Flashcards in Rivers And Water Deck (71):
The volume of water in a river. There is less in the uplands.
What are the four types of erosion?
Hydraulic action, abrasion, attrition and solution.
Smaller pebbles and stones are bounced along the river bed, picked up and dropped as the flow of the river changes.High energy.
How does a waterfall form?
A river meets soft rock which is eroded faster than harder rock.
Vertical erosion happens and a step in the river forms.
Abrasion and other forms of erosion causes undercutting.
Hydraulic action causes a plunge pool to form.
The hard rock is undercut and collapses and the water fall retreats up stream.
Finer sand silt-sized particles are carried along in the flow of the river. The water looks brown and it is low energy.
Eroded rocks get picked up and are smashed against each other. They get smaller and their edges rounder.
Why might deposition occur in a river?
It happens when the velocity of the river slows down. This can happen because the volume of water in the river falls
The amount of eroded material in the water increases.
The water is shallower
The river reaches its mouth.
Large boulders and stones are rolled along the river bed. High energy.
Explain lateral erosion.
This widens the river and channel. Dominant in the middle and lower courses.
Why is the water slower on the inside bend of a menader?
The channel is shallower and there is more friction.
What are the negatives of flood warnings?
It doesn't stop a flood. Living in a place that floods a lot will increase insurance prices. People may not hear the warnings.
What are the four types of transportation?
Traction, suspension, saltation and solution.
Explain vertical erosion.
This causes the channel and valley to deepen making it V shaped. Happens mostly in the upper course.
Where is is the fastest currant?
On the outside of the river.
What are the two land forms you can find in meander?
A river cliff on the outside bend where is is erosion and a slip off slop on the inside bends where deposition takes place. It is a deposit of sand and smaller particles.
Minerals like limestone and chalk are dissolved in the water and carried along. Low energy.
Where are meanders mostly found?
In the middle course where there is more lateral erosion.
How does a levee form?
Often serval meters higher than the flood plain.
Happens in the lower course where a lot of eroded material is
During a flood, eroded material is deposited on the edges of a river bank. Heavy material is closer to the river as it gets dropped first.
What is discharge measured in?
Cumecs. Square meters per second.
What were the responses to the flooding of Bangladesh?
Boats and emergency services sent out.
Repair to sewage systems.
New laws to stop deforestation.
7 dams being built.
5000 flood shelters being built to hold the population.
What is surface run off?
When water flows over land to get to a river.
What type of erosion happens on the outside of a meander?
Lateral erosion in the form of abrasion and hydraulic action.
What can affect peak discharge and the lag time?
Lots of rain is a short space of time means more runoff and a smaller lagtime.
Hot, dry or freezing conditions can make the ground hard,increasing runoff and decreasing lagtimes.
The rock type. Permeable or impermeable.
Previous weather conditions. Is the ground saturated?
Land use. In an urban area there is lots of impermeable concrete.
What are the negatives of preparation?
Doesn't guarantee safety from a flood. Expensive to modify buildings. It could give people a false sense of security.
Explain Chanel straightening and the positives.
Meanders are cut out by building artificial straight channels.
Water moves through the area quicker as it doesn't have to travel as far, reducing the risk of flooding.
Explain flood warnings.
People are warned about possible floods by TV, radio, newspapers and the internet. The impact of flooding is reduced as people can move things upstairs, put up sandbags and evacuate.
What is the lag time?
The time between the peak flow and the peak dischage.
What is a meander?
They are bends in the river's course.
Explain flood plain zoning.
Restrictions are put in place so you can't build in areas that are prone to flooding. The risk of flooding is reduced as there will be less impermeable surfaces, concrete, and less surface run off.
The impact of flooding is reduced as there is nothing to be damaged.
Name some of positives of the the Kielder reservoir?
The hydroelectric power, powers a town of 10,000.
All of the north east of England has water.
How much water can the Kielder reservoir hold?
188,000 million litres of water.
What were the environmental affects of the flooding in Bangladesh?
Land was submerged for 50 days.
2,000,000 acres of farming land submerged
500,000 cattle dead.
Buildings are modified to reduce the damage caused by flooding. People make plans of what to do if there is a flood.
The impact of flooding is reduced. Buildings are less dameged.
Where is the Kielder reservoir?
In the cheviot hills, just south of Scotland,40km north west of Newcastle.
What caused the the flooding in Bangladesh in 2004?
70% of the nation is less than 1m metre below sea level.
150 million people there. Densely populated.
Poor planing and poorly maintained rivers.
Snow melted causing flooding.
Urbanisation produced lots of surface run off.
Explain the negatives of building dams.
There are very expensive and settlements may have to be flooded. Eroded material is deposited in the dam and not in the rivers course meaning farm land can become less fertile.
Why was the Kielder reservoir built?
Planners felt that the steel and ship building industry would need more water.
How much did the Kielder reservoir cost to build?
What caused Boscastle to flood?
Before there was 25%more rain than normal meaning the ground was saturated.
One inch of rain in 15cm
Surrounded by hills of impermeable slate.
Debris blocked a bridge causing water to go around.
It is at a natural confluence of the rivers Paradise, Jordan and Valency meaning it is well shaped for water to flow through.
75 mm of rain(what falls in a normal month) fell in 2 hours.
What are the negatives of channel straightening?
Flooding may happen downstream and there is more erosion there as the water passes through faster.
What were the social effects of the 2004 flooding?
Six million people lived in makeshift shelter.
Five million suffered water born diseases.
800 dead, rice plans washed away
Millions with no food.
What were the effects of the flood at Boscastle?
1000 cars were washed away.
Tourism (90% of the areas GDP) was damaged.
The church had six feet of mud in it.
52 properties needed £15,000-£30,000 of repairs that lasted six months.
Large damages to infrastructure. No phone lines, electricity,gas,water.
What are some of the negatives of the Kielder reservoir?
Farmers lost land families had to move.
There is a risk of contaminating one river ecosystem by the transfer of water.
An area of outstanding natural beauty was lost.
What were the responses to the Boscastle flood?
Seven westland sea king helicopters rescued 150 people, meaning no-one died.
The car park is being raised so it is further from the river.
£800,000 was spent on making the river Jordan able to carry twice the amount of water.
How does an ox-bow lake form?
First there is a meander and erosion causes the outside bends to get closer, meaning there is only a small amount of land between the two bends.
This land is broken through. (Generally because of a flood)
Deposition cuts off the meander forming a lake.
Explain dams and reservoirs and the benefits.
A dam is built across a river. They store water in times of heavy rain reducing the risk of flooding. It can be used as drinking water and hydroelectric power can be generated.
Eroded rock is picked up and scraped against the channel wearing it away. It is the most common type of erosion.
The river water dissolves some types of rocks, like limestone and chalk.
Explain hydraulic action.
The force of water breaks rock away from the river channel.
Where is the river Tees?
It is in Northern England. It goes from the North Pennines, eat for 85 miles and ends in the north sea near Middlesbrough.
Explain the reservoir at Cow green.
It can hold 41 million cubic meters of water. This prevents flooding by capturing excess water in times of high rain fall.
However it is very expensive.
It has a 58.9 km squared catchment area.
Explain the flood plain zoning at the River Tees.
Low lying areas next to the river can'r be built on.
This reduces the need of flood defences and property isn't damaged.
However the land can't be used.
Explain dredging at the River Tees.
It happens in the lower Tees basin.
Sand and silt is removed from the river bed meaning more water can be carried reducing the chance of it going over the edge.
It is expensive.
Explain the tees barrage.
It is in the lower Tees basin.
It reduces the chance of flooding by river and sea. It opened 25KM of waterway. Regenerated derelict land along the riverside. Created jobs
It cost £54 million and prevents tidal movements up stream.
Explain channel straightening at the river Tees.
It is at the Mandale loop.
This shortened the river by 4km. Water can move out to sea quicker reducing the chance of a flood.
However more erosion happens down stream as it is moving faster.
Explain the Yarm flood defence system.
It in the marker town of Yarm.
Gabions have been put in place along the river. Parts of the river have been reinforced with concrete,pipes have been used to redirect water. It is a massive system for really big floods that only happen every 100 years. Fishing platforms, flower beds and street furniture have been put up.
However it cost 2.1 million for floods that only happen every 100 years.
Where are the Keyhaven Marshes?
In the south east, in the lee of hurst castle spit.
What are the characteristics of the Keyhaven Marshes?
It is an area of salt Marshes formed in a lee. There are grasslands scrubs, salt marches and reed beds.
Give examples of vegetation in the Keyhaven Marshes and how they have adapted to the area.
Cordgrass is salt tolerant and quickly colonises the mud flats. Long roots means it isn't swept away in the tide and they help to trap sediment and stabiles the soil. There are many types of grasses, scrubs and reed beds.
What threatens Keyhaven marshes?
The salt marsh is retreating by up to 6mm a year. Don't know why. Tourism means is is damaged by trampling, parking and pollution. Mariners use the creeks to moor boats.
The hurst castle spit can be breached. In 1989 50-80mm was exposed to the sea and was eroded in 3 months.
What are the answers to the problems in Keyhaven marshes?
In 1996 £5 million was spent in rock armour and beach nourishment to protects the spit.
It is now a SSSI. The area is carefully monitored and manged to keep a rich biodiversity.
How has the demand for water in the UK increased?
In the last 25 years the amount of water used in the UK increased by 50%
The UK population is predicted to increase by 10 million people over the next 20 years.
Explain the demand and availability of water within the UK.
The north and west of the UK have high rainfall meaning lots of water.
The south east and midlands have high population densities meaning there is a high demand for water.
The south east and midlands are areas of water deficit and in the north and west there is a water surplus.
How could the UK manage the water supply by transferring water?
One way is to transfer water form areas of surplus to areas of deficit. For example, Birmingham (deficit) is supplied with water from the middle of Wales (surplus)
What are the problems caused by transferring water?
The dams and aqueducts that are needed are expensive.
It could affect the wildlife that lives in the rivers. Fish migration patterns could be disrupted by dam building.
There may be political issues. People may not want to give their water to another county.
Other than water transfer, how could the UK water supply be managed?
Build more reservoirs to store water. However this involves flooding settlements and relocating people.
Fixing leaky pipes would mean less water is lost during the transfer. Millions of litres of water are lost everyday through leaky pipes around London.
How could the demand for water be reduced?
People can reduce the amount of water they use by taking showers instead of baths, running washing machines only when full and be using the hosepipes less.
Water companies want people to use water meters. This charges people for the exact volume of water they used. People who have them will be careful with the amount of water they use.
What is the source?
Where a river begins.
What is the mouth?
Where a river ends and joins the sea.
What is the water shed?
The boundary of the drainage basin.