Institute for Water Resources

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Tales of the Coast
Sharing the Coast

Navigation

Coastal waters provide plentiful fishing sources, and inlets are convenient harbors. Because of these natural conditions, fishing and navigation have taken place along the coast for thousands of years.

Maritime commerce and fishing remain crucial economic activities today. Millions of short tonnage is shipped through U.S. ports every year, particularly along the Gulf coast, in New England, and in California. While commercial fishing continues to be an important economic activity, sport-fishing and recreational navigation have grown as well.

The need to maintain navigable waterways has led to problems as vessels have grown in size. Facilitating deep-draft navigation is one of the Corps' oldest missions, and they continue to implement solutions to encourage this critical component of the American economy.

Major U.S. ports continue to increase in size and serve larger ships. Dramatic increases in container traffic and a recent trend for container ships to exceed Panama Canal size constraints have helped fuel the need for deeper ports and expanded, modernized terminals.

At the same time, dynamic coastal conditions can present challenges to navigation. Inlets between barrier islands on the Atlantic and Gulf coasts can close naturally due to longshore sediment transport. The Pacific coast is a high-energy coast with dangerous wave conditions in many locations. The mouth of the Mississippi River features naturally meandering channels that have made navigation difficult since initial settlement.

In response, the Corps dredges a large number of navigable waterways to maintain conditions suitable for deep-draft navigation. The Corps and contractor dredges remove millions of cubic meters of material each year to sustain port and waterway viability, particularly as container ships increase in size.

The Corps has also built stabilization structures at most inlets and harbors. Jetties and breakwaters are examples of structural responses that are critical for facilitating safe navigation. These and other hard structures can deflect wave energy and block littoral drift, thereby maintaining safety and navigability.

 

Dredging

Dredging in the coastal zone is the largest single item in the Corps' budget because over 90% of the Nation's top 50 ports for foreign commerce require regular dredging.

Stabilizing the Inlet

Structures such as jetties can alter sediment transport and cause negative consequences, including erosion of adjacent shores. Therefore, a range of coastal engineering concerns factor into such projects.