Rivers Flashcards
Load
Material transported by the river
Mouth
Where river ends
At a lake or sea
Source
Where’re river starts
Usually in mountains
Course
Path the river takes as it flows from an upland area down through its valley until it enters the sea
Tributary
Stream or smaller river that connects to a larger river
Distributaries
River channels that branch off from a main river channel
Confluence
Where two rivers meet
Estuary
Tidal mouth of the rivers
Large and flat mud at low tide
Flood plain
Floor of river valley that consists of sediments deposited by the river
Alluvium
Rock particles deposited by a river
Makes soil fertile
Drainage basin
Land that is drained by a river and its tributaries
Eutrophication
High nitrate levels combined with phosphates ages excessive plant and algae growth, a deteriorating precess that results in lack of oxygen and the death of the river
Water shed
High land separating river basins
Gradient
Slope of a river profile. Steep close to source and gets gentler as it reaches towards the sea
River discharge
Volume of water carried by a river at any time
River drainage patterns (4)
Dendritic (tree)
Radial (wheel)
Trellised (right angles)
Deranged
Dendritic drainage forms where
Rocks have equal hardness
Radial patterns form where
Mountains
Trellised patterns form where
There is hard and soft rock and area experienced folding
Deranged patterns Are found where
Glaciación has impacted the landscape
Four types of river erosion
Hydraulic action
Solution
Abrasion
Attrition
Hydraulic action
Erosion by Force of moving water
Cavitation
A form of hydraulic action
Air bubbles in water colapse sending out shock waves that weaken banks
Solution
Chemical erosion by chemicals in river taken from passing over rocks eg limestone and chalk
Attrition
Particles in the rivers load are constantly colliding and eroding each other making smooth round pebbles
Abrasion
The rivers load scratching and scraping the river channel. The greater speed, the bigger the load and it’s more energised to erode
Four types of river transportation
Suspension
Saltation
Traction
Solution
Suspension
Small particles are carried by the river water
Saltation
Larger material bounces along the river bed eg pebbles
Traction
Larger materials like large pebbles and sometimes boulders are rolled along the bed. Usually in times of high water due to flood
Solution transportation
Minerals eg from limestone and chalk are soluble in water and carried dissolved in the water
Two reasons a river will deposit its load
A reduction in speed
The size of its load increases
Why might a river reduce its speed
It’s coming up to a lake or sea
Drought
Slope decrease
Meet an obstruction eg dam
Reasons the amount of load carried by a river might increase
Mass movement eg landslide into a river
Heavy rainfall
Fast flowing tributaries
Landforms in youthful stage
V shaped valley
Potholes
Interlocking Spurs
Waterfall
What is a v shaped valley
A narrow, steep sided valley where the river completely fills the base
What is a pothole
Hollows in the river bee but by swirling water and rock
What is an interlocking spur
River takes a winding course as it cuts around areas of resistant and less resistant rock
Landforms in the mature stage
Meander
Floodplain
What is a floodplain
A wide, flat floor of the river valley that folds after periods of heavy rain
Landforms in old course of river
Oxbow lakes,
Levees
Delta
What is an oxbow lake
A crest shaped lake formed when a meander is cut off from a river. They have a short life span as they have no constant flow of new water
What is an oxbow lake called when alluvium is deposited into it
Meander scar or mort lake
What is a delta
Flat area formed by deposition of alluvium by a river when it enters slow moving water
3 types of delta
Arcuate
Bird foot
Estuarine
3 gorges dam size in height, length
2km long
180m high
Where is 3 gorges
Yangtze River China
How long did 3 gorges take to build and how much did it cost
17 years
48 billion
Why was 3 gorges built
Prevent flood (1931- 13500 killed) Generate HEP for 60 million people -reducing coal intake
Impacts of 3 gorges dam
1 million relocated to divert river
Reservoir slows velocity of river - blockage problems that engineers have solved by flushing
Land downstream is deprived of alluvium and farmers must buy fertiliser
Yangtze dolphin declared extinct in 2007
Where is ardnacrusha dam
Shannon
How long did ardnacrusha take to build
Who built it
How much was it
4 years
Germán Siemens
5 million
Ardnacrusha meant Shannon had to be redirected to where
Head race canal
Effects of ardnacrusha redirection
Lakes water rise
Flooded farms
Farmers compensated
Flooding in carrick on Shannon
Dry up some parts - destroying aquatic life
What is Shannon used for now
3% of total energy usage
Tourism
Dam attracts foreign industry
Used by ESB
