Glossary

Disclaimer
We have attempted to provide accurate information in this glossary. However, errors, omissions and modifications are always a possibility. The Coastal Commission and its agents and employees provide no warranty, either express or implied, as to the accuracy, reliability or completeness of the furnished information. The Coastal Commission and its agents and employees shall not be liable for any damages whatsoever, including damages based on passive or active negligence, arising out of the use of or reliance on the information in this glossary.

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AB - Assembly Bill.

Accrete - To add new material gradually to pre-existing material; opposite of erode.

Accretion - Enlargement of a beach area caused by either natural or artificial means. Natural accretion on a beach is the build-up or deposition of sand or sediments by water or wind. Artificial accretion is a similar build-up due to human activity, such as the accretion due to the construction of a groin or breakwater, or beach fill deposited by mechanical means.

Aeolian transport - Movement of sediment by the wind. Aeolian sediments have a greater angularity of the grains, compared with waterborne particle.

Alluvium - Soil (sand, mud, or similar eroded material) deposited by streams. This deposit may be a stratigraphic (layered) deposit beneath the surface.

APN - Assessor's Parcel Number; identifies each parcel or lot for tax assessment purposes.

Aquaculture - A form of agriculture as defined in Section 17 of the Fish and Game Code. Aquaculture products are agricultural products, and aquaculture facilities and land uses shall be treated as agricultural facilities and land uses in all planning and permit-issuing decisions governed by this division.

Aquifer - An underground layer of porous rock, sand, or other earth material containing water, into which wells may be sunk.

Arcuate - A curved somewhat semi-circular feature; used to describe a rounded, concave shoreline.

Armor - To fortify a topographical feature to protect it from erosion (e.g., constructing a wall to armor the base of a sea cliff).

Armor rock (armor stone) - Natural or man-made rock or rock-like structures that are used for shoreline protection. Commonly, armor rock is used as the outermost layer of a groin or revetment. Many forms of these rocks are utilized; their overall stability depends largely on the type of mechanical interlock between the units, and in-place fitting.

Artificial headland - A hard structure extending from the shore and turning parallel to it; built to stabilize the shoreline locally as a natural headland would.

Artificial nourishment - The process of enlarging a beach with material (usually sand) obtained from another location.

ATF - An after the fact permit application is a coastal development permit application filed by the applicant after a development has occurred in order to seek authorization for the development.

Backbeach (dry beach) - The sand area inundated only by storm tides or extreme high tides. These areas supply sands to the dune system.

Backshore - The region of the shore or beach lying between the foreshore and the coastline and acted upon by waves only during severe storms.

Bar - An elongated sand ridge found offshore, composed of sand or gravel eroded from the beach.

Barchans - The crescent shaped sand mounds that form when there is one dominant wind direction but a limited supply of sand.

Bathymetry - Related to submarine contours or topography; also refers to depth measurements.

Beach - The expanse of sand, gravel, cobble or other loose material that extends landward from the low water line to the place where there is distinguishable change in physiographic form, or to the line of permanent vegetation. The seaward limit of a beach (unless specified otherwise) is the mean low water line.

Beach nourishment program - Plan for conducting a series of beach nourishment projects at a specific location, typically over a period of 50 years. The program would be based on establishing the technical and financial feasibility of beach nourishment for the site and would include plans for obtaining funding and sources of sand for its duration.

Beach nourishment project - Placement of sand on a beach to form a designed structure in which an appropriate level of protection from storms is provided and an additional amount of sand (advanced fill) is installed to provide for erosion of the shore prior to the anticipated initiation of a subsequent project. The project may include dunes and/or hard structures as part of the design.

Beachfill - Sand or other material used to artificially replenish a beach. Dedicated beachfill is that which has been obtained specifically for beach replenishment. Opportunistic beachfill is that which has been excavated for other purposes then made available for beach replenishment.

Beachgrass - Any of the genus Ammophila of deeply rooted, tough, perennial grasses that grow on sandy beaches and are often planted to combat beach erosion.

Bedrock - Solid rock underlying soil and younger rock layers; generally the oldest exposed geological unit.

Berm - A nearly horizontal portion of the beach or backshore formed by the deposit of material by wave action. Some beaches have no berms and others may have one or several.

Bight - A bay caused by a bend in the coastline.

Block fall - A type of landslide; specifically used to describe failure of a vertical cliff.

Blowouts - Circular rims or depressions formed where sand has been removed by wind; often caused by removal of vegetation.

Bluff (or cliff) - A scarp or steep face of rock, weathered rock, sediment or soil resulting from erosion, faulting, folding or excavation of the land mass. The cliff or bluff may be simple planar or curved surface or it may be steplike in section. For purposes of (the Statewide Interpretive Guidelines), cliff or bluff is limited to those features having vertical relief of ten feet or more and seacliff is a cliff whose toe is or may be subject to marine erosion.

Bluff edge (or cliff edge) - The upper termination of a bluff, cliff or seacliff. When the top edge of the cliff is rounded away from the face of the cliff as a result of erosional processes related to the presence of the steep cliff face, the edge shall be defined as that point nearest the cliff beyond which the downward gradient of the land surface increases more or less continuously until it reaches the general gradient of the cliff. In a case where there is a steplike feature at the top of the cliff face, the landward edge of the topmost riser shall be taken to be the cliff edge. The termini of the bluff line, or edge along the seaward face of the bluff, shall be defined as a point reached by bisecting the angle formed by a line coinciding with the general trend of the bluff line along the seaward face of the bluff, and a line coinciding with the general trend of the bluff line along the inland facing portion of the bluff. Five hundred feet shall be the minimum length of bluff line or edge to be used in making these determinations (from Public Resources Code Section 13577).

Bluff top retreat (or cliff top retreat) - The landward migration of the bluff or cliff edge, caused by marine erosion of the bluff or cliff toe and subaerial erosion of the bluff or cliff face.

Bore - To make a hole in or through with a drill or other device. Used commonly for determining stratigraphic (sedimentary) history, to reveal information on past site conditions and provide some guidance on future site stability or erosive potential.

Borrow area - An area from which construction or beach replenishment material is mined for use in a different area.

Breach - A breakthrough of part, or all, of a protective wall, beach sand barrier, beach berm, or the like by ocean waves, river or stream flow, mechanical equipment, or a combination of these forces. Breaching is sometimes purposefully done to protect a region from river overflow.

Breaker - A wave breaking on a shore, over a reef, etc. Breakers may be classified into four types; spilling, plunging, collapsing, and surging.

Breakwater - A structure or barrier protecting a shore area, harbor, anchorage, or basin from waves, usually constructed as a concrete or riprap (rock wall) structure.

Breccia - A type of sedimentary rock containing course, angular fragments.

Bulkhead - A structure or partition used to retain or prevent landslides and mass land movement. A secondary purpose is to protect the upland against damage from wave action.

Caisson - A supporting piling constructed by drilling a casing hole into a geologic formation and filling it with reinforcing bar and concrete; using for foundations.

California Least Tern - An endangered bird species that nests on beaches and in salt marshes along California; smallest of the terns.

Cantilever walls - Vertical walls that use a deep foundation to resist horizontal wave forces. Walls are often constructed of pre-fabricated panels that are jetted or driven into the sand. Typically for every foot of exposed wall there should be at least half a foot of buried foundation wall to prevent overturning. (Engineered designs may vary, based on site-specific conditions.)

CCMP - California Coastal Management Program.

CCR - California Code of Regulations.

Cementation - The process by which loose sediment is bound together into rock.

Certificate of Compliance - A certificate of compliance is a document issued and recorded by a local agency certifying that the subject parcel is a lot that complies with the requirements of the Subdivision Map Act and related local ordinances or certifying that the lot will comply with such requirements upon satisfaction of certain conditions.

CFR - Code of Federal Regulations.

Clast - Rock composed of fragments.

Coastal access - The ability of the public to reach, use or view the shoreline of coastal waters or inland coastal recreation areas and trails.

Coastal county - A county or city and county which lies, in whole or in part, within the coastal zone.

Coastal-dependent development or use - Any development or use which requires a site on, or adjacent to, the sea to be able to function at all.

Coastal development permit (CDP) - A permit for any development within the coastal zone that is required pursuant to subdivision (a) of Section 30600.

Coastal plan - The California Coastal Zone Conservation Plan prepared and adopted by the California Coastal Zone Conservation Commission and submitted to the Governor and the Legislature on December 1, 1975, pursuant to the California Coastal Zone Conservation Act of 1972 (commencing with Section 27000).

Coastal-related development - Any use that is dependent on a coastal-dependent development or use.

Coastal zone - That land and water area of the State of California from the Oregon border to the border of the Republic of Mexico, specified on the maps identified and set forth in Section 17 of that chapter of the Statutes of the 1975-76 Regular Session enacting this division, extending seaward to the state's outer limit of jurisdiction, including all offshore islands, and extending inland generally 1,000 yards from the mean high tide line of the sea. In significant coastal estuarine, habitat, and recreational areas it extends inland to the first major ridgeline paralleling the sea or five miles from the mean high tide line of the sea, whichever is less, and in developed urban areas the zone generally extends inland less than 1,000 yards. The coastal zone does not include the area of jurisdiction of the San Francisco Bay Conservation and Development Commission, established pursuant to Title 7.2 (commencing with Section 66600) of the Government Code, nor any area contiguous thereto, including any river, stream, tributary, creek, or flood control or drainage channel flowing into such area.

Cobble - Well-rounded rocks along the shore and in river channels. Cobble size particles are between pebbles and boulders, generally larger than coarse gravel (76 mm). California has numerous cobble beaches, with cobble exposed year-round or covered by sand during mild wave periods and exposed during and after storm conditions.

Continental shelf - The zone bordering a continent and extending from the low water line to depth (usually about 180 meters) where there is a marked or rather steep descent toward a greater depth.

Contour - A line on a topographic map or bathymetric (depth) chart representing points of equal elevation with relation to a datum (point or set of points). Contour lines are usually spaced into intervals for easier comprehension and utilization.

Cretaceous - A period of geologic time spanning 136-64 million years ago.

Cumulative effect (cumulative impacts) - The incremental effects of an individual project shall be reviewed in connection with the effects of past projects, the effects of other current projects, and the effects of probable future projects.

Current - A flow of water in a particular direction. Such flows can be driven by wind, temperature or density differences, tidal forces, and wave energy. Currents are often classified by location, such as longshore current, surface current, or deep ocean currents. Different currents can occur in the same general area, resulting in different water flows, for example, a rip current can flow perpendicular to the shore through the surf zone, a long shore current may flow southerly, parallel to the coast and a seasonal deep water current may flow to the north.

Delta - An area of loose deposit of silt, sand, and gravel, roughly triangular in shape, formed at the mouth of a river or rivers.

Development - On land, in or under water, the placement or erection of any solid material or structure; discharge or disposal of any dredged material or of any gaseous, liquid, solid, or thermal waste; grading, removing, dredging, mining, or extraction of any materials; change in the density or intensity of use of land, including, but not limited to, subdivision pursuant to the Subdivision Map Act (commencing with Section 66410 of the Government Code), and any other division of land, including lot splits, except where the land division is brought about in connection with the purchase of such land by a public agency for public recreational use; change in the intensity of use of water, or of access thereto; construction, reconstruction, demolition, or alteration of the size of any structure, including any facility of any private, public, or municipal utility; and the removal or harvesting of major vegetation other than for agricultural purposes, kelp harvesting, and timber operations which are in accordance with a timber harvesting plan submitted pursuant to the provisions of the Z'berg-Nejedly Forest Practice Act of 1973 (commencing with Section 4511).

DFG - California State Department of Fish and Game.

Diffraction (of water waves) - The phenomenon by which energy is transmitted laterally along a wave crest. When a barrier, such as a breakwater interrupts part of a train of waves, the effect of diffraction is manifested by propagation of waves into the sheltered region within the barrier's geometric shadow.

Dissipate - To break up, scatter, dispel, or dispense energy. The many forms of breakwaters and revetments act as dissipaters of wave energy.

Distributary - The branching channels of marine deltas generated as a result of the reduction of the channel gradient and consequent deposition within the channel.

Downcoast - In the United States usage, it is the coastal direction generally trending toward the south; also the way in which current flows.

Downdrift - The direction of predominant movement of littoral (shore) materials.

DPR - California State Department of Parks and Recreation.

Dune - Ridges or mounds of loose, wind-blown material usually sand. A dune structure often has a back and foredune area. Stable dunes are often colonized by vegetation.

DWR - California State Department of Water Resources.

Dynamic equilibrium - A beach or coastline condition where neither erosion nor accretion is occurring, but where the beach is continuously being reshaped by wave action.

Easement - a limited right to make use of a land owned by another, for example, a right of way across the property.

Ebb tide - The period of tide between high water and the succeeding low water; a falling tide (opposite = flood tide).

Energy facility - Any public or private processing, producing, generating, storing, transmitting, or recovering facility for electricity, natural gas, petroleum, coal, or other source of energy.

Eocene - A period of geologic time spanning 54-38 million years ago.

Equilibrium beach width - The mean distance between the shoreline and backbeach line at which sand contributions and losses are balanced.

Erode - The gradual wearing away and removal of land surface by various agents such as waves; opposite of accrete.

Erosion - The wearing away of land by natural forces. On a beach, the carrying away of beach material by wave action, currents or the wind.

ESA - Endangered Species Act.

Escarpment - A more or less continuous line of cliffs or steep slopes facing in one general direction, caused by erosion or faulting.

ESHA (environmentally sensitive habitat area) - The Coastal Act defines ESHA as any area in which plant or animal life or their habitat are either rare or especially valuable because of their special nature or role in an ecosystem and which could be easily disturbed or degraded by human activities and development. (PRC 30108.5)

Estuary - The region near a river mouth in which the fresh water of the river mixes with the salt water of the sea.

Eustatic - Refers to worldwide changes in sea level.

Evaluation - Process by which a project's performance is determined relative to criteria developed for this purpose.

Fault - A rock fracture accompanied by displacement.

Feasible - Capable of being accomplished in a successful manner within a reasonable period of time, taking into account economic, environmental, social, and technological factors.

Federal coastal act - The Federal Coastal Zone Management Act of 1972 (16 U.S.C. 1451, et seq.), as amended.

Federal Consistency Review - As described in the 1972 Federal Coastal Zone Management Act, states with approved coastal management programs are responsible for reviewing proposed federal and federally-authorized activities to assess their consistency with the state program. These activities, within the coastal zone or outside the coastal zone, that affect any land or water use or natural resource of the coastal zone shall be carried out in a manner which is consistent the enforceable policies of the coastal management program.

Feeder beach - An artificially widened beach serving to nourish downdrift beaches by natural littoral currents or forces.

Fetch - The area in which sea waves are generated by a wind having a fairly constant speed and direction. Commonly associated with waves over the deep portion of the ocean that exhibit fairly stable speed and direction.

Fill - Earth or any other substance or material, including pilings placed for the purposes of erecting structures thereon, placed in a submerged area.

Fillet - The concave accumulation of sand upcoast of a natural or artificial structure.

Filter cloth - A type of strong permeable plastic cloth that is used landward of seawalls or revetments to reduce or minimize scour behind the wall.

Flood tide - The period of tide between low water and the succeeding high water; a rising tide. (opposite = ebb tide)

Forebeach (wet beach) - The sand area affected regularly by tides and wave action.

Foreshore (or beach face) - Region of the coast extending from the berm crest (or the highest point of wave wash at high tide) to the low-water mark which is measured at low tide.

Formation - A unit of rock that is distinctive and persistent over a large area.

Fossiliferous - Rock units containing fossils.

Gabions - A mesh box or enclosure filled with rocks, cobbles, stones, etc. and used as building units for dams, dikes, or shoreline protection.

Geohazard - A risk associated with geologic processes or events.

GIS (Geographic Information System) - A GIS is a computer system capable of assembling, storing, manipulating, and displaying geographically referenced information. A GIS allows analysis of spatial relationships between many different types of features based on their location in the landscape.

Gravity walls - Massive, self-supporting walls which resist horizontal wave forces through their sheer mass. (For example, the O'Shaughnessy Seawall in San Francisco weighs approximately 12 tons per linear foot.)

Groin - A shoreline protection structure built (usually perpendicular to the shoreline) to trap nearshore sediment or retard erosion of the shore. A series of groins acting together to protect a section of beach is known as a groin system or groin field.

Groundwater - Subsurface water occupying the zone of saturation usually found in porous rock strata and soils.

Gunnite - Slurry concrete that is sprayed onto forms or structures; often used as a facing material for structural seawalls or retaining walls. Almost all strength comes from the supporting material or forms.

Headland (Head) - A high, steep-faced projection extending into the sea, usually marking an area of fairly stable and rigid landform.

Holocene - In geologic time, less than 11,000 years ago; also called Recent.

Implementing actions - The ordinances, regulations, or programs which implement either the provisions of the certified local coastal program or the policies of Chapter 3 of the Coastal Act which are submitted pursuant to Section 30502.

Jetty - On open seacoasts, a structure extending away from the shore, which is designed to prevent shoaling of a channel and to direct and confine the stream or tidal flow. Jetties are built at the mouths of rivers, harbors, or tidal inlets to help deepen and stabilize the access channel.

Lagoon - A shallow body of water, such as a pond or lake, usually located near or connected to the sea.

Land use plan - The relevant portions of a local government's general plan, or local coastal element which are sufficiently detailed to indicate the kinds, location, and intensity of land uses, the applicable resource protection and development policies and, where necessary, a listing of implementing actions.

LCP (Local Coastal Program) - Local coastal program means a local government's (a) land use plans, (b) zoning ordinances, (c) zoning district maps, and (d) within sensitive coastal resources areas, other implementing actions, which, when taken together, meet the requirements of, and implement the provisions and policies of, this division at the local level.

Leeward - The direction toward which the wind is blowing.

Liquefaction - The process of becoming liquid, especially applied to sand that loses its bearing strength due to strong shaking.

Littoral - Of or pertaining to a shore, especially of the sea.

Littoral cell - A region that encompasses most features affecting sediment transport. The boundaries of the cell are usually delineated by river drainage areas, promontory headlands, or submarine canyons on the periphery, the continental shelf-continental slope boundary on the seaward side and by inland ridges and river inlets on the landward side. Sediment within these cells generally travel seaward by river drainage, southward (downcoast) by longshore currents, and are eventually lost to the continental slope area or submarine canyon.

Littoral drift - The sedimentary material moved in the littoral zone under the influence of waves and currents; consisting of silt, sand, gravel, cobbles, and other beach material.

Littoral transport - The movement of sediment in the littoral zone by waves, currents, and tides. This includes movement parallel (longshore transport) and perpendicular (on-offshore transport) to the shore.

Littoral zone - The region where waves, currents, and winds interact with the land and its sediments. This region comprises a backshore, foreshore, inshore, and offshore and is broken down into littoral cells.

Local coastal element - That portion of a general plan applicable to the coastal zone which may be prepared by local government pursuant to this division, or any additional elements of the local government's general plan prepared pursuant to Section 65303 of the Government Code, as the local government deems appropriate.

Local coastal program - A local government's (a) land use plans, (b) zoning ordinances, (c) zoning district maps, and (d) within sensitive coastal resources areas, other implementing actions, which, when taken together, meet the requirements of, and implement the provisions and policies of, this division at the local level.

Local government - Any chartered or general law city, chartered or general law county, or any city and county.

Longshore - Parallel to and near the shoreline.

Longshore current - A flow of water in the breaker zone, moving essentially parallel to the shore, usually generated by waves breaking at an angle to the shoreline.

LUP (Land Use Plan) - Land use plan means the relevant portion of a local government's general plan, or local coastal element which are sufficiently detailed to indicate the kinds, location, and intensity of land uses, the applicable resource protection and development policies and, where necessary, a listing of implementing actions.

Marine terrace - A flat or gentle seaward sloping wave-cut bench, which is a remnant of an old coastline. Marine terraces are conspicuous along most of the California coast where uplift has occurred.

Mean high water - The 19-year average of all high water heights (if the tide is either semidiurnal or mixed) or the higher high water heights if the tide is diurnal. For diurnal tides high water and higher high water are the same.

Mean higher high water - The 19-year average of only the higher high water heights.

Mean low water - The 19-year average of all low water heights (if the tide is either semidiurnal or mixed) or the lower low water heights if the tide is diurnal. For diurnal tides low water and lower low water are the same.

Mean lower low water - The 19-year average of only the lower low water heights.

Mean sea level - The 19-year average height of the surface of the sea for all stages of the tide, usually determined from hourly height readings (see NGVD of 1929).

Mesa - An isolated, relatively flat geographical feature, often demarcated by canyons (from Spanish mesa, table).

Midden - Refuse heap or other deposit left by ancient humans.

Miocene - A period of geologic time spanning 27-26 million years ago.

MOA - Memorandum of Agreement.

Monitoring - Systematic collection of physical, biological, or economic data or a combination of these data on a beach nourishment project in order to make decisions regarding project operation or to evaluate project performance.

MOU - Memorandum of Understanding.

National Geodetic Vertical Datum of 1929 (NGVD) - A fixed reference for elevations, equivalent to the 1929 Mean Sea Level Datum. The geodetic datum is fixed and does not take into account the changing stands of sea level. NGVD should not be confused with mean sea level. (see Mean Sea Level)

Nearshore zone - An indefinite zone extending seaward from the shoreline well beyond the breaker zone; it defines the area of nearshore currents.

NOAA - National Oceanic and Atmospheric Administration.

Nourishment - The process of replenishing or enlarging a beach. It may be brought about naturally by longshore transport or artificially by the deposition of dredged materials.

NPS - National Park Service

NPS - Nonpoint source pollution or polluted runoff.

OCRM - NOAA's Office of Ocean and Coastal Resource Management.

Offshore - Off or away from the shore. This area extends from beyond the breaker zone to the outer limit of the littoral zone and beyond.

Onshore (inshore) - The region between the seaward edge of the foreshore and the seaward edge of the breakers or waves.

OTD (offer to dedicate) - An OTD is a document, recorded against the title to a property, which is an offer of dedication to the people of the State of California of an easement over the property or a portion of the property. Generally, an OTD allows for specific uses in of the area of the property involved (for example, allowing the public to walk across the area). The offer conveys an easement in perpetuity only upon its acceptance on behalf of the people by a public agency or by a nonprofit private entity approved by the executive director of the Coastal Commission.

Overwash - The process by which severe storm waves sweep over a dune, beach, or shore structures, often causing flooding.

PCH - Pacific Coast Highway

Perched beach - A sill that retains sand (sediment) behind or landward of it. The sill can be placed offshore or above the high tide line to hold and protect a fill and eliminate the need for offshore sand to form a stable beach.

Perimeter foundation - A foundation type that supports a building on a low wall or footing extending around the outer edge of the building.

Permit - Any license, certificate, approval, or other entitlement for use granted or denied by any public agency.

Person - Any individual, organization, partnership, limited liability company, or other business association or corporation, including any utility, and any federal, state, local government, or special district or an agency thereof.

Pile - A long, heavy timber or section of concrete or metal driven or drilled into the earth or seabed to serve as a support or protection.

Pleistocene - A period of geologic time spanning 2 million - 11,000 years ago.

Pliocene - A period of geologic time spanning 7-2 million years ago.

Pocket beach - A small beach formed between two points or headlands, often at the mouth of a coastal stream. Pocket beaches are common throughout the California coastline.

Port governing body - The Board of Harbor Commissioners or Board of Port Commissioners which has authority over the Ports of Hueneme, Long Beach, Los Angeles, and San Diego Unified Port District.

Prime agricultural land - Those lands defined in paragraph (1), (2), (3), or (4) of subdivision (c) of Section 51201 of the Government Code.

Public Trust Lands - Public Trust lands shall be defined as all lands subject to the Common Law Public Trust for commerce, navigation, fisheries, recreation, and other public purposes. Public Trust Lands include tidelands, submerged lands, the beds of navigable lakes and rivers, and historic tidelands and submerged lands that are presently filled or reclaimed and which were subject to the Public Trust at any time. (From California Code of Regulations, section 13577; see tidelands and submerged lands.)

Public works -

(a) All production, storage, transmission, and recovery facilities for water, sewerage, telephone, and other similar utilities owned or operated by any public agency or by any utility subject to the jurisdiction of the Public Utilities Commission, except for energy facilities.

(b) All public transportation facilities, including streets, roads, highways, public parking lots and structures, ports, harbors, airports, railroads, and mass transit facilities and stations, bridges, trolley wires, and other related facilities. For purposes of this division, neither the Ports of Hueneme, Long Beach, Los Angeles, nor San Diego Unified Port District nor any of the developments within these ports shall be considered public works.

(c) All publicly financed recreational facilities, all projects of the State Coastal Conservancy, and any development by a special district.

(d) All community college facilities.

Quaternary - A period of geologic time comprising the past 2 million years; includes the Pleistocene and Holocene ages.

Receiver beach - For beach nourishment, the area where beach material is placed.

Recurved or concave-faced walls - Vertical concrete walls with either a seaward facing curve at the top of the wall or along the entire height of the wall. The purpose of the curved face is to reflect the wave energy seaward and prevent overtopping or toe scour.

Reflection - Redirection of a wave when it impinges on a steep beach, cliff or other barrier;

Refraction - (1) Process which changes the direction of a wave moving into shallow water at an angle to the contours -- the part of the wave advancing in shallower water moves more slowly than the part in deeper water, causing the wave crest to bend toward alignment with the underwater contours. (2) Bending of wave crests by currents.

Retaining wall - Low wall used to support or retain an earth embankment or area of fill.

Revetment - A sloped retaining wall; a facing of stone, concrete, blocks, rip-rap, etc. built to protect an embankment, bluff, or development against erosion by wave action and currents.

Rill - The channel of a small stream or gully.

Rip current - A strong surface current flowing seaward from the shore. It usually appears as a visible band of agitated water and is the return movement of water piled up on the shore by incoming waves and wind. With the seaward movement concentrated in a limited band its velocity is accentuated. Rip currents can pull inexperienced swimmers and waders into deeper water away from the shore. Since a rip current is usually quite narrow, the most effective way to get out of it is to swim perpendicular to the direction of the flow (in most cases, parallel to the beach). Rip currents can often develop adjacent to a jetty or groin.

Riprap - A protective layer or facing of rock, concrete blocks or quarrystone, placed to prevent erosion, scour, or sloughing of an embankment or bluff.

RWQCB - Regional Water Quality Control Board.

Sand by-pass - Deliberate transfer of sand along the shore around a barrier such as a jettied harbor entrance or inlet. In the case where sand accumulates preferentially on one side of an inlet, this action may result in nourishment of the beach on the eroding (receiving) side.

Sand source - Resource of sand that can be economically used for beach nourishment. The sand must meet the requirements for size distribution and cleanliness and its removal and transfer must not create unacceptable environmental effects. The source may be on land, offshore, in a nearby inlet, or in a navigational channel, a shoal, or other area in which sand accumulates.

Sandstone - A rock composed predominantly of sand grains that have undergone cementation.

SB - Senate Bill.

Scarp (beach scarp) - An almost vertical slope along the beach caused by wave erosion. It may vary in height from a few centimeters to a meter or more, depending on wave action and the nature and composition of the beach.

Scour - Removal of material by waves and currents, especially at the back, base, toe or edges of a shore structure.

Sea - The Pacific Ocean and all harbors, bays, channels, estuaries, salt marshes, sloughs, and other areas subject to tidal action through any connection with the Pacific Ocean, excluding nonestuarine rivers, streams, tributaries, creeks, and flood control and drainage channels. Sea does not include the area of jurisdiction of the San Francisco Bay Conservation and Development Commission, established pursuant to Title 7.2 (commencing with Section 66600) of the Government Code, including any river, stream, tributary, creek, or flood control or drainage channel flowing directly or indirectly into such area.

Sea level - The height of the ocean relative to land; tides, wind, atmospheric pressure changes, heating, cooling, and other factors cause sea-level changes.

Seas (waves) - Waves caused by wind at the place and time of observation. (see swell).

Seawall - A structure separating land and water areas, primarily designed to prevent erosion and other damage due to wave action. It is usually a vertical wood or concrete wall as opposed to a sloped revetment.

Second units - Auxiliary residential units on a lot with an existing primary residential unit. Second units may lack full facilities, such as kitchens.

Sediment - Grains of soil, sand, or rock that have been transported from one location and deposited at another.

Sediment budget - An account of the sand and sediment along a particular stretch of coast; the sources, sinks, rates of movement, or the supply and loss of sediment.

Seiche - A standing wave oscillation in an enclosed waterbody that continues (in a pendulum fashion) after the cessation of the originating force. Seiches can be caused by tidal action or an offshore seismic event.

Sensitive coastal resource areas - Those identifiable and geographically bounded land and water areas within the coastal zone of vital interest and sensitivity. Sensitive coastal resource areas include the following:

(a) Special marine and land habitat areas, wetlands, lagoons, and estuaries as mapped and designated in Part 4 of the coastal plan.

(b) Areas possessing significant recreational value.

(c) Highly scenic areas.

(d) Archaeological sites referenced in the California Coastline and Recreation Plan or as designated by the State Historic Preservation Officer.

(e) Special communities or neighborhoods which are significant visitor destination areas.

(f) Areas that provide existing coastal housing or recreational opportunities for low- and moderate-income persons.

(g) Areas where divisions of land could substantially impair or restrict coastal access.

Shale - A rock composed predominantly of clay minerals.

Shoal - A shallowing of the depth of water, often a navigational channel. This shallowing may be caused by the deposition of river sediments or littoral materials and often becomes a hazard to navigation. Incoming ocean waves will heighten and may break as they approach the shallowing shoreline. Dredging and channel modification is often utilized to reduce deposition.

Shore - Narrow strip of land in immediate contact with the sea, including the zone between high and low water. A shore of unconsolidated material is usually called a beach.

Shore protection - Structures or sand placed at or on the shore to reduce or eliminate upland damage from wave action or flooding during storms.

Shoreline - Intersection of the ocean or sea with land; the line delineating the shoreline on National Ocean Service nautical charts and surveys approximates the mean low water line from the time the chart was prepared.

Shoreline armoring - Protective structures such as vertical seawalls, revetments, riprap, revetments, and bulkheads built parallel to the shoreline for the purposes of protecting a structure or other upland property.

Slab foundation - A foundation type that supports a building in a thin layer of steel reinforces concrete.

SLC - State Lands Commission

Slough - To erode the uppermost layer of soil, or to crumble and fall away from the face of a cliff.

Soldier pile wall - Vertical pilings or steel H-beams deeply embedded into the sand or bedrock, with horizontal planks or beams landward of the vertical supports.

Special district - Any public agency, other than a local government, formed pursuant to general law or special act for the local performance of governmental or proprietary functions within limited boundaries. Special district includes, but is not limited to, a county service area, a maintenance district or area, an improvement district or improvement zone, or any other zone or area, formed for the purpose of designating an area within which a property tax rate will be levied to pay for a service or improvement benefiting that area.

Special treatment area - An identifiable and geographically bounded forested area within the coastal zone that constitute a significant habitat area, area of special scenic significance, and any land where logging activities could adversely effect public recreation area or the biological productivity of any wetland, estuary, or stream especially valuable because of its role in a coastal ecosytem.

Spit - A small, naturally formed point of land or a narrow shoal projecting into a body of water from the shore.

State university - The University of California and the California State University.

Still water level - The elevation that the surface of the water would assume if all wave action were absent.

Storm surge - A rise above normal water level on the open coast due to the action of wind stress on the water surface. Storm surge resulting from a hurricane also includes the rise in level due to atmospheric pressure reduction as well as that due to wind stress.

Structure - Includes, but is not limited to, any building, road, pipe, flume, conduit, siphon, aqueduct, telephone line, and electrical power transmission and distribution line.

Subaerial - Formed, existing, or taking place on the land surface; contrasted with subaqueous or underwater.

Subaerial erosion - Erosion that occurs on the land surface due to removal of surface material by wind, water, weathering, and gravity. (see erosion).

Submarine canyon - A steep-sided underwater valley commonly crossing the continental shelf and slope.

Submerged lands - Submerged lands shall be defined as lands which lie below the line of mean low tide (from California Code of Regulations, section 13577; see Public Trust Lands).

Surf zone - Area between the outermost breaking waves and the limit of wave uprush.

Surficial - Relating to the earth's surface.

SWRCB - State Water Resources Control Board.

Talus - A pile of rock debris at the base of a cliff.

TDC (Transfer of Development Credit) - A transfer of development credit program is used to mitigate the cumulative impacts from new subdivisions in the coastal zone. For each new parcel created, the development potential of one or more existing parcels must be extinguished through a recorded document. This process helps ensure that the overall development potential in an area does not increase and directs development to those areas more suitable for development.

Tectonic - Related to the earth's surface.

Terrace - A gently sloping platform cut by wave action.

Tidal epoch (National Tidal Datum Epoch) - The specific 19 year period adopted by the National Ocean Service as the official time segment over which tide observations are taken and averaged to form tidal datums. This period occurs when the new and full moon would recur on the same day of the year. The present tidal epoch used is 1960 through 1978.

Tidal prism - The total amount of water that flows into a harbor or estuary or out again with movement of the tide, excluding any freshwater flow.

Tidal range - Difference between consecutive high and low (of higher high and lower low) waters. (see tides).

Tidal wave - Wave movement of the tides. Often improperly used for tsunamis (see tsunami).

Tide - The periodic rising and falling of the water that results from gravitational attraction of the moon and sun, and other astronomical bodies, acting upon the rotating earth. The California coast has a mixed tidal occurrence, with two daily high tides of different elevations and two daily low tides, also of different elevations. Other tidal regimes are diurnal tides, with only one high and one low tide daily, and semidiurnal, with two high and two low tides daily, with comparatively little daily inequality between each high or each low tide level

Tidelands - Tidelands shall be defined as lands which are located between the lines of mean high tide and mean low tide (from California Code of Regulations, section 13577; see Public Trust Lands).

Tie-back walls - Vertical walls that are braced into the material behind them by tie rods or cables connecting to anchors or deaden.

Tombolo - Bar or spit that connects or ties an island to the mainland or to another island.

Transverse dunes - The ridges and sand mounds that form essentially perpendicular to the prevailing wind direction. These form when there is one dominant wind direction and a large supply of sand.

Treatment works - Has the same meaning as set forth in the Federal Water Pollution Control Act (33 U.S.C. 1251, et seq.) and any other federal act which amends or supplements the Federal Water Pollution Control Act.

Tsunami - A long period wave, or seismic sea wave, caused by an underwater disturbance such as a volcanic eruption or earthquake. Commonly misnamed a Tidal Wave.

Undertow - A seaward current near the bottom on a sloping inshore zone, caused by the return, under the action of gravity, of the water carried up on the shore by waves. Commonly misnamed a Rip Current.

Upcoast - In the United States usage, the coastal direction, generally trending toward the north, from which a current comes. Sediment will often deposit on the upcoast side of a jetty, groin, or headland, reducing the amount of sediment that is available for transport further downcoast.

Updrift - The direction opposite that of the predominant movement of littoral materials.

USACOE - U.S. Army Corps of Engineers

USC - United States Code.

Wakefield bulkhead - Vertical boards imbedded in sand using a tongue and groove arrangement, with horizontal planks reinforcing the seaward face.

Watershed - The geographical area drained by a river and its connecting tributaries into a common source. A watershed may, and often does, cover a very large geographical region.

Wave - A ridge, deformation, or undulation of the surface of a liquid. On the ocean, most waves are generated by wind and are often referred to as wind waves.

Wave climate - The range if wave parameters (Height, period and direction) characteristic of a coastal location.

Wave height - The vertical distance from a wave trough to crest.

Wave length (wavelength) - The horizontal distance between successive crests or between successive troughs of waves.

Wave period - The time for a wave crest to traverse a distance equal to one wavelength, which is the time for two successive wave crests to pass a fixed point.

Wave run-up - The distance or extent that water from a breaking wave will extend up a beach or structure.

Wave-cut platform - The near-horizontal plane cut by wave action into a bedrock formation at the shoreline.

Wetland - Lands within the coastal zone which may be covered periodically or permanently with shallow water and include saltwater marshes, freshwater marshes, open or closed brackish water marshes, swamps, mudflats, and fens.

Windward - The direction from which the wind is blowing.