Archive for the ‘Hydrographic surveys’ Category
From a NOAA National Ocean Service podcast…
Boaters rely on NOAA’s nautical charts for depth measurements so they don’t accidentally ground on sandbars or other underwater obstructions. See how NOAA updates nautical charts with high tech tools —including new experimental ocean “robots” that are small enough to survey the nation’s shallowest coastal areas.
Coastal planners, fishery managers, and oceanographic researchers will soon reap important seafloor and water column data from the coast of Washington, when NOAA Ship Rainier undertakes a special project in the waters within and near the Olympic Coast National Marine Sanctuary in May.
The blue lines indicate NOAA Ship Rainier’s survey project areas. From north to south, the project encompasses Juan De Fuca Canyon (65 square nautical miles), Quinault Canyon (378 square nautical miles), and Willapa Canyon (189 square nautical miles). The teal dots in Quinault and Willapa canyons are the locations of deep underwater natural methane gas seeps being investigated in a University of Washington research project. The green shaded area is the extent of the Olympic Coast National Marine Sanctuary.
The project, which is being managed by NOAA’s Integrated Ocean and Coast Mapping program, grew from NOAA’s National Centers for Coastal Ocean Science seafloor mapping prioritization exercise among coastal stakeholders from federal and state (Oregon and Washington) agencies, tribes, and academia. The group determined that one of the biggest needs by most of the organizations was a better understanding of canyon depths, seafloor, and habitat.
A scientific team of experts from the College of Charleston, University of Washington, and Oregon State University will contribute to the NOAA-led multi-disciplinary survey project, gathering data for a host of research projects and ocean management activities. In general, the data will collect swath bathymetry, acoustic backscatter, and water column data to:
- inform regulatory decisions on coastal development;
- provide benthic habitat mapping and seafloor characterization for sustainable fisheries initiatives, and to help assess fishery stocks and critical spawning aggregation locations;
- better understand and manage shelf and canyon resources;
- aid in resolving multiple-use conflicts;
- advance research in determining chemical and biological contamination levels; and
- provide a data repository for the development of ocean tourism and recreational fishing.
Some specific research projects are also planned.
- A University of Washington scientist will analyze the water column plumes over natural methane gas seeps in the planned survey areas. The university is a leader in the study of methane hydrates.
- Because Rainier heads to Alaska after the survey in the sanctuary, the ship will also conduct an exploratory survey to obtain seafloor imagery and data over a newly discovered mud volcano in the upper continental slope offshore of Dixon Entrance, just off the Inside Passage near Ketchikan, Alaska. California State researchers will use the data from this 40 square nautical mile survey to analyze the seafloor shape, assess the area for effects on potential tsunamis, and identify unique biological communities.
As part of her regular mission, Rainier will acquire depth measurements and other hydrographic data throughout the entire project to update NOAA nautical charts 18480 and 18500 off the coast of Washington, and chart 17400 in Alaskan waters. The corresponding electronic navigational charts (NOAA ENC®) are US3WA03M, US3AK40M, and US3AK40M.
Chris Stubbs, from the College of Charleston, will serve as the project’s chief scientist. Cmdr. Edward J. Van Den Ameele is Rainier’s commanding officer.
NOAA ship Rainier, a 48-year-old survey vessel, is part of the NOAA fleet of ships operated, managed and maintained by NOAA’s Office of Marine and Aviation Operations, which includes commissioned officers of the NOAA Corps, one of the seven uniformed services of the United States, and civilian wage mariners.
The U.S. Board on Geographic Names recently named four previously unknown basins in the United States Exclusive Economic Zone (EEZ) in the Gulf of Mexico, honoring retired NOAA officers who mapped the area in the late 1980s and early 1990s. The names — Armstrong Basin, Floyd Basin, Matsushige Basin and Theberge Basin — were proposed by Texas A&M University, based on their new compilation of bathymetry drawn largely from the NOAA multibeam mapping project conducted by now-decommissioned NOAA ships Whiting and Mt. Mitchell.
A basin in the Gulf of Mexico was named after retired NOAA Captain Andrew Armstrong.
Retired NOAA Capt. Richard P. Floyd was the commanding officer of NOAA Ship Whiting from February 1990 to March 1992; he was followed by retired Capt. Andrew A. Armstrong III, who was CO from February 1992 to January 1994. Retired NOAA Capt. Roy K. Matsushige was commanding officer of NOAA Ship Mt. Mitchell from December 1988 to January 1991, followed by retired Capt. Albert E. Theberge, who served as CO from January to November 1991. The officers led the bathymetric mapping operations under the direction of NOAA’s Office of Charting and Geodetic Services, a predecessor of today’s Office of Coast Survey.
Cartographers rely on the Board of Geographic Names, for good reason!
Since 1890, federal cartographers have relied on the decisions of the U.S. Board on Geographic Names — the 125-year multi-agency federal program to standardize names of geographic features — that operates under the umbrella of the Department of the Interior.
“The Board on Geographic names has its intellectual roots in the earliest map-making efforts,” explains Theberge. To illustrate the need for standardization in the U.S., Theberge points to a November 7, 1805, report by the famed explorer William Clark.
“Ocian in view! O! the joy… Great joy in camp we are in view of the Ocian, this great Pacific Octean which we been So long anxious to See.”
As Theberge points out: “In one sentence, Clark gives the reasons for the Board.”
EEZ mapping project achieved policy and technical objectives for U.S.
The four NOAA commanding officers led surveys for the EEZ mapping project, which was active between 1984 and 1991. The project originated from President Ronald Reagan’s 1983 proclamation establishing a U.S. Exclusive Economic Zone, which created a 200-mile-wide nautical “belt” around the U.S. and territories, adding over 3,000,000 square nautical miles to the nation’s jurisdiction.
In response to the EEZ proclamation, both NOAA and the United States Geological Survey embarked on mapping programs. The USGS used a deep-water, very wide swath, side scan sonar system called GLORIA, which gave a qualitative picture of the seafloor somewhat akin to aerial photography; and NOAA used both medium depth multibeam sounding systems (150 meters to 1000 meters) and deep water systems (1000 meters depth to full oceanic depth), which gave quantitative (depth) values. As opposed to widely-spaced single beam trackline in deep water areas, NOAA’s program attained 100% bottom coverage with the then-new (to the civil community) multibeam systems.
The Gulf of Mexico was one region of the mapping program, as maps were produced for waters of the East Coast, Gulf of Mexico, West Coast, Alaska, and Hawaii. In a paper presented at the 1988 Exclusive Economic Zone Symposium, the goals of mapping in the Gulf of Mexico (actually applicable to all EEZ regions) were espoused:
- Build the foundation of a marine environmental geographic information system for solving global and regional change problems.
- Improve targeting of scientific and engineering efforts involving higher-cost, manned, submersible investigations and remotely-operated vehicle operations.
- Better manage the living and mineral resources of the EEZ.
- Better model the physical oceanography of the Gulf of Mexico, including factors affecting water mass movements, acoustic propagation paths, and sediment transport regimes.
- Model geological and geophysical hazards affecting coastal regions and offshore construction.
- Discover and/or define unique or previously unknown marine environments for designation as marine sanctuaries or protected areas.
- Improve and enhance nautical charts and bathymetric maps.
This early multibeam mapping effort helped develop many concepts that Coast Survey later built on in shallow water multibeam charting, such as methods for correcting and calibrating beam pointing errors, use of GPS, ray-bending algorithms to account for refraction of beams, etc. Philosophically, the project also helped pave the way for the era of digital paperless survey data acquisition and processing, as EEZ survey operations significantly reduced the vast amounts of paper fathograms, printouts, and other products that accompanied classical hydrographic survey operations.
In 1992, a report by the Marine Board of the National Research Council addressed the needs of mapping the EEZ. It noted:
“EEZ mapping and survey activities of the USGS and NOAA have been impressive, especially given the limits on funding, assets, and human resources. …The current activities depend on individual efforts and assets that are, in many instances, borrowed or diverted from other projects.”
By the time the report was written, circumstances — including the grounding of the Queen Elizabeth II in Martha’s Vineyard Sound — dictated that NOAA devote more resources to inshore charting. The EEZ project was terminated but it left a legacy of new and improved methods, as well as a gentle nudge towards a paradigm shift from primarily paper data acquisition to digital data acquisition.
We still use the digital data gathered by the EEZ mapping project. During the monitoring of the Deepwater Horizon oil spill, NOAA used the data as its underlying bathymetric dataset. The spill was near Whiting Dome and Mitchell Dome, which were named respectively for their discovery by the NOAA ships Whiting and Mt. Mitchell during the EEZ project.
New project picks up where the EEZ project left off
Today, a new national deep-water bathymetric mapping project is underway, picking up where the EEZ project left off. The Office of Coast Survey’s Joint Hydrographic Center at the University of New Hampshire, along with NOAA’s Office of Ocean Exploration, is leading the bathymetric mapping work of the interagency U.S. Extended Continental Shelf (ECS) Project. Using today’s modern high-resolution descendants of the multibeam systems aboard Whiting and Mt. Mitchell, the ECS Project the ECS Project is mapping the continental slope in several regions, including the Gulf of Mexico, to establish the outer limits of the U.S. continental shelf in areas beyond the 200 nautical mile EEZ. Andy Armstrong, of recently named Armstrong Basin fame, continues to use his bathymetric mapping expertise, now conducting mapping operations for the ECS Project.
New data will update nautical charts around the country
As sure as spring arrives, NOAA vessels and independent contractors are hitting the seas for the nation’s 182nd hydrographic surveying season, collecting data for over two thousand square nautical miles in high-traffic U.S. coastal waters.
NOAA Ship Ferdinand Hassler heads out to survey.
“Nautical charts are the foundation for the nation’s maritime economy, and NOAA hydrographers spend months at sea, surveying critical areas to ensure safe navigation for the shipping, fishing, and boating communities,” said Rear Admiral Gerd Glang, director of the Office of Coast Survey.
“Spring is the traditional beginning of the survey season,” Glang explained. “After a winter of data processing, ship maintenance, and personnel refresher training, the NOAA survey ships and Coast Survey navigation response teams are anxious to get to their survey assignments.”
U.S. waters cover 3.4 million square nautical miles, including a seafloor that is constantly changing due to storms, erosion, and development. To keep the nation’s suite of over a thousand nautical charts up to date, the Office of Coast Survey annually plans hydrographic survey projects to measure water depths and identify new navigational hazards. Survey planners consider requests by marine pilots, port authorities, the Coast Guard, the boating community and others when setting the year’s schedule.
Planned 2016 survey projects
- Penobscot Bay, Maine, most of which hasn’t been surveyed since the 1950s, will get its first modern NOAA multibeam echo sounder survey, to acquire data for needed chart updates.
- Buzzards Bay, Massachusetts, is the subject of a multiyear project for updating charts. 2016 is the third year, and the survey ship will validate U.S. Geological Survey interferometric survey data for charting, and will align with NOAA’s Remote Sensing Division lidar data.
- Chesapeake Bay is also the subject of a multiyear survey project for updating charts. NOAA Ship Ferdinand R. Hassler will work offshore, while launches from NOAA Ship Thomas Jefferson will survey in the vicinity of Hampton Roads concurrent to the ship’s maintenance period in drydock.
- Wilmington, North Carolina, survey project will support the U.S. Coast Guard Atlantic Coast Port Access Route Study.
- Savannah, Georgia, needs hydrographic survey data for the port deepening project in preparation for post-Panamax ships.
- Sabine, Louisiana, will have a continuation of last year’s project to survey part of the approaches to Port Arthur and Calcasieu.
- Atchafalaya, Louisiana, will have a continuation of last year’s project to survey part of the approaches to Morgan City.
- Approaches to SW Pass, Louisiana, will be surveyed at the request of the U.S. Coast Guard and the Bureau of Ocean Energy Management, to provide new chart data for consideration of a proposed anchorage area near Port Fourchon.
- Chandeleur Sound, Mississippi, will have surveys to acquire critical updates since Hurricane Katrina.
- Yukon River, Alaska, will be partially surveyed to validate a new charting approach using satellite-derived bathymetry.
- Etolin Strait, Alaska, will also validate satellite-derived bathymetry data, as well as establish a survey corridor between Nunivak Island and mainland Alaska. This project will provide data for some of the new charts identified in the U.S. Arctic Nautical Charting Plan.
- Dutch Harbor, Alaska, will benefit from a shore-based survey operation simultaneous with a NOAA Fishpac project, as the ship’s smaller launches will acquire more data at the site of the 2015 M/V Fennica grounding.
- Kodiak Island, Alaska, will have another year of a multi-year surveying campaign in this critical area for increasing fishing and tourism.
- Prince of Wales Island, Alaska, needs updated survey data to improve charts to Tlevak Strait, expanding to Sukkwan Strait and Howkan Narrows.
- Behm Canal, Alaska, will get its third (and final) year of survey work to circumnavigate Revillagigedo Island as well as George and Carol Inlet, Alaska.
The surveys will be conducted by NOAA’s four dedicated survey ships ‒ Thomas Jefferson, Ferdinand Hassler, Rainier, and Fairweather ‒ and private companies that survey on a contract basis with NOAA. The NOAA ships are operated and maintained by the Office of Marine and Aviation Operations, with hydrographic survey projects managed by the Office of Coast Survey.
The schedule for Coast Survey’s navigation response teams (NRTs), 3-person boats that work closer in shore to acquire data for nautical chart updates, was announced earlier.
by Ensign Kaitlyn Seberger, onboard NOAA Ship Thomas Jefferson
Nautical charts are an important tool in navigating safely in coastal waters, and Coast Survey’s mission is to keep these charts up to date. However, maintaining accurate charts can be a challenge in locations where sandy shoals may shift seasonally and present a danger to navigation. These areas differ from the current nautical charts, and bottom contours change so rapidly that it may seem an impossible task to keep up using the traditional survey methods. Office of Coast Survey and NOAA Ship Thomas Jefferson are seeking a solution to this ongoing problem and may have an answer with satellite-derived bathymetry.
Satellite-derived bathymetry (SDB) begins with using multi-spectral satellite imagery, obtained by satellites such as Landsat and WorldView2, which compares green and blue color bands.
Multi-spectral satellite imagery of Mutton Shoal in Nantucket Sound, overlaid on the chart.
Green color bands are attenuated by the water faster than blue bands and help to infer relative depths of the water (blue areas being deeper than green). These images are then transformed into a color range scale applicable to the color scale used when surveying with a multibeam echo sounder. With the color range applied, reds on the image represent an area that may be shoal whereas blues and greens represent deeper water.
Satellite-derived bathymetry of Mutton Shoal with a color range scale that is correlated with the color scale used for multibeam processing.
Since the images are based on attenuation of color bands, depth can only be inferred, so survey equipment (such as vertical beam and multibeam sonars) is necessary to acquire true depth.
This fall, NOAA Ship Thomas Jefferson investigated the use of satellite-derived bathymetry imagery as a new survey tool. Survey technicians will calibrate the application of this imagery through bathymetry studies for Nantucket Sound and Chincoteague Island. NOAA Lt. Anthony Klemm, who is leading the studies, chose these project areas because they both had relatively clear shallow water and were in a highly changeable area. At these locations, he chose specific shoals for exploration based on vessel traffic density.
In October, Thomas Jefferson spent two days in Nantucket Sound researching shifting shoals using the satellite-derived imagery overlain on the most recent chart. Ensign Marybeth Head developed line plans to acquire data over the potential location of shoals as seen with the satellite images, as well as their charted locations. Survey launches acquired multibeam data in water deeper than six feet, and Z-Boats were sent in to acquire vertical beam data in areas too shoal for the launches to safely operate.
The video shows Z-boat surveying alongside the launch in shoals too shallow for the launches to operate safely. (Video credit: ENS Head)
Satellite-derived bathymetry of Mutton Shoal with multibeam data from the investigation overlaid. This picture demonstrates how accurate the location of the shifted shoal was compared to the SDB imagery.
During routine conductivity, temperature, and depth casts for sound speed velocity, Ensign Head and Ensign Kaitlyn Seberger used a Secchi disk to determine the attenuation coefficient at each cast location for later comparisons.
The satellite imagery was a vital tool in project planning, as well as determining safe navigation of the ship and the survey launches. Below is a picture of the chart location where Thomas Jefferson intended to anchor. The adjacent image is the satellite-derived bathymetry imagery indicating the anchorage would have been within a shoal area and unsafe for anchoring.
Side-by-side picture of the chart and SDB imagery for the intended anchorage location in Nantucket Sound. SDB imagery indicated a shoal that covered half of the anchorage safety circle. A Z-boat verified the indicated shoal was almost 30 ft shoaler than charted and without this useful imagery, the ship and launches could have run aground.
Ensign Head determined safe passage routes for the survey launches, using the satellite-derived bathymetry imagery overlaid on a chart of the area, as the charted soundings were not reliable. For example, a safe passage route between the study areas and the ship was located between two shoals that had shifted considerably from the chart of the area. Sections of the passage are currently charted at 20 feet or more of water, but the fathometer on the launch displayed depths of less than 10 feet.
Boat sheet for the launches indicating a potential safe passage route from the project area to the ship.
After processing the multibeam data, Ensign Head determined that more than half of the charted shoals in the project area had shifted and the red zones depicted in the satellite-derived bathymetry imagery were significantly shoaler than charted depths for the surrounding area. Results from the investigation showed that the satellite-derived bathymetry for Nantucket Sound was exceptionally accurate and aided in the identification of current navigational dangers.
However, more research is needed regarding the use of satellite-derived bathymetry as a contemporary survey method. Limitations on use of the imagery can include variables such as cloud cover, turbidity, Chlorophyll a, and other water quality properties that may affect attenuation. Despite these challenges, satellite-derived bathymetry is a new tool that could support survey efforts by reducing the amount of time and area necessary to survey and by increasing the effectiveness of NOAA’s efforts to efficiently provide safe navigation to the local mariner.
By Starla Robinson, project manager in Coast Survey’s Hydrographic Surveys Division
Two hundred years after Otto von Kotzebue and the crew of the Ruiric explored what would later be named Kotzebue Sound, NOAA ships Fairweather and Rainer follow in the same tradition. Two centuries ago they were searching for the Northwest Passage in support of trade. Today, we explore to improve the science and safety of navigation in support of commerce, environmental protection, and local communities. Our bathymetric data and observations will also be used to better inform coastal decision-making.
Original chart of Kotzebue Sound (left). 1973 chart of Kotzebue Sound (right). Today’s chart of the project area is not significantly different from that of 1973.
Many things have changed since the crew of the Ruiric braved these waters. However, operations in the Arctic are still challenging. For much of the year Kotzebue Sound is frozen over. The remote location makes arriving and maintaining basic needs of the ships and crew difficult–just being here is a success.
Technology has made navigation safer and surveying more efficient. For example, rather than the discrete lead lines that were once used to obtain depth measurement data in this project area (which is about the size of Delaware), multibeam echo sounders acquire the same amount of data in just one square meter. For multibeam surveys, the speed of sound must be measured in the water column and the motion of the vessel must be recorded and corrected in the data. We use side scan sonar to produce imagery of the sea floor. GPS is used to triangulate our position rather than sailors taking bearings on shore stations. To better refine our precision, we construct horizontal and vertical control stations that must be operational before bathymetry data can even be collected.
It takes teamwork on and off the ship and NOAA has brought together many resources. Contractors are used to establish vertical control stations recording water levels. The Center for Operational Oceanographic Products and Services (CO-OPS) monitors the data and creates tide models. Subject matter experts in side scan sonar assist with the surveying effort. Teams on land plan and support the expedition and continue to process the data for the chart after the ships have left. Many things have to align to make our charting efforts a success.
On the ship, our exposed location limits survey activities. The small boats for survey can only be deployed when the sea state is safe. Teams must brave the surf to maintain the control stations. The crews of the Rainier and Fairweather work hard to take advantage of windows of good weather. They work long hours, in rough conditions, away from convenience and family, in pursuit of the chart. We are today’s explorers seeing the full picture of the seafloor for the first time.
NOAA survey progress map highlighting hydrographic survey coverage by NOAA ships Fairweather and Rainier as of August 17, 2015.