The river EXE + water cycle Flashcards
(28 cards)
Natural factors change the water cycle over time;
-Natural variation
-Storm events
-seasonal changes
Human factors change the water cycle over time;
-farming
-land use change
-water abstraction
How do storms and precipitation affect the water cycle
-Intense storms generate more precipitation and higher peak discharges than light rain showers
-This larger input of water causes flows to increase in size
-Some flows (such as infiltration) may not be able to occur rapidly enough, increasing the runoff
How might seasonal changes affect the water cycle:
-Variation of inputs, flows, and stores in the water cycle varies with the season, e.g. winter in the UK
-During the winter, temperatures drop to below 0 °C, causing water to freeze- this can decrease flows, while the store of frozen water increases- when temperature increases again, flows can be much heavier than usual
Most plants show seasonal…
Variations- vegetation slows precipitation as it intercepts its movement to the river channel- interception is highest when there is plenty of vegetation, and deciduous trees have their leaves
The more vegetation in a drainage system, the more water is lost through…
Evapotranspiration (before it reaches the river channel)- this reduces infiltration and increases the lag time in the hydrography of that drainage basins river
Definition of farming practices:
The various methods and techniques used in agriculture to cultivate crops and raise livestock
Example of how farming practiced affect the water cycle:
A way to reduce evaporation when growing bananas is to net the bananas as they do in the Jordan Valley, Israel
Effects of farming practices on the water cycle
-Crops increase infiltration due to increasing interception and therefore slowing the velocity of flow
-Ploughing up the surface means more infiltration
Temporal effect of farming practices on the water cycle
In summer, more water is needed to irrigate crops because evapotranspiration is higher due to increased temperatures
Definitiom of land use change:
The process of altering how people structure and utilise the Earth’s Surface
Example of land use change:
Sudan- conflict forced people to remove areas of forest to use for fuel, allowing for deforestation of a large area- lost 60% of forest over the past 30 years- less interception- more overland flow
effects of urbanisation (land use change) on the water cycle:
Urbanisation- greater risk of floods due to impermeable rock- destruction of aquatic habitat
Temporal/ spatial effect of land use change:
-locally, deforestation decreases the rate of transfers in the water cycle due to less precipitation, until a possible desertification
-More affluent areas (Europe) have already completed the m, majority of their urbanisation
Definition of water abstraction:
Process of taking or extracting water from a natural source for various uses (drinking/ irrigation)
Example of water abstraction:
In the Middle East, water is abstracted from underground aquifers, which were formed thousands of years ago (fossil aquifers). They are in serious danger of being depleted as the rate of recharge in these aquifers is far slower than the rate of use
Where is the River Exe?
Exeter
Southwest England
Somerset + Devon
Where does the River Exe originate?
Exnead in Exmoor National park
The River Exe is a site…
of special scientific interest
What % of the River Exe is agricultural land?
67%
What % of the River Exe is woodland?
15%
How long is the River Exe?
60 miles
What kind of hydrography does the River Exe have?
Flashy flood hydrography
What is the Exmoor Mires project?
Restores peat bogs by blockage drainage ditches.
Aimed to restore 2000 hectares of Exmoor back to its original boggy conditions.
By 2015, over 100 hectares of moorland had been restored to their original boggy conditions. Nearly 100km of ditches had been blocked
