The The Hydrological Hydrological

CycleCycle

Higher GeographyHigher Geography

The HydrosphereThe Hydrosphere

The Hydrological CycleThe Hydrological Cycle

What you need to know:What you need to know: Be able to draw a diagram of the Be able to draw a diagram of the

hydrological cycle.hydrological cycle. Describe its main elements.Describe its main elements. Explain how balance is maintained Explain how balance is maintained

within the system.within the system.

What is the Hydrological What is the Hydrological Cycle?Cycle?

The hydrological cycle is the system which describes

the distribution and movement of water between the

earth and its atmosphere. The model involves the continual circulation of water between the oceans,

the atmosphere, vegetation and land.http://www.metoffice.gov.uk/education/teachers/key-stage3/lessonplan-hydrological-

cycle/animation

The Hydrological cycleThe Hydrological cycle

Describing the Cycle:Describing the Cycle:

EvaporationEvaporation

Solar energy Solar energy powers the cycle. powers the cycle. Heat energy from Heat energy from the sun causes the sun causes evaporationevaporation from from water surfaces water surfaces (rivers, lakes and (rivers, lakes and oceans) and….oceans) and….

… … transpirationtranspiration from from plantsplants. . Transpiration Transpiration is essentially is essentially evaporation of water evaporation of water from plant leaves.from plant leaves.

EvapotranspirationEvapotranspiration – – water loss to the water loss to the atmosphere from atmosphere from plants and water plants and water surfaces.surfaces.

CondensationCondensation

The warm, moist The warm, moist air (containing air (containing waterwater vapourvapour) ) rises and, as it rises and, as it cools, cools, condensationcondensation takes place to form takes place to form cloudsclouds..

AdvectionAdvection

Wind energy may Wind energy may move clouds over move clouds over land surfaces land surfaces where …where …

PrecipitationPrecipitation

……precipitationprecipitation occurs, either as occurs, either as rain or snow rain or snow depending on depending on altitude.altitude.

StemflowStemflow (red (red arrows) – arrows) – Precipitation flows Precipitation flows down stems and down stems and branches to groundbranches to ground

ThroughflowThroughflow (yellow) Rate at (yellow) Rate at which precipitation which precipitation flows through flows through branchesbranches

Run off / Overland flowRun off / Overland flow

The rainwater The rainwater flows, either over flows, either over the ground (the ground (run run offoff) into rivers ) into rivers and back to the and back to the ocean, or…ocean, or…

Groundwater flowGroundwater flow

… … infiltrates infiltrates downwards downwards through the soil through the soil and rocks where it and rocks where it is returned to the is returned to the oceans through oceans through groundwatergroundwater flow.flow.

Groundwater flowGroundwater flow

Hydrological Cycle BingoHydrological Cycle Bingo

Also called the hydrological cycle

Split your page into 8 squares and write one word from the list below in the each square

Condensation Ground Water Infiltration

Evaporation Precipitation Percolation

Run off Evapotranspiration Interception

Saturation The Hydrological Cycle The water table

The water cycle balanceThe water cycle balance Usually the water cycle is in balance, and Usually the water cycle is in balance, and

the amount of the amount of precipitationprecipitation falling will falling will slowly soak into the ground and eventually slowly soak into the ground and eventually reach the rivers.reach the rivers.

However, if rain falls for a long period of However, if rain falls for a long period of time or if the ground is already soaked or time or if the ground is already soaked or saturated with water then the chance of saturated with water then the chance of flooding is increased.flooding is increased.

Under the groundUnder the ground

A closed systemA closed system The hydrological cycle is a good example of a The hydrological cycle is a good example of a

closed system: the total amount of water is the closed system: the total amount of water is the same, with virtually no water added to or lost from same, with virtually no water added to or lost from the cycle.the cycle.

Water just moves from one storage type to Water just moves from one storage type to another. another.

Water evaporating from the oceans is balanced by Water evaporating from the oceans is balanced by water being returned through precipitation and water being returned through precipitation and surface run off.surface run off.

Your TurnYour Turn

Write down the meaning of the following Write down the meaning of the following words:words:

InfiltrateInfiltrate Groundwater flowGroundwater flow Surface runoffSurface runoff EvapotranspirationEvapotranspiration Closed systemClosed system

Use the New Higher Geography Textbook p.10 to help you.

Then complete Activity 1 (a) – (c)

Human Inputs to the CycleHuman Inputs to the Cycle

Although this is a closed system there is a Although this is a closed system there is a natural balance maintained between the natural balance maintained between the exchange of water within the systemexchange of water within the system

Human activities have the potential to Human activities have the potential to lead to changes in this balance which will lead to changes in this balance which will have knock on impacts. have knock on impacts.

For example as the earth warms due to For example as the earth warms due to global warming the rate of exchange in global warming the rate of exchange in the cycle (between land and sea and the cycle (between land and sea and atmosphere) is expected to increase. atmosphere) is expected to increase.

Human InputsHuman Inputs Some aspects of the hydrologic cycle can Some aspects of the hydrologic cycle can

be utilized by humans for a direct be utilized by humans for a direct economic benefiteconomic benefit

Example: generation of electricity Example: generation of electricity (hydroelectric power stations and (hydroelectric power stations and reservoirs) reservoirs)

These are effectively huge artificial lakes These are effectively huge artificial lakes and this will disrupt river hydrology and this will disrupt river hydrology (amount of water in a river)(amount of water in a river)

Other Human ActivitiesOther Human Activities

Paving, compacting soils, and altering the Paving, compacting soils, and altering the nature of the vegetation (including nature of the vegetation (including deforestation)deforestation)

The mining of ground water for use in The mining of ground water for use in agriculture and industryagriculture and industry

Large amounts of water vapour released Large amounts of water vapour released into the atmosphere from industrial into the atmosphere from industrial activityactivity

Large changes in vegetation by wildfire, Large changes in vegetation by wildfire, logging, clearance for agriculturelogging, clearance for agriculture

Impacts Impacts

These human activities can lead to These human activities can lead to increase chances of flooding increase chances of flooding

Increases in soil erosionIncreases in soil erosion A cooling effect on the north west of A cooling effect on the north west of

Europe (climate change)Europe (climate change) Possible higher precipitation levels in Possible higher precipitation levels in

the Arctic but less in the Tropicsthe Arctic but less in the Tropics