Hydrological Characteristics (Cambridge (CIE) IGCSE Geography)

The Characteristics & Processes of Rivers

Water on Earth

• Only 2.5% of the water on Earth is freshwater

• 68.7% of freshwater is stored in glaciers and ice sheets and 30% is groundwater

• The remaining 1.3% of freshwater is in rivers, soil moisture, lakes and the atmosphere

• All water is part of the hydrological cycle

Hydrological cycle 

• The hydrological cycle is a closed system 

• Water is constantly recycled through the system

• Within the hydrological cycle, there are stores and transfers (flows)

Stores

• Stores are those places where water is held for some time. These include:

  • water in the atmosphere in the form of water vapour or water droplets in clouds

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

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

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

  • ice and snow

  • seas and oceans 

Flows (or transfers)

• Flows are how water is moved around the hydrological cycle. They include:

  • Evaporation

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

  • Condensation

    • When water cools and changes from water vapour into a liquid (water droplets), forming clouds

  • Transpiration

    • When plants release water vapour from their leaves 

  • Evapotranspiration

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

  • Precipitation

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

  • Overland flow

    • Any water flowing across the Earth's surface

  • Infiltration

    • When water moves down from the surface into the soil

  • Percolation

    • The transfer of water down into rocks and aquifers

  • Through flow

    • The movement of water through the soil between the groundwater store (water table) and the surface 

  • Groundwater flow

    • The flow of water through rock