Lecture Notes: River X Case Study - AQA Geography (Water and Carbon)

Introduction

• Purpose: Overview of River X as a local catchment case study in AQA Level Geography, focusing on water and carbon cycles.
• Key Themes:
  • Relationship between carbon and water cycles
  • Impact of environmental changes and human activity
  • Effects of precipitation on drainage basin stores and transfers
  • Implications for water supply and flooding

River X Overview

• Tributaries: Numerous tributaries contribute to a higher drainage density.
• Topography:
  • Primarily highlands (Exmoor and Dartmoor), with steep valley sides.
  • 50% of the median land is above 171 meters.

Land Use and Characteristics

• Grassland: 50% of area, less efficient in intercepting water; used for grazing.
• Urban Areas: 4.5% (e.g., Exeter).
• Woodland: 13%, more efficient in water retention due to evapotranspiration and stem flow.
• Permeability:
  • 62% low permeability (sandstone)
  • 3% high permeability

Flood Risk

• Properties at Risk: Approximately 11,000 properties at 1% flood risk annually.

Hydraulic System

• Local open system.

Human Activities Impacting River X

Peatland Restoration

• Purpose: Restore land to saturated conditions to retain carbon.
• Exmoor Peat Bogs:
  • Man-made drainage ditches for farming led to peatland degradation.
  • Peat drying releases carbon and methane.
  • Increased silt and sediment load raises flood risk.
• Exmoor Mires Project:
  • Blocks drainage ditches, costing £2.2 million, covering 2,000 hectares.
  • Benefits: slows water flow, reduces sediment, improves water quality, and enhances carbon storage.

Wimbleball Reservoir

• Constructed in 1979, dammed a tributary of River X.
• Provides water supply and regulates water flow to mitigate flood and drought impacts.

Agricultural and Urban Impacts

• Cattle Grazing: Compacts grassland, reducing infiltration capacity.
• Relief Channels: Constructed in Exeter (e.g., Trew’s flood relief channel) to manage excess water flow and reduce flood risk.

Environmental and Water Quality Improvements

• Improved water quality due to reduced sedimentation, lowering water treatment costs.

Conclusion

• Limited current research on River X.

Key Takeaways

• Importance of managing human activities to mitigate flood risks and improve carbon and water cycle relationships.
• Successful projects like the Exmoor Mires Project demonstrate effective strategies in peatland restoration and flood management.
• Continued monitoring and adaptive management are crucial for sustainable water resource management in catchment areas like River X.