Chapter_1_Coasts_-_Should_Coastal_Environments_Matter

GATEWAY 1: How and why are coastal environments different and dynamic? What are coasts? ● Coast ​ is ​ area where land meets sea, covering land that is affected by waves and tides. ● Coast can be ​ cliffed, sandy, rocky, muddy ​ . Factors affecting coastal environments ● Waves ​ affect coastal environments - constructive waves and destructive waves. ● Tides ​ affect coastal environments by affecting processes like coastal erosion, sediment transport and deposition. ● Currents ​ like longshore current helps transport sediments, giving rise to a sandy coast. ● Geology ​ like hard resistant rocks leads to less erosion and less resistant rock leads to more erosion ● Human ​ activities create pollution and can affect a coast. ● Types of ecosystem ​ can cause differences. Mangrove systems or coral reefs can affect how a shore develops as they reduce the impact of waves on a coast. What are waves and how are they generated? Wave terminology ● Wave length ​ is the horizontal distance from crest to crest or trough to trough. ● Wave height ​ is the vertical distance between crest and trough. ● Wave frequency ​ is number of wave crests or troughs that pass through a fixed point. ● Wave steepness ​ is ratio of wave height to wavelength. ● Wave period ​ is time waves take to travel through one wavelength. ● Crest ​ is highest part of wave ● Trough ​ is lowest part of wave. Factors affecting wave energy ● Wind speed ​ because the faster winds blows, the greater the wave energy. ● Wind duration ​ because the longer the wind blows, the larger the waves are. ● Fetch ​ , which is the distance over which the wind has travelled over seas and oceans to form waves affects wave energy too because the greater the fetch the more energy waves have ● The higher the wave energy is, the steeper the wave and shorter it becomes. Waves in the open ocean or close to the coastline ● Waves in the open ocean have a long wavelength and low wave height, particles in the ocean also move in an orbit. ● Waves close the coastline, however, do not move in an orbit. ○ The water close to the coastline is shallow and waves start to interact with the seabed, changing shape. ○ As the waves continue travelling in shallow water, the base of the wave slows down due to friction. ○ This causes wave height to increase and wavelength to decrease. ○ Eventually this reaches a point where the base of the wave stops but the wave crest becomes steeper and topples over. ○ This causes the process of waves breaking onto the coast. How do waves affect coastal areas? Waves on the beach ● Swash ​ is formed when waves break and water rushes up a beach. Swash moves up the beach in direction of waves, carrying sediments with it. ● Backwash ​ is created when the swash loses energy due to gravity and friction to the sea and returns back to it, forming backwash. Backwash carries sediments fro