most relevant literature and reports.

Establish Geodetic Control

• Complete geodetic control monumenting and surveying in coordination with NGS, and counties. We will complete a network of geodetic control survey monuments. This is needed to accurately reference and reproduce periodic beach profile surveys for analysis and determination of volumetric beach change, and ensure accuracy of shoreline mapping and delineation of various shoreline features, project areas, and legal boundaries. The monuments will also be used to transition from topographic to bathymetric mapping surfaces. Specific tasks include:
  • Establish new control monuments along the coastal corridor.
  • Enhance existing vertical and horizontal control using GPS.
  • Post process GPS data to calibrate control network.
  • Work with NGS to "blue-book" new 3D control monuments within the network.

Barrier Accretion/Erosion Studies

• PSU will finish across-barrier Ground Penetrating Radar (GPR) profiling at 20 locations, roughly spaced at 3-5 km intervals in the Ocean Shores, Grayland Plains, and Clatsop Plains barrier-plain complexes. One or two shore-parallel GPR profiles will also be run at the northern end of the Willapa Spit (Long Beach Peninsula). These subsurface records will be compared to linear dune-ridge mapping (surveying) to establish shore-parallel time lines of barrier accretion. We will also look for possible evidence of episodic erosion-accretion events in these barrier-plain complexes. Such erosion-accretion cycles have been observed on the Long Beach Peninsula, and they are hypothesized to represent coseismic-interseismic strain cycles in the Cascadia margin.
• PSU will finish vibracoring at approximately two sites each along the GPR/Dune Ridge profiles to establish the nature of apparent subsurface reflectors and to recover organic materials for C-14 dating of prehistoric shoreline positions. These data will be used to establish net shoreline accretion rates. Eventually, the established time lines will be used together with topographic data to establish prehistoric sand-accumulation rates in the prograding barrier-dune complexes. Vibracores will be split, photographed, logged, and subsampled in the field. All vibracores will be archived at the PSU Core Lab for the duration of the study.
• Ecology will continue to conduct beach profiling surveys at approximately 20 locations throughout the study area. Beach surveys will be conducted with GPS equipment. In places of 3D relief, a series of closely spaced transects will be taken. Semi-annual surveys from selected monuments would document seasonal changes in sediment transport direction and relative nearshore sediment transport rates for the adjacent reaches. Ecology will also monitor storm induced beach morphology change. Repeated surveys and sediment sampling will be conducted after major storms at selected sites.
• USGS will asses bluff erosion rates and determine sediment input to the sediment budget from the eroded bluffs. Historical aerial photographs will be digitized and goereferenced using ground control points and compared.

Shoreline Change Analysis

• Ecology will continue with compilation and analysis of historical data on shoreline change. This will involve:
  • Obtaining historical aerial photos, topographic surveys, digital data, and maps.
  • Reviewing survey reports to determine accuracies and limitations.
  • Digitizing surveys, and aerial photos and/or compile digital data in GIS ArcInfo format.
  • Producing products such as orthophotos.
  • Analyzing and quantifying historical shoreline and topographic change over decadal time scales.
  • Determining spatial and temporal gaps in data coverage.
  • Augmenting data gaps where possible with data from other sources.
  • Comparing shoreline changes with available bathymetric data and/or analysis conducted by USGS.
  • Determining needs for new aerial photography and/or topographic surveying.

• PSU will use available survey data and historic aerial photos to construct shoreline positions between the Columbia River and Tillamook Head, OR. We expect to establish shoreline positions from the late 1800's (pre-jetty) the early 1900's (pre-dams) the mid 1960's, and the current shoreline position. PSU will use shoreline position criteria and estimated error analysis developed by WA-DOE collaborators. The shoreline positions will be digitized for GIS (ArcInfo) compatible files for compilation by WA-DOE.

Bathymetric Change Analysis

• Collect and digitize historic bathymetric data from NOS boat sheets. Post-1950's data have already been digitized by NOS and are available on CD-ROM.
• Combine with historic shoreline data and contour historic bathymetric data.
• Develop cost-sharing plan with Corps of Engineers (Portland and Seattle District) to acquire new high-density bathymetric data for the inner shelf out to the 10 or 20 m contour.

Sediment Source Analysis

• Conduct historical analysis of dredge disposal quantities for the Columbia River and Estuary. Present day estimates of offshore dredge disposal suggest rates nearly equal to late Holocene fill rates for Grays Harbor. Quantifying the dredging records for the Columbia will require cooperation with the Portland District Corps of Engineers.
• Initiate plans for quantifying sediment fill volumes in the reservoirs behind dams on the Columbia River. Determine which dams should be assessed, and plan bathymetric surveys and coring surveys. This effort will be closely coordinated with the Portland District COE. Whether or not sediment has accumulated behind any of the dams, and if so how much sediment, is a critical question that must be addressed by this study.
• Resample and date previously collected cores from the mid-shelf mud deposit to asses Holocene sediment supply variations of the Columbia River.
• Analyze previously obtained high-resolution seismic data from the mid-shelf mud deposit for Holocene stratigraphy and sedimentation rates.

Inner Shelf/Bay Framework Studies

• Process newly collected seismic and side-scan sonar data from the inner shelf. Combine existing seismic and sample data from the study with newly collected data.
• Conduct an estuarine mapping and sampling program using high-resolution seismic (geopulse and 3.5 kHz) and sidescan (Kline) imagery for Willapa Bay and Columbia River estuary. Seismic profiling in the bays will be used with subsequent coring to determine Holocene fill rates
• Conduct an inner shelf coring cruise to collect sediments for dating and interpreting the seismic data collected in summer 97. These surveys will provide the regional framework upon which to design subsequent process oriented studies. In addition, they will provide inner shelf sediment accumulation rates and volumes for the sediment budget.

Shoreface Processes

• Work with the Corps of Engineers to enhance statistical analysis of wave climate from the collected data. This work would be accomplished through the existing Cooperative Agreement between Ecology and the Corps of Engineers, Coastal Engineering Research Center for the Washington Coastal Data Information Program. We will monitor wave and current measurements collected from the Grays Harbor entrance area, and begin historical data analysis.
• Initiate coastal circulation modeling.
  • Modify existing code for applicability to the SW Washington coast.
  • Develop grid for numerical models for study area.
  • Identify necessary data for input as boundary conditions to numerical model.
• Initiate large-scale wave refraction modeling. Plan and begin purchasing wave gauges for field testing of wave refraction models. Purchase and deploy meteorological stations.

Coastal Change Modelling

• Ecology will begin beach morphology change modeling. The suite of numerical models developed by the Army Corps of Engineers, GENESIS and SBEACH, will be tested on beaches within the study area. Although these models are quite simple and involve many assumptions, they can still provide insight into current and potential beach erosion problems. The results from this initial modeling effort will aid in the development of more detailed and site specific modeling later in the study.
• USGS in cooperation with CSIRO will initiate large-scale coastal evolution modeling. Models WAVE and SEDSIM from Martinez and Harbaugh will be evaluated for applicability to the SW Washington coast.

Develop Database/GIS

• Ecology will further develop a coastal database and information management system. The database will be merged with GIS in ArcInfo format using ArcView, and specified for storage and maintenance on the Shorelands and Water Resources Program Facility Site of Ecology's Information Management System. Ecology and USGS will develop a GIS database and information management system. We will continue with initial efforts that involve:
  • Establishing data format and quality control standards.
  • Converting and integrating existing data and databases with GIS ArcInfo system.
  • Determining uses and relational data needs.
  • Developing a GPS and GIS data dictionary.

Workshops and Outreach

• Ecology and USGS will conduct a technical workshop for local groups. The purpose of the workshop is to obtain input, recommendations, and guidance from local groups and end users of products developed from this study. We will also strive to educate locals on our understanding of the coastal littoral system and update them on research progress. The forum would also help identify information transfer, data products, and deliverables needed to answer fundamental questions.
• We will coordinate planning and studies with local groups and with related projects to enhance both the site specific and regional studies. A coordinated effort will reduce costs and/or improve quality and quantity of the overall effort. Ecology will facilitate a mechanism for information exchange and local input through a Pacific and Grays Harbor County Inter-Local Agreement and establishment of an advisory group.
• Ecology and USGS will also coordinate with other projects and studies to enhance partnerships and agency collaboration to develop opportunities to leverage funds for related and concurrent studies. Specifically, we will coordinate with the following projects:
  • The Grays Harbor Long-Term Study with Corps of Engineers, Grays Harbor County, Port of Grays Harbor, Cities of Westport and Ocean Shores.
  • The Willapa Bay Navigation Project with the Corps of Engineers, Shoalwater Bay Indian Tribe, Department of Transportation, Pacific County, and Port of Willapa Harbor.
  • The Willapa Bay Study with the Environmental Protection Agency and Willapa Alliance.
  • The Mouth of the Columbia River MCCP Study and the Columbia River Channel Deepening Project with Corps of Engineers.
  • The Tsunami Hazard Mapping Project with the Oregon State Department of Geology and Mineral Industries and Oregon Graduate Institute.
• We will facilitate public information and participation. Ecology will serve as the major coordinating entity between local groups and federal agencies. The following elements will assist in bridging research needs and results with local concerns and issues:
  • Initiate local advisory group in coordination with Grays Harbor and Pacific Counties.
  • Conduct public workshops and education outreach.
  • Develop education interpretive programs and displays to be implemented and co-sponsored with the Coastal Resources Science Center.
  • Develop and maintain a home page for the study on the internet.
  • Develop information bulletins and public involvement opportunities.

Accomplishments to Date

• Organized briefings to local and county officials, to Ecology director and staff, and to locals lobbying group in USGS headquarters.
• Developed an initial database and cataloged data and reference materials.
• Completed inventory of geodetic control.
• Completed draft Holocene sediment thickness map for the inner shelf.
• Updated the Washington Wave Data Base.
• Conducted GPR surveys of selected barrier sites.
• Developed WA Department of Ecology Home Page for the Erosion Study.
• Identification, purchase, installation of ERDAS remote sensing/orthophoto rectification software.
• Created orthophotos and orthophoto mosaics for Pacific County, Washington from NOAA 1995 photography. Grays Harbor county work is in progress.
• Transferred scanned photos, orthorectified imagery, and other information to stable storage media (CDROM).
• Developed digitizing methodology for extracting mean high water lines and erosion reference features from current and historical photography.
• Assisted in the continued development of the control network being constructed for the study. Work includes collection of benchmark data sheets, site reconnaissance, preparation of recovery reports, proposing new monuments, and development of the GPS observation plan.
• Planned for GPS survey of coastal areas and collection of ground control points for use in the orthophotorecification process.
• Trained in the numerical model GENESIS, and attended Image Processing workshop at Oregon State University
• Installed the North Cove videography (Argus) station. The station has been taking images since October, 1996.
• Initiated beach morphology monitoring program including surveying beach profiles at sites occupied by Bascom in '46 and '47, mapping beach surfaces at hot spots such as Westport, Ocean Shores and Ledbetter Point, and surveyed shorelines.

USGS Cooperators

Products

• Gelfenbaum, Kaminsky, Sherwood, and Peterson, SW Washington Erosion Study Workshop report, OFR.
• Peterson, Phipps, and Gelfenbaum, Grays Harbor Holocene fill history, OFR.
• Kaminsky, Ruggiero, Gelfenbaum, and Peterson, Long-term coastal evolution and regional dynamics of a US Pacific northwest littoral cell, Coastal Dynamics 97, abs.

• Open File Report on the Holocene fill in Grays Harbor
• Paper on the regional variation of barrier development in the Columbia littoral cell
• Isopach map of inner shelf Holocene sand sheet based on reconnaissance seismic data
• Inner shelf surficial geologic map based on reconnaissance geophysical, sidescan sonar, and surface sediment data
• Shoreline change maps