Rivers Flashcards
Precipitation
Water falling from the clouds e.g. snow, hail, rain.
Evaporation
When water becomes a gas.
Condensation
When gas becomes tiny droplets of water.
Surface runoff
The water slides down a mountain or area.
Ground water
Water gets absorbed into the soil and then reappears and joins the sea.
Transpiration
Transpiration is the process where plants absorb ground water through the roots and then give off water vapor through pores in their leaves.
Waterfall (9 steps)
There are 9 steps:
- There is hard + soft rock
- Soft rock erodes quicker than hard rock
- A notch develops
- Erosion deepens the notch
- Plunge pool is developed
- No support of hard rock on top
- Hard rock collapses into plunge pool
- Repeats for thousands of years
- A gorge is formed as the waterfall retreats
Transportation (4 types)
4 different types:
- Suspension = light material is carried along the river
- Traction = large boulders roll along the river bed
- Solution =Minerals dissolve in water, chemical change
- Saltation = Small pebbles bounce on the river bed
What is a Meander?
A meander is a bend in a river. It starts at a slight bend and grows more and more.
How are meanders formed? (6 steps)
- Outer bank gets eroded
- Materials are deposited at the inner bank
- Outer bank = worn away
- Inner bank = grows
- A meander forms
- Over time the meander grows more ‘loopy’.
What is an Oxbow lake?
Cut of curve in a meander. An oxbow lake is a U-shaped lake that forms when a wide meander of a river is cut off, creating a free-standing body of water.
What are some flood causes? Physical and Human? Give 3 examples of each.
Physical causes:
- Heavy rainfall
- Natural disasters
- Melting snow
Human causes:
- Urbanization (more people = more buildings = more gutters, drains, pipes… all leading to the sewer = water in river faster)
- Deforestation (the plants will not absorb the water through their roots - meaning more water)
- Global warming (high temperatures = +evaporation, global warming = polar ice caps melting = rise in sea level)
Flood prevention. Give 3 examples of hard engineering and soft engineering to stop flooding.
Hard: (controlled disruption of natural processes by using man-made structures)
- Flood defenses = walls, used in places where there are lots of people living
- Embankments = raised banks along the river
- Making storage areas for water
Soft: (natural environment is used to help reduce coastal erosion and river flooding)
- Land use zoning = this is where the land next to a river is unused, so that flooding can happen without any harm
- Afforestation = plant roots absorb water
- Warning system = if a flood were to happen
The drainage basin: Source Mouth Valley Estuary Floodplain Watershed
Source - Where the river starts
Mouth - Where the river emerges into another river
Valley - Area with higher land on each sides
Estuary - Wide river mouth into the sea.
Floodplain - Flatland beside the river which floods when the river overflows.
Watershed -Boundary between one river basin and the next basin.
What is hard engineering?
Hard = preventing flooding using man made structures.
What is soft engineering?
Soft = using natural environment to prevent flooding.
