Water (rivers)

Processes that are associated with rivers
1. Erosion
  1. Abrasion
    1. Rocks Act like sand paper against the banks and cliffs
  2. Hydraulic action
    1. The pure power of the water pushes into cracks
  3. Corrosion (solution)
    1. Acidic water dissolves rock/mineral
  4. Attrition
    1. Rocks that are being carried bang into each other making themselves smaller rocks
2. Transportation
  1. Traction
    1. Large rocks and boulders rolled along the river bed
  2. Saltation
    1. Pebbles bounce along the river bed
  3. Suspension
    1. Sand and clay sized particles are carried,suspended in the water
  4. Solution
    1. Dissolved particles carried in the water
  5. The movement of material carried by the river
3. Deposition
  1. When the river loses energy it drops the material it is carrying. it drops the heaviest material first and the lighter material last
Rivers
1. Upper coarse
  1. V-shaped valleys, interlocking spurs, waterfalls, gorges
2. Middle coarse
  1. Meanders and OX bow lakes
3. Lower course
  1. Floodplains and levees
4. Formations
  1. This is how a waterfall forms
  2. eanders and OX bow lakes
5. Drainage basin
  1. An area of land drained by a river and all of its tributaries
  2. Factor that can increase or decrease flooding
    1. Increase
      1. Steep slopes(means that water travels faster towards the river increase the likelyhood of flooding
      2. Lack of vegetation/deforestation( there is less trees to intercept the rainfall meaning more of the water enters the river)
      3. Impermeable bedrock( water can'nt infiltrate into the ground and so more flows over the surface)
      4. Building on the floodplain
        More impermeable concrete surfaces
      5. Saturated ground
      6. Size of a drainage basin
    2. Drainage basin
      1. Watershed ( the area of high land forming the boundary and edge of a river basin
      2. Source( where a river begins)
      3. Mouth (where a river meets the sea)
      4. Confluence( the point at which two rivers meet)
      5. Tributary ( a small river or stream that joins a larger river)
      6. Channel ( this is where the river flows)
      7. Drainage basin ( this is the area of land drained by a river and its tributaries
6. storm hydrograph
  1. Shows a rivers response to a particular rainfall event, it shows how quickly the water gets into the river. the quicker the water reaches the river the more likely there is to be a flood event
CASE STUDY
1. Niagara falls
  1. People have utilised the waterfall to make a profit from tourism i.e. Hotels,Restaurants,Museums,information centres,Boat rides and Helicopter rides which take full advantage of the tourism)
    1. ADVAN(creates jobs and improves the economy)
    2. DISADVAN( are that the falls become overcrowded, the tourist attractions can make it look like a theme park and the tourists can have an environmental impact though erosion,pollution and litter)
2. Boscastle
  1. Contributers to the flooding in boscastle
    1. Human factors
      1. Village developed on flat land of floodplain
      2. Natural channel of river has been walled preventing it from adjusting to variations in discharge
    2. Natural factors
      1. Narrow valley with interlocking spurs
      2. 185mm of rainfall in 5 hours
      3. Steep valley sides that encourage rapid runoff
      4. The village as it is at the confluence of 2 rivers
  2. Monday 16th August 2004
  3. 60mm of rainfall fell in 2 hours
  4. The ground was saturated due to weeks of above average rainfall
  5. Effects
    1. Short term
      1. People are homeless and have no access to money within a week of the flood
      2. Damage caused by river to cars and people other belongings, also includes their homes
    2. long term
      1. The pain and anguish of the flood in 2004 may still effect people who lost their homes or treasured percessions
      2. Fear of more freak floods
      3. Financial difficulties, as it will take a long time for the insurance companies to pay for the damage caused
      4. Tourism actually increased in the long term
Hard and soft engineering
1. Hard
  1. Artificially trying to alter and control the course of a river
  2. Usually more expensive
  3. Not always environmentally friendly
  4. Less aesthetic
  5. Can be very effective
  6. Can cause unforeseen problems further down stream
  7. Building a DAM to control and regulate water flow
  8. Building LEVEES to provide protection against flooding
  9. STRAIGHTENING the river channel to avoid settlement or speed up the flow of water through an area
  10. WIDENING AND DEEPENING the river channel to increase the amount of water the river can hold
2. Soft
  1. using the natural features of a river to try and control flooding
  2. Usually cheaper
  3. More environmentally friendly
  4. Can be less effective
  5. AFFORESTATION planting trees to increase the amount of interception and reduce the amount of water entering the river
  6. PLANNING LAWS the local authority can introduce policies to stop developments being built on the floodplain
  7. MANAGED FLOODING the river is allowed to flood naturally in some places to prevent it flooding in populated areas
  8. EARLY WARNING SYSTEMS floodline and flood plans have been set up by the environment agency to prepare residents in flood prone areas
Future foolding in the uk
1. No. people at high risk of flooding will rise from 1.5 million to 3.5 million
2. Cost of flood damage will rise from £1billion a year to £27 billion a year
3. Climate change is one of the main cause of the extra flood risk
4. 10% of UK homes are on floodplains as new homes need to be built this could increase
5. What should be done to reduce this
  1. Householders encouraged not to pave over gardens, this creates more permeable surfaces in towns and cities
  2. Block drainage in upland mountain areas and develop more peat bogs to store water. this stores water in the mountains meaning less reaches the river
  3. Make homes more flood proff by putting plug sockets higher up walls etc
  4. Restrict building on floodplains
  5. Invest in flood defence schemes but be weary of hard engineering that can cause further problems downstream

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Water (rivers)

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