Rivers Flashcards
Example- managing floods
Where is banbury located?
Cotswolds, above oxford
Much of the town is on a floodplain
Example- managing floods
How has banbury been affected by flooding?
Led to closures of town railway station
Local roads shut
Houses and businesses damaged
Example- managing floods
What has been done to reduce the risk of flooding?
- earth embankment built parallel to motorway creating a flood storage area. Collects rainwater.
- raising the a361 road in flood storage area
- new earth embankment and flood walls to protect property
- new pumping stations
Example- managing floods
Name 3 social costs and benefits
- reduces levels of anxiety and depression through fear of flooding
- quality of life of locals with improved footpaths and green areas
- raised a361 route into banbury will be open during a flood, avoids disrupting peoples lives
Example- managing floods
3 economic benefits and costs
- cost about £18.5 million
- by protecting 441 houses and 73 commercial properties benefits estimated to be over £100million
- donors include environment agency and Cherwell district council
3 environmental costs and benefits
- 1000000 tonnes of earth needed to build embankment extracted nearby creating a small resivour
- new biodiversity plan habitat was created using ponds trees and hedgerows
- part of floodplain will be allowed to flood if levels get to high
Name 3 characteristics of the upper course
- steep/ v shaped valley
- narrow shallow channel
- high bed load
Name 4 features of the upper course
- v shaped valleys
- interlocking spurs
- waterfalls
- gorges
Name 3 characteristics of the middle course
- open gentle sloping valley with floodplain
- wider deeper channel
- more suspended sediment
Name 3 features of the middle course
- meanders
- river clifff
- slip of slopes
Name 3 characteristics of the lower course
- flat and wide floodplain
- wide, open valley
- very wide and very deep
Name 3 features of the lower course
- ox bow lakes
- flood plains
- levees
Name 3 processes of erosion
- solution
- attrition
- abrasion
What is solution?
When the river flows over limestone or chalk, the rock is slowly dissolved
What is attrition?
When stones carried by the river knock against each knock against each other, gradually making the stones smaller and more rounded
What is abrasion?
When the load carried by the river repeated hits the bed or banks dislodging particles into the flow or the river
What is hydraulic action?
The force of the water hitting the river bed and bank. This is most effective when the water is moving fast and there is a lot of it
What are the 4 main types of transportation
Solution
Suspension
Traction
Saltation
What is solution?
Dissolved load
What is traction?
Large particles rolled on the river bed
What is suspension
Small sediment held in the river
What is saltation
Bouncing of particles too heavy to be suspended
When is a waterfall commonly formed
When a river flows over a relatively resistant band of hard rock
What is a gorge?
A narrow steep sided valley that is usually found down stream of a waterfall
How is a gorge formed
Formed by the gradual retreat of a waterfall
What is a thalweg
Outside bend where erosion occurs as it is the fastest flowing water with lots of energy
What is the formation of a floodplain
1- meanders migrate across floodplain due to lateral erosion. When they reach the edge of the flood plain the erode the valley side = wide floodplain
2- when river floods it deposits silt creating flat floodplain, layers bulid up to form thick fertile alluvium
What is a levee
How is it formed
What is it
A raised river bed found along side a river in the lower course
Formed by flooding
Ridge of sediment is deposited naturally to build up levee
What is an estuary
Are transitional zones between the river and costal environments
Example- river tees
Where is it
Where is the source
North east of england
Pennie hills neat cross fell
List 3 ways of things increasing the risk of a flood
- after a long period of winter rain
- torrential storms
- volume lf water from rain over flows its banks
3 ways physical factors increase flood risks
Geology (rock type) - impermeable rocks
Precipitation - rainfall
Steep slopes - rapid transfer of water
3 human factors increasing flood risks
Deforestation- trees absorb when they are gone no where for water togo
Urbanisation - impermeable surfaces
Agriculture - ploughed land water can run quickley through it
What is soft engineering
Involves working with natural river processes to manage the flood risk
3 ways of soft engineering on managing floodplains
Wetlands and flood storage areas - aloud to flood, water stored
Floodplain zoning - land only used for certain things
River restoration - course of river ch aged deliberately slow down river flow….
What are the 3 levels of flood warning
Flood watch - flooding of low lying land and roads expected
Flood warning - threat to homes
Severe flood warning - extreme danger to life
How has banbury been affected by flooding x3
- closure of towns, railway station
- £12.5 million damage
- homes and buisnesses affected
What was done to reduce floods at banbury 3
- earth embankment area built parallel to motorway flood storage area
- raising motorway so if it floods people can still travel
- new pumping station transfer excess water
3 social costs and benifits or flood at banbury
- reduced anxiety + depression through fear
- quiality of live improved new footpaths and green areas
- raised a361 route so people can still travel
3 economic costs and benifits of the flood at banbury
- £18.5 million
- donors - environmental agency + Cherwell district council
- by protecting houses benefit of up to £100mil
3 environmental costs and benefits of the flood at banbury
- earth needed for embankment was dug up and small resivour was made
- new biodiversity plan created with ponds and trees
- part of floodplain aloud to flood if levels get too high
