20 terms

Factors affecting the water cycle over time

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Storm and rainfall event
An individual storm is defined as a rainfall period separated by dry intervals of at least 24 hours and an individual rainfall event is defined as a rainfall period separated by dry intervals of at least 4 hours.
Hurricane Matthew
An example of a storm event
Percolation
The downward movement of water within the rock under the soil surface
Run-off
All the water that enters a river channel and eventually flows out of the drainage basin.
Overland flow
The tendency of water to flow horizontally across land surfaces when rainfall has exceeded the infiltration capacity of the soil and all surface stores are full to overflowing
Interception storage
The precipitation that falls on the vegetation surfaces or human-made cover and is temporarily stored on these surfaces. Intercepted water can be either evaporated directly to the atmosphere, absorbed to the canopy surfaces or transmitted to the ground surface.
Pastoral farming and arable farming
Different types of farming practices
Water abstraction
The process of taking water from a source either permanently or temporary.
Examples of land use changes are
Ubanisation, deforestation, soil drainage, water abstraction and farming practices.
How can deforestation affect the water cycle
When forests are removed the new vegetation generally has fewer leaves and shallower roots. This means it uses less water than the forest it replaces.
What is soil drainage
Subsurface drainage removes excess water from the soil profile. It is usually carried out through a network of perforated tubes installed 60-120 cm below the soil surface.
Deforestation
The process of removing tree canopy, has a massive impact on interception, infiltration and overland flow
Water use
Reduces with deforestation as plants take in less water over time
Evapotranspiration
Is reduced after deforestation because the replacement vegetation has fewer leaves and roots, and is less dense
Overland flow and throughflow
Increase after deforestation because of the lack of vegetation
Soil drainage
Channels dug into fields to remove excess water from a soil profile and prevent water logging of a plant
Perforated tubes
are inserted 60 to 120cm under the surface to drain some fields
Water table lowers
Because of soil drainage
London Basin
An example of water abstraction from chalk aquifers
Irrigation
The artificial watering of plants by people, is the main cause of excessive water abstraction
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