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In 2005, the NOAA Ship Rainier conducted hydrographic surveys in Prince William Sound, Alaska. One of the interesting surveys that was conducted involved a receding glacier in Columbia Bay. Since the area was last surveyed in 1994, the Columbia Glacier's terminus has receded nine miles. Where once there was ice, there is now water.
The shaded area in red on the chart to the left represents 15.74 square nautical miles that are currently charted as ice and land; an area once occupied by the Columbia Glacier of Prince William Sound. Located near Valdez, Alaska, the glacier empties into Columbia Bay. |
The survey area was at times full of icebergs, growlers, and smaller masses of ice, which made it difficult to work. Other times, it was relatively clear and easier to navigate. The glacier’s influence is ever-present; it is felt in the cold air and seen on the bare rock hills that overlook Columbia Bay. Below to the left, some of the Rainier’s crew survey through corridors formed by the ominous bergs.
A tide gauge was required in the survey area, the installation of which was overseen by Rainier tides officer LTJG Samuelson. She explains, “The gauge was installed to monitor the effects of the glacial moraine on the regional tide.” A moraine is created when a retreating glacier deposits rocks and debris in a pile at the end of the glacier and can affect tidal flow. According to the data acquired by the gauge, the moraine had little influence on the tidal flow. The gauge was active from August 31, 2005 to October 3, 2005. A tide gauge consists of an orifice, bubbler tube, nitrogen tanks, the computer, GPS receiver antenna, GOES transmission antenna, solar panel, battery, and an assortment of hardware used to secure the components to the site.
Pictured above and to the right is ENS Hauser beside the gauge setup. The blue tarp shelters the computer, which is housed inside a weatherproof case, the nitrogen tank, and the battery. The tripod mount holds the GPS receiver and GOES antenna, and the solar panel is on the ground next to the tripod. The orifice is mounted underwater and measures the height of water above. Below, Seaman Surveyor Muzzey guides GVA Guberski as they clear ice to allow divers to reach the orifice during the gauge removal.
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