Article

The Atlantic Intracoastal Waterway isn't the only "water highway" in the U.S. The Gulf Intracoastal Waterway runs from Carrabelle, Florida, to Brownsville, Texas.

Photograph by Jessica Cecci, MyShot

Construction Corps
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.”

Dredging

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.”

Vocabulary

Term Part of Speech Definition Encyclopedic Entry

Army Corps of Engineers

Noun

government organization concerned with construction projects.

assess

Verb

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.

barge

Noun

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.

cartographer

Noun

person who makes maps.

channel

Noun

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.

commercial

Adjective

having to do with the buying and selling of goods and services.

data

Plural Noun

(singular: datum) information collected during a scientific study.

debris

Noun

remains of something broken or destroyed, waste, or garbage.

downed

Adjective

fallen or crashed.

dredge

Verb

to remove sand, silt, or other material from the bottom of a body of water.

economy

Noun

system of production, distribution, and consumption of goods and services.

engineer

Noun

person who plans the building of things, such as structures (construction engineer) or substances (chemical engineer).

engineering

Noun

the art and science of building, maintaining, moving, and demolishing structures.

essentially

Adverb

basically or in general terms.

ferry

Noun

boat or ship that transports people, cargo, and goods across a waterway.

fleet

Noun

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.

hopper

Noun

funnel-shaped chamber from which materials can be discharged below.

hull

Noun

main body of a ship.

hurricane

Noun

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.

hydrographic

Adjective

having to do with the measurement, description, and mapping of the surface waters of the Earth.

inland

Adjective

area not near the ocean.

inlet

Noun

small indentation in a shoreline.

map

Noun

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.

navigation

Noun

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.

region

Noun

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.

sediment

Noun

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.

sonar

Noun

method of determining the presence and location of an object using sound waves (echolocation).

sophisticated

Adjective

knowledgeable or complex.

sound

Noun

body of water, larger than a bay, partially surrounded by land.

sounding

Noun

measurement of the depth of a body of water in a specific area.

storm

Noun

severe weather indicating a disturbed state of the atmosphere resulting from uplifted air.

survey

Noun

a study or analysis of characteristics of an area or a population.

topographic

Adjective

having to do with maps based on natural and human-made features of the land, and marked by contour lines showing elevation.

transport

Verb

to move material from one place to another.

vessel

Noun

craft for traveling on water, usually larger than a rowboat or skiff.

vital

Adjective

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.)

Credits

Media Credits

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Writer

Stuart Thornton

Editors

Jeannie Evers
Kara West

Producer

Caryl-Sue, National Geographic Society

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