Inputs

• The main input is precipitation, which can vary in a number of different ways. All these characteristics can have a significant effect on the drainage cycle.
• Form


  Rain, snow or hail. Clearly, with snow, entry of water into the drainage system will be delayed.
• Amount


  This will affect the amount of water in the drainage basin and the fluxes within it.
• Intensity


  The greater the intensity, the greater the likelihood of flooding.
• Seasonality


  This is likely to result in the drainage basin system operating at different flow levels at different times of the year.
• Distribution


  This is significant in very large drainage basins, such as the Nile and the Ganges, where tributaries start in different climate zones.