CCEA GCSE geography revision

• What is the input of the drainage basin?

  Precipitation
• Stores of the drainage basin?

  The storage is Interception by vegetation
• Transfers?

  Surface runoff overland flow and infiltration through flow percolation groundwater flow
• Outputs?

  River discharge and Evapotranspiration
• Identify and defin the following characteristics of a drainage basin
• Water shed?

  A ridge of Highland that forms the boundary between two adjacent drainage basins
• Source?

  Where a river begins
• Tributary?

  Stream or small river which flows into a bigger one
• Confluence?

  Point where two or more streams meet
• What is at the end of a river

  The mouth
• River processes and landforms
• What are the erosional processes?

  H- Hydraulic action

  A- Attrition

  C- Corrosion

  A- Abrasion
• What are the transportation processes?

  S- Solution

  S- Saltation

  S- Suspension

  T- Traction
• Explain how a waterfall, meander, slip-off slope, river cliff, floodplain and levees are created
• How is a waterfall formed?

  • There are two bands of rock. A layer of hard rock over all there of soft rock.

  •The soft rock is more easily eroded so it is undercut. This happens because of erosion such as abrasion.

  •The river falls into a plunge pool caused by hydraulic action which is the force of moving water.

  •This causes further under cutting.

  •The hard rock begins to overhang until eventually the rock becomes too heavy and collapses.

  •The waterfall will then retreat backwards and form a steep sided gorge.
• How is a meander formed?

  In the under is abandoned in a river that occurs because of differences in velocity (speed of the river.)

  On the other band the water is traveling fastest.

  This means erosion occurs causing a deep channel

  A river cliff is created as the water undercuts the bank (abrasion and hydraulic action)and will eventually fall into the river

  On the inner band the water is slower and deposition occurs the channel is shallow here and I slip off slope is created over time as material is deposited.
• How is a floodplain created?

  A levee is a raised bank formed on the banks of a river, in the lower course. Levees are formed by the repeated flooding. The water will overflow from the river channel onto the surrounding land (flood plain). of the river.
• The case study sustainable management of rivers CASE STUDY A (1 of 2)
• River management strategies the Mississippi River
• Background information

  One of the largest drainage basins in North America it drains water from the third of the USA.

  When flooded in 2011 around 25,000 people were evacuated and the property damage costs were estimated at $3 billion
• Hard engineering methods

  Dams

  The flow of the main tributary has been controlled by 100 dams
• Raised levees

  Levees were raised to 15m and strengthened to enclose the river channel for a stretch of 3000km
• Soft engineering methods

  Aforestation

  In the uppercourse trees have been planted in areas such as Tennessee valley to intercept some of the rainfall and stabilize the soil.
• Washlands

  In 2011, the more ganza spillway was opened to flood around 12,000 kilometers squared of farmland in louisnna deli Bartley preventing that water from reaching the city of New Orlando

  Cheep

  Lovely to look at
• Somerset levels 2014 2 of 2 case study
• Information

  The Somerset levels is a low laying region in the West of England as it has a naturally high water table and per drainage it is an area prone to flooding

  In winter 2013-14  saw it experience prolonged flooding which was described as the worst in over century
• Human causes

  The river tone + parrot had not been dredged properly in 20 years leaving farmland and homes without proper defences from the floods
• Physical causes

  The contamination of imperable bedrock (clay) and low interception levels means that the area is naturally at the risk of flooding

  High tides cause flood water to back up along the rivers across the levels + moores

  England received 207 mm of rainfall in January 2014
• Impacts on people

  P: replenishes drinking water supplies especially Wells

  N: spreads waterborne diseases such as chorla

  P: countries such as Bangladesh and Egypt rely on floods to help crops like rice grow

  N: crops grown on vertile floodplains can be washed away in a flash flood
• Impacts on the environment

  P: fish benefit as they can l breed in the standing flood water

  N: flooding can wash chemicals or sewage into the local rivers and so pollute them

  P: in dry areas flood spring relief from drought providing drinking water for wild animals.

  N: wild animals may join or lose their habitat during a flood
• HACA- Hydraulic action

  The power of the sea can physically wash away soft rocks like boulder clay. Under storm conditions with strong waves ,hundreds of tonnes of seawater can hit the coast also air can be trapped and small cracks within our cliff when I wave breaks against it this compressed air can widen the cracks, eventually leading to sections of cliff breaking away from the main cliff face.