UNIT 1C - River Landscapes in the UK Flashcards
What is Hydraulic action?
force of water breaks rock particles away from the river
What is abrasion?
eroded rocks are picked up and rubbed against the river, wearing it away (most erosion)
What is attrition?
eroded rocks picked up by the river smash into each other and break into smaller fragments, edges are rounded off, decrease slowly the closer it gets to the mouth
What is solution?
river water dissolves some rock ( chalk and limestone)
What is traction?
large particle boulders are pushed along river bed by force of water
What is suspension?
small particles like silt and clay are carried along
What is saltation?
pebble-sized particles bounce along the river bed by force of water
What is solution?
soluble materials dissolve in water and are carried along
What does the long profile of a river show you?
the gradient (steepness) changes over its course
Features of the upper course?
steep, v-shaped valley, steep sides narrow, shallow channel
Features of the middle course?
gently sloping valley sides, wider, deeper channel/ medium
Features of the lower course?
gentle, very wide, almost flat, valley very wide, deep channel
What is vertical erosion?
deepens river channel, making it v-shaped. Dominant in upper course, high turbulence causes rough, angular particles scraped along bed, intense downward erosion
What is lateral erosion?
widens the river valley (and channel) during formation of meanders, dominant in middle and lower course
What is deposition?
is when a river drops the eroded material its transporting when it slows down
Where are waterfalls and gorges found?
in the upper course
How are waterfalls formed?
where a river flows over hard rock and followed by soft, softer rock is eroded ( hydraulic action and abrasion) creating a step in the river, as water goes over it, it erodes more and more. A steep drop is eventually created, hard rock is eventually undercut by erosion, it becomes unsupported and collapses, this is repeated and waterfall reseeds more and more
What is interlocking spurs?
the upper course of the river, eroding downwards, it cant erode laterally so they wind round the high hillsides, they interlock with each other like a zip
How are meanders formed?
current (flow of water) is faster on the outside bend because its deeper, ;ess friction. More erosion takes place on the outside bend, river cliffs, current is slower (shallower) more friction, eroded material is deposited on the outside bend, slip-off slopes
How are ox-bow lakes formed?
erosion causes outside bends to come closer, until theirs a small amount left, river breaks through land (during flood) river goes through shortest course, depostion cuts of meander and creates ox-bow lake
What are flood plains?
flat areas of land that flood.
What happens in flood plains?
wide valley floor occasionally gets flooded, when it floods water slows down and deposits eroded material, builds up flood plain. Meanders migrate across making it wider, as well as downstream, flattening valley floor, deposition builds from flood plains (slip-off slopes)
What are estuaries?
they are tidal areas, meets the sea
Explain estuaries?
found at the mouth, land is closest to sea level and river is at its widest, (falls and rises every day) water floods over the banks carry silt and sand. as it reaches highest point, water is moving very slowly so sediment deposits . More and more builds up creating mudflats, at low tides muddy banks are exposed
How long is river clyde?
160km long
What is in the mouth of river clyde?
An estuary
List some features of river clyde?
- the estuary is about 3km wide
- meanders between motherwell and glasgow
- interlocking spurs at crawford, 300-500m high
- ox-bow lake is beginning to form
- as well as gorge along the river
What is river discharge?
the volume of water that flows per second
What is river discharge measured in?
cumecs
What is peak discharge?
highest discharge
What is lag time?
delay between peak rainfall and peak discharge
What is rising limb?
increase in river discharge as rain water flows into river
What is falling limb?
decrease in river discharge as river returns to normal level
What is Prolonged rainfall?
soil becomes saturated, increase surface run-off
What is heavy rainfall?
arrives to quickly for infiltration, lots of run-off
What is geology?
soils and some rocks are impermeable so run-off is increased, when it rains, discharge increases rapidly
What is relief?
if a river is in a steep-sided valley, water reaches channel faster, water flows more quickly on steeper slopes
Examples of soft engineering?
Flood warning, planting trees, preperation and flood plain
Examples of hard engineering?
Dams and reservoirs, embankments, flood relief
Pros and cons of dams and reservoirs?
stores water, reduce flooding, drinking water, expensive, eroded material is deposited farmland is left fertile
Pros and cons of embankments?
holds more water, expensive, severe flooding if water rises above or breaks it
Pros and Cons of flood relief?
takes water elsewhere, discharge reduced, control the water through gates, water levels get to high could flood, increased discharge
Pros and cons of flood warnings?
gives people time to move, take appropriate precautions, doesnt stop flooding, people may not hear it
Pros and cons of planting trees?
discharge and flooding reduced, reduces soil erosion, provides habitats, less farmland
Pros and cons of preparation?
building take less damage, people know what to do, less worrying, expensive, doesn’t guarantee safety
Pros and cons of flood plain?
impermeable surfaces aren’t created, no buildings to be damaged
