Rivers

Question 1

types of erosion

Answer 1

abrasion
hydraulic action
attrition
solution

Question 2

hydraulic action

Answer 2

the sheer power of the waves as they smash against the cliff. air becomes trapped in the cracks in the rock and causes the rock to break apart from the pressure.

Question 3

attrition

Answer 3

rocks in the water knock against each other. they break apart to become smaller and rounder

Question 4

abrasion

Answer 4

pebbles grind along a rock platform, like sandpaper. over time, the rock becomes smooth

Question 5

solution (erosion)

Answer 5

sea water dissolves certain types of rocks and breaks down some rock. in the UK, chalk and limestone cliffs are prone to this.

Question 6

types of transportation

Answer 6

traction
saltation
solution
suspension

Question 7

traction

Answer 7

where pebbles and larger material are rolled along the seabed

Question 8

saltation

Answer 8

where small pieces of shingle or large sand grains are bounced along the sea bed

Question 9

suspension

Answer 9

small particles such as silts and clays are suspended in the flow of the water

Question 10

solution (transportation)

Answer 10

when materials in rocks like chalk and limestone are dissolved in sea water and then carried in solution. the load is not visible

Question 11

characteristics of the upper course

Answer 11

steep gradient
V-shaped valley, steep sides.
Narrow, shallow channel
Bedload is large and angular
Lots of vertical erosion
low velocity
small discharge

Question 12

characteristics of the middle course

Answer 12

medium gradient
Gently sloping valley sides. Wider, deeper
channel
Load becomes smaller and less angular.
Lateral erosion increases

Question 13

characteristics of the lower course

Answer 13

gentle gradient
Very wide, almost flat valley, very wide, deep
channel
Large amount of load but the size is small and
very rounded. A lot of lateral erosion occurs
high velocity
large discharge

Question 14

formation of meanders

Answer 14

1. In the middle course, the river has more energy and the land is flatter. This causes the river to meander and more lateral
   erosion occurs. There is a disturbance making a hole in one bank. Water flows into it and erodes it, beginning a bend.
2. Water flows faster on the outside bend, eroding it creating a river cliff.
3. Material is deposited in the slow moving water on the inside bend creating a slip-off slope
4. over time the amplitude of the bend increases making the meander more pronounced

Question 15

formation of oxbow lakes

Answer 15

1. Oxbow lakes begin with a meander.
   2 . The water on the inside of the bend is moving slowly and has less energy, so material is deposited here.
2. Water flows faster on the outside bends eroding them so that they get closer together.
3. Gradually over time, two outside bends can erode so much that the meander neck narrows until they touch and during a time of flood, the water can break through the land between them. The river takes the straighter, faster route so less water flows around the bend
4. Material is deposited in the slow moving water in the old bend, cutting if off and creating an ox-bow lake.

Question 16

formation of a v-shaped valley

Answer 16

1. Water collects on high ground after heavy rain and begins to flow downhill because of gravity. Gradually, the river erodes the underlying rock creating a channel.
2. The sides of the channel are exposed to the weather. Weathering breaks up the rocks on the valley sides.
3. The weathered rock on the valley sides falls into the river channel (mass movement). some is carried away by the river
4. the process repeats, and the v-shaped valley becomes deeper.

Question 17

features of the upper course

Answer 17

waterfalls
v-shaped valleys
inter-locking spurs

Question 18

features of the middle course

Answer 18

meanders

Question 19

features of the lower course

Answer 19

meanders
ox-bow lakes
floodplains
levees

Question 20

physical causes of river flooding

Answer 20

antecedent rainfall
impermeable rock
relief
weather conditions

Question 21

human causes of river flooding

Answer 21

urbanisation
agriculture
deforestation
climate change

Question 22

causes of river flooding: urbanisation

Answer 22

surfaces like roads are impermeable&raquo_space; more surface run-off&raquo_space; water returns to the river faster increasing the risk of flooding. rainwater also flows into drains which returns water to the river faster

Question 23

causes of river flooding: agriculture

Answer 23

irrigation up and down (instead of across) hillsides creates channels&raquo_space; allows water to reach rivers faster&raquo_space; increasing discharge

Question 24

causes of river flooding: deforestation

Answer 24

less interception&raquo_space; rain reaches the ground faster&raquo_space; ground is more likely to become saturated&raquo_space; more surface run-off&raquo_space; water returns to the river faster increasing discharge

Question 25

causes of river flooding: climate change

Answer 25

warmer air can hold more water >> more frequent intense storms >> increasing discharge

Question 26

causes of river flooding: antecedent rainfall

Answer 26

soil is saturated >> more surface run-off >> water returns to the river faster increasing discharge

Question 27

causes of river flooding: impermeable rock

Answer 27

no infiltration >> more surface run-off >> water returns to the river faster increasing discharge

Question 28

causes of river flooding: relief

Answer 28

steep slopes increase surface run-off >> water returns to the river faster increasing discharge

Question 29

causes of river flooding: weather conditions

Answer 29

hot, dry soils can bake the soil making it impermeable >> more surface run-off >> water returns to the river faster increasing discharge

Question 30

how does urbanisation affect river processes and landscapes

Answer 30

- Urbanisation has caused towns to grow, meaning there are fewer permeable surfaces. Water flows into the rivers, increasing discharge. - Increasing demand for housing has led to new houses being built on floodplains. This changes the natural landscape. - Rivers may be channelised or made to flow underground to make room for urban developments. If this happens, erosion and deposition cannot take place.

Question 31

how does agriculture affect river processes and landscapes

Answer 31

- Field drains can improve farmland, but quickly move water into streams and rivers, and can destroy natural wetland landscapes. - Forests can be felled to make way for farmland. Trees intercept rainfall, helping to reduce surface run-off. Removing trees means water reaches rivers more quickly. - Abstracting water for irrigation reduces the flow and velocity of a river so deposition occurs rather than erosion. - ploughing fields up and down a slope can increase the amount of sediment in rivers and increase deposition.

Question 32

how does industry affect river processes and landscapes

Answer 32

- Industry is a big user of water, so can reduce the amount of water in rivers, leading to less erosion. - Industrial processes can pollute rivers if chemicals or waste are spilled or dumped into them. This can destroy plants and animals and change the natural landscape.