Geography - Rivers

Question 1

What makes landscapes in the UK distinctive?

Answer 1

• Upland areas in Wales, Scotland and Northern England
• Lowland areas in Southern England
• River and coastal areas e.g. Jurassic coastline
• Land use - how farming, mining, National Parks affect landscape
• Culture - the history of the area
• Geology - features resulting from different geology
• Vegetation - woodland, grassland

Question 2

How are physical landscapes in the UK affected by human activity?

Answer 2

• Honeypot site - attracts a large number of people due to easy access or natural beauty
• Carrying capacity - when the number of visitors exceeds the carrying capacity it can damage the landscape
• Impact of visitors on Lake District - congestion on roads, footpath erosion, shops selling souvenirs, house prices increase due to second homes…however, boosts local economy, jobs created, business see increase in trade.

Question 3

How can landscapes in the UK be managed? (Lake District)

Answer 3

Lake District:
- Repairing footpaths with stronger materials
- Creating new paths to protect other areas
- Fencing off damaged areas
- Information boards
- Banning parking on verges

Question 4

What is a drainage basin?

Answer 4

An area drained by a river and its tributaries

Question 5

What is lateral erosion?

Answer 5

horizontal/sideways erosion (when water wears away the land)

Question 6

What is evaporation?

Answer 6

When a liquid (e.g. water) turns to a gas (e.g. water vapour) when heated

Question 7

What are the 4 types of erosion?

Answer 7

• Abrasion
• Attrition
• Hydraulic action
• Solution

Question 8

What is abrasion?

Answer 8

When material (e.g. boulders) carried by the river smashes/rubs against the river’s bed and banks, wearing it away

Question 9

What is attrition?

Answer 9

Rocks carried by the river smash into each other. This makes them gradually become smaller and rounder.

Question 10

What is solution?

(erosion)

Answer 10

Where water has a chemical reaction with rock e.g. limestone and dissolves it

Question 11

What is hydraulic action?

Answer 11

When the power of the water forces air into cracks in the bed and banks. This causes the rock to break apart and the cracks to become wider

Question 12

What are the 4 types of transportation?

Answer 12

• Traction
• Saltation
• Suspension
• Solution

Question 13

What is traction?

Answer 13

When large, heavy pebbles are rolled along the river bed. This is most common near the source of a river, as here the load is larger.

Question 14

What is saltation?

Answer 14

When pebbles are bounced along the river bed, most commonly near the source.

Question 15

What is suspension?

Answer 15

When lighter sediment is suspended (carried) within the water, most commonly near the mouth of the river.

Question 16

What is solution?

(transportation)

Answer 16

The transport of dissolved chemicals. This varies along the river depending on the presence of soluble rocks.

Question 17

What is deposition?

Answer 17

When a river drops the material it has been carrying due to a loss of energy.

Question 18

Where does deposition most commonly occur?

Answer 18

• Where the velocity of a river decreases e.g. on the inner bend of meanders
• At the mouth (where the river meets the sea)
• On the floodplain when a river floods
• Shallow water/when the volume of water decreases

Question 19

What are the three main processes of a river?

Answer 19

• Erosion
• Transportation
• Deposition

Question 20

What are some landforms found along a river’s course?

Answer 20

• V-shaped valleys
• Waterfalls
• Meanders
• Oxbow lakes
• Floodplains

Question 21

What happens to the width of the river along its course and why?

Answer 21

Increases
- As a river reaches its lower course, lateral erosion becomes more common (as gradient decreases) which widens the river

Question 22

What happens to the discharge of a river along its course and why?

Answer 22

Increases
- As more tributaries join the river, more water enters the river

Question 23

What happens to the velocity of the river along its course and why?

Answer 23

Increases
- Bedload is smaller and banks + bed are smoother, meaning that friction decreases and velocity increases

Question 24

What happens to the gradient of the river channel as the river flows downstream and why?

Answer 24

Decreases
- Meander migration widens the valley floor
- Lateral erosion flattens the valley - creating floodplains

Question 25

How are interlocking spurs formed?

Answer 25

- At its source, a river is small and has limited energy - It flows naturally from side to side around ridges of more resitant rock, creating spurs

Question 26

How are V-shaped valleys formed?

Answer 26

- Vertical erosion takes place, deepening the river channel - Weathering attacks the sides/slopes - This weakens the rock until mass movement moves the materal downslope

Question 27

Describe the formation of waterfalls and gorges.

Answer 27

- Waterfalls are formed when hard (more resistant) rock overlays soft rock - Soft rock is eroded more rapidly (through hydraulic action and abrasion) - This undercuts the hard rock, creating an overhang - The force of the water creates a plunge pool - The hard rock overhang collapses because it has no support - The process repeats, retreating upstream and leaving a gorge (a steep sided valley) where it once was

Question 28

Describe the processes that occur at meanders.

Answer 28

- Water flows fastest on the outside of a meander, eroding the banks and creating a river cliff - On the inside of the bend (where the river is flowing slower) deposition takes place creating a slip-off slope

Question 29

How are Oxbow Lakes formed?

Answer 29

- Erosion on the outside of the bend narrows the neck of the meander, moving the meanders closer together - When there is a high discharge (usually in flood conditions,) the river cuts accross the neck, taker a new, straighter and shorter route - Deposition occurs, cutting off the original meander and leaving an Oxbow Lake - This lake will dry up over time since no more water is flowing into the lake

Question 30

What are floodplains?

Answer 30

Areas of land either side of a river that become covered in water when a river bursts its banks

Question 31

How are floodplains formed?

Answer 31

- Erosion removes any interlocking spurs from a V-shaped valley, creating a wide and flat area on either side of the river - Material is deposited onto the floodplain during floods, increasing the height of the floodplain over time - **Meander migration takes place in a river's lower course** - Erosion + deposition in a meander move a meander accross the valley floor, widening and flattening it

Question 32

What are some physical causes of flooding in Boscastle?

Answer 32

- Intense rainfall, 185mm in 5 hours, did not allow time for water to infiltrate therefore overland flow increased - Large amount of rainfall earlier in the week and an input of 3 million tonnes of water meant ground was saturated and could hold no more water - Confluence of 3 rivers, Valency, Jordan and Paradise drained a small drainage basin of just 40Km2 - Geology - impermeable sandstone did not allow water to infiltrate and therefore overland flow increased - Steep valley sides reduced infiltration - Thin soils couldn't hold much water

Question 33

What are some human causes of flooding in Boscastle?

Answer 33

- Narrow bridges became blocked with trees easily, diverting water into the streets - Deforestation results in fewer trees to intercept and store water - more water gets to the river - Urbanisation results in water flowing rapidly into drains over impermeable surfaces - water gets to the river channel quickly + drains can get clogged up

Question 34

What are some short term effects of flooding on Boscastle?

Answer 34

- Water rushed down streets at 40mph as a 10ft wall of water ripping up roads and destroying both bridges - 80 cars in the car park were swept away in minutes - 6 properties were destroyed outright. Most others needed £15,000-£30,000 repairs - Harbourside Hotel and Witch Museum damaged - Most houses had 2 feet deposit of mud

Question 35

What are some long term effects of flooding on Boscastle?

Answer 35

- Loss of trade amounted to £15m - Bed of the river Jordan was 10 feet higher - Most shops stayed shut for the rest of the season - Trade and tourism reduced - Value of homes permanently reduced - some by half - as less people wanted to buy houses there due to bad reputation in media - Stress and anxiety

Question 36

How does Shrewsbury protect itself against flooding?

Answer 36

- Demountable barrier system – 1.5m to 3m tall, offers protection from 1 in 100 year flood - Adding two new pumping stations to reduce water backing up in drains, £3.5 million scheme - 1 in a 100 year chance - Flood embankments, located in a conservation area, so made sure they blended into the surrounding area. £2.4 million scheme, reduce the level of flood risk to a 1 in 100 - Clywedog dam and reservoir, in the upper course of the Severn. Gives some protection immediately downstream but little benefit to Shrewsbury - Natural flood meadows (washlands) exist upstream of Shrewsbury and provide some protection - Levees constructed to provide protection for low lying agricultural land. Reduce risk of flooding to 1 in 10 or 20 chance in a year

Question 37

What are some advantages and disadvantages of hard engineering?

Answer 37

Advantages: very effective, strong and durable Disadvantages: expensive, visually unattractive

Question 38

What are some advantages and disadvantages of soft engineering?

Answer 38

Advantages: relatively cheap, blends in with the natural environment Disadvantages: may not be as strong/long lasting, can lead to conflict/controversy (e.g. washlands - allowing places to flood)

Question 39

What is floodplain zoning?

Answer 39

Where areas in a city are set aside for certain functions to reduce the impact of flooding Examples: - Areas close to a river are set aside for sports and recreational activities - can be lost - Hospitals occupy higher land away from the risk e.g. JR - Residential areas tend to be on higher ground than industries due to the risk of life

Question 40

What is a river regime?

Answer 40

The pattern of a river's flow over a period of time

Question 41

Explain some factors that effect a river's regime.

Answer 41

- Precipitation: more precipitation (e.g. in the winter) leads to an increase in flow and discharge during that time - Geology: Impermeable ground means a fluctuating regime - Forests: Trees mean more interception and therefore less water reaching the river - Loss of leaves in the winter means less interception and more water reaching the river

Question 42

Why are some methods of flood prevention controversial in Shrewsbury?

Answer 42

- Could spoil the historic beauty of the town - People unsure how useful flood protection actually is - The impact of the environment could be too great - Is it worth the money? - Disturbs locals while construction is taking place - Places (e.g. farmers fields) are allowed to flood - Negative impacts downstream (e.g. little water or higher risk of flooding)

Question 43

Why are flood defences in the Thames Estuary controversial?

Answer 43

- Conflicting views over how long the Thames Barrier will be useful for - hard to predict future changes and how they might impact - Flood walls being used are protecting properties but others feel they funnel the water towards London - Managed realignment - landowners do not want farmland flooded but does soak up pollutants and provides a habitat, as well as protecting places further upstream - Building houses in the Thames Gateway - prime building land but increasing the risk of flooding

Question 44

How are levees formed?

Answer 44

- When a river floods, sediment is deposited onto the floodplain - The river loses energy and deposits the largest material first (closest to the river) and then the smallest material (furthest away) - After many floods, the sediment builds up and increases the height of the banks - This means that the river can carry more water and therefore helps protect against future floods