THEME 2

Related Case Study:

Hurricane Katrina

• High air pressure > Air is sinking > Clouds can't form > Dry
• Low air pressure > Air is rising > Clouds can form > Wet
  

Anticyclone:

• A slow moving weather system caused by high pressure of 1016mb.
• Low wind speeds (shown on a weather map by the isobars being spread out).
• In summer it brings high temperatures and the opposite for winter.

• Drought and water shortages.
• More forest fires in summer as vegetation dries out.

• There may be a hose pipe ban.
• There may be water rationing.
• In the winter, local councils will grit the roads if it will be below 0'C.

• Those involved in outdoor activities will gain.
• Tourist related businesses will gain in summer.
• The elderly and those with health problems are more at risk in extreme hot or cold weather.

• Warm and cold air meet at the front and then the warm air forces its way into the cold air.

• Two lots of rain.
• A lot of cloud on and near the fronts.
• High wind speeds.

• Flooding if the depression brings a lot of rain.
• In winter, it may bring snow if the temperatures are low enough.
• Structural damages due to high wind speeds.

• The Environment Agency issues flood warnings.
• Schools may be forced to close.
• Football matches may have to abandon matches.

• The Environment Agency is responsible for monitering rivers.
• Commuters may have to change their journey plans.
• Parents may have to arrange child care at short notice.

• Very low pressure weather systems.
• Strong winds.
• Heavy rainfall.

Tropical depressions have winds less than 38mph, Tropical storms have winds between 39-73mph and hurricanes have winds over 74mph.

• Recorded on the Saffir - Simpson scale.

How do hurricanes form?:

• Low pressure area.
• Warm water.
• Coriolis Force.
• The atmosphere.
• The wind.

When?

• It was formed over the Bahamas on 23rd August 2005.
• Crossed Florida as a small hurricane.
• Strengthened rapidly over the Gulf of Mexico.
• Second landfall on the 29th August 2005 in Louisiana.
• The storm broke up on the 31st August 2005.

Where?

• The city of New Orleans, in Louisiana.
• Alabama was also affected.

Causes?

• Sea temperature of 27'C.

Effects:

• 1800 people died.
• The costs are estimates at $75 billion.
• 1 million people were evacuated from New Orleans.
• 80% of New Orleans were submerged under 6ft of water.
• 9000 people took shelter in the Superdome.
• The government were criticised for not helping the people of New Orleans quickly enough.

Related Case Study:

Amazon Rainforest / Bramcote Woods

• Maintaining a steady supply of clean water to rivers.
• Preventing soil erosion.
• Reducing the risk of river floods.
• Providing natural meterials such as timber for building, or plants for medicine use.
• Providing food stuffs such as honey, fruit and nuts.

How can ecosystems be managed sustainably?

• Allowing access to parts of an ecosystem and protecting the rest.
• Encouraging responsible use of an ecosystem - Sign posts, Bins, Fences, Paths.
• Encouraging activities that use the wood in a non-harmful way.
• Replanting trees that are removed.

Different Groups of People:

The wood is managed by Broxtowe Council. People who use the wood are:

• People walking their dog.
• Families.
• People keeping fit.
• Mountain bikers.
• Local school children taking a short cut.
• Horse riders.

Negative:

• Soil erosion from people walking and mountain biking.
• Litter and vandalism.

Positive:

• Tree planting at the top of the hill.

Related Case Study:

Sahel

 The Sahel is located in the southern region of the Sahara Desert, Africa.

Causes of desertification:

• An increase in population --> Deforestation --> Overcultivation --> Loose top soil blown away or eroded by rainfall ..
• An increase in population --> An increase in cattle --> Overgrazing --> Less vegetation --> Loose top soil blown away or eroded by rainfall ..

Human Causes and Solutions:

• Deforestation = Afforestation.
• Overcultivation = Educate the farmers to use the land in a productuve way.
• Overgrazing = Plant acacia trees for use as food for the animals.
• Over use of fertilisers = Use genetically modified crops.
• Lack of irrigation = Build terraces on the land to help conserve water.
• Poverty/Civil War = Build stone lines across fields.

Physical Causes and Solutions:

• Climate change and drought = Irrigation schemes or dams.
• Variations in seasonal rainfall = Storing water during rainy seasons and plant more drought tolerant crops (GMC)
• High pressure systems = None

Groups of People:

• The people who live in the Sahel region struggle to survive. Many face starvation or malnutrition.
• The United Narions has a convention to tackle the problems of desertification.

Related Case Study:

River Trent and Flood Defences in Duffield

Related Case Study:

The Dorset Coast

 Dorset is a county in South West England on the English Channel coast.

• Old Harry is an example of a stack.
• Durdle Door is an example of an arch.
• Swanage Bay is an example of a bay between two headlands.
• Kimmeridge is an example of a wave-cut platform.

Headlands and Bays - Erosional Landforms:

• This type of coastline is called discordant.
• This coastline is eroded by abrasion and hydraulic action.
• Soft rock is eroded quicker to create bays.
• Swanage Bay is made from clays and sands.
• Hard rock is left sticking into the sea as headlands.

Wave-cut Platforms and Cliff Recession - Erosional Landforms:

• Weather weakens the top of the cliff.
• The sea attacks the base of the cliff forming a wave-cut notch.
• The notch increases in size causing the cliff to collapse.
• The notch forms between the wave height at high and low tide.
• The backwash carries the rubble towards the sea forming a wave-cut platform.
• The process repeats and the cliff continues to recede.

Caves, Arches and Stacks - Erosional Landforms:

• These features are formed on cliffs or headlands that are made of hard rock.
• This hard rock is eroded by abrasion and hydraulic action.
• Old Harry is made from chalk.
• Durdle door is made from limestone.

Depositional Landforms:

• Sandbanks is an example of a spit.
• Chesil Beach is an example of a tombolo.

Spits, Bars and Tombolos - Depositional Landforms:

• Spits are created by deposition. 
• They are formed where the prevailing wind blows at an angle to the coastline.
• A tombolo is a spit that has joined onto an island.

Why do coastal processes need to be managed?

• Increasing development of coastal areas including urban areas means there are more people at risk from coastal flooding.
• This risk is likely to increase in the future as climate change causes rising sea levels and an increase in the number of coastal storms.
• The value of coasts for leisure and recreation.
• Increased economic/transportation/industrial value in industries like oil refineries and ports.
• Increased environmental/nature conservation value of coastal wetlands

How are coastlines managed?

• Hold the existing defence line - To maintain or increase the level of protection provided by defences in their present location.
• Advance the existing defence line - Building new defences on the seaward side of the existing defence line to reclaim land.
• Managed realignment - Allowing the shoreline to position to move backwards (or forwards) in a controlled way.
• Do nothing - A decision to not invest in providing new or maintaining existing defences.

Management Methods:

• Gabions - Hard engineering
• Sea walls - Hard engineering
• Rip rap - Hard engineering
• Groynes - Hard engineering
• Beach replenishment
  
• Revetments - Hard engineering
• Breakwaters - Hard engineering

Swanage Bay:

• Sea wall,
• Groynes and,
• Beach replenishment.

 They have a hold the line policy.

Holderness Coast:

• Concrete sea walls,
• Wooden groynes and,
• Rock armour.

Arguments For and Against Sea Defences:

• People have lived in these areas for generations.
• Houses, schools, roads, hotels, agricultural land will be lost.
• The cost is expensive.
• The land is not that valuable in some places.

V-Shaped Valleys - Erosional Landform:

• Vertical Erosion - Results in a number of distinctive landforms including the steep sloping v-shaped valley through which the river flows in its upper course.
• Over time the sides of this valley are weakened by weathering processes.
• As the river flows through the valley it is forced to swing from side to side around more resistant rock outcrops (spurs).

Waterfalls - Erosional Landform:

• Waterfalls often form where hard rock lies over the top of a softer rock.
• The water drops over the edge and swirls around in the plunge pool which erodes the soft rock.
• The soft rock is eroded back.
• The hard rock is left to overhand.
• The position of the waterfall moves backwards (retreats).
• Over a long time this will carve out a deep sided velley called a gorge.

Meanders - Erosional and Depositional Landforms:

• In the middle course, the river has more energy and a high volume of water.
• The gradient here is gentle and the lateral (sideways) erosion has widened the river channel.
• Outside of the bend = The force of the water erodes and undercuts the river bank on the outside of the bend where water flow has most energy due to decreased friction.
• Inside of the bend = The river's flow is slower so it has less energy. This means material is deposited, as there is more friction.
• On the outside bend, a steep bank called a river cliff is formed.
• On the inside, the build-up of deposited material creates a slip off slope.

Floodplains and Levees - Depositional Landforms:

• Levees are the higher banks that develop at the edge of the river.

River Flooding:

 A flood is a period of high river discharge or, alone the coast, an extremely high tide.

 A hydrograph is a graph to show changes in discharge of a river over a period of time.

• Urban areas - Increases the risk of flooding due to being covered in impermeable surfaces.
• Deforestation - Increases flood risk because trees intercept some of the rain.
• Intensity of the rainfall - A heavy rainstorm will put a lot of water onto the land in a short period of time.

Causes:

• Farmers have removed trees in Derbyshire.
• High rainfall for many weeks - In Rolleston, they recieved 75mm in 24hrs.
• Impermeable surfaces in Derby and Burton on Trent.

Effects:

• Notts County football match was cancelled.
• Trains were cancelled between Crewe and Derby.
• Toot Hill school in Bingham was closed.
• Fire crews were called out to rescue stranded animals.

Managed:

• Dam Construction.
• River Engineering.
• Dredging.
• Afforestation.

• Governments and developers often favour large hard enginerring options, such as dam building. Building a dam and a reservoir can generate income. Profits can be made from generating electricity or leisure revenue.
• Environemtal groups and local residents often prefer softer options, such as planting trees. Soft options cause little damage to the environment and do not involve the resettlement of communities.
• Effective flood management strategies should be economically, environmentally and socially sustainable. Sustainable strategies allow management without compromising the needs of future generations.