Scour

– Scour is the local erosion caused by swift-moving water at the interface between a structure and the sediment or substrate in which it is located. In the coastal zone, scour is of particular concern at bridge pilings or at the base of bulkheads, seawalls, and other manmade structures.

Sea Level Rise

– Sea level rise is the long-term increase in mean sea level. It can be measured on a global scale, based on the global mean sea level, or at a local level. When measured locally, sea level rise is frequently computed in tandem with regional land elevation changes (such as subsidence). The long-term trend in sea level rise, accounting for regional land change, is known as relative sea level rise.

Seawall

– A vertical structure built along a portion of coastline to prevent erosion and other damages due to wave impacts. A seawall typically offers more protection to an area than a bulkhead, and design will usually address storm surge, wave overtopping, toe scour, uplift caused by waves, and direct wave attack.

Sediment Budget

– Sediment budget is the amount of budget added to and removed from the coastal system over an area of interest and time frame. The amount of sediment into the system less the amount of sediment out of the system yields a net sediment remaining within the system. A positive sediment budget indicates a sediment surplus and can lead to aggradation. A negative sediment budget indicates a sediment deficit and can lead to shoreline erosion.

Sediment Transport

– Sediment transport is the movement of sediment within a nearshore system caused by wave breaking and the net direction of winds, waves, and currents. The sediment transport accounts for why an area may be accreting (aggrading) or eroding over time.

Semi-diurnal Tide

– A semi-diurnal tide is a tide that has a cycle of approximately one-half of a tidal day (12.4 hours) and generates two high tides and two low tides each day. The predominating type of tide throughout the world is semi-diurnal.

Setup, Wave

– Wave setup is the vertical increase in water surface elevation due to the presence of breaking waves. In contrast to individual wave crests which are easily observable, wave setup occurs as a relatively gradual increase in the water surface across a broad area and is typically indiscernible to the naked eye.

Setup, Wind

– Wind setup is the vertical increase in water surface elevation due to the force of the wind piling up water along a shoreline. Wind setup can contribute to high tides and is a component of storm surge.

Shoaling, Wave

– Shoaling refers to the phenomenon whereby wave heights increase as waves propagate towards the shoreline and enter shallower water. When waves reach a critical point where the ratio between wave height and water depth becomes too steep, the waves break.

Shoreline Change

– Shoreline change is the gain or loss of land area along the coastline that classifies if a shoreline is accreting (aggrading) or eroding. Shoreline change can be measured over the long-term (decades), due to geological, morphological, or meteorological trends, or short-term, due to episodic events (e.g., tropical storms).

Spring Tide

– The spring tide is the tide when there is the largest difference between high and low tide in a day. The spring tide typically occurs two times each month during new moon and full moon phases.

Stillwater Elevation

– The stillwater elevation, also known as stillwater level (SWL), is the elevation of the top of water without including the crests of individual wave but including wave setup. When being used to describe storm conditions, SWL includes storm surge.

Storm Surge

– Storm surge is the increase in water surface elevation due to a combination of reduced atmospheric pressure (typical before and during tropical systems) and wind and wave setup. Storm surge does not include the crests of individual waves.

Storm Tide

– Storm tide is the elevation that combines the storm surge and the expected tidal elevation that would have occurred at that time without a storm.

Subsidence

– Subsidence is the sinking of the ground due to many location-specific factors including sediment characteristics and reduction in amount of subsurface water.