Assess the potential causes and impacts of changes to the water balance within a named catchment area? Flashcards
What should the 3 paragraphs be about?
- Peat drainage ditches
- Wimbleball Reservoir
- Exmoor Mires Project
What should you include in your introduction?
- Water budget is balance between inputs/outputs
- River Exe is 82.7km
- 1295mm precipitation
What is the point for peat being dug up?
Early 1970s, peat bogs dug to create drainage ditches for local farmers to increase crop yields (negative impact)
What evidence is there for drainage ditches having an impact?
- Less water stored in soil
- Water quality reduced
- Water flow increased
Explain the impact of drainage ditches?
Less water stored - less infiltration > increase in overland flow > increase risk of flooding (increase through 84.4% impermeable rock and elevation in North) > shorter lag time
Water flow increase - river discharge increases > risk of flooding (flashy)
Reduced water quality - water collects silt from ditches > disturbs river life (salmon)
What is the link for drainage ditches?
Has negative impact on water balance
What is the point of Wimbleball Reservoir?
1979 reservoir built in River Haddeo (150 hectares)
What evidence is there for Wimbleball reservoir having an impact?
- Water can be controlled
- Flattened out river regime
- Provided Exeter and East Devon with water
Explain the impact of Wimbleball reservoir?
Flattened river regime/water control - prevents peaks and troughs of water discharge > bankfull not reached > less risk of flash flooding
Water supply - make places self sufficient
What is the link for Wimbleball reservoir?
Positive human impact water balance (helps maintain dynamic equilibrium)
What is the point for the Exmoor Mires Project?
Aim to restore 2000 hectares of drainage ditches
What evidence is there for Exmoor Mires Project having an impact?
- More water storage in upper catchments
- Improved water quality
- Improved grazing and water supply for animals
Explain the impact of Exmoor Mires Project?
More water storage > more infiltration > lower discharge > gentle rising limb
Improved water quality - benefits river life
What is the link for the Exmoor Mires Project?
Positive human impact on water balance (dynamic equilibrium)
WHat should you include in your conclusion?
- Overall human impact has been positive
- Despite past errors, human impact has actually improved for humans and environment
- Water balance is becoming more stable
