River Processes

Nota:

• river processes

1. flooding

   Nota:

   • Looking at the diiference between MEDC's and LEDC's
   1. Boscastle
      1. 2004 aug
      2. 60mm of rain in 2 hours
      3. impermeable surfaces
      4. 23 sq km of land flooded
         1. evacuations
      5. 100 buildings damages
         1. rebuilt
      6. water pollution
         1. littering
      7. £4.6 million spent on flood defences
   2. Bangladesh
      1. 80% of land is on a flood plain
         1. 70% of land is only 1 meter above sea level
      2. 7 million houses destroyed
         1. 25 million homeless
      3. farm land destroyed
      4. aid given
         1. £2 million given by UK
      5. 1000 dead
      6. 8th July 2004
   3. flood prevention
      1. soft
         1. planting trees
      2. hard
         1. e.g. dams
   4. causes
      1. impermeable surfaces
      2. lots of rain
2. Transport
   1. saltation
      1. small particles bounce along the surface
   2. suspenion
      1. very small particles flout about
   3. solution
      1. particles dissolve in water
   4. traction
      1. larger particles roll
3. Erosion
   1. solvent action
      1. dissolves soluble metirals
   2. hydraulic action
      1. breaking down of rocks
   3. attrition
      1. when the load hits against each over
   4. abrasion
      1. When rocks hit against the bank taking out chunks
4. Courses of the river
   1. upper
      1. vertical erosion, v-shaped valley
   2. middle
      1. lateral erosoin
   3. Lower
      1. Wide, fast flowing, little erosoin
5. Meanders
   1. fast flow on the outside
      1. erosion on the outside
      2. deposition on the inside
   2. OX- bow lakes
      1. Erosion on the outside
         1. forms a cliff on the outside
      2. forms a horse shoe shape
7. Resevior
   1. stores water where there is a surples
      1. Provides water in the areas of deficit
   2. Kielder water
      1. Holds 200 billion litres of water
         1. took 2 years to fill
         2. only 10% of water is ever used
      2. Took 6 years to build opened in 1981
      3. Feed by river North Tyne
      4. Hydroelectric power plant
      5. Cost £161million
      6. Deforistion
8. waterfalls and gorges
   1. Waterfall
      1. water runs along hard rock then erodes down the soft rock
   2. goarges
      1. 1. this happens because of hydraulic action
      2. the hard rock is undermined and then it collapses is repeated over and over to form a steep sided valley
9. Storm hydrograph
   1. Shows the lag between rain fall and flooding
      1. gap between peak rain fall and peak discharge
   2. fators
      1. impermeable
         1. short lag time
      2. permable
         1. longer lag time
10. glossary
    1. precipitation- water falling from clouds like rain and snow
    2. interception- water that does not reach the ground
    3. transpiration- water lost from the surface of the plant to the atmosphere
    4. evapotranspiration- covers both evaporation and transportation
    5. percolation- the moment of water through a body of water
    6. infiltration- water enters the ground
    7. through flow- movement of water through soil
    8. confluence- the place where 2 rivers meet
    9. watershed- the boundary the flood plane