Transcript Hydrological Cyle - Jordanhill School

Hydrosphere
Lesson starter:
What do we mean by
Hydrosphere?
Title: Hydrosphere
• 21/07/2015
• Aims:
• To find out the relationship water has with the planet
Earth.
• To look at the Hydrological cycle and understand
how it works.
• To find out how river drainage basins effect flooding
and river flow.
• To look at the different features of rivers from their
source to their mouth.
Water on planet Earth
•Why do you think
that the study of
the Hydrosphere is
important to us?
Water on planet Earth
This all means
that studying the
• It is a vital resource that we take for granted in
Hydrosphere
is
countries
such as the UK.
more
important
• It is estimated that there will be vast water
shortages
around
world before 2050 and that it
now that
itthe
ever
will lead to tension between countries.
has been.
• Water is extremely important to us!
• Many people believe that this could lead to future
wars, much like the oil wars of the late 1990’s.
• We are also at constant risk of flooding and water
levels rising over the planet.
So where is all of our water
• Take the sub heading:
• Location of the Earth’s water.
• Underneath try and write a list of
where you think all of the Earth’s
water can be found.
• 4 minutes.
The
Hydrological Cycle
Task: The Hydrological cycle
• You have been given a piece of
poster paper in front of you. In your
group I want you to explain the
Hydrological cycle.
• Try your best – I don’t expect you to
be an expert yet. You may use
diagrams.
Part 2
• You have now been given a diagram
that has no labels on it.
• You must now try and annotate on
the labels that you think should go
onto the diagram.
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Hydrological Cycle (Closed
System)
Percolation
Hydrological Cycle (Closed
System)
Percolation
Hydrological Cycle (Closed
System)
In your groups write a detailed description of the hydrological cycle
and how it works. You should structure it like an exam style question
worth 5 marks.
The global hydrological
cycle is a closed system.
What does this mean?
Copy
A closed system means that nothing is ever
added or taken away. The amount of water in
the system stays the same but it is just
transferred and stored in different ways at
different times.
• https://www.youtube.com/wa
tch?v=al-do-HGuIk
The Hydrological cycle
• Heat from the sun results in evaporation of
water from the oceans
• Moist air is blown inland; advection
• Condenses further as it rises over
mountains
• Precipitation falls
• Rainwater returns to the sea/oceans via
rivers and streams ; or overland flow
The Hydrological cycle
• Some precipitation falls as snow. Snow and ice stored in
glaciers, so slow down the rate of return of moisture
• Water can infiltrate the soil and moves slowly down the
slope; as throughflow
• Or percolating into the rock stored as groundwater store
• Vegetation take up water and through photosynthesis
release water for evaporation as transpiration. Also
known as evapotranspiration.
• Process starts again when water returns back to the
ocean
• Closed system; no water is lost or gained through the
process
• http://earthguide.ucsd.edu/earthguide/diagrams/wat
ercycle/
Hydrological cycle lesson 2
Drainage Basins
• 21/07/2015
• Aims:
• To find out what we mean by drainage basins.
• To look at the hydrological cycle of a drainage basin.
Answer the following questions:
1) What are labels 1-9?
2) Is the hydrological cycle a
closed or open cycle?
Lesson starter:
Answer the following questions:
3)
Describe the global
hydrological cycle.
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3
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What is a drainage basin?
• A drainage
basin is an
area of land
drained by a
river and its
tributaries
(river system).
Drainage Basins:
A drainage basin is the catchment area of a river and
its tributaries.
The boundary of the catchment area is called the
watershed.
Drainage basins involve water being returned to the
oceans as part of the global hydrological cycle.
What is important in drainage basins is not the size of
the basin but how much water flows through it.
Watersheds
•http://techalive.mtu.edu
/meec/module01/whatis
watershed.htm
Diagram of drainage basin.
The hydrological cycle of a
drainage basin.
•An OPEN system
means that it has
INPUTS and
OUTPUTS.
Soil Infiltration
Precipitation
Soil Moisture Storage
•Out of the boxes
here which ones are
inputs, outputs and
processes (storage
or movement)?
Rivers flowing into the
sea
Groundwater
Overland Flow
Interception
Percolation
Throughflow
Surface Storage
Evaporation
INPUTS
TRANSFERS
OUTPUTS
Precipitation
Interception
Evaporation
Surface Storage
Rivers flowing
into the sea
Soil Infiltration
Soil Moisture
Storage
Percolation
Groundwater
Overland Flow
Throughflow
The Drainage Basin is an OPEN system
An OPEN system means that it has INPUTS and
OUTPUTS.
• http://www.bbc.co.uk/learnin
gzone/clips/thehydrological-cycle/406.html
Past paper question:
• “A drainage basin is an open system with
four elements—inputs, storage, transfers
and outputs.”
• Describe the movement of water within a
drainage basin with reference to the four
elements above.
• 7 marks
Inputs
The main input to the system is precipitation. The type of precipitation
(rain or snow, etc), the intensity, the duration and frequency all have
an effect on the amount of water in the system. Each subsystem of the
drainage basin system will also have inputs and ouputs, and the
output from one stage of the diagram will form the input for another.
Storage
Water is stored in a drainage basin on the surface in lakes and
channels or underground in the groundwater store. Water reaches the
groundwater store via the processes of infiltration and percolation.
During these processes, some water will be stored in the soil and
rock. The amount of water stored will vary depending on the porosity
of the soil and on the permeability of the rock. Water can also be
temporarily stored via interception. This refers to the storage of water
on leaf and plant stems. Dense foliage may result in little water
reaching the ground, since it often evaporates from the leaves.
Transfer
The sum of all the water flowing over the drainage basin’s surface is
called runoff. It is made up of streamflow, which is flow through
permanent river channels and overland flow or surface runoff.
Overland flow transfers water through the basin either as sheetwash,
across the surface, or in tiny channels called rills. Beneath the
surface, water is transferred via throughflow, which is the movement
of water through the lower soil towards rivers, and groundwater flow.
Groundwater flow is typically very slow. Water that has been
intercepted by foliage may also be transferred, either directly as
throughfall, or by running down branches and stems via stemflow.
Outputs
The final release of the water in a drainage basin is known as its
output. Typically, rivers flowing into the sea will be the main output of
a drainage basin. Some water will also be lost via evapotranspiration.
This process refers to direct evaporation, and also to the extend that
moisture lost from leaves will result in plants withdrawing water from
the soil via their roots.
Factors affecting a
drainage basin output
• What factors do you think affect the
output/discharge of a river basin?
(What factors make the water flow
out faster or slower)
• Can anyone think of an answer?
• Take 2 minutes to discuss and come
up with ideas.
Factors affecting a
drainage basin output
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Interception
Relief
Soil
Rock type
Rock type
Drainage density
Other use of the river
Land use
• Now that you know some of the factors discuss how
you think each one could affect output.
Interception
• Water can be intercepted in many different ways and this
can greatly affect the river basin discharge.
• More trees and vegetation means that discharge will be
decreased as water is stopped and stored.
Relief
• How steep is the land? If it is very steep then water will
run through the basin quickly and it will have a greater
discharge. If it is flat then the opposite will happen as the
water will flow gently, reducing discharge.
Soil
• If the soil is very thin in an area then there will be less
infiltration (percolation) and therefore groundwater flow
and through flow will happen more quickly leading to a
greater discharge. If the soil is thick and takes up a lot of
water then this will mean that the discharge is less as it
is stored in the soil.
Rock type
• If the rock type is impermeable (water can’t
get through it – granite for example), then
you will get far more surface run off. This
increase the speed of water discharge.
• If the rock is permeable – chalk for example
then you will get more through flow and
groundwater flow, reducing the speed of
water discharge.
Drainage density
• The higher the drainage density the greater
the discharge.
• The more streams that you have the greater
the drainage density will be.
• (Drainage density is the total length of all the
streams and rivers in a drainage basin
divided by the total area of the drainage
basin.)
Drainage density
• (Drainage density is the total length of all the
streams and rivers in a drainage basin
divided by the total area of the drainage
basin.)
Other use of the river
• If the river is not used for other reasons (by
humans) then output is generally increased.
• If the river is used for industry, HEP,
reservoirs, irrigation or domestic use – all of
these will decrease discharge.
Land use
• If it is urban then there will be an increase of
tarmac (impermeable layer) and drains
which increase runoff.
• Urban also means less trees and forestry–
this will mean less trees for interception and
exposed soil, increasing output speed.
Land use
• Rural areas mean less tarmac,
drains and concrete.
• Trees and crops mean more
interception decreasing output.
• Lot of vegetation
• Urban area
• Rural area
• HEP station
• Thick soil
• Impermeable rock
Lesson plenary
• Think, pair, share:
• Working in 2’s you will answer the following questions
and be ready to feed back.
Q1) Is the hydrological cycle of a drainage basin a
closed or open system?
Q2) In what ways is water stored in a drainage basin.
Q3) What factors affect the output of a drainage basis?
• Extension work below:
Task 1:
Using your New Higher Geography textbook, page 12.
Answer question (a), (b), (c) and (d) in Activity 2.
You have 30 minutes to do this
Task 2
With the aid of an diagram, describe the
movement of water within the drainage
basin system.
You have 15 minutes to answer this question