The U.S. Army Corps of Engineers was made a permanent branch of the U.S. Army on March 16, 1802. The Corps has constructed fortifications and lighthouses and helped survey and map the nation's frontiers. During the 20th century, the Corps focused on flood control and producing hydroelectric energy, among other water issues.
By Stuart Thornton
Tuesday, August 9, 2011
Stretching from Norfolk, Virginia, to Miami, Florida, the Atlantic Intracoastal Waterway is an inland channel for recreational boaters and commercial shipping. The waterway is maintained by the U.S. Army Corps of Engineers (USACE). The mission of USACE is to “provide vital public engineering services in peace and war to strengthen our nation's security, energize the economy, and reduce risks from disasters.”
At Wilmington District headquarters in Wilmington, North Carolina, USACE surveys and maps the conditions of waterways in the coastal regions of North Carolina and south-central Virginia.
Todd Horton, chief of the waterways management section, says USACE boats, equipped with sophisticated sonar, cross over sections of the Atlantic Intracoastal Waterway every day. The district’s survey boat fleet consists of the Gillette, the Beaufort, and the Sanderson.
“They determine how deep the water is,” he says. “We do hydrographic surveys, which are water surveys, basically.”
A GPS signal determines the location of where the survey is conducted, and the sonar equipment records the depth of the waterway at that point. “They will collect all the soundings,” Horton says. “Whatever they survey that day, they send to us that night.”
The information becomes a new or updated data layer for online maps of the waterway. The maps are updated every 24 to 48 hours. The waterway maps help recreational boaters and commercial shippers avoid running aground or hitting obstacles.
Cartographer Adam Faircloth is one of the people who create the waterway maps. “Data comes to us in a lot of different formats,” he says. “My job is to take satellite imagery, hydro data and topographic land surveys to create maps.”
Horton says the sections of the waterway that connect to inlets change frequently. Even small changes to the depth or width of a channel can require different navigation from boats and ships.
“If you get a big storm, that can blow material into the waterway,” he says. “Anywhere it intersects our inlets, that’s pretty much the worst.”
When the waterway’s channels become shallow because of sediment build-up, the U.S. Army Corps of Engineers sends a dredge boat to remove the material and make the channel deeper. The Wilmington District has the only shallow-water dredging fleet in the nation. This fleet includes the Currituck, the Merritt, and the Fry, which will soon be replaced by the Murden.
The Merritt and the Fry are sidecast dredges that pump the sediment onboard. Then, with a long, arm-like tool called a discharge pipe, the dredges cast the sediment about 45 meters (150 feet) from the channel. Both the Merritt and the Fry were Navy vessels initially built to pick up downed aircraft during World War II.
Roger Bullock, the Wilmington District’s chief of navigation, explains how the Currituck removes the sediment differently than the Merritt and the Fry. “The dredge in motion essentially vacuums material from the channel . . . transporting it to its hopper bin,” he says. “When full, it sails from the channel to a designated dumping site and the hull splits open, side-to-side, allowing the material to fall freely out of the bottom.”
North Carolina’s famous Outer Banks are constantly in motion, making dredging and managing the waterway difficult. One of the district’s greatest challenges, for instance, is to keep the Oregon Inlet channel deep enough for its constant stream of fishing boat traffic. Oregon Inlet is a body of water that connects Pamlico Sound to the Atlantic Ocean.
Bodie Island, the barrier island to the north of the inlet, is migrating south. As the island drifts, sediments gather in the channel.
“That’s the only access to the northeastern corner of North Carolina [by boat],” Horton says. “Lately, we’ve had to keep a [dredge] vessel there almost continuously.”
Another special vessel the U.S. Army Corps of Engineers uses in the district is the debris-removal vessel the Snell. The Snell has removed sunken boats and a plane from the district’s waterways.
During the late summer and fall months, the Wilmington area can be hit with hurricanes. Some of the hurricanes that have landed in the region include Hurricane Fran in 1996 and Hurricane Floyd in 1999. The Wilmington District works with the U.S. Coast Guard (USCG) when hurricanes strike.
“Typically, we are the first boats surveying depths in the shipping channels, then the ferry channels, and continue on into storm-impacted priorities,” Bullock says. The Coast Guard and the Corps inspect waterways for debris and missing navigational aids, such as lighthouses and buoys. “We present the results to the USCG and make recommendations for opening channels,” Bullock says.
Changing Needs of a Nation
The USACE Wilmington District notes that its section of waterway is used differently than when it first was completed in 1940. Then, the waterway was a major commercial route with ships and barges transporting goods throughout the southeast.
Today, rather than viewing a barge transporting goods, engineers are just as likely to see a family heading out to go fishing. “Commercial traffic is decreasing, because they [shipping businesses] are going to larger ships that can’t access the waterways,” Horton says. “Now it’s become more of a recreational area.”
Term Part of Speech Definition Encyclopedic Entry Army Corps of Engineers Noun
government organization concerned with construction projects.
to evaluate or determine the amount of.
Atlantic Intracoastal Waterway Noun
(1,930 kilometers/1,200 miles) series of natural and artificial canals running from Norfolk, Virginia, to Key West, Florida, maintained by the U.S. Army Corps of Engineers for recreational boating and commercial shipping traffic.
large, flat-bottomed boat used to transport cargo.
barrier island Noun
long, narrow strip of sandy land built up by waves and tides that protects the mainland shore from erosion.
person who makes maps.
waterway between two relatively close land masses.
Encyclopedic Entry: channel coast Noun
edge of land along the sea or other large body of water.
Encyclopedic Entry: coast coast guard Noun
branch of a nation's armed forces that is responsible for coastal defense and protection of life and property at sea.
having to do with the buying and selling of goods and services.
data Plural Noun
(singular: datum) information collected during a scientific study.
remains of something broken or destroyed; waste, or garbage.
fallen or crashed.
to remove sand, silt, or other material from the bottom of a body of water.
system of production, distribution, and consumption of goods and services.
person who plans the building of things, such as structures (construction engineer) or substances (chemical engineer).
the art and science of building, maintaining, moving, and demolishing structures.
basically or in general terms.
boat or ship that transports people, cargo, and goods across a waterway.
group of ships, usually organized for military purposes.
Global Positioning System (GPS) Noun
system of satellites and receiving devices used to determine the location of something on Earth.
funnel-shaped chamber from which materials can be discharged below.
main body of a ship.
tropical storm with wind speeds of at least 119 kilometers (74 miles) per hour. Hurricanes are the same thing as typhoons, but usually located in the Atlantic Ocean region.
Hurricane Floyd Noun
(1999) storm causing damage in the Bahamas and throughout the East Coast of the United States and Canada.
Hurricane Fran Noun
(1996) storm causing damage throughout the East Coast of the United States and Canada.
having to do with the measurement, description, and mapping of the surface waters of the Earth.
area not near the ocean.
small indentation in a shoreline.
symbolic representation of selected characteristics of a place, usually drawn on a flat surface.
Encyclopedic Entry: map migrate Verb
to move from one place or activity to another.
art and science of determining an object's position, course, and distance traveled.
Encyclopedic Entry: navigation obstacle Noun
something that slows or stops progress.
Outer Banks Noun
barrier islands off the coast of the U.S. state of North Carolina.
any area on the Earth with one or more common characteristics. Regions are the basic units of geography.
Encyclopedic Entry: region route Noun
path or way.
satellite imagery Noun
photographs of a planet taken by or from a satellite.
solid material transported and deposited by water, ice, and wind.
Encyclopedic Entry: sediment shipping Noun
transportation of goods, usually by large boat.
sidecast dredge Noun
small, shallow-water vessel designed to remove material from the channels of small coastal inlets.
method of determining the presence and location of an object using sound waves (echolocation).
knowledgeable or complex.
body of water, larger than a bay, partially surrounded by land.
measurement of the depth of a body of water in a specific area.
severe weather indicating a disturbed state of the atmosphere resulting from uplifted air.
a study or analysis of characteristics of an area or a population.
having to do with maps based on natural and human-made features of the land, and marked by contour lines showing elevation.
to move material from one place to another.
craft for traveling on water, usually larger than a rowboat or skiff.
necessary or very important.
World War II Noun
(1939-1945) armed conflict between the Allies (represented by the United States, the United Kingdom, and the Soviet Union) and the Axis (represented by Germany, Italy, and Japan.)