5. What is hydrological cycle?
• The movement of moisture and energy BETWEEN
air, land and sea.
• Oceans, rivers, clouds and rain – all contain water
in a frequent state of change.
• The circulation and conservation of water from
the land to the sky and back again
• An example of a system which a set of
components is linked
6. How does the hydrological cycle work?
• The components of the cycle are:
– Evaporation
– Transpiration
– Evapotranspiration
– Potential EVT
– Actual EVT
– Condensation
– Precipitation
– Percolation
– Groundwater
– Run-off
7.
8. Evaporation
• A process by which water
is converted from its liquid
form to gaseous form
• transferred from land and water masses to the
atmosphere.
• Evaporation from the oceans accounts for 80%
• 20% coming from inland water and plant surfaces.
9. Evaporation
• Wind speed: the higher
the wind speed, the
more evaporation
• Temperature: the higher
the temperature, the
more evaporation
• Humidity: the lower the
humidity, the more
evaporation
11. Evapotranspiration
The total loss
of moisture
from an area
by direct
evaporation
and
transpiration
12. Evapotranspiration (EVT)
Potential EVT Actual EVT
• The amount of water • Is what
that could be lost by actually
evapotranspiration. occurs.
• For example, it is • In the UK
there is more
potentially high EVT water
in deserts, but the available for
amount that can take evapo-
place is limited due transpiration
to the minimal than takes
moisture available. place
13. CONDENSATION
A process of the change of
water vapour into water
–Transported water vapour
and forms tiny droplets in
clouds
14. Precipitation
• The deposition of moisture
from the atmosphere on the
earth’s surface
• The most important input into
the system forms includes
snow, hail, rain, and fog.
15. Percolation
• The process by which the
rain water soaks through
the soil into the rocks
• Water moves downward
• Infiltrates through soil
until reaches water table
• Water in the soil does not remain there but moves down slowly
into the lower layers of soil and rock.
• It creates groundwater storage found in rocks and this may
later be moved sideways through the rock via groundwater
flow.
16. Groundwater
• The place where water is stored
underground in the rock
• Some of the groundwater is
trapped between rock or clay
layers
• Water that infiltrates the soil
flow downward until it
encounters impermeable rock
then travels laterally
• The location where water
moves laterally is known as
‘aquifers’
21. At a global scale, the hydrological cycle is a closed system
• Water is circulated continuously fuelled by energy
from the sun
• No effective gains or loses
• Fixed amount of water
22. Exercise
1. Define hydrological cycle. (2)
2. Draw a well-labelled with brief explanation of the
following on the diagram:
a. Evaporation
b. Transpiration
c. Condensation
d. Precipitation
e. Percolation
f. Groundwater
g. Run-off (18)
3. Explain why hydrological cycle is a closed system. (5)
