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.

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