hydrographic

• examples of stores in global hydrological cycle:

  • oceans
  • lakes
  • aquifers
  • cryosphere
• river discharge is measured in cumecs
• river discharge is the volume of water flowing in a river
• peak discharge - maximum discharge in a period of time
• peak rainfall - max rainfall in the period of time
• lag time - interval between peak rainfall and discharge
• rising limb - when discharge is rising
• falling limb - when the discharge is falling
• the larger the catchment area of the river basin , the higher the peak discharge but the longer the lag time
• more circular the catchment area shape is in the river basin , the shorted the lag time
• what rock type lengths the lag time and reduce the peak discharge?

  rock and soil is permeable i.e limestone - precipitation will be able to infiltrate
• what happens if soil is fully saturated?

  no infiltration , leading to increase surface runoff , increasing the peak discharge
• ploughing of agriculture land will decrease...?

  surface runoff , causes lag time to increase and peak discharge to decrease
• areas that remain forested will see reduced peak discharge due to an increase in infiltration and interception of rain by vegetation
• urbanisation leads to an increase in number of impermeable surfaces
• impermeable surfaces lead to an decrease in infilitration , an increase in surface runoff and ultimately a reduction in the lag time

  • shorter lag time means a greater peak discharge