Systems and processes in coastal environments Flashcards
What is Erosion?
The wearing away of the Earth’s surface by the mechanical action of processes of glaciers, wind, rivers, marine waves and wind.
What is the Fetch?
Refers to the distance of open water over which a wind blows uninterrupted by major land obstacles. The length of fetch helps to determine the magnitude (size) and energy of the waves reaching the coast.
What is mass movement?
The movement of material downhill under the influence of gravity, but may also be assisted by rainfall.
What is weathering?
The breakdown and/or decay of rock at or near the Earth’s surface creating regolith that remains in situ until it is moved by later erosional processes. Weathering can be mechanical, biological/organic or chemical.
What is the vital role wind plays in wave formation?
Waves are created by the transfer of energy from the wind blowing over the sea surface (referred to as the ‘frictional drag’ of the wind). The energy acquired by waves depends upon the strength of the wind, the length of time it is blowing and the fetch.
What is the wave frequency or wave period?
This is the time for one wave to travel the distance of one wavelength, or the time between one crest and the following crest passing a fixed point.
What are Constructive waves?
Waves with a low wave height, but with a long wavelength (up to 100m) and low frequency of around 6-8/min. Their swash tends to be more powerful than their backwash and as a consequence beach material is built up. Material is slowly, but constantly, moved up the beach, leading to the formation of ridges.
What are Destructive waves?
Waves with a high wave height with a steep form and high frequency (10-14/min). Their swash is generally stronger than their backwash, so more sediment is removed than is added. As they approach the beach, they rapidly steepen, and, when breaking, they plunge down. Very little material is moved up the beach, leaving the backwash to pull material back down the beach.
What sources does coastal sediment come from?
Streams or rivers flowing into the sea, Estuaries, Cliff erosion, Offshore sand banks, Material from a biological origin - including shells, coral fragments and skeletons of marine organisms.
What are sediment cells?
Distinct areas of coastline separated from other areas by well-defined boundaries, such as headlands and stretches of deep water. They can vary in size. The larger ones are divided into smaller sections to allow closer study and management called sub cells. (Between Flamborough Head and Humber Estuary an example).
What is the coastal sediment budget?
Best thought of as being similar to a bank account, and is defined as the balance between sediment being added to and removed from the coastal system,.
What does coastal erosion control?
It controls the level of the deficit as they remove material from the shoreline, and if more sediment is removed than is added then the coastline will recede.
