Rivers

Rivers

The water cycle and drainage basin
1. evaporation
  1. condensation
    1. precipitation
      1. infiltration
        when water filter though the ground and the tiny pores in the soil
      2. transpiration
        water evaporated from leaves
      3. throughflow
        rainfall/water flow through soil
      4. percolation
        water moves downwards through soil into saturated rocks
      5. surface storage
        precipitation retained on the ground surface
      6. groundwater flow
        deep movement of water through underlying rock
      7. soil moisture
        water is stored in soil
river processes
1. erosion
  1. the wearing away of the river bed and banks or the loads
  2. HYDRAULIC ACTION
    1. high velocity water pushes air into cracks on the banks
  3. ATTRITION
    1. loads bumping into each other and breaks
  4. ABRATION
    1. loads that are thrown against bed and banks causing them to be worn away
  5. SOLUTION
    1. acid and alkali dissolve the bed & banks
2. transportation
  1. SUSPENSION
    1. particles supended in the river carried by its flow
  2. SALTATION
    1. pebbles are bounced along the river bed
  3. SOLUTION
    1. dissolved materials
  4. TRACTION
    1. big boulders bouncing along the bed
  5. the movement of the load down the river
3. deposition
  1. the laying down of a river's loads as its velocity decreases
  2. factors
    1. less water
    2. increasing amount of loads
    3. shallow
    4. recah its mouth
  3. drop its biggest load first
river landscapes
1. drainage basin
  1. source
    1. the start of a river
  2. tributary
    1. a small stream that joins a large river
  3. confluence
    1. where a tributary joins a large river
  4. an area of land drained by a river and its tributaries
  5. watershed
    1. the edge of a river basin
  6. mouth
    1. the end where a river joins the sea
2. long profile
  1. UPPER COURSE
    1. v-shape valley
    2. narrow
    3. shallow
    4. waterfall/gorges
      1. river flows over the hard resistant rock
        erodes the less resistant soft rock quickly
        abration and hydraulic action undercuts the hard rock leaving an overhung and a plunge pool
        overhang collapses
        repeated collapsing
        steep sided gorge
    5. interlocking spurs
      1. the river wind around the spurs because it's near its source and is not powerful enough to cut through the spurs so it has to flow around them
  2. MIDDLE COURSE
    1. gentle sloping valley
    2. wider/deeper
    3. meanders
      1. faster flow on the outside bend, slower flow on the inside bend
        faster flow : more energy and erosion, forming a river cliff
        slower flow : less energy and deposition forming slipp-off slopes
        over time erosion on the outside and deposition on the inside makes the neck becomes narrower
        swan's neck meander
        swan's neck part of the meander becomes filled with sediments, creates a straight path for the river
        ox-bow lake
    4. river cliff
    5. slip off slope
  3. LOWER COURSE
    1. floodplain
      1. migrating meanders erode the sides of the valley
        wide
      2. migrating meanders leaves deposite of sand and clay
        flat
    2. levees
      1. river breaks its banks
        deposit biggest loads firstalong the side of the river channel creating a levee
    3. estuary
      1. where river meets the sea
        salt and fresh water mixes
      2. high tide
        incoming water stops the river flow
        deposites fine silts + sand that were in suspension
        making mud flats
flooding
1. PHYSICAL FACTORS
  1. precipitation
  2. geology
  3. steep slopes
2. HUMAN FACTORS
  1. urbanisation
  2. deforestation
  3. agriculture
3. HYDROGRAPHS
  1. peak rainfall
    1. highest amount of rainfall
  2. rising limb
    1. how quickly discharge rises
  3. peak discharge
    1. highest recorded discharge
  4. lag time
    1. time difference between peak rainfall & discharge
  5. falling limb
    1. reduced discharge once run-off has passed
  6. base flow
    1. normal flow of a river
  7. bankfull discharge
    1. horizontal line : level of dischargeabove which flooding will occur
4. BANBURY FLOODS
  1. impact of 1998 flood
    1. closure of railway station
    2. 12,500,000 pound worth of damage
    3. closure of shops and businesses, homes damaged
  2. FLOW CONTROL STRUCTURE
    1. low flow
      1. the weir control the flow
    2. medium flow
      1. upstream baffle controls the flow
    3. high flow
      1. downstream baffle controls the flow
  3. EARTH EMBANKMENT
    1. the borrow area
      1. resevoir
      2. hardwick & huscote
      3. embankment
        storage area
5. FLOOD MANAGEMENTS
  1. FLOOD RELIEF CHANNEL
    1. man made river channel
  2. FLOOD WARNINGS
  3. FLOODPLAIN ZONING
    1. land use restrictions on the floodplain

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