1. Hydrology
and
Fluvial
Geomorphology
HYDROLOGICAL CYCLE

2. Condensation

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

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

10. Transpiration
A process by
which plants
lose water
vapour into the
air through
their leaves or
stems

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’

19. Run-off
•the water that returns
to the land which
flows downhill or on
the surface of earth

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)