Topic 4 Flashcards
What is hold the line?
Hold the line is when costal defences are used to stop an aria from eroding, this can be expensive
What is advance the line
When new sea defences are built in front of existing defences this is even more expensive than hold the line.
What is strategic retreat?
When some arias are left to erode while investment is put into areas of more value. Compensation is given to people caught in the less valuable zones
How are waterfalls made and where are they found?
Water falls are found in the upper corse and are made when a layer of more resistant rock lies on top of a layer of less resistant rock. The less resistant rock erodes underneath quickly the rivers bed load erodes down to form a plunge pool. Then the overhang collapses.
What happens when a waterfall erodes back?
A steep gorge is formed.
Where are v shaped valleys found and how a they formed?
V-shaped valleys are found in the upper course and are made when a river erodes downwards and the sides collapse Eva weathering, this creates the shapes of interlocking spurs at the rivers bends, often dictated by the resistance of the rock bands.
What are meanders and where are they found?
Meanders are found in the middle course when the river begins to erode sideways, forming a large bend. On the outside of the bend the current flows fastest and strongest, this erodes the side creating a river cliff, on the inside of the bend the current is less powerful so it deposits material creating a dip-slope.
Extra information about meanders.
The land around the meander is often flat with embankments at the edges, this is a floodplain.
Meanders continue to erode they can loop back on themselves until only an narrow neck of land is left.
What is a storm hydrograph?
A hydrograph measures the rainfall and discharge of a river during a storm.
What is the peak discharge
The highest amount of water going though a point in the river at one time.
What is the peak rainfall
The highest amount of rainfall in one day
What is the lag time?
The time between the peak rainfall and the peak discharge.
What kind of hydrograph has a short lag time?
A flashy hydrograph
Name two human factors that effect lag-time
Deforestation and urbanisation
Name two physical factors that effect lag time
Steep relief and saturated soil
