Summary River Dee Case study for Rivers topic of Edexcel GCSE Geography

River Dee Case Study

Long Profile:




Upper course:

 Source is 460m above sea level – rainfall >3000mm
 V shaped valley with steep upland slopes – runoff is high
 Geology: Hard igneous rocks – resistant to erosion
 Narrow/shallow channel full of angular stones – friction slows down the river
 Vertical erosion

Middle course:

 Wider and flatter valley (floodplains) – gradient decreases
 Smaller and rounder sediments
 Lateral erosion
 Discharge and velocity increase as more tributaries join

Lower course:

 Rainfall <750mm
 Geology: softer rocks e.g. sandstone
 Wide flat valley
 Lateral erosion
 Wide and deep channel
 Velocity is greatest due to less friction
 Increased discharge as more tributaries join
 High sediment load – muddy water

Catchment

 94% is rural (forestry and farming)
 Important source of water for 3m people
 Famous for commercial and recreational fishing
 Supports large areas of habitats including rare species such as the otter and water vole

Changes to the river

Building of reservoirs

 Growing demand in 1960s – reservoirs built to store water during winter
 Llyn Brenig collects 800k cubic metres of water a day and can hole 60m cubic metres in total
 Discharge downstream reduced – reduces flood risk

Building of flood defences