Geography Reference
In-Depth Information
SUMMARY
• Naturalwaterpathways,climate,vegetationcover,soiltype,
topography and management of the landscape influences how
the chemistry of precipitation is modified as it moves through
the landscape into rivers, lakes and deep groundwater.
• Thepathwaysthatwatertakesthroughandoversoilsandrocks
influence the response of river flow to precipitation events.
• Overlandlowproductionbyiniltrationandsaturation-excess
mechanisms generally results in shorter lag times and higher dis-
charge peaks in the river than in deep throughflow and ground-
water dominated systems. However, the exact outcome can
depend on soil and bedrock type, topography, vegetation cover
and climatic conditions.
• Floodinganddroughtsusceptibilityhavebeenheavilymodiied
by human action causing changes in water flowpaths, water
storage and therefore in river flow.
• Coastalareasaredominatedbywaveandtidalprocessesthat
drive weathering and sediment movement.
• Coastallandformscanbecharacterisedbywave-dominatedfea-
tures such as beaches, tide-dominated features such as estuaries
and river-dominated features such as deltas.
• Coastalmanagementmustincorporateunderstandingofweath-
ering and sediment transport processes because it is a tightly bal-
anced system. Stopping natural sediment movements in one
location on the coast may cause additional erosion and major
coastal problems a little further along the coastline.
• Icesheetsandglacierserodedramaticnewlandformssuchas
U-shaped valleys, horns and arêtes. They also create deposits
that form other more subdued landforms such as moraines, stoss-
and-lee forms and drumlin fields. These features can be seen in
areas that are no longer glaciated but provide evidence of former
colder climates.
• Permafrostisfrozengroundwhichcovers25percentofthe
Earth's land surface.
• Anactivelayerofmeltnearthesurfaceoperatesinthesummerin
permafrost areas meaning that the ground periodically subsides.
• Buildingsandinfrastructurehavetobecarefullydesignedinperma-
frost areas to cope with seasonal melt of the upper active soil layer
