Cooperative Agreement # 02WRAG0057
ANNUAL REPORT ON THE STUDY OF NEARSHORE FLUID AND
SEDIMENT PROCESSES AT KACHEMAK BAY - HOMER, ALASKA
USING VIDEO METHODS
by
Northwest Research Associates (NWRA)
Bellevue, WA
for
United States Geological Survey (USGS)
Coastal and Marine Geology Program
Submitted to Drs. Peter Ruggiero and Guy Gelfenbaum: 29 Jan 2005
US Geological Survey
345 Middlefield Rd MS-999
Menlo Park, CA 94025
650-329-5433 – Voice (Ruggiero)
650-329-5483 – Voice (Gelfenbaum)
650-329-5190 - Fax
pruggiero@usgs.gov - email (Ruggiero)
ggelfenbaum@usgs.gov - email (Gelfenbaum)
Second Year Completed
Contact Information:
NorthWest Research Associates
14508 NE 20th Street
Bellevue, WA 98005
For Technical Questions: Dr. Joan Oltman-Shay, 425.644.9660 x314, 425.644.8422 (fax) joan@nwra.com
For Contract Questions: Ms. Yvonne Pipkin, 425.644.9660 x220, yvonne@nwra.com
i
Cooperative Agreement # 02WRAG0057
TABLE OF CONTENTS
Table of Contents .......................................................................................................................... ii
1.
Background ............................................................................................................................1
1.1
Kachemak Bay ............................................................................................................... 1
1.2
Statement of Problem ..................................................................................................... 1
1.3
Goals and objectives ...................................................................................................... 2
1.3.1
Long-Term Goal ..................................................................................................... 3
1.3.2
Scientific Objectives ............................................................................................... 3
2.
Results from the First- And Second-Year Effort ................................................................3
2.1
Year One ........................................................................................................................ 3
2.2
Year Two........................................................................................................................ 6
3.
Company Information and Key Personnel ..........................................................................6
3.1
Company Information .................................................................................................... 6
3.2
Key Personnel ................................................................................................................ 7
ii
Cooperative Agreement # 02WRAG0057
1. BACKGROUND
1.1 KACHEMAK BAY
Kachemak Bay is located on the western tip of the Kenai Pennisula (Figure 1). The bay
is the home of the Alaskan unit of NOAA’s National Estuarine Research Reserve System
(NERRS), which was established to provide opportunities for long-term coastal research and
monitoring, estuarine education, and to provide a basis for more informed coastal management
decisions. The proposed study site is on the north shore of Kachemak Bay, near the town of
Homer.
Figure 1. Location map of the Kachemak Bay Research Reserve.
The significant coastal processes at work in Kachemak Bay include tectonics, variations
in sediment supply due to episodically eroding bluffs, an 8+ m tide range, and a sea-dominated
nearshore. The intra-tidal cycle variability of wave-current interactions apparently has a
significant impact on both the magnitude and the direction of sediment transport.
1.2 STATEMENT OF PROBLEM
Distinguishing features of Kachemak Bay are a 4-mile long spit of sand (Homer Spit) that
extends into the bay from the north shore (Figure 2) and an 8-m tide range. This spit is
morphodynamically connected to eroding bluffs northwest of the spit. From the perspective of
the State and the Kachemak Bay Research Reserve there are two primary objectives for studying
the coastal processes along the spit and adjacent bluffs:
1
Cooperative Agreement # 02WRAG0057
1. Coastal Erosion: Understand and quantify both the short- and long-term
morphodynamics in the nearshore as a function of both wave energy and sand supply.
The sand supply at this location was greatly increased following the 1964 earthquake that
caused massive land subsidence on the east side of Cook Inlet. The subsequent
introduction of sand from bluff toe erosion provided the bulk of the sand supply to the
system. It is hypothesized that construction of newly proposed shore protection structures
may cause localized sand starvation and increased shore erosion within the town of
Homer, both along the spit and the bluffs to the northwest.
2. Nearshore Habitat: Whereas the sand volume appears to have recently decreased in the
nearshore, the deeper water benthos still has considerable sediment. In fact a kelp bed
was destroyed recently following a massive movement of sand during a winter storm.
The kelp bed habitat was found to be buried by over 1 meter of sand this past summer.
The kelp beds provide habitat for many other organisms and are the basis for the
nearshore ecosystem.
Figure 2. Aerial view of the Homer ABMS Site. The cameras are located at the point on the
headland from which the black lines are radiating. The black lines demark the field-of-views of
each of the eight cameras. The power of the camera lens used for each view is also shown in
mm. The distance from the cameras are indicated by the circles labeled 500 and 1000m.
2
Cooperative Agreement # 02WRAG0057
1.3 GOALS AND OBJECTIVES
1.3.1 Long-Term Goal
Improve our understanding of the large-scale coastal fluid and sediment processes of the
nation’s coastlines for the purpose of developing predictive capabilities and monitoring methods
that will contribute to the foundation upon which informed coastal management decisions can be
made.
1.3.2 Scientific Objectives
This proposal is part of a collaborative research effort with Drs. Guy Gelfenbaum and
Peter Ruggiero. The following represents the objectives of this joint effort.
The Kachemak Bay study site is unusual in its macro-tidal, high-wave energy, large-scale
features (surf zone, tidal flats, and morphology). These extreme parameters set this site apart
from the other sites studied by nearshore oceanographers. A study of this extreme beach genre is
likely to reveal aspects that are only subtle on other beaches, and may reveal processes unique to
this type of beach.
Objective 1: Monitor shoreline and morphology changes frequently enough to observe
episodic changes, before and after extreme tides and high waves, and long enough to determine
statistical trends in sediment movement.
Objective 2: Integrate the shoreline and morphology observations with information on
waves, tides, currents, presence or absence of hard structures, size and health of the ecosystem
for the purpose of developing an understanding of the interplay between fluids, sediments, and
the ecosystem.
2. RESULTS FROM THE FIRST- AND SECOND-YEAR EFFORT
2.1 YEAR ONE
The focus of the first year effort was on 1) system design, equipment calibration and
preparation, and installation of the ABMS, 2) routine daily acquisition and quality control
operations, and 3) data preparation, logging, and project web site development and maintenance
for dissemination of data.
The first year was very successful. We were most fortunate to be able to place the ABMStation on a headland east of the Beluga Slough. Our cameras and the camera platform are on
private property, in the backyard of a homeowner; our communication system is in their
greenhouse. This remarkable location provides the opportunity to watch fluid and sediment
processes around the headland. The original ABM-Station design was expanded to eight
cameras to allow for full coverage around the headland (Figure 2).
3
Cooperative Agreement # 02WRAG0057
The station was installed in February 2003 on an elevated platform designed by NWRA
and built by the City of Homer (Figure 3). The difficulty of obtaining ground-control-points
(GCPs) in the field-of-view of each of the cameras, especially those pointing directly offshore,
was successfully overcome by using a combination of painted rocks and night lights on the
distant Homer Spit as GCPs. There was some movement of the cameras in the first few weeks,
including concerns about eagles landing on the cameras, but camera movement has since
quieted. The geometries of all field-of-views have been proven to be tractable so that good
rectifications and merges of images are expected.
Figure 3. View of the camera tower looking south across the Kachemak Bay.
An example rectified- and merged-image composite is shown in Figure 4. A close-up of
one of the sand slugs of interest, believed to migrate from the Beluga Slough, can be seen in
Figure 5.
The web site developed for these data can be found at www.planetargus.com by clicking
on ABMS sites to bring up a map of the world and clicking near the town of Homer, Alaska to
bring up the Argus Homer site. The site provides both a background explanation of the effort as
well as access to the last hourly image acquired and the archive of images.
4
Cooperative Agreement # 02WRAG0057
Figure 4. Example rectified- and merged-image composite of the nearshore around the headland
at a moderately low tide. The black denotes the area not in the field-of-view of the cameras. The
image picks up1) the shoreline location (dark line at bottom of image against the near-solid
white, 2) the streams from the Beluga Spit (white branches on the left of image), 3) the finegrain, sorted sand against the coarse, darker sediment (sand slugs on the right side, near the water
edge), and other geomorphic features.
Figure 5. Example rectified- and merged-image composite zooming in on an interest area, in
this case the location of a sand slug.
5
Cooperative Agreement # 02WRAG0057
2.2 YEAR TWO
The focus of the second year effort was on 1) routine daily acquisition and quality control
operations, 2) geometry solutions for image rectification, 3) data preparation, logging, and
project web site maintenance for dissemination of data, and 3) support for data analysis.
In September 2003, NWRA hosted a workshop for Argus users. Stefan Aarninkhof, from
Delft Hydraulics, was invited to the workshop to instruct users on the application of Delft’s
Argus Runtime Environment toolbox for analysis of Argus data. In attendance was Peter
Adams. After the workshop, it was decided that Delft’s toolbox was the right tool for USGS to
apply to the Homer data.
The results of Homer analysis effort were presented at the Portland AGU Oceans meeting
in January 2004 (Adams et al., 2004). Evident from the analysis is the transport eastward of
fine-grain sediment over larger-grain cobble, in the form of “sand waves” or “sand slugs.” This
transport is counter to the tidal currents and preliminary results suggest that the transport is a
result of episodic wind and wave energy from the west. The sediment is likely eroded from the
bluffs to the west of the Beluga Slough. The Argus observations show the sand waves moving
offshore at the Slough mouth only to migrate back towards shore east of the mouth for further
transport eastward. Highest morphology transport rates (~80m in two months) were observed
when waves from the west were largest.
In Spring 2004, a few of the semi-permanent ground control points (GCPs) were
degrading and the geometry solutions for one of the cameras indicated errors in shoreline
mapping at extreme low tide. In July 2004, new GCPs were made (painted rocks) and surveyed.
The new GCPs were successfully applied to the full data set to obtain improved geometry
solutions.
Data collection routines have been modified in the second year to obtain high-temporalresolution shoreline location information. During Spring tides, data is collected in 15-minutes
intervals as opposed to the standard hourly interval. This provides finer mapping of intertidal
bathymetry.
Reference
Adams, Peter, P. Ruggiero, G. Gelfenbaum, G. C. Schoch, J. Oltman-Shay, 2004, “Nearshore
sediment transport along the mix-grained beachs of Kachemak Bay, Alaska,” AGU
Oceans, Portland, Oregon.
3. COMPANY INFORMATION AND KEY PERSONNEL
3.1 COMPANY INFORMATION
NorthWest Research Associates, Inc. (NWRA, www.nwra.com) is a research group
performing basic and applied research and technical services in Earth Sciences. The company
6
Cooperative Agreement # 02WRAG0057
has approximately 68 technical and support staff, most with advanced degrees (Ph.D., M.S.,
B.S.). NWRA was incorporated in Washington State in 1984 and has divisions in Bellevue, WA
(also the Headquarters), and Boulder, CO (with an satellite office at Tucson, AZ). Specific areas
of expertise include nearshore and coastal oceanography, coastal beach video monitoring and
surveying, meteorology and atmospheric sciences, space physics, computational fluid dynamics,
geophysical fluid dynamics, ice dynamics, optics, instrument development and field deployment,
computer graphics and image processing, digital signal processing, expert systems development,
medical technology, and World Wide Web technology development.
This project is taking place at the Bellevue Division. The Bellevue facility includes over
8,000 square feet of office space and more than 2,000 square feet of laboratory space. Facilities
available to NWRA staff include an experimental fluids laboratory, including a tilt tank and a
tow tank (also used for instrument calibration), a field staging and instrument development
laboratory, a clean laboratory for development and testing of laser/optical measurement and
inspection systems, a technical library, conference rooms, computer network, internet
communications and ftp capability, and desktop publishing and reproduction equipment. The
local computer network consists of Windows NT and Sun Microsystems workstations and
servers. An extensive data storage capability is maintained on the network, as well as full back
up and security subsystems.
3.2 KEY PERSONNEL
Dr. Joan Oltman-Shay is a Coastal Physical Oceanographer/Engineer and is NWRA’s
chief scientific advisor on the design and application of the ABMS technology. Dr. OltmanShay is a Senior Research Scientist and President at NWRA and is also an Affiliate of the School
of Oceanography at the University of Washington and the College of Oceanic and Atmospheric
Sciences at Oregon State University. Dr. Oltman-Shay’s area of expertise is nearshore and
coastal oceanography. After graduating from Scripps Institution of Oceanography in 1986 she
joined Dr. Rob Holman, the inventor of the Argus Beach Monitoring Station, for four years at
the Coastal Image Processing Lab at Oregon State University. She has spent most of her career
designing and implementing field and modeling studies of wave and current dynamics in the surf
zone. As a nearshore specialist, she works actively with geologists and engineers on the
interplay of sediments and fluids, particularly the movement of sand on beaches. She has
worked on several programs for the U.S. Army Corps of Engineers (USACE), including
designing instrument arrays and developing data analysis software for the Field Research
Facility’s 8-meter, high-resolution wave directional array.
Mr. J. Francis Smith (MS) is an Electrical/Mechanical Engineer for NWRA. Mr. Smith
is an expert on the design, development, and fielding of both remote sensing and in situ
technologies for collecting environmental data related to ionospheric, atmospheric and
oceanographic processes. This experience includes analog and digital electronics, electrical
(power) systems, mechanical design of structures and submerged instruments, optical system
design, RF systems and antenna design, programming and data analysis and laboratory
equipment design. Mr. Smith also supervises the fabrication, assembly, installation and
operation of the hardware systems under his purview. He has recently installed two ionospheric
monitoring stations at remote locations in Alaska, and is currently designing a new antenna
system for a third station. He was the mechanical and electronic engineer for NWRA’s Beach
7
Cooperative Agreement # 02WRAG0057
Probing System. Mr. Smith served as the director of the Northwest Regional Calibration Center,
a NOAA-owned oceanographic instrument primary-calibration facility operated by NWRA,
which maintained NIST-traceable standards for temperature, pressure and salinity. Shortly after
graduation from Seattle University (BSEE) Mr. Smith worked as an Assistant Brewmaster at the
Rainier Brewing Company, Seattle WA.
Mr. John Begenisich is a network systems specialist and web designer. He will serve as
a communications specialist and the web master for the proposed project. He has extensive
expertise in software engineering and network administration. Mr. Begenisich's duties at NWRA
have included local network administration (Windows, UNIX, LINUX) and managing network
and Internet communications, as well as web site design, development, and management. Mr.
Begenisich has played a crucial role in the Total Electron Content (TEC) portions of the High
Frequency Active Auroral Research Program (HAARP). He designed the scheme and built the
software for the collection, archival, and presentation of remote TEC field data for HAARP.
8