floods Flashcards
What physical things can cause a flood
heavy rainfall, dry ground, impermeable surfaces, overly saturated soil, snowmelt, steep slopes, compact soil.
What human things can cause a flood
dam breaks, climate change, urbanisation, deforestation
Sometimes after heavy ____ or a fast snow melt there may be too much water for the ____ to hold.
rainfall and river
The river will overflow its ____ and flow onto the ____ either side of it.
banks and land
This is called a river ______.
flood
Usually when it rains the water will soak into the ______.
ground
However, if it is unable to soak into the ground it will flow _____ and into the river. This is the most common cause of _________.
downhill and flooding
What are the steps of river flooding
1) heavy rainfalls
2) some water will soak into the ground but some won’t
3) Water runs downhill, over the surface
4) water quickly reaches the river.
5) river level rises
6) the river floods.
What is Urbanisation
When people settle and lay roads and paths, the water cannot flow over these as they are impermeable and runs into the river.
What is deforestation
When trees are cut down, they can no longer intercept water running down, so more water flows into the river.
Will it flood- very dry soil
yes as the water will just run over it as it is impermeable.
Will it flood-steep slopes
yes as the water will come down and will not have time to saturate the soil.
Will it flood- lots of trees
No, as the trees will intercept the water as it runs through woodland.
Will it flood- large cities or towns
Yes, as the concrete is impermeable and water will just run over it.
Will it flood- soft soil
No, as it is permeable and can be saturated by the rainfall.
