Long profile

Long profile

1. diagram showing how a river’s gradient changes with distance down stream.

2. upper course

   • vertical erosion is dominate process. (bed is eroded greatly and banks are not)
   • Steep gradient which gradually flattens out as the river erodes to base level.
     • increases the river’s competence and capacity
       • main processes is erosion
     • overcome high friction
       • low hydraulic radius
   • Large amounts of gravitational potential energy
   • Transports large pieces of angular rock eg large boulders using traction because it doesn’t have enough kinetic energy
   • Rough nature of the upper course water, increase water turbulence

3. middle course

   • Less GPE, more kinetic
   • lateral erosion
     • corrosion is the main process
     • increases width but no change in dept
     • valley's side slope more gently
   • smaller size of load
     • transported in suspension and saltation
   • River can flood depositing particles onto its floodplain
     • Land either side of channels width has increased and become a flood plain

4. lower course

   • Competence and capacity are reduced
     • main process is depostion.
       • floodplain
         • very wide
       • mouth
   • low GPE
   • little lateral erosion
     • smoother channel
     • meanders
   • very small particles eg slits and clay
   • transported
     • suspension
     • erosion

5. distance inceases = gradient decrease as the shape of the river gets deeper and wider.