EQ4: Why Is There A Variety Of River Landscapes In The Uk And What Are The Processes That Shape Them? Flashcards
(24 cards)
Does the channel width increase or decrease downstream?
Increase
Does the velocity increase or decrease downstream?
Increase
Does the channel bed roughness increase or decrease downstream?
Decrease
Does river discharge increase or decrease downstream?
Increase
Does the sediment load volume increase or decrease downstream?
Increase
Does the slope angle (gradient) increase or decrease downstream?
Decrease
What is the definition of vertical erosion?
The gravity of the river and the low discharge means the river erodes downwards through hydraulic action and abrasion.
Does the sediment particle size increase or decrease downstream?
Decrease
What is the definition of hydraulic action?
The sheer physical force of water eroding the banks and bed
What is the definition of abrasion?
The load of the water eroding the river banks
Does the channel depth increase or decrease downstream?
Increase
The river erodes on the (outside/inside) of the bend where the current flows stronger and faster.
Outside
What is the definition of discharge?
It is the volume of water flowing in a river at one particular point and time.
What is discharge measured in?
It is measured in cubic meters per second (cumecs)
What is the definition of peak rainfall?
When the heaviest rainfall occured
What is the definition of peak discharge?
The time when the highest river discharge occurred.
What is the definition of lag time?
The time taken between the peak rainfall and peak discharge
What is the definition of the rising limb?
The river level is rising
What is the definition of the falling limb?
The river level is falling
What is the definition of a flashy hydrograph?
A hydrograph that responds quickly to rain, with a high peak and a short lag time
How does deforestation affect flooding?
1) less interception
2) soil becomes saturated quicker
3) little infiltration
4) more surface run-off
5) discharge increases
How does steep relief have an affect on flooding?
Where there are steep slopes, surface run-off will be greatest and less chance of infiltration due to gravity
How does urbanisation have an affect on flooding?
In urban areas there is less infiltration as a result of the impermeable rock surfaces
How does impermeable rock cause flooding?
Impermeable rock does not allow water to move through it.
