Assess the importance of natural variation and human impact on changes in the water cycle
over time [20 marks]
Natural variation and human impact both have significant effects on changes in the water
cycle over time. Seasonal flooding, land use change and water abstraction are all factors
that contribute to changes in the water cycle. However, as populations are growing and
availability of water and space is running out, it could be seen that humans are having a
greater impact on the water cycle than natural variation.
Land use change for deforestation is impacting the water cycle significantly over time. As the
population is growing, there is a higher demand for food, which requires more farmland as
more crops and animals are required. As a result, more land is needed and so deforestation
is occurring at a faster rate. Replacing trees with crops reduces interception and
evapotranspiration and increases infiltration. This creates a positive feedback cycle as there
is less water in the atmosphere available for precipitation, so less water is held in the
hydrosphere. However, man has tried to counter this by using afforestation to replace the
deforested areas and in turn increase interception and evapotranspiration. This means that
more water is held in the atmosphere and the biosphere so river flow increases. Therefore
human impact has a large impact on the water cycle over time, but this can be reduced
through afforestation.
Water abstraction is another method which impacts changes in the water cycle over time. As
populations increase, there is a greater need for water held in the lithosphere. This puts
increasing pressure on water sources over time and sometimes, when these sources are
depleted, we access underground stores for water for human use. For example, aquifers are
used, particularly during long dry periods. When the outputs of water in the aquifer become
greater than the inputs, then there is a decline in the global long-term water stores as the
river sources dry out and there is less water held in the hydrosphere. Irrigation is the main
cause of groundwater exploitation. In the US, the Ogallala aquifer is being depleted so
quickly that it cannot cope with the human demand for water. This aquifer is responsible for
30% of the irrigation in the US, therefore the water loss threatens the existence of towns. It
also supports 1/6 of global grain produce, therefore the effects of the streams and rivers
Voordelen van het kopen van samenvattingen bij Stuvia op een rij:
Verzekerd van kwaliteit door reviews
Stuvia-klanten hebben meer dan 700.000 samenvattingen beoordeeld. Zo weet je zeker dat je de beste documenten koopt!
Snel en makkelijk kopen
Je betaalt supersnel en eenmalig met iDeal, creditcard of Stuvia-tegoed voor de samenvatting. Zonder lidmaatschap.
Focus op de essentie
Samenvattingen worden geschreven voor en door anderen. Daarom zijn de samenvattingen altijd betrouwbaar en actueel. Zo kom je snel tot de kern!
Veelgestelde vragen
Wat krijg ik als ik dit document koop?
Je krijgt een PDF, die direct beschikbaar is na je aankoop. Het gekochte document is altijd, overal en oneindig toegankelijk via je profiel.
Tevredenheidsgarantie: hoe werkt dat?
Onze tevredenheidsgarantie zorgt ervoor dat je altijd een studiedocument vindt dat goed bij je past. Je vult een formulier in en onze klantenservice regelt de rest.
Van wie koop ik deze samenvatting?
Stuvia is een marktplaats, je koop dit document dus niet van ons, maar van verkoper Oliviams. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €4,93. Je zit daarna nergens aan vast.
