4.5: What Are The Challenges For Coastal Landscapes And Communities And Why Is There Conflict About How To Manage Them Flashcards
Why is sea level rising
The two major causes of global sea level rise are thermal expansion caused by warming of the ocean (since water expands as it warms) and increased melting of land-based ice, such as glaciers and ice sheets.
How bad will sea level get and how will it affect different places around the world
Thermal Expansion: When water heats up, it expands. About half of the past century’s rise in sea level is attributable to warmer oceans simply occupying more space.
Melting Glaciers and Polar Ice Caps: Large ice formations, like glaciers and the polar ice caps, naturally melt back a bit each summer. In the winter, snows, primarily from evaporated seawater, are generally sufficient to balance out the melting. Recently, though, persistently higher temperatures caused by global warming have led to greater-than-average summer melting as well as diminished snowfall due to later winters and earlier springs. This imbalance results in a significant net gain in the ratio of runoff to ocean evaporation, causing sea levels to rise.
How will erosion effect erosion and deposition
Climate change forecasts predict an increase in global temperatures; over the past 25 years an increase of 0.2°C per decade has been observed*.
This is likely to cause global sea levels to rise yet further — they are currently rising around 3 mm per year* — and an increase in the frequency and magnitude of storm events.
When these two factors are combined it will have the effect of focusing wave energy closer to the shore and cliff faces, leading to increased rates of coastal erosion in areas where cliffs are composed of soft rocks.
How will climate change affect storm frequency, intensity, and storm surges
Another factor associated with storm events is ‘storm surge’. Extreme low pressure over an area can cause sea level to rise locally, which can lead to coastal flooding in low-lying areas, and overtopping of sea defences.
The current research into the effects of climate change on tropical storms demonstrates not only the virtues and transparency of the scientific method at work, but rebuts the frequent suggestion that scientists fit their findings to a pre-determined agenda in support of climate change. In the case of storm frequency, there is no consensus and reputable scientists have two diametrically opposed theories about increasing frequencies of such events.
How will storms and storm surges affect people and the environment
A storm surge is a rise in sea level that occurs during tropical cyclones, intense storms also known as typhoons or hurricanes. The storms produce strong winds that push the water into shore, which can lead to flooding. This makes storm surges very dangerous for coastal regions.
Explain how groynes and sea walls work
These waves promote erosion at the toe of the wall and can cause severe damage to the sea wall. In some cases, piles are placed in front of the wall to lessen wave energy slightly. The first implemented, most easily designed and constructed type of seawall. Vertical sea walls deflect wave energy away from the coast.
A groyne is a rigid hydraulic structure built from an ocean shore or from a bank that interrupts water flow and limits the movement of sediment.
Explain how beach replenishment and slope stabalisation work
Beach Profile Nourishment describes programs that nourish the full beach profile. In this instance, “profile” means the slope of the uneroded beach from above the water out to sea.
What are the advantages and disadvantages for each management type?
Advantages of the technology top: If performed well, the benefits of nourishment are many and varied. Most importantly, beach nourishment reduces the detrimental impacts of coastal erosion by providing additional sediment which satisfies erosional forces.
Protects the base of cliffs, land and buildings against erosion. Can prevent coastal flooding in some areas. Expensive to build. Curved sea walls reflect the energy of the waves back to the sea.
Advantages
prevents longshore drift as sand builds up on one side of the groyne
keeps beach in place for tourist industry
effective for many years
Disadvantages
unnatractive - difficult to walk along the beach
disrupts natural processes such as long shore drift
expensive
What is the difference between hard and soft engineering? Which is best?
Soft engineering options are often less expensive than hard engineering options. They are usually more long-term and sustainable, with less impact on the environment. There are two main types of soft engineering. This replaces beach or cliff material that has been removed by erosion or longshore drift.
What is strategic realignment, which areas might be left to erode?
Coasts are important for many different reasons and for different groups of people. They provide:
places to live
places to work, eg fishing, ports and power stations
places to relax - leisure and tourism industries
wildlife habitats
beautiful scenery
educational value, eg geology and natural history
You can probably think of many more reasons why coasts need to be protected.
It is not possible to completely stop the power of natural forces from changing the coast. People try to protect some areas from erosion but this can have negative impacts as well as positive.
Explain why ITCM schemes are a sustainable form of coastal
management
Itcm is sustainable because it protects high earning areas and lets areas that do not earn a lot will be left to erode this is good because they will make money and protect valuable land.
