Case study of a river catchment at a local scale: River Exe Revision

• What is the case study for a River Catchment at a local scale?

  The River Exe in Devon
• Where is the River Exe located?

  South West England
• Where is the River Exe's source?

  In the hills of Exmoor in Somerset
• Where does the River Exe flow through?

  Through Tiverton and Exeter
• Where does the River Exe end?

  To the sea at Exmouth on the south coast of Devon
• Where is the River Exe located? ( location, source,through,ends)

  It is located in South West England. It flows from its source in the hills of Exmoor in Somerset through Tiverton and Exeter, to the sea at Exmouth on the south coast of Devon
• State the River Exe's tributaries

  It has an extensive network of tributaries
• State the River Exe's drainage density

  Has a high drainage density
• What are of the River Exe are we focusing on?

  The upper catchment of River Exe
• What are the 3 key characteristics of the River Exe

  1. Relief (natural factor impact flood hydrograph)2. Geology (natural factor)3. Land use (physical factor)
• Size of the area of the upper catchment


  The area of the upper catchment is 601km²
• Maximum elevation of the upper catchment and where

  Its maximum elevation of 514m in the North
• Describe land and lowest elevation of the upper catchment and where

  Land flatter in the South with the lowest elevation being 26m
• Describe the slopes in the River Exe

  Steep slopes
• What type of rock and percentage is the catchment underlained by?

  An estimated 84.4% of the catchement is underlain by impermeable rocks
• What type of impermeable rock?

  Predoiminantly Devoniain sandstones
• Would a steep slope give a flashy or subdued hydrograph?

  A steep slope would give a flashy hydrograph
• Why would a steep slope give a flashy hydrograph?

  Due to the fact that the hydrograph would have a steep rising limb and short lag time
• Would impermeable rock give a flashy or subdued hydrograph?


  Imperbeable rock would give a flashy hydrograph
• Why would imperable rock give a flashy hydrograph?

  Due to the fact that the hydrograph would have a steep rising limb and short lag time
• Land use: What is most of the land with % in River Exe?

  Most of the land is agricultural grassland, which covers 67% of the catchment
• Land use: How much of the catchment in % does arable farmland cover in River Exe?

  With some arable farmland covering 15% of the catchment
• Land use: How much of the catchment in % does urban areas cover in River Exe?

  Urban areas cover 4.5% of the catchment
• Name the 2 recent developments in the Exe Catchment?

  1. Wimbleball reservoir 2. Peatland restoration: Exmoor Mires Project
• Year of Wimbleball reservoir project?

  1979
• 2 Aims of Wimbleball Reservoir

  1. To supply water to Exeter and parts of Devon.2. To regulate water flow
• Size of Wimbleball Reservoir: What is it's surface area

  Surface Area of 150 hectares
• 2 Advantages of Wimbleball Reservoir

  1. Reduces risk of flooding downstream ∴ ensures a sustainable water supply2. It has a large biodiveristy with range of animals e.g Hedgehogs and Weasels ∴ enviromentally sustainable
• Disadvanatge of Wimbleball Reservoir

  It was showed that the main thermal effects of water held in reservoirs and then released can raise mean water temps∴ eliminate freezing conditions ∴ depress summer maximum values
• Aim of Exmoor Mires Project

  Restores peat bogs by blocking drainage ditches.
• Peatland restoration on Exmoor: Exmoor Mires Project - Year if project?

  1998
• 2 Advantage of Exmoor Mires Project

  1. Improved water quality so is less expensive to treat ∴ economically sustainable 2. Reduced runoff by 32%
• Disadvanatge of Exmoor Mires Project

  Costs £4.5 million