4.5 Challenges for coastline. Flashcards
Why is the sea level rising?
- As air temperatures rise (due to climate change) the water in the oceans is warmed and expands. This process is called thermal expansion.
- As ice sheets and glaciers melt, they increase the amount of water in the oceans.
How bad will sea level get and how will it affect different places around the world?
Most predictions say the warming of the planet will continue and is likely to accelerate. Oceans will likely continue to rise as well, but predicting the degree to which they will rise is an inexact science. The Intergovernmental Panel on Climate Change says we can expect the oceans to rise between 11 and 38 inches (28 to 98 centimeters) by 2100, enough to swamp many of the cities along the U.S. East Coast. Experts predict that in less than 100 years, the Maldives will no longer exist.
How will climate change affect erosion?
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?
In the future, rising sea levels will only exacerbate the storm surge problem. Around the globe, sea levels are estimated to rise 1 to 3 feet by 2100 due to climate change, and researchers say that in places like New Orleans 1 foot of sea level rise may lead to a 3 or 4 foot storm surge rise.
How will storms and storm surges affect people and the environment?
When a cyclone hits land, the accompanying storm surge will most often flood the surrounding coastal area. Flooding is responsible for most deaths and economic damage associated with tropical cyclone landfalls. When a hurricane hit Galveston, Texas, in 1900, the storm surge was responsible for approximately 6,000 deaths. In East Pakistan (now Bangladesh), the Bhola cyclone killed as many as 500,000 people in 1970. The storm surge from the Bhola cyclone was estimated to be 10 meters (33 feet) high.
Explain how groynes and sea walls work
Sea walls are the most obvious defensive methods. Sea walls are exactly that. Giant walls that span entire coastlines and attempt to reduce erosion and prevent flooding in the process. They’re big, ugly and very expensive requiring constant maintenance so that they don’t fail.
Groynes are relatively soft hard engineering techniques. They’re low lying wooden walls that extend out to sea. The idea of groynes is to capture sand that moves down the beach via longshore drift and help build up a larger section of beach in front of an area that’s experiencing coastal erosion.
Explain how beach replenishment and slope stabalisation work
If you must repair a beach, this is probably the most gentle approach. Replenishment consists of pumping sand onto the beach and building up the former dunes and upper beach. Sufficient money is never available to replenish the entire beach out to a depth of 40 feet. Thus, only the upper beach is covered with new sand, so that in effect, a steep beach is created.
Advantages of Beach nourishment, disadvantages
It is natural, and cheap. However, the beach has to be closed for a short period.
Advantages/Disadvantages of Slope stabilisation
It stops erosional slumping effectively, however it is a costly process and requires the beach to be closed for a long time.
What is the difference between hard and soft engineering? Which is best?
Hard engineering is working to stop nature. Soft engineering is working with nature. The best method is soft engineering, as it is often cheaper and looks nicer.
What is strategic realignment and which areas might be left to erode?
Strategic realignment is the allowing of areas to flood naturally. Usually, this will be considered to be areas of low value - eg places not being used for housing and farmland.
Explain why ITCM schemes are a sustainable form of coastal management.
What’s an ITCM scheme? Pretty sure this isn’t a thing in Geography.
