Changes to the water cycle

• Deforestation

  Less interception by trees, leading to soil compaction, so surface runoff increases.

  Reduces evapotranspiration.

  Increased river discharge and risk of localised flooding.

  Less vegetation means transpiration decreases.

  Soil not held together by roots, so soil water storage decreases.
• Seasonal changes

  Spring; more vegetation growth so more interception by vegetation.

  Summer; less precipitation. Increased rates of evaporation due to temperature increase.

  Autumn; Less vegetation growth so less interception. Seasonally more rainfall.

  Winter; Frozen ground becomes impermeable which encourages run off.
• urbanisation

  Roads and buildings with impermeable surfaces increase surface runoff and decreases infiltration. This reduces lag-time but increases flood risk.

  Green Roofs and Sustainable Urban Drainage Systems (SUDS) use grass and soil to reduce the amount of impermeable surfaces.
• Agriculture

  Irrigation (industrial movement of water by human intervention) leads to groundwater depletion.

  Pastoral farming leads soil compaction, reducing infiltration (and increasing surface runoff)

  Arable farming’s ploughing and mineral extraction leads to looser soil, which decreases surface runoff.