Should we continue to defend our coasts Flashcards
What factors affect the strength of waves?
Wave strength depends on wind speed, how far and how long the wind blows, water depth, and the shape of the coastline.
What is the difference between constructive and destructive waves?
Constructive waves have a strong swash and weak backwash, helping to build up beaches with low, long waves in calm weather. Destructive waves have a strong backwash and weak swash, causing erosion with tall, steep waves during stormy conditions.
Define the following types of marine erosion and explain how they are eroding the coast: hydraulic action, abrasion, corrosion, attrition.
Hydraulic action breaks rocks through wave pressure, abrasion wears down the coast with particles, corrosion dissolves rocks chemically, and attrition smooths rocks as they collide.
How are erosional landforms created?
Erosional landforms are created by marine erosion, with headlands and bays forming from different rock types, caves eroding into arches that collapse into stacks and stumps, and wave-cut platforms forming at the base of cliffs.
How do the waves transport sediment through longshore drift?
Longshore drift is the movement of sediment along the coast, caused by waves hitting the shore at an angle. The swash moves sediment up the beach at an angle, and the backwash pulls it straight back, creating a zigzag pattern along the shore.
Define deposition and explain when it occurs.
Deposition is the process where sediment carried by water, wind, or ice is dropped and settles in a new location. It occurs when the energy of the transporting medium (like waves or wind) decreases, causing it to lose its ability to carry sediment, which then settles on the shore, riverbed, or other surfaces.
Explain the formation depositional landforms – what is a spit and how is it formed?
A spit is a narrow, elongated landform that forms when sediment, moved by longshore drift, is deposited where the coastline changes direction. Over time, the sediment builds up, extending into the sea, and may form a hooked tip if currents or winds change direction.
How can coasts be protected?
Coastal defences like sea walls, revetments, gabions, groynes, and beach nourishment protect the coast by reducing wave energy and preventing erosion, with beaches being the best natural defence as they absorb wave energy.
What are the problems caused by defending the coast?
Coastal defences can harm the environment by disrupting natural processes and habitats, and they can be costly and less effective over time.
Why is the sea level rising?
Sea levels are rising due to two main factors: thermal expansion, where seawater expands as it warms, and melting ice, as glaciers and polar ice caps melt due to global warming. These combined effects are causing the volume of water in the oceans to increase, leading to higher sea levels.
What are the impacts of sea level rise: social impacts, economic impacts and environmental impacts?
Sea level rise causes displacement of coastal communities, damages infrastructure, and harms local economies. It also leads to habitat loss, increased erosion, and saltwater intrusion into freshwater sources.
How are the Maldives trying to protect themselves against sea level rise?
The Maldives is addressing sea level rise by building a floating city, elevating islands like Hulhumalé, and planting mangrove forests for natural protection. They are also investing in renewable energy and seeking global support and climate financing to secure their future.
