living in the uk- the river wye Flashcards
What is the name of the case study
A UK river basin
How long is the River Wye
Over 210 km
Where is the source of the River Wye
High in the Plynlimon Hills, Central Wales
Describe the course of the River Wye
It flows mostly south-eastwards and joins the River Severn at Chepstow.
Mainly flows through moorland and farmland.
How has the course of the River Wye been impacted by human activity
It is fairly natural but has been impacted by the construction of dams and reservoirs.
Which geomorphic processes are active along the River Wye
Erosion, transportation, and deposition
Which processes are active in the rivers upper course
Weathering (freeze thaw due to low temperatures) as well as high rainfall causes mass movement on the exposed river valley
Describe the geology of the River Wye in the upper course
The river flows through impermeable shales and gritstones. High rates of flow after rainfall events result in significant erosion and in turn formation of landforms
Impact of geology on river landforms along the River Wye
Rapids near Rhayader- alternating bands of hard and soft rock, popular site for canoeists
Flat valley to the South of Hereford- weak mudstones and sandstones easily eroded to form meanders
The Wye Valley (a gorge) between Goodrich and Chepstow- a river cuts through tough carboniferous limestone rock
Average rainfall in the River Wye basin
725 mm
Average rainfall in the Plynlimon Hills
Can exceed 2500 mm
Impact of high amount of rainfall
Much of the rainfall occurs in winter- little vegetation to absorb surplus water. Leads to rapid river flows, increased erosion and flooding potential.
River landforms found along the River Wye
Waterfalls (e.g. Cleddon Falls) formed on the tributaries, V-shaped valleys in the upper course, levees and floodplains in the middle and upper course (formed by extensive alluvium deposition).
Describe the location of the River Wye in terms of urbanisation
It flows through several large settlements- Rhayader, Hay-on-Wye, Hereford, and Chepstow
Over 200,00 people live in the Wye and Usk river valleys
Describe three ways in which the flood risk been reduced in Hereford
Storage lakes constructed above the town e.g. Letton Lake- stores surplus water
Flood walls constructed to protect 200 properties- cost of £5 million
Parts of the floodplain above the town deliberately allowed to flood to reduce pressure downstream
Human activity- how has tree planting affected geomorphic processes
Helps to stabilise slopes- reduces mass movement. This in turn reduces the amount of sediment in the river which reduces the flooding risk. Also causes a reduction in deposition downstream.
Negative impact of reducing flooding events
Means that there is less sediment available for floodplains, and levees may not build up. Artificial levees will have to be built instead.
Positive impact of tree and vegetation planting
Stabilised slopes means better access for walkers
Increases amount of water stored- flood height reduced by 20%
