Booklet 4 - River Exe Flashcards
(22 cards)
Human Factors causing changes to the Water Cycle
- Farming
- Land Use Change
- Water Abstraction
Physical Factors causing changes to the Water Cycle
- Natural Variation
- Storm Events
- Seasonal Changes
Definition of Farming Practices
The various methods and techniques used in agriculture to cultivate crops and raise livestock
Example of how farming practices affects the Water Cycle
A way to reduce evaporation when growing bananas is to net the bananas, as done in the Jordan Valley, Israel
Impacts of Farming Practices on the Water Cycle
- Crops increase infiltration, soil water rates and interception compared to bare ground, reducing runoff
- Evapotranspiration also increases, which may increase rainfall in the area.
- Ploughing breaks up the surface so more water can infiltrate, reducing the amount of runoff.
- Heavy machinery can also pack down the soil, preventing infiltration.
Temporal Change occurring as a result of Farming Practices’ impact on the Water Cycle
In Summer, more water is needed to irrigate the crops due to more evapotranspiration due to higher temperatures
Definition 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 forestry to use for fuel, allowing for deforestation of a large area - lost 60% of forest cover in the past 30 years - less interception - more overland flow
Effects of Land Use Change (Urbanisation) on the Water Cycle
Greater risk of floods due to increasing impermeable surfaces and the destruction of habitat
Temporal/Spatial Change occurring as a result of land Use Change’s impact on the Water Cycle
- Locally, deforestation decreases the rate of transfers in the water cycle due to less precipitation, until a possible desertification
- More Affluent areas have already completed the 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
Exe Head in Exmoor National Park
% Land Use of the River Exe Drainage Basin
Agricultural Grassland - 67%
Woodland and Arable Farmland - 15%
Moors and Peat Bogs - 3%
How long is the River Exe
60 Miles
What type of flood hydrograph does the River Exe Drainage Basin have?
Flashy Flood Hydroograph
What is the Exmoor Mires Project
- Aimed to restore 2000 hectares of Exmoor to the naturally present boggy conditions by blocking drainage ditches with peat and moorland bales
- By 2015, 1000 hectares had been restored, nearly 100km of ditches blocked, raising the water table by 2.65 cm
What is the Wimbleball Reservoir
- Construction began in 1970, finishing in 1979
- This Dams River Haddeo, one of the River Exe’s tributaries
- Located within Europe’s first International Dark Sky Reserve on Exmoor
- Peak Discharge lowered, more regulated and a decreased flooding risk
History of the River Exe
For decades, drainage ditches have been dug in peat bogs on Exmoor to make it suitable for farming. This increased the speed of the River Exe and reduced the water quality as more silt was carried downstream. This peat was used for domestic fuel use.
What % of the Water Balance of the River Exe does runoff account for?
65% due to impermeable bedrock
How fast does the River Exe respond to rainfall?
Slowly, due to the rural nature of the lower catchment.
