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Flashcards in Rivers Deck (35)
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1
Q

What is river discharge?

A

the amount of water passing a specific point at a giventime.

2
Q

What is river discharge measured in?

A

Cubic meters per second
or Cumec

3
Q

What 2 factors affect the amount of discharge?

A

Volume – the amount of water in the river

Velocity – the speed of the river

4
Q

How does discharge as the river moves downstream?

A

The dischargeincreasesbecause of the increase volume as more tributaries join the river.

5
Q

Why does river discharge increase as you go downstream?

A

the channel gets wider and deeper downstream and so the river can hold more water.Thevelocity/speedofthe river also increases as you move downstream. There is more water in the river in the channel because tributaries are adding more watertothe river.

6
Q

How does the UK’s weather and climate affect river processes?

A

Winter would have the most erosion.There is more rain and therefor more water to erode the river and so more Hydraulic Action and Abrasion on the river bank and bed. Cold conditions in the winter will cause more freeze thaw to occur.

7
Q

How does the UK’s weather and climate impact on river landforms?

A

Levee-this is a raised river bank. It is made when the river repeatedly floods. So heavy rain makes this feature.

8
Q

What is a levee made?

A

A levee is a lower course feature
It is created by repeated flooding

When the river floods, the water moves out of the channel
The energy levels in the water all rapidly when this happens.

The river drops its load on the river bank
The heaviest (bigger bits of load) material will be dropped later, on the flood plain

After many floods the levees are formed.

9
Q

What is a flood plain?

A

Flood plan is a lower course feature.
It is made by meander migration

As the meander moves it leaves flat land behind it on the slip of slope.

The flood plain will be covered the the river floods.

10
Q

What is an meander migration?

A

On a meander, water travels at different speeds. Fast on the outside and slow on the inside.

Fast water erodes and slow water deposits.

These processes work together to move the meander. This is called meander migration.

11
Q

What is an ox bow lake?

A

As a meander gets bigger, due to meander migration, a meander neck is formed. It is eroded on both sides and eventually the river breaks through and goes straight on.

The OBL is formed. After a while the OBL will dry out.

12
Q

Describe interlocking spurs

A

A spur is a upper course feature.

In this part of the river, the load is big and angular. This means the river travels slowly and there is a lot of friction. The river uses up to 90% of its energy to overcome the friction.

When the river meets pieces if land sticking out, it goes around it and a spur is formed.

13
Q

Describe how urbanisation impact rivers?

A

Building roads and drains means that water can reach the river quicker than rainfall.
This means the river is more likely to flood because there is too much water in the river channel.

Channelisation is put in place so the river bank is reinforced, the housing is protected and stops meander migration.

Building large ports for industry in a river can also be disrupted.

Poole Harbour in Dorset has to be dredged regularly as the river sediments and reduced deposition are dropped and block up the channel, meaning that large ships cannot get passed.

14
Q

Describe how agriculture impact rivers?

A

When deforestation occurs it affect rivers as it interferes with the process interception (when the rainwater hits the trees leaves and takes time to reach the ground) and throughflow (when water flows through soil).

Fewer trees mean that the rainwater reached the ground faster, impacting erosion rates as the river will be more powerful.

Farmers use more chemical fertiliser, which impacts the ecology (plants and animals in the river), causing algae bloom and water channels to be clogged.

Farmers drain land close to rivers with artificial drainage ditches that allow water to flow to the rivers quickly, which can cause flooding as the natural river landscape is changed.

15
Q

How does heavy rainfall cause flooding in a river?

A

The ground is saturated and the raincoat flows into the river quickly

16
Q

How does Cloudburst in a Thunderstorm cause flooding in a river?

A

the rain droplets are so large and fall so quickly that there is no time for the water to sink into the ground; water runs very quickly into the river and causes flooding.

17
Q

How does Sudden Rise in temperature cause flooding in a river?

A

a rapid thaw can happen; rivers are unable ti coop with the amount of water and flood

18
Q

How does Silted up river channels cause flooding in a river?

A

this makes the channel smaller and more likely to flood.

19
Q

How does Removal of Vegetation on valley slopes cause flooding in a river?

A

if there is less interception that water will move to the river more quickly

20
Q

How does Settlements built on the Floodplains cause flooding in a river?

A

storm drains allow water ti move into rivers at greater speed and so make flooding more likely.

21
Q

How does Global Warming cause flooding in a river?

A

melting of the polar ice caps and rise in sea levels, flooding low-lying coastal areas

22
Q

How does Dams may burst cause flooding in a river?

A

which causes excess water in river channels and flooding of large areas.

23
Q

What is a damn?

A

a large, usually concrete structure built across a river valley to hold back water.

24
Q

What is a reservoir?

A

large areas of water that are created after the flow of a river had been controlled, often by building a dam

25
Q

What is a channelisation?

A

the river channel is made deeper, wider and straighter

26
Q

What are the advantages and disadvantages of a dam?

A

Stores water behind the dam; hydroelectric power can be produced as water is released through the dam.
Effective for many years

Very visible - makes residents feel safe.
They can be seen as ugly-may put tourists off.
Can cause problems with salmon trying to make their way upstream.
Sediments can be trapped behind the dam causing a lack of deposition further downstream
Very expenseive to build
The visual impact on river landscapes as the concrete they are made from is very unnatural.

27
Q

What are the advantages and disadvantages of a reservoir?

A

Reservoirs can provide drinking water for the urban areas.
Creates a large area of water that can be used for recreational activities.

Very expensive to control the flow of the water.
Settlements and farming land can be lost when a valley is flooded
River landscapes are flooded with loos of land and settlements
Disrupts the natural process at work in the river valley as sediment is trapped in the reservoir.
Has a visual impact on the river landscape a

28
Q

What are the advantages and disadvantages of channelisation?

A

The river channel can hold more water, so less likely to flood
Visual, so makes residents feel safe

Expensive
River landscape is changed and can look unnatural
Disrupts the natural process at work in the river channel
The water can travel faster to places downstream and possibly cause flooding there

29
Q

Describe floodplain-zoning

A

land that is close to the river is seen as low value because flood risk; it is used for recreation, for example sports fields. Housing areas would be further away on more valuable land that is less likely to flood.

30
Q

Describe washlands

A

the river is allowed to flood these areas it could be farmland or recreational land close to settlements.

31
Q

What are the advantages and disadvantages of floodplain-zoning and washlands?

A

Provides potential habitat for birds and animals
Very cheap as no defences need to be built
Provides recreational facilities such s sports fields for local residents.
The ecology of the landscape is changed each time the river floods
River landscapes are left relatively unchanged for the majority of the time

Large areas of land cannot be built on; residents may not understand why.
Flooding takes the land out of action regularly; this could anger people who are using it for recreation.

32
Q

What is a waterfall and how is it made?

A

Waterfalls are an Upper and Middle course feature.

At the start a small step forms as soft rock that is eroded quicker that the hard rock.

At the bottom of the step lots of erosion occurs forming a plunge pool.

The main erosion processes are hydraulic action and abrasion.

As the plunge pool grows its undercutting the cap rock.

Eventually the cap rock falls into the plunge pool due to gravity

This process is repeated many times and the waterfall moves upstreams.

This is called waterfall retreat and forms a gorge.

33
Q

What are the effect on people does river flooding have?

A

Loss of life from people and livestock drowning.
Damage to peoples homes and belongings.
Contamination of fresh water supplies by sewage water.
Communication links can be destroyed if bridges and roads are washed away.
Disruption to gas and electrical supplies.

34
Q

What are the effect on the environment does river flooding have?

A

Destruction of crops.
The ecosystem is affected as animals such as rabbits could drown and the vegetation they eat is destroyed which messes up the balance of an ecosystem.
Can cause different plant species to develop on the flooded land, which makes it hard and expensive for farmers to cultivate the land again.
Fields of food crops can be flooded, so there could be a lack of food in the area.

35
Q

What impact does the river have for tourism?

A

The Wye was one of the earliest tourist honeypots with visitors flocking to the area in the 1700’s. The cliff ascent and walks at a Pierefiels Tank were landscaped at this time. Tourism still flock to the area. There are many lookout points, walks, a number of castles and Tintem Abbey which dates back to the eleventh century.