Archive for the ‘Hydrographic surveys’ Category

Correcting chart discrepancies at Alaska’s Whale Passage   Leave a comment

by Ensign Sarah Chappel, NOAA Ship Rainier

NOAA Ship Rainier recently surveyed Whale Passage, which separates Whale Island from Kodiak Island, Alaska. The area has never been surveyed with modern full bottom coverage methods, and some project areas were last surveyed by lead lines around a hundred years ago. The area frequently experiences 7 knot currents, making rocky or shoal areas particularly treacherous. Whale Passage is a high traffic area for fishing vessels, U.S. Coast Guard cutters, barges, ferries, and small boats, which is why updating the area’s nautical charts is so important.

entrance to Whale Passage

Strong currents push around Ilkognak Rock daymark at the entrance of Whale Passage. (Photo by LTJG Damian Manda)

The dynamics of the passage and surrounding area create several challenges for the hydrographic survey teams. The local tidal and current models are not well-known. To resolve this, Rainier was instructed to install four tide gauges in the greater project area, compared to a typical requirement for one gauge. Two of these gauges are a mere 4.5 nautical miles apart, in and just outside of Whale Passage itself. Some areas are so narrow and experience such high currents that it is only possible to survey in one direction in order to maintain control of the launch. The coxswain must plan each turn carefully, to avoid being pushed into dangerous areas. Ideally, these areas would be surveyed at or near slack tide. However, the slack in this survey area is incredibly brief and the predicted slack periods did not match what survey crews saw in the field.

The bathymetry is so dynamic that, even in relatively deep water, boat crews must remain alert for rocks and shoals. The survey teams found several large rocks in locations significantly different from where they were charted. Furthermore, the presence of large kelp beds increases the difficulty of surveying: they can foul the propellers on the launches, add noise to the sonar data, and can also obscure the presence of rocks.

While the work within Whale Passage, and the neighboring Afognak Strait on the north side of Whale Island, is challenging, it is also high-value. In addition to correcting the positions of known rocks and hazards, Rainier and her crew found a sunken vessel. Most importantly, though, they found areas that were charted twice as deep as they actually are. When the chart reads 8 fathoms (48 feet) and the actual depth is only 4 fathoms (24 feet), commercial traffic utilizing the passage could be in serious danger of running aground. Thus far, Rainier has submitted two DTON (danger to navigation) reports for depths significantly shoaler than charted. These new depths are already published on the latest version of chart 16594.

Rainier's multibeam sonar data shows a sunken fishing vessel in the vicinity of Whale Passage.

Rainier‘s multibeam sonar data shows a sunken fishing vessel in the vicinity of Whale Passage.

NOAA Ship Rainier will continue to survey the vicinity of Whale Passage, as well as the waters near Cold Bay out in the Alaskan Peninsula, for the remainder of the survey season before heading home to Newport, Oregon.

Rainier and launch

NOAA Ship Rainier recovers a survey launch after a morning of surveying and data collection. (Photo by LTJG Damian Manda)

 

Posted July 16, 2014 by NOAA Office of Coast Survey in Hydrographic surveys, Rainier

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NOAA improves public access to hydrographic survey descriptive reports   1 comment

by Marcus Cole, Coast Survey’s Cartographic & Geospatial Technology Program

Many are familiar with hydrographic surveys used to update nautical charts.

It isn’t enough, however, to collect just bathymetry during a survey. Without the context, such as when the data was collected, what instrumentation was used, or which tide stations were used to adjust the bathymetry to a particular datum, the data can’t be compiled into a chart update. The data can’t be discovered for a fish habitat study, or an analysis of coastal erosion, or tsunami inundation modeling. And, until two years ago, this metadata (data about data) was collected in a paper document that hadn’t changed much during the last century.

Experts from NOAA’s National Geophysical Data Center (NGDC) and Coast Survey’s Hydrographic Surveys Division recently ramped up the intensive process of overhauling their hydrographic survey metadata system ‒ an investment in resources that has increased efficiency, reduced errors, improved access, and enabled data discovery for anyone accessing the publicly available files.

Find descriptive reports from NGDC's interactive map.

Find descriptive reports from NGDC’s interactive map.

This particular effort centered on a new metadata format for descriptive reports (DR) that accompany every hydrographic survey. The report is a critical document that supplements and helps characterize the hydrographic data itself. For example, the DR lists the conditions under which the survey was performed, factors that might affect the survey’s adequacy and accuracy, who collected the data, how it was collected and processed, the equipment and procedures used, and the results. This metadata is essential for evaluating the survey, updating charts, and contributing to NOAA’s historical and legal archive.

Coast Survey’s new method of tracking metadata for DRs uses a format readable by both humans and computers: eXtensible markup language (XML). XML defines a set of rules for encoding documents that enables automation for many metadata-related processes:

  • producing, editing, and transferring survey metadata;
  • searching for text in a document;
  • transforming data formats; and
  • publishing standards-compliant metadata to multiple data warehouses from a single record.

Automation reduces the errors that may come from manual data entry, decreases the time needed to generate a DR, and enables data to be linked to other information pipelines. The biggest benefit from all these improvements in automation, however, is consistency. Just as datums are consistently defined and used in hydrographic surveys, metadata in the new XML DR architecture will be consistently generated and applied, leading to greater intercomparability between surveys. Furthermore, this change aligns with NGDC, where hydrographic survey data is archived. NGDC is adapting its data archiving and management infrastructure to take advantage of XML DR.

Not only does the new XML architecture make it easier to share data between Coast Survey and NGDC; it also helps integrate information from other branches of NOAA and the wider survey-interested community. Some of that information includes:

XML DR may also help Coast Survey integrate survey planning and ship resource management, extending its impact and utility even further.

A team of NOAA Corps officers, CIRES/University of Colorado contract staff, and Coast Survey experts worked together to foster these technology changes. As a result of their efforts to make data more consistent and accessible, it is as easy to learn something about H00001, the first survey conducted in 1837 in Long Island Sound, as it is to view H12381, a modern LIDAR survey from the Florida Keys.

NOAA hydro field season underway   1 comment

The 2014 hydrographic survey season is underway, with the NOAA fleet beginning its projects for this year.

Have you ever wondered how Coast Survey goes about determining where to survey and when? Several considerations go into prioritizing survey plans, which are laid out several years in advance. Coast Survey asks specific questions about each potential survey area.

  • Is it considered a critical area? If so, how old are the most current survey data?
  • Have local pilots or port authorities submitted reports of shoaling, obstructions or other concerns?
  • Does the U.S. Coast Guard or other stakeholders from the maritime community (e.g., fisheries, energy, pipelines) need surveys for economic development or ecological protection?

Coast Survey’s 2014 projects reflect these priorities.

Alaska

NOAA Ships Rainier and Fairweather will be surveying Kodiak Island, specifically Kupreanof Strait to the north and Sitinak Strait to the south. These are considered emerging critical areas, because of both old soundings (1900-1939 for North and 1900-1969 for South Kodiak Island) and increased demand from the tourism and commercial fishing industries to chart safe passages closer to shore.

Kodiak N and S_text_inlet

The Rainier will also continue her work in Cold Bay. The projects focus on charting potential areas of refuge for ships approaching the harbor, especially when currents are strong. Cold Bay is a very small harbor town on the Aleutian Peninsula. (You may recall that when the Rainier visited last year, all eight of the town’s school children came aboard to learn about driving the ship and making nautical charts!)

One of NOAA’s hydrographic services contractors will survey Bechevin Bay, a priority area because it constitutes the easternmost passage through the Aleutians from the Bering Sea to the Gulf of Alaska. In addition, hydrographic surveys in this area will help validate an algorithm, being tested by NOAA’s Remote Sensing Division, that estimates water depth strictly from satellite imagery.

Bechivin Bay and Cold Bay_Aleutian_text

West Coast

Fairweather will survey south of the San Juan Islands, in the Straits of Juan de Fuca in Washington. The team will also investigate reported shoaling in Friday Harbor.

One of Coast Survey’s navigation response teams, NRT6, is surveying in San Francisco Bay, where the San Francisco Bay Pilot Association requested surveys in San Pablo Bay and Suisun Bay at the Reserve Fleet area, and in Richmond Harbor to address charting discrepancies and other concerns. The ship will then survey Anchorages 22 and 23 (Carquinez Strait, near Benicia, CA) to chart a shoal that has migrated toward the federal channel and caused a tug and barge to run aground.

Gulf of Mexico

Pilots and port authorities requested hydrographic surveys in Galveston Bay and the vicinity, and NRT4 is responding. Anchorages in this area are of particular interest; the team will survey Anchorage Basin A in Bolivar Roads and the newly charted barge channels and charted features along the main Houston Ship Channel.

A NOAA contractor will survey in Louisiana, offshore of Barataria Bay. About 5,000 deep-draft vessels transit the Southwest Pass of the Mississippi River per year. Surveys will be looking for turnoffs and turning basins for large vessels. A re-survey of sandy, changeable bottoms in the areas of Mobile Bay, Alabama, and Panama City, Florida, will also be conducted to finish surveying approach lanes to these ports. A NOAA contractor will survey the approaches to Lake Borgne/Lake Ponchartrain in Louisiana, where charts still use data acquired by the U.S. Coast Survey in the 1800s.

NRT1 is surveying in Panama City, Florida, acquiring data in St. Andrews Bay and West Bay. The team will also investigate shoaling and a changing channel course in Grand Lagoon, depths and features in West Bay and West Bay Creek, and depths along the Gulf Intracoastal Waterway. After they finish up in Florida, NRT1 will continue the rest of the 2014 survey season in Louisiana.

Western GOM_text_inlet

East Coast

NRT2 will survey in the St. Johns River area near Jacksonville, Florida, in response to a request for support from the U.S. Coast Guard. The survey team will investigate hazards to navigation in the waters of a proposed anchorage area seven nautical miles northeast of St. Johns Point.

NRT5 will survey in the area of Eastern Long Island Sound. Along with providing contemporary hydrographic data, this survey will support the Long Island Sound Seafloor Mapping Initiative. NOAA Ship Thomas Jefferson will also survey in Long Island Sound, performing essential habitat mapping in Fishers Island Sound, and continuing Post Tropical Cyclone Sandy surveys that were started in 2013.

LI Sound_Sandy_text

In central Chesapeake Bay, the research vessel Bay Hydro II  will survey critical areas, measuring depths where shifting sands and shoaling have been reported. NOAA Ship Ferdinand R. Hassler will survey a possible wind turbine site in the approaches to the Bay.

The Hassler will survey off the coast of Portsmouth, New Hampshire. This data will contribute to habitat mapping and the state’s effort to locate sand resources for beach replenishment.

Finally, the Thomas Jefferson and Hassler will survey an area offshore of Rhode Island Sound to identify a safe route for deep draft oil tankers. The area is also a potential site for wind turbines.

Navigation Response Team 1 finds vehicle during survey of Intracoastal Waterway, assists sheriff’s office   Leave a comment

While surveying the approaches to Panama City (FL), St Andrews Bay, and West Bay, Coast Survey’s Navigation Response Team 1 recently made an unexpected find. When team members Mark McMann and Aurel Piantanida reviewed hydrographic data collected with their side scan sonar and multibeam echo sounder, they discovered an upside-down vehicle in Panama City’s West Bay Creek, part of the Intracoastal Waterway (see chart 11385).

NRT 1's multibeam echo sounder captures the submerged car's image.

NRT1′s multibeam echo sounder captures the submerged car’s image.

The vehicle location was adjacent to the channel maintained by the Army Corps of Engineers, and so it was not an obstruction to navigation. However, it was near a bulkhead where a local company loads gravel onto barges, and NRT1 was concerned about the safety of the barges.

NRT 1's side scan sonar shows the car adjacent to the channel in West Bay Creek.

NRT1′s side scan sonar shows the car adjacent to the channel in West Bay Creek.

The team relayed the information to Bay County’s sheriff who sent divers to the location. With the NRT’s assistance, the sheriff’s divers found the vehicle and called in heavy equipment from the local gravel company to remove it.

The Bay County Sheriff's office called in heavy equipment operators to remove the car found by NRT1.

The Bay County Sheriff’s office called in heavy equipment operators to remove the car found by NRT1.

Why was the 2007 Ford Escape in the creek? The investigation is in the able hands of the Bay County Sheriff’s Office. In the meantime, thanks to the sheriff’s response, led by Sgt. William T. Brotherston, a risk to the barges was removed.

The star on West Bay Creek marks the location of the submerged car.

The star on West Bay Creek marks the location of the submerged car.

obstruction_West_Bay_Creek_Chart_Location

Beyond the charts: geological highlights from NOAA’s 2013 hydrographic field season in Alaska   1 comment

–By Christy Fandel, Coast Survey physical scientist

Have you ever wondered what lies beneath the charted soundings on a nautical chart? While surveying Alaskan waters during the 2013 hydrographic field season, collecting bathymetry to update NOAA’s nautical charts, hydrographers revealed many interesting geologic features on the seafloor.

NOAA focuses a significant portion of our ocean mapping effort along the Alaskan coast. The Alaskan coastline represents over 50% of the United States coastline and dated nautical charts are inadequate for the increasing vessel traffic in this region. NOAA surveys are essential for providing reliable charts to the area’s commercial shippers, passenger vessels, and fishing fleets.

This past season, NOAA-funded hydrographic surveys in Alaska revealed many interesting geological features on the seafloor. Three surveys, in particular, took place in southeastern Alaska in the Behm Canal, along the Aleutian Chain within the coastal waters surrounding Akutan Island, and around Chirikof Island.

These three areas were surveyed by the NOAA Ship Rainier and surveying contractor Fugro-Pelagos during the 2013 field season.

These three areas were among the areas surveyed by the NOAA Ship Rainier and surveying contractor Fugro-Pelagos during the 2013 field season.

In May, hydrographic surveying conducted by NOAA Ship Rainier in the Behm Canal revealed two distinct geological features. In the northern region of the canal, scientists identified a long, meandering ancient river. This ancient submarine river is nearly 40 km in length with up to 50 m in relief. Further south, Rainier surveyed a large volcanic-like feature. The surveyed volcano appears to have a distinct caldera, or collapse-feature that most likely formed after the volcanic eruption.

Multibeam bathymetry of the northeastern portion of the Behm Canal shows a large, meandering submarine river. The cross-sectional inset highlights the relief of the channel, nearly 50 m, as shown by the red box.

Multibeam bathymetry of the northeastern portion of the Behm Canal shows a large, meandering submarine river. The cross-sectional inset highlights the relief of the channel, nearly 50 m, as shown by the red box.

Multibeam data acquired by NOAA Ship Rainier shows a large volcanic feature in the southern portion of the Behm Canal.

Multibeam data acquired by NOAA Ship Rainier shows a large volcanic feature in the southern portion of the Behm Canal.

Directly following the Behm Canal survey, Rainier transited west to survey the coastal waters surrounding Chirikof Island. The acquired bathymetric data revealed a stark northeast-trending fault in the southeastern portion of the survey area. This surveyed fault is distinguished by a clear misalignment across the fracture.

The red box outlines the northeast-trending fault along the coast of Chirikof Island, shown with bathymetry acquired by the Rainier.

The red box outlines the northeast-trending fault along the coast of Chirikof Island, shown with bathymetry acquired by the Rainier.

Concurrently, an Office of Coast Survey hydrographic surveying contractor – Fugro-Pelagos  – was surveying off the western coast of Akutan Island. Fugro’s hydrographers identified a large volcanic feature within the acquired bathymetric data. The surveyed volcanic feature is believed to be either a volcanic vent or cinder cone volcano. The multiple circular rings outlining this feature may represent the successive lava flows that formed the volcano.

Multibeam bathymetry acquired by Fugro, around Akutan Island, shows a large volcanic vent or cinder cone volcano, marked by multiple circular rings that represent the successive lava flows that formed the volcano.

Multibeam bathymetry acquired by Fugro, around Akutan Island, shows a large volcanic vent or cinder cone volcano, marked by multiple circular rings that represent the successive lava flows that formed the volcano.

With the upcoming 2014 hydrographic field season quickly approaching, the number of geologic discoveries will only increase. Extending all along the Aleutian Chain, from Kodiak Island to Bechevin Bay, the planned surveys for the 2014 field season will surely reveal many interesting and previously unknown geologic features.

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