03/27/2025

Coastal Solutions Compendium

Coastal Resilience Glossary

(Originally Created by Keerthana Vidyasagar for the 2022 Coastal Leadership Academy)

All definitions are from Living on the Coast, US Army Corps of Engineers, Detroit Division, unless otherwise noted. For additional information and diagrams, visit the USACE Detroit Coastal Processes website. 

A

Accretion

Buildup of a beach by waterborne and/or airborne material, usually sand, gravel, and larger stones.

Armoring

Manmade structures such as seawalls, revetments, bulkheads, geotubes, etc., intended to prevent damage to properties situated on the coast. (Mangor)

B

Beach

The zone of unconsolidated material (usually sand, gravel, or larger stones called “shingle”) that extends landward from the low water line to the place where there is a marked change in material or to the line of permanent vegetation (usually the effective limit of storm waves).

Beach Nourishment or Beach Fill

The process of replenishing a beach with material (usually sand) obtained from another location.

Bluff

A slope with relatively complex soil structure or erosional processes, rising from the backshore of a beach with a crest elevation of 20 feet (6 meters) or more above the backshore elevation. Bluffs are sometimes defined as high, steep banks or cliffs.

Breakwater

A structure built to reduce wave activity in the waters at the leeside. It can be linked to the shore or positioned offshore. (Mangor)

C

Coast

A strip of land of indefinite width (may be several kilometers) that extends from the shoreline inland to the first major change in terrain features. The land regarded as near the shoreline.

Coastline

The boundary between coastal upland and the shore.

Coastal Development

Any activity likely to alter the physical nature of the coastal zone in any way, including construction of buildings, waste deposits, removal of natural vegetation, dredging, land reclamation, and mineral extraction (excluding fishing activities). (Mangor)

Coastal Special Flood Hazard Area

Special Flood Hazard Areas (SFHAs) along the coasts that have additional hazards due to wind and wave action. These areas are identified on Flood Insurance Rate Maps (FIRMs) as zones V, V1-V30, and VE. (FEMA)

Critical Dune Areas

Public lands and private properties where development, silvicultural, and recreational activities are regulated by Part 353, Sand Dunes Protection and Management, of the Michigan Natural Resources and Environmental Protection Act. (EGLE)

D

Downdrift

The direction of predominant movement of littoral materials.

Dunes

Ridges or mounds of loose, wind-blown material, usually sand.

E

Environmental Area

An area of the shoreland determined by the department on the basis of studies and surveys to be necessary for the preservation and maintenance of fish and wildlife. Regulated under Part 323 of the Michigan Natural Resources and Environmental Protection Act. (EGLE)

Erosion

The wearing away of land or a lakebed by natural forces, including wave action, currents, or wind.

F

Fetch

The area over which waves and wind setup (or surge) are generated by a wind having a fairly constant speed and direction.

Flood Risk Area

Any area which is within the 100-year floodplain of a Great Lake or a connecting waterway, as identified under Part 323 of the Michigan Natural Resources and Environmental Protection Act. (EGLE)

G

Groin

A shore protection structure built (usually perpendicular to the shoreline) to trap littoral drift or retard erosion of the shore.

H

High-Risk Erosion Areas

Shorelands of the Great Lakes where erosion has been occurring at a long-term average rate of one foot or more per year for at least 15 years. Regulated under Part 323 of the Michigan Natural Resources and Environmental Protection Act. (EGLE)

L

Littoral

Pertaining to the shore of a lake or sea.

Littoral Material

Sand and stones moved by waves and currents near the shore.

Littoral Transport or Littoral Drift

The movement of littoral material by waves and currents, including both longshore (parallel) and on-offshore (perpendicular) transport.

Littoral Zone

The zone extending seaward from the shoreline to just beyond the breaker zone.

Longshore or Alongshore

Parallel to and near the shoreline.

Longshore Current

The littoral current in the breaker zone moving essentially parallel to the shore, usually generated by waves breaking at an angle to the shoreline.

N

Nearshore

A zone extending seaward from the shoreline beyond the breaker zone, typically to about 66 feet (20 meters) water depth.

M

Mitigation

Measures aimed at countering, alleviating, or partially obviating the adverse consequences of threatening developments or events with human or natural causes. (Mangor)

O

Ordinary High Water Mark (OHWM), Local

The elevation or line along the shoreline as defined in the municipality’s zoning ordinance for purposes of measuring a shoreline setback.

Ordinary High Water Mark (OHWM), Natural

A line on the shore where there is an indication that water is present. The Natural OHWM is used to identify where the public has the right to walk along the Great Lakes shoreline

Ordinary High Water Mark (OHWM), Regulatory

The elevation along the shoreline where a construction permit is required for activities like dredging, seawalls, and permanent structures. Defined by the Michigan Natural Resources and Environmental Protection Act and referenced to the International Great Lakes Datum 1955 (IGLD 55).

• Lake Erie: 572.2'
• Lake St. Clair: 575.3'
• Lake Michigan/Huron: 580.5'
• Lake Superior: 602.6'

Overtopping

The passing of water over the top of a beach berm, dike, or other shore protection structure due to wave runup or surge action.

R

Recession

The landward movement of the shoreline, beach, or lakeward edge of a bank or bluff.

Revetment

A structure of stone, concrete, etc., built to protect a shore against erosion by wave action or currents. Often used for shore protection with sloping lakeward faces.

Riprap

Protective layers of stone, randomly placed to prevent erosion, scour, or sloughing of a slope. Also used to describe the stone itself.

S

Sediment

Loose fragments of rocks, minerals, or organic material transported by air, wind, ice, and water, and deposited. It also includes materials that precipitate from overlying water or chemically form in place.

Seiche

An oscillation of the water mass in a lake that continues after the originating force has stopped, typically caused by atmospheric forces in the Great Lakes.

Setback or Setback Distance

A selected (or required) space between a building (or other structure) and a boundary.

Shore

The narrow strip of land in immediate contact with the lake, including the zone between high and low water lines. A shore of unconsolidated material is usually called a beach.

Shoreline

The intersection of a lake with the shore or beach.

Storm Surge (Wind Setup, Storm Rise)

A rise above normal water levels on the open coast due to wind stress on the water surface over a long distance (fetch).

W

Water Budget/Water Balance

An accounting of all the water that flows into and out of a project area, including wetlands, lakes, and other points of interest. Development can alter the natural supply of water, and a water budget helps evaluate possible impacts and mitigation actions. (EGLE)

Wave Runup (Swash)

The rush of water up a structure or beach following the breaking of a wave, measured as the vertical height above still-water level to which the rush of water reaches.

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Sources:

• US Army Corps of Engineers - Detroit District: Living on the Coast

• Mangor, Karsten (2021): Definitions of Coastal Terms

• EGLE - Michigan Department of Environment, Great Lakes, and Energy

• FEMA - Federal Emergency Management Administration (Glossary)