P1: Rivers

Question 1

long profile

Answer 1

How the Steepness of the River changes from source to mouth.
Upper course - steep
Middle course - shallow
Lower course - almost flat near the mouth

Question 2

Cross profile

Answer 2

How the river and its valley change shape.
Upper course - V - shaped valley
Middle - sloped hills and shallow river
Lower course - Flat sides and deep river.

Question 3

Vertical erosion

Answer 3

Happens in the upper course

Question 4

Lateral erosion

Answer 4

In the lower course because the gradient is lower.

Question 5

Attrition

Answer 5

The load collides into each other and becomes smaller fragments

Question 6

Solution

Answer 6

Water dissolves certain rocks

Question 7

Hydraulic action

Answer 7

Water forces air into crack which then explode under pressure.

Question 8

Abrasion

Answer 8

The process of scraping or wearing something away

Question 9

Traction

Answer 9

large boulders are rolled

Question 10

saltation

Answer 10

The bouncing of sediment

Question 11

suspension

Answer 11

fine clay and sediment is lifted and carried

Question 12

Deposition

Answer 12

When sediment can not be carried anymore by the river because the energy drops leading to the sediment being dropped on the riverbed.

Question 13

Interlocking spurs

Answer 13

Occurs where there are bands of resistant and less resistant rock. Vertical erosion is high as there is a steep gradient so it cuts out a v- shaped valley. Weathering wears the valley sides. River winds around the more resistant rock

Question 14

Rapids

Answer 14

vertical bedding- differential erosion.
There is turbulent flow on the steps.

Question 15

Waterfall / gorge

Answer 15

Vertical bedding - vertical erosion is dominant.
differential erosion happens by abrasion and hydraulic action forms rapids.
Undercutting occurs - because splash back happens where the most turbulent flow is. Creates an overhang. A plunge pool forms. Gravity causes the cap rock to collapse. This makes the plunge pool deeper.

Question 16

V- shaped valley

Answer 16

formed where vertical erosion is dominant usually in the upper course.

Question 17

Meander cross section

Answer 17

The point of fastest flow is the thalweg.
Around the inside of the meander deposition occurs. Water is flung to the outside because of the centrifugal force, this erodes the river cliff.

Question 18

Meander formation

Answer 18

The straight river encounters areas of difference which causes uneven velocity across the river.
Slow velocity on the inside + deposition.
Fast velocity on the outside + erosion.
Meander gets more pronounced and the neck gets more narrower.
Eventually two meanders connect and flow straight.
Oxbow lake.

Question 19

Ox-bow lake

Answer 19

The oxbow lake gets cut off when two meanders meet. leaves a meander scar as it dries up.
Sometimes this is caused by a flood.

Question 20

levees

Answer 20

build up parallel to a river on a raised bank. formed after multiple floods take place. The sediment is picked up by the river in the centre where the flow is fastest and the heaviest sediment is deposited first when the river discharge slows down. The smaller pieces of sediment are slowly deposited as the energy of the river decreases. sediment dropped off at a stratified rate

Question 21

Flood plain

Answer 21

is a wide valley floor on either side of the river which is there to be flooded. When a river floods the water slows down, loses energy and deposits the material. Meanders widen as the migrate of floodplains.

Question 22

Estuary

Answer 22

found at river mouths.
The land is close to sea level and the river valley is at its widest.
When the water floods its banks it carries silt and sand over onto the valley floor and deposits the sediment.
Over time more mud builds up creating mudflats. at low tides these are exposed.

Question 23

River tees

Answer 23

Cow green reservoir - releases water when precipitation is low
Ox-bow lakes at Portrackmersh- straightened for transport in 1810.
Tees barrage - built for flood control
Tees estuary - 22 miles inland. Seals sand is a mudflat.

Question 24

How does Prolonged rain affect flood risk?

Answer 24

Ground would be saturated if there is a lot of rain already.
Rain continues until soil-water can not store the water. Water enters rivers leading to floods.

Question 25

How does Heavy rain affect flood risk?

Answer 25

During winter there are many bands of depression. This means that the soil will be saturated from previous rainfalls. when it can no longer store water, surface runoff is increased. Rainwater enters rivers quicker leading to higher discharge and floods.

Question 26

How does sudden snow melt affect flood risk?

Answer 26

Sudden increases in temp in below freezing areas will melt the snow very quickly. The water will run across the ground as the soil can no longer store and surface runoff is increased.
This causes floods

Question 27

How does the geology affect flood risk?

Answer 27

The rock found in mountains is impermeable rock such as slate. the rock increases the surface runoff.

Question 28

How does the relief affect flood risk?

Answer 28

relief - height and slope of land.
Steep slopes - surface runoff on mountain sides before rain can inflitrate the soils.

Question 29

Hydrograph

Answer 29

Peak discharge - the point where the volume of water is at its highest.
lag time - the delay between peak rainfall and peak discharge.
Rising limb - the increase in river discharge
falling limb - the decrease in river discharge.

Question 30

Dams and reservoirs

Answer 30

Dams are barriers and reservoirs are formed behind it.
Adv - reservoirs control water flow, produce hydroelectric power,
Disadv - very expensive, materials are deposited in the reservoir, so farmland downstream will be less fertile

Question 31

channel straightening

Answer 31

meanders are removed to create straight lines.
Adv - Water leaves the area more quickly,
Disadv - flooding downstream, causes erosion.

Question 32

embankments

Answer 32

raised wall along riverbanks.
Adv - river can hold more so less floods.
Disadv - expensive and risk of severe flooding if water rises above this level.

Question 33

Flood relief channel

Answer 33

Channels are built to divert water.
Adv - Gates can mean the water can be controlled.
Disadv - increased discharge where the relief channel rejoins the river.

Question 34

Warning and preparation

Answer 34

People are aware and can be ready for the flood such as using sand bags.
Adv - Gives people time to evacuate
Disadv - they don’t prevent floods and could give a false sense of security.

Question 35

Flood plain zoning

Answer 35

Restrictions to prevent building on the flood plain in areas that will flood.
Adv - flood risk is reduces and the impact is reduced
Disadv - There is a housing shortage already so we need more buldings

Question 36

Planting Trees

Answer 36

Increases interception
Adv - Discharge and flood risk decrease, provides habitats for wildlife. Prevents soil erosion.
Disadv - Less land available for farming

Question 37

River restoration

Answer 37

Making the river more natural by removing man- made levees so the floodplain can naturally flood.
Adv - Discharge reduced so less chance of flooding downstream
Disadv - Local flood risk can increase.