Rivers Flashcards
(27 cards)
What is the upper course of a river like?
It is at the top of a river where there are steep valleys receiving high amounts of rainfall each year, It is fast flowing and has a high carrying capacity so often contains lots of sediment. Valleys are often V-shaped
What is the middle course of a river like?
It is where the river starts to meander around the landscape, where there is a lower gradient and good farmland. The water flows slower but there are much higher quantities of water. Valleys are often U shaped.
What is the lower course of a river like?
This is where the river widens and turns into an estuary. It is deep. It has very high quantities of water and a low gradient so is useful for ports. This means that cities are often built next to them as they are flat and useful in trading but have large flood plains. It is often _/ shaped.
Where is a river’s discharge at the highest?
At the lower course where the river is wide and contains lots of water.
what is the sediment like at each stage of the river?
Upper course = large and angular
middle course = small and less angular
Lower course = very small and round
What is attrition?
When rocks in the water crash into each other, the sides and bottom of the river causing them to get smoother and smaller.
What is corrosion?
Where the rock chemically reacts with the water and starts to dissolve,
What is hydraulic action?
Where air gets trapped in the banks of rivers and explodes causing them to break down.
What is abrasion?
When rocks in the water hit against the river sides and breaks them down.
What is solution?
Soluble sediment dissolved in river water
What is suspension?
Where small particles are suspended in fast flowing water.
What is traction?
Where large boulders roll slowly along the river bed.
What is saltation?
Where small particles bounce along the river bed.
What is soil creep?
Little bits of soil moving slowly downhill
What are landslides and mudflow?
They are forms of slumping where large volumes of material go down a hill.
What is mass movement?
Material moving downhill due to gravity.
what does a river’s hydrograph show?
It shows how a river responds to a rainstorm. The bar graph at the bottom shows the amount of rainfall and the line shows the river discharge in meters cubed per second. The bottom shows the lag time. The shorter the lag rime and steeper the rising limb, the greater the risk of flooding.
What is meant by a river drainage basin?
It is the area of land drained by a river where there is high rainfall and often steep slopes. The edge of it is known as the watershed. It is like a basin as where the water flows out is like the plug hole.
What is river discharge and how is it calculated?
It is the volume of water flowing through a river at a given point. It is measured in cumecs (cubic meters per second)
How is a meander formed?
It is formed when fast flowing water from a river erodes away the outside of a bend through abrasion. The then slower flowing water on the inside of the bend deposits sediment on the inside of the bend causing it to meander.
What is an oxbow lake and how is it formed?
An oxbow lake is where a meander is cut off from a river and is formed when a bend is eroded away so much that it cuts through the land into another part of the river and deposited sediment separates the oxbow lake from the rest of the river.
What are flood walls and what are the advantages and disadvantages of using them?
They are high walls built alongside a river to increase its capacity and prevent flooding. Pros- they are one-off costs and are useful in city centres where space is limited. Cons- they disperse water quickly and can increase flood risk downstream.
What are embankments/levees and what are the advantages and disadvantages of using them?
Embankments raise the levels of river banks that are often built at a distance from the river to further increase the capacity. Pros- they can be made to blend in with the environment, protect houses and businesses. Cons- Water can go over the top or they can burst causing greater damage.
What is dredging and what are the advantages and disadvantages of using it?
It is dredging (removing mud/rubbish/weeds from the seabed) to increase river flow and the capacity. Pros- protects people living near rivers and does not damage the environment. Cons- it is expensive and must be done every year and increases flood risk downstream.
