Archive for July 2012

Arctic reconnaissance survey checks old soundings to prioritize future surveys   3 comments

NOAA Ship Fairweather starts the Arctic reconnaissance survey on August 1, 2012

NOAA’s Office of Coast Survey, Alaska, and the nation’s economic vitality have been intertwined for 145 years. We strengthen that bond on August 1, as NOAA Ship Fairweather begins a reconnaissance survey to the northernmost tip of the Alaska’s Arctic coast. Fairweather will check soundings along a 1,500 nautical mile coastal corridor from Dutch Harbor, Alaska, to the Canadian border. (At least, we hope Fairweather can go all the way to the Canadian border… The ice cover is a little stubborn this summer, and may not recede sufficiently for safe passage. CMDR Jim Crocker, the ship’s commanding officer and chief scientist of the party, will keep us updated through the coming weeks. Watch this blog site for Fairweather updates!)

Regardless of whether ice interferes with the final northern leg of the survey, the sounding samples acquired by Fairweather throughout the reconnaissance will provide critical information needed to prioritize NOAA’s future survey projects in the Arctic.

COAST SURVEY TIES TO ALASKA GO BACK 145 YEARS

The U.S. Coast Survey, one of NOAA’s predecessor organizations, was instrumental in the U.S. decision to purchase Alaska. In 1867, Coast Surveyor George Davidson led the party making a geographical reconnaissance of Alaska, to assess the Russians’ offer to sell “Russian America” to the United States. He assured U.S. officials that Alaska would bring valuable resources to the nation, and we purchased Alaska for $7.2 million.

Coast Survey started its post-Davidson Alaska work in 1871, when Assistant William H. Dall led survey teams that took soundings, triangulated Alaskan coasts, and made astronomical observations. Dall’s teams provided the information for the first U.S. nautical charts of Alaskan harbors and coves. (See this chart of Sanborn Harbor, 1872, for example.) Coast Survey leadership, in their annual reports to Congress, foresaw that Alaska’s resource development would severely challenge the woefully inadequate transportation infrastructure at the time, and more hydrographic field parties were dispatched to Alaskan waters through the rest of the 19th century.

This illustration was produced by John Whiddon, Coast Survey, Marine Chart Division

As indicated in this image, which displays the vintage of the U.S. Coast & Geodetic Survey (“geodetic” was added to the agency name in 1878) and NOAA soundings along the Fairweather reconnaissance path, vast swathes of lead line measurements were collected more than a hundred years ago. Some of the small-scale charts in Alaskan waters use soundings from Captain Cook (1770s vintage) or even Vitus Bering (circa 1740). While it is difficult to pinpoint exact sources, some soundings could also come from British Admiralty charts or Russian Empire charts.

FAIRWEATHER RECONNAISSANCE WILL HELP PRIORITIZE FUTURE SURVEYS

Fast forward to this century. Modern ships navigating sea lanes in the Arctic should not be expected to trust ocean depth measurements reported by Captain Cook. A tanker, carrying millions of gallons of oil, should not be asked to rely on measurements made with lead lines, before modern technology allowed full bottom surveys. Unfortunately, that’s exactly what navigators have to do, in too many cases.

Coast Survey has made it a priority to update the nautical charts needed by commercial shippers, passenger vessels, and fishing fleets transiting the Alaskan coastline in every greater numbers. In June 2011, we issued the Arctic Nautical Charting Plan, a major effort to update Arctic nautical charts for the fairways, approaches, and ports along the Alaskan coast.

Before our cartographers can update the charts, however, they need up-to-date and accurate depth measurements. NOAA’s Office of Coast Survey is committed to getting that data.

Capturing the seafloor’s rich history while positioning America for the future   Leave a comment

Coast Survey’s Navigation Response Team 4 is conducting a year-long survey of the sea floor in the Port of Houston and Galveston Bay navigational areas, re-measuring ocean depths and searching for dangers to navigation. Coast Survey will use the data to update future nautical charts to help mariners protect lives and increase shipping efficiencies. Recently, the team also found an opportunity where they could support marine archeological preservation.

Last week, the navigation team worked with federal and state partners who help us understand the rich history – and the secrets of human sorrows – lying on the seafloor. In collaboration with NOAA’s Flower Garden Banks National Marine Sanctuary and the Texas Historical Commission’s Marine Archeology Division, the navigation response team — with the State Marine Archeologist onboard —  re-mapped the location of two historically significant wrecks. (Some of the data was collected under an antiquities permit, as Texas requires for investigating historic shipwrecks in state waters.)

“With the often-shifting sediment around here, there are periods of covering and uncovering, so archeologists like to periodically map historically significant wrecks to see what’s changed,” explained Nick Forfinski, the navigation response team’s leader. “We were ‘in the neighborhood,’ surveying for maritime commerce, and we were able to obtain up-to-date images of the wrecks while we were here.”

The steamship City of Waco is one of the historical wrecks that Forfinski’s crew was asked to survey. The steamship burst into flames and sank on Nov. 8, 1875, and 56 people died. The sunken ship was ordered to be demolished in 1900, to protect navigation in the area.

“The collaboration between NOAA experts and the Texas Historical Commission brings a unique combination of expertise and resources to learning more about the hidden history in the Gulf of Mexico,” said Texas State Archeologist Pat Mercado-Allinger. “We are grateful to the NOAA Team for this opportunity to remap this historically important shipwreck.”

Forfinski’s team captured some fascinating images of the City of Waco, created from data they gathered during last week’s hydrographic survey.

CityOfWaco_Multibeam

This image was created from data acquired by NRT4’s multibeam echo sounder. NOAA hydrographic survey units use multibeam echo sounder systems to acquire full (and partial) bottom bathymetric coverage, to measure depths over critical items such as wrecks, obstructions, and dangers-to-navigation, and for general object detection.

CityOfWaco_Sidescan

This image was created from data acquired by NRT4’s side scan sonar. A side scan creates a “picture” of the ocean bottom. For example, objects that protrude from the bottom create a light area (strong return) and shadows from these objects are dark areas (little or no return), or vice versa, depending on operator preference.

Using hydrographic surveys for multiple purposes, like “piggybacking” wreck mapping on to a navigation safety project, makes for smart resource sharing. It positions America for the future while helping to preserve its past.

Survey discovers exposed natural gas pipeline south of Mobile Bay   1 comment

Ocean floors are always changing. Coast Survey’s hydrographic surveys are intended to find and measure those changes. Often, we need to do more than that, as shown by a recent survey of the seafloor in Alabama coastal waters.

A Coast Survey contractor ‒ David Evans and Associates ‒ found a large high-pressure natural gas pipeline that had been uncovered and was lying exposed, as shown by this side scan sonar image. The exposed 36-inch diameter pipeline, pressured to 2,100 psi, posed a threat to navigation and the environment.

Side scan sonar of exposed pipeline

NOAA navigation manager Tim Osborn worked in concert with the contractor to report the danger to the Department of Interior Bureau of Ocean Energy Management (BOERME), and to the U.S. Coast Guard District 8 Headquarters Waterways Section. Tim and the contractor were able to provide precise positions, imagery, and other resources.

The Coast Guard is warning mariners to avoid the area.

The pipeline delivers over 1.3 billion cubic feet of natural gas per day to the 20 million residents of Florida. In addition to posing a threat to the marine environment, an accidental rupture of the pipe could cause a national economic impact in losing a huge supply of energy.

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Learn more about hydrographic surveys and side scan sonar.

Meet the men and women of today’s Coast Survey   Leave a comment

LCDR Ben Evans commands NOAA’s newest survey vessel, the Ferdinand R. Hassler

Since President Thomas Jefferson asked for a survey of the coast in 1807, Coast Survey has been the nation’s trusted source for nautical charts covering the coastal waters of the U.S. and its territories.

Nature is never static, especially in systems as powerful as ocean coastlines. Human activities are constantly reshaping vast areas, both on shore and underwater. Today, NOAA’s hydrographic surveys continue to traverse U.S. waters, measuring the ocean depths of the constantly shifting sea floor, acquiring data on changing shorelines, and searching for underwater dangers to navigation.

This blog will feature the work being done by the men and women of NOAA’s Office of Coast Survey to protect life and property, on ships and on shore. Visit often, and learn how these NOAA Corps officers, physical scientists, cartographers and technicians produce the precise and accurate navigational products that mariners trust.

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