Geography Flashcards
What country’s use soft enginering?
LEDC poor country’s
Give three benefits of soft engineeing?
Cheap
Leaves fertile silt
Gives free water
What’s the term for where two rivers meet?
A confluence
Why does a confluence create a bigger discharge?
Because the tributaries are adding more water
What type of graph shows a flood?
A hydrograph
Name an area we have studied where soft engineering is used?
Bangladesh
Why do country’s like Bangladesh use soft engineering, give three reasons.
They need the fertile soil that the flood leaves behind,
They also need the water,
Costs nothing
How many flood shelters are there in Bangladesh?
5000
Name 3 reasons why soft engineering is a bad idea.
Costly to clean up and repair the damage,
Floods homes/roads/livestock
Causes death of animals
Name a country where hard engineering is used?
USA
How many dams were built on the Tennessee river?
29
What are the odds of a flood in Mississippi River?
1 in 500
What type of power does the Mississippi River make, thanks to these dams?
How expensive is this power?
Hydro electric, which comes at a cost of £0
To date, how much money has been saved by the building of 29 dams on the Tennessee river, protecting the Mississippi River?
£4 billion
What happened in 1992 regarding the 29 dams on the Tennessee river?
In 1992 it rained south of the dams, which caused 60 people to die
Straightening the course of a river creates what?
More land on the flood planes
What is abrasion?
Rubbing of bed + banks by the load
What is hydrolic action
Force/impact of running water hitting into the banks/bed
What is solution?
Minerals in alkaline rock (limestone) are dissolved by acidic rain water
How much did the building of 29 dams on the Tennessee river cost?
£7 billion
Name 3 problems with the aftermath of the straightening of the course of a river?
It takes ages for the land to be created.
Fertile silt never left on the flood plain again.
Very expensive
Name 3 benefits of the aftermath of the straightening of the course of a river
Better for transport-> better for trade
Creates more land
Water passes to sea faster
When does lateral erosion occur?
Oxbow lakes
As the river cliffs are undercut and collapse, the meander neck narrows until the outer banks almost touch. In normal flow the river lacks the energy to snap the meander neck.
In a flood does the river have enough energy to snap the meander neck, and if so what by?
Yes and hydrolic action
After a meander neck has broken through what happens after the flood?
Water has drained away small particles sediment and pebbles are deposited either side of the new straight channel. These form natural embankments called leveés these prevent river water from entering the former meander.
Overtime the water in the oxbow lake evaporates, leaving a meander scar
Name two things that lateral erosion does?
Created wide flat flood plains.
Large wide meanders and oxbow lakes
Name two things that vertical erosion does?
Steep sided V shaped valley
Straight flowing rivers
What is river discharge?
The volume of water passing a given point in a river.
What is river discharge measured in?
Cumecs (cubic meters per second)
OXBOW LAKES
Name five things the inner bank does.
Has slowest energy
Carries far less energy
Deposits loads as not enough energy to carry load along
Heaviest load is rounded pebbles
Slip of slope
What’s a slip off slope?
Forms on the inside of a meander bend as a result of deposition in the slower flowing water
OXBOW LAKES
Name 5 thinks the outer bank does?
Has the fastest flow
Has the highest energy levels
Transports load in suspension
Abrasion of outerbank and hydrolic action
River cliff
