Registered Civil Engineer (Port & Waterway) key terms

The largest or most demanding ship type, in dimensions and displacement, that a port facility or channel is planned to serve throughout its design life and is used to size berths, turning basins, and channels.

The period within a tidal cycle when water depth over a shoal or entrance exceeds the minimum required by a vessel, allowing it to transit safely without dredging.

The total volume of water that enters and leaves an estuary or basin between high and low tide, governing flushing capacity, sediment exchange, and the stability of an inlet cross-section.

The net longshore movement of sediment along a coast driven by waves approaching at an angle, which causes shoreline accretion on one side of a structure and erosion on the other.

The average height of the highest one-third of waves in a sea state, a standard statistical descriptor used to characterize design wave conditions and to calibrate wave hindcasts.

The bending of wave crests as waves travel over varying water depths, because wave speed decreases in shallow water; it concentrates wave energy on headlands and diverges it in bays.

The spreading of wave energy into the sheltered zone behind a breakwater or obstacle, causing waves to curve around the structure and generate agitation inside a harbor basin.

The time interval between successive wave crests passing a fixed point; it controls wave length, run-up, and the response of moored vessels and floating structures.

The vertical distance above still-water level that an incoming wave climbs on a sloping or armored structure, used to set crest elevations of breakwaters, seawalls, and revetments.

The volume of water passing over the crest of a breakwater or seawall during wave attack; excessive overtopping can damage equipment, endanger personnel, and flood protected areas.

A shaped concrete block or natural rock placed on the outer layer of a rubble-mound structure to resist wave forces; interlocking shapes such as tetrapods improve stability at reduced weight.

A breakwater built from graded rock or concrete armor units with a core of finer material, relying on its mass and interlocking slope to dissipate wave energy rather than resist it as a solid wall.

A breakwater formed by large prefabricated concrete or steel boxes floated into position and sunk onto a prepared foundation, typically used where rock is scarce or space is limited.

A structure built seaward of a harbor or berth to reduce wave action inside the protected area, enabling safe mooring and cargo operations; it may be rubble-mound, caisson, or composite.

Low-amplitude but persistent wave motion inside a basin, often caused by wave diffraction, reflection, or resonance, which can make moored vessels surge and strain mooring lines.

A standing oscillation of water in an enclosed basin whose natural period matches forcing from waves, wind, or atmospheric pressure changes, producing sustained surging at berths.

The designated length of quay or wharf where a vessel moors for cargo handling or passenger transfer; its length, depth alongside, and equipment determine which vessels it can serve.

The flat working area immediately behind a quay wall between the water edge and cargo sheds or storage, used for crane travel, vehicle movement, and temporary cargo handling.

A retaining structure along the water edge that supports the apron and resists earth and water pressures, allowing vessels to moor alongside at sufficient depth.

A retaining wall formed by interlocking steel, concrete, or timber piles driven into the seabed, commonly used for quay walls and cofferdams where a flexible, economical solution is suitable.

A retaining wall whose lateral deflection is restrained by tie rods or ground anchors connected to an anchor block or deadman behind the wall, reducing bending moments and embedment depth.

A temporary watertight enclosure built in the sea or riverbed so that construction can proceed in dry conditions; it is removed or incorporated into the permanent structure afterward.

Loss of soil shear strength when saturated loose sand is shaken and pore pressures rise to the point that effective stress vanishes, a key hazard for marine fills and quay walls under seismic loading.

A borehole test in which a split sampler is driven by a standard hammer and the blow count recorded, providing an index of soil density and strength widely used in marine site investigation.

An in-situ test pushing an instrumented cone into the ground while recording tip resistance and sleeve friction, giving a continuous soil profile in soft marine clays and sands.

Material placed behind retaining structures or in open water to create land above the water level; its gradation, compaction, and drainage govern settlement and stability of the new land.

Time-dependent compression of saturated soft soil as water is squeezed out under added load, a major design concern for reclamation and structures founded on marine clay.

Placing temporary surcharge fill, often with vertical drains, to consolidate soft ground before construction so that most settlement occurs before the permanent structure is built.

The removal of seabed or riverbed material to create or maintain navigable depth, form basins, or obtain fill; it may be mechanical, hydraulic, or a combination.

A self-propelled dredger that drags a suction pipe along the seabed while underway, storing the dredged mixture in a hopper for transport and disposal or reclamation.

A stationary dredger that uses a rotating cutter head to loosen hard material and a suction pipe to pump it away, suited to rock, stiff clay, and precise trench or basin excavation.

The water depth available for navigation, usually referenced to chart datum and reduced by allowances for squat, wave-induced motion, and sediment accumulation to give safe under-keel clearance.

The vertical distance between a vessel's keel and the seabed, comprising allowances for squat, heel, wave response, and survey error; it must remain positive for safe transit.

The decrease in a vessel's under-keel clearance and change in trim caused by increased water velocity beneath the hull when moving through shallow or confined water.

The reference level from which water depths on nautical charts and dredging design levels are measured, usually set near lowest astronomical tide so that depths are mostly greater than charted.

The circular area in a basin or harbor with sufficient depth and width for a vessel to turn around, sized from its length and maneuverability plus clearance allowances.

A shore-perpendicular structure built from the beach into the sea to trap littoral drift and widen the beach, though it commonly causes erosion downdrift of its position.

The artificial placement of sand on a beach to restore or widen it, offsetting erosion from littoral drift or structures; the fill must match native sediment size to remain stable.

The enclosed basin between two gates in a navigation lock where vessels are raised or lowered by filling or emptying the chamber to the level of the adjacent reach.

A mechanical structure that raises or lowers vessels between water levels in a caisson or inclined trough, using less water than a lock and suited to large level differences.

Works such as training dikes, groins, and revetments that stabilize a river channel, maintain navigable depth, and control flow and sediment to support inland waterway transport.

A low structure built into a river channel to concentrate flow, deepen the navigation channel, and guide sediment movement, often in permeable or impermeable form.

The designated navigable route within a waterway, marked by buoys or beacons and maintained to a specified depth and width for the vessels it serves.

A formal process identifying, predicting, and mitigating the environmental effects of a port or waterway project before approval, including consultation and a monitoring plan.

The placement of dredged sediment at sea, onshore, or in beneficial reuse such as reclamation, subject to testing for contamination and to permit conditions.

The present value of a project's benefits divided by the present value of its costs; a ratio above one indicates the project is economically justified at the chosen discount rate.

The sum of a project's discounted future cash flows minus its initial cost, used to compare alternatives; a positive value indicates the investment adds value at the given discount rate.

The rate used to convert future costs and benefits into present values, reflecting the time value of money and the opportunity cost of public or private capital.