Rivers

Rivers

1. Hydrological cycle

   • Inputs
     • Precipitation
   • Outputs
     • River runoff
     • Transpiration
     • Evaporation
   • Stores
     • Interception
     • Surface
     • Vegetation
     • Groundwater
     • Channel
     • Soil
   • Water balance
     • P=Q+E+/-change in storage
       • Where P = precipitation, Q = runoff, E = evaporation and transpiration
     • Water surplus occurs when precipitation > evapotranspiration. Occurs November to April.
   • Transfers
     • Throughfall/stemflow
     • Percolation
     • Infiltration
     • Throughflow
     • Surface runoff
     • Channel flow
     • Groundwater flow

2. Storm hydrograph

3. Long profile

   • Bradshaw Model

4. Processes

   • Hjurlstrom
   • Erosion
     • Attrition
     • Hydraulic action
     • Abrasion
     • Corrosion
   • Transportation
     • Solution
     • Suspension
     • Traction
     • Saltation
   • Deposition
   • Weathering
     • Chemical
     • Physical
     • Biological

5. Valley profiles

6. Channel characteristics

   • Capacity
     • Total load actually transported
   • Competance
     • Maximum size of a particle that a river can carry
   • Wetted Perimeter
   • Hydraulic radius
     • The efficiency of the river. Ratio between cross sectional area and wetted perimeter

7. Landforms from erosion

   • V-shaped valley
     • Interlocking spurs
   • Meanders and oxbow lakes
     • Slip off slope
     • River cliff
     • Lateral erosion
   • Pools and riffles
   • Waterfalls and gorges
   • Potholes

8. Landforms from deposition

   • Deltas
     • Birds foot, cuspate and arcuate
   • Braided rivers
   • Floodplain and levees
   • Alluvial fan
     • Apron, apex, fan

9. Rejuvenation

   • Causes
     • Sea level change
       • Eustatic
       • Isostatic rebound
   • Landforms
     • Incised meanders
     • Entrenched meanders
     • River terraces
     • Kninck points

10. Flooding

    • Causes
      • Sea level rise
      • Building on floodplains
      • Prolonged rainfall
      • Intense rainfall
      • Snow melt
      • Deforestation
    • Impacts
      • Social
        • Death
        • Displacement
        • Diseases - cholera
      • Economic
        • Compensation
        • Insurance
        • Loss of property, businesses
      • Environmental
        • Damages crops, but in long term alluvium increases fertility

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