The Global Hydrological Cycle

1. The Global Hydrological Cycle Draw and describe the Global Hydrological Cycle. Explain how a balance is maintained within the Global Hydrological Cycle.

2. Water as a finite resources • 1.4 billion cubic kilometres of water within the planets hydrosphere. • 3% is freshwater. • 77.2% of this is in cold storage. • 22.4% is in groundwater storage. • 0.35% in lakes and swamps. • 0.01% in rivers and streams.

3. Uneven distribution of water • A small amount available for human use and consumption. • Usually in the wrong place and the wrong time. • From earliest times people have sought to harness and control the rivers.

6. Hydrological Cycle • Evaporation: The transfer of water from the sea to the air as water vapour. • Condensation: Water vapour (gas) changes back into water (liquid). It forms • small droplets which are visible as clouds. • Precipitation: Water falls to earth as either liquid (rain) or in a frozen state • (snow, hail). • Stream / Surface Run Off: Most water returns to the sea in the form of • rivers. • Evapotranspiration: evaporation of moisture from vegetation • Ground water Flow: Some water returns to the sea as groundwater through soil • and rocks. • Infiltration: The point at which rainfall seeps into soil. • Percolation: The seepage of water downwards through rocks. • Throughflow: The movement of water downwards through soil back to the sea. • Groundwater Zone: Storage area for water which is slowly released back to the sea via springs and rivers. • Interception – When precipitation is prevented from falling to the surface by leaves/dense forests.