The Hydrological Cycle (Edexcel IGCSE Geography)

Characteristics of the hydrological cycle

• The hydrological cycle is a closed system 

• Water is constantly recycled through the system

• The hydrological cycle includes stores and transfers

Stores of the hydrological cycle

• Stores are those places where water is held for a period of time

• Stores of the hydrological cycle include:

  • the atmosphere where water is stored in the form of water vapour or as water droplets in clouds

  • surface stores such as puddles, lakes, rivers and reservoirs

  • aquifers which are permeable rocks such as limestone and sandstone which can hold water 

  • ice and snow

  • seas and oceans 

• Interception is how precipitation is prevented from reaching the ground, usually by being caught on leaves or branches

  • Some of the water will be stored on the leaves and evaporate into the atmosphere

  • The remaining water will flow down the leaves, branches and trunk until it reaches the ground (stemflow)

Transfers of water within the cycle

• Transfers are how water is moved around the hydrological cycle.

• Transfers include:

  • evaporation is the change of water from a liquid to a gas (water vapour) due to heat from the sun

    • This process transfers water from the surface up into the atmosphere

    • higher temperatures and strong winds lead to increased evaporation

  • condensation occurs when water cools and changes from water vapour into a liquid (water droplets)

    • Condensation leads to the formation of clouds

  • when plants release water vapour from their leaves this is known as transpiration

    • This process transfers water from the plants into the atmosphere

  • evapotranspiration is the combined transfer of water vapour from the Earth's surface and plants

  • precipitation is the transfer of water from the atmosphere to the Earth's surface in the form of hail, sleet, rain or snow

  • overland flow is any water flowing across the Earth's surface

  • when water is transferred from the surface into the soil, this is known as infiltration

  • percolation is the transfer of water from the soil into the rocks and aquifers

  • throughflow occurs when water is transferred through the soil between the surface and the water table

  • groundwater flow is the transfer of water through rocks

Advection

• The horizontal movement of water droplets and water vapour in the atmosphere is known as advection

• Advection is essential to move water around the atmosphere as air masses