Theme A: River Environments

Question 1

Drainage Basin:
Percipitation

Answer 1

Input: a rainfall, hail, sleet or snow

Question 2

Drainage Basin:
Interception

Answer 2

Store: vegeatation/trees delay or slow down the rate at which rainfall reaches the ground

Question 3

Drainage Basin:
Surface Storage

Answer 3

Store: water is temporarily stored on the ground’s surface

Question 4

Drainage Basin:
Soil / Moisture Storage

Answer 4

Store: soil is capeable of holding water for a while

Question 5

Drainage Basin:
Surface Runoff

Answer 5

Transfer: water which moves over the surface of the land

Question 6

Drainage Basin:
Infiltration

Answer 6

Transfer: water sinking into the soil

Question 7

Drainage Basin:
Through Flow

Answer 7

Transfer: water flowing through the soil

Question 8

Drainage Basin:
Percolation

Answer 8

Transfer: water sinking down through the rock

Question 9

Drainage Basin:
Groundwater Flow

Answer 9

Transfer: water flowing slowly from the rock into the river

Question 10

Drainage Basin:
River Discharge

Answer 10

Output: water flowing away in the river

Question 11

Drainage Basin:
Evapotranspiration

Answer 11

Output: water turning into water vapour in the air, and water turned into water vapour by plants through their leaves.

Question 12

Drainage Basin Charcteristics:
Watershed

Answer 12

The boundary of a drainage basin which usually follows a ridge of higher ground (e.x mountains)

Question 13

Drainage Basin Charcteristics:
Source

Answer 13

The place at which a river begins

Question 14

Drainage Basin Charcteristics:
Tributary

Answer 14

Small rivers or streams which flow into the main river

Question 15

Drainage Basin Charcteristics:
Confluence

Answer 15

The point at which a tributary meets the main river

Question 16

Drainage Basin Charcteristics:
River Mouth

Answer 16

The place where a river enters/meets the sea

Question 17

How a River Changes Downstream:
Gradient

Answer 17

• This is the steepness of the slope the river flows down
• As a river goes downstream, it gets les step
• This is because the river does more downwards erosion near the source, and more sideways erosion near the mouth

Question 18

How a river changes downstream:
Depth

Answer 18

This is a measure from the top of the water to the river bed. As the river goes downstream, the river gets deeper. This is because the river erodes downwards as it travels.

Question 19

How a river changes downstream:
Width

Answer 19

This is the distance from one side of the river to another. As the river goes downstream, the river gets wider, because the river erodes sideways as it travels downwards.

Question 20

How a river changes downstream:
Discharge

Answer 20

This is the amount of water passing a point in a certain time. As the river goes downstream, the discharge increases. This is because more water flows into the river from each tributary. Water flows faster with less friction.

Question 21

How a river changes downstream:
Load

Answer 21

This is the material a river is carrying (mud, sand, pebbles, rocks). As the river goes downstream, particles get smaller and more rounded. This is because particles knock against each other and break each other up. Sharp, angular edges get knocked off.

Question 22

Name the four erosion processes carried out by a river

Answer 22

1. Corrasion (Abrasion)
2. Attrition
3. Solution
   4, Hydraulic Action

Question 23

Describe and explain corrasion

Answer 23

This is the grinding of rock fragments carried by a river channel, against the bed and banks of a river. This action causes the river channel to widen and deepen. This grinding is most powerful during a flood, when large fragments of rock are carried along by a river,

Question 24

Describe and explain attrition

Answer 24

This is the collision of rock fragments, (suspended in water) against one another. Rock particles are broken into smaller pieces and become smoother as the process continues?

Question 25

Describe and explain solution - as a method of erosion

Answer 25

This is the process by which a river’s water chemically reacts with soluble minerals in rocks and is dissolves them.

Question 26

Describe and explain hydraulic action

Answer 26

This is a form of mechanical weathering that is caused by the force of moving water. It can undermine riverbanks on the outside of a meander or force air into cracks within exposed rock in waterfalls such as Niagra Falls.

Question 27

Describe and explain solution - as a method of transportation

Answer 27

Soluble minerals dissolve iin the water and are carried in solution. This is a chemical change affecting rocks such as limestone and chalk, and may result in discoloured water. For example; the rivers of the Mournes often appear yellow/brown as they are stained from iron coming off the surrounding peat bog.

Question 28

Describe and explain suspension

Answer 28

The smallest load, like fine sand and clay, is held up continually within the water. This makes the water appear opaque. Some rivers carry huge quantities of suspended material.

Question 29

Describe and explain saltation

Answer 29

This is the bouncing of medium-sized load, like small pebbles and stones, along the river bed.

Question 30

Describe and explain traction

Answer 30

This is the rolling of large rocks along the river bed. This requires a lot of energy. Load carried in this way is called bed load. The largest bed load will only be moved like this in time of severe flooding.

Question 31

When is deposition likely?

Answer 31

Deposition likely if: - the river enters a lake or sea, slowing its flow - the river floods onto its floodplain, where it flows very slowly - there is an area of shallow water, slowing the rivers flow - the load is increased suddenly, for example, after a landslide

Question 32

Discuss the formation of a waterfall

Answer 32

1. A waterfall is formed when a layer of hard rock overlies a layer of softr rock 2. The river erodes the soft rock easily, so there is a step in the river bed. Eventually this becomes deeper, making a waterfall 3. Hydraulic action and abrasion make a plunge pool at the bottom of a waterfall 4. More erosion undercuts the hard rock, leaving it hanging over the plunge pool 5. The overhanging hard rock falls into the plunge pool, and the position of the waterfall moves backwards

Question 33

Discuss the formation of a meander

Answer 33

- A meander is a bend in a river caused by erosion. - On the *outside* of the bend you will find the *fastest flow* of water because there is *little to no FRICTION* - As the fastest flow goes downstream, it erodes and creates a *river cliff*. - On the *inside* of the meander bend you will find the *slowest flow* of water. **It is not able to transport its load due to its slow flow.** - This deposition creates a **slip-off slope**. - Eventually, the outside bends will further erode and merge to create an *oxbow lake*. - The inside bends of the meander are cut off. - They are now called an **oxbow cut off lane**.

Question 34

Discuss the formation of levees and floodplains

Answer 34

- Flat land either side of the river will be covered in water if the river bursts its banks: this is callled a floodplain. - When the water slows down, it looses energy. This means it will deposit a load (sediment) which is fertile. - The heavier, larger particles are deposited first, building up on the river bank, while smaller particles can be carried along the floodplain. - This means that over time the river banks will build up into long mounds called levees made of the larger particles.

Question 35

Name and locate the river which you have studied in the British Isles

Answer 35

Name: **River Parret** Location: **Somerset Levels, South West England**

Question 36

Explain the HUMAN CAUSES of why the river you have studied flooded

Answer 36

- Rivers had not been dredged properly in 20 years, so they were full of silt and could not hold the water. - Houses were build in Taunton and Bridgewater nearby, so that water drains quickly from the impermeable surfaces, and arrives quickly in the rievr, making the river more likely to flood. It was also pumped away from these areas to protect homes built on former floodplains.

Question 37

Explain the PHYSCIAL CAUSES of why the river you have studied flooded

Answer 37

- Low lying land, with grassy vegetation, doesn't intercept much rain, and the impermeable clay which doesn't soak up the water. This leads to an increase in surface runoff. - Severe weather storms in December/January in Southern England during 2013/2014, giving **207mm** of rain in January, more than twice of what was expected, and the highest since 1910. - High tides caused the water in the river to back up into the River Parret, so floodwater could not leave this area.

Question 38

Discuss the *positive* Impacts of Flooding on PEOPLE

Answer 38

- Replenishes drinking water supplies, especially wells - Provides sediment that naturally fertilises the soils of the floodplain - Countries rely on floods to help crops grow - Can encourage innovative solutions in future building design, such as building houses on stilts to avoid floodwater, or tiling all gorund floor walls and floors to facilitate easy clean-up after flooding.

Question 39

Discuss the *negative* Impacts of Flooding on PEOPLE

Answer 39

- Spreads waterborne diseases such as cholera - People and animals can be made homeless or even drown - Buildings and infrastructure can be damaged or destroyed - Crops grown on fertile floodplains can be washed away in a flash flood - Can increase house insurance costs for home owners, or even make it impossible for them to ensure the home at all

Question 40

Discuss the *positive* Impacts of Flooding on the ENVIRONMENT

Answer 40

- Fish benefit as they an breed in the standing floodwater - In dry areas, floods bring relief from drought, providing drinking water for wild animals

Question 41

Discuss the *negative* Impacts of Flooding on the ENVIRONMENT

Answer 41

- Flooding can wash chemicals or sewage into the local rivers and so pollute them - Wild animals may drown or lose their habitat during a flood

Question 42

**Flood Mamagement Methods:** Dams

Answer 42

Allow water to be stored rather than surging downstream and causing floods there, they can also be used for water supply, hydro-electricity and recreation

Question 43

**Flood Mamagement Methods:** Flood Walls

Answer 43

Walls built beside rivers that are likely to flood in urban areas - they take up less space than levees

Question 44

**Flood Mamagement Methods:** Levees

Answer 44

These make the river banks higher so more water can be held in the channel

Question 45

**Flood Mamagement Methods:** Straightening and Deepening of the River

Answer 45

Water flows faster in a straight and deeper river so it leaves the area without causing problems

Question 46

**Flood Mamagement Methods:** Washlands

Answer 46

Parts of the floodplain, often used as pasture in the summer, that can be allowed to flood in the winter - one form of flood storage

Question 47

**Flood Mamagement Methods:** Land Use Zoning

Answer 47

Land that is at the highest risk of flooding is not used for flooding, but used for playing fields or for pasture

Question 48

**Flood Mamagement Methods:** Afforestation

Answer 48

Trees take up water by their roots and reduce the amount of water that reaches the river, so it is less likely to flood

Question 49

Name all HARD ENGINEERING river management methods

Answer 49

- Dams - Flood Walls - Levees - Straightening and Deepening of the River

Question 50

Name all SOFT ENGINEERING river management methods

Answer 50

- Washlands - Land Use Zoning - Afforestation

Question 51

Name and locate a river that you have studied outside of the British Isles

Answer 51

Name: **The River Mississippi** Location: **USA**

Question 52

Engineering Method Used in the River Mississippi: **Levees** Short description Is it sustainable?

Answer 52

The levees have been built at 15m high for 3,000km along the river Sustainable? - Yes

Question 53

Engineering Method Used in the River Mississippi: **Dams** Short description Is it sustainable?

Answer 53

Over 100 dams were built along tributaries Sustainable? - Yes

Question 54

Engineering Method Used in the River Mississippi: **Straightening and Deepening of the River** Short description Is it sustainable?

Answer 54

Engineers cut through meanders to straighten 1750km of channel, to make the river flow faster Sustainable? - No

Question 55

Engineering Method Used in the River Mississippi: **Afforestation** Short description Is it sustainable?

Answer 55

Afforestation in the Tennessee Valley - teh trees absorbed the water Sustainable? - Yes

Question 56

Engineering Method Used in the River Mississippi: **Land Use Zoning** Short description Is it sustainable?

Answer 56

Houses near the river were bought and then demolished, and areas of the floodplainare turned into green spaces Sustainable? - Yes