River Management

Question 1

What factors influence river landscapes in the UK?

Answer 1

Climate, geology, and human activity

Question 2

Define porosity in the context of rocks.

Answer 2

Porosity is a measure of how much water can be stored in pore spaces between grains of rock

Porous rocks like sandstones can hold significant amounts of water.

Question 3

What type of rocks are known to be permeable?

Answer 3

Sandstone and limestone

These rocks allow water to pass through due to their vertical and horizontal joints and cracks.

Question 4

What is permeability?

Answer 4

Permeability is a measure of how easily water can travel through a rock

Question 5

What are impermeable rocks?

Answer 5

Rocks that have few pore spaces or joints, causing water to flow over them on the surface

Examples include most igneous rocks like granite and metamorphic rocks like slate.

Question 6

Name a type of sedimentary rock that is impermeable.

Answer 6

Clay

Question 7

Where can water be stored in regions with impermeable geology?

Answer 7

At the surface

This leads to the formation of lakes and rivers as natural surface stores of water.

Question 8

What is the purpose of damming rivers?

Answer 8

To control flooding and create reservoirs for water supply

Question 9

How many large dams are there in the UK?

Answer 9

168 large dams

Question 10

What is a drainage basin?

Answer 10

The area of land from which a river collects its water

Water is stored in rivers, vegetation, soil, and rocks within a drainage basin.

Question 11

What is surface run-off?

Answer 11

Water that flows over the ground

This occurs when precipitation falls and does not infiltrate the soil.

Question 12

What is infiltration?

Answer 12

The process of water flowing into the soil

Question 13

What happens to water after it infiltrates the soil?

Answer 13

It moves slowly downhill as throughflow

Question 14

What is groundwater flow?

Answer 14

Water that percolates deeper into the ground and enters the bedrock

Question 15

List factors that affect rates of infiltration, throughflow, and groundwater flow.

Answer 15

• Size and shape of the drainage basin
• Steepness of its slopes
• Amount of rainfall throughout the year
• Intensity of rain storms
• Amount and type of vegetation cover
• Permeability and porosity of the soil and rocks

Question 16

What is the influence of geology on water flow and storage?

Answer 16

Geology affects how quickly water flows through a drainage basin and the amount of water it can store.

Question 17

What is discharge in the context of rivers?

Answer 17

The amount of water in a river, measured in cubic metres per second, or cumecs.

Question 18

Define annual regime in relation to rivers.

Answer 18

The pattern of discharge in a river over one year, typically shown in a hydrograph.

Question 19

What are aquifers?

Answer 19

Bands of porous rock that can hold huge quantities of water. These groundwater stores are also known as aquifers.

Examples are chalk and some types of sandstone

Question 20

What is recharge in the context of aquifers?

Answer 20

Water that enters an aquifer.

Question 21

What is discharge in the context of aquifers?

Answer 21

Water that leaves an aquifer.

Question 22

What does it mean to abstract water?

Answer 22

To take water from either a surface or groundwater store.

Question 23

What is over-abstraction?

Answer 23

Taking water from a store faster than it can be recharged.

Question 24

When was the last significant drought in the UK?

Answer 24

In 2005 and 2006.

Question 25

What are flash floods?

Answer 25

Floods caused by high volumes of rainfall in a very short period, leading to a sudden rise in river levels.

Question 26

What conditions can lead to flash floods in the UK?

Answer 26

Hard, baked dry ground that prevents rainfall from soaking in quickly.

Question 27

What are seasonal floods?

Answer 27

Floods that occur due to seasonal variations in rainfall, often after prolonged rain when the ground is saturated.

Question 28

What can cause flooding when snow melts?

Answer 28

Frozen ground preventing water from infiltrating the soil.

Question 29

How do human actions increase flood risk?

Answer 29

Paving over soil creates impermeable surfaces, reducing infiltration and increasing flood risk. So, growth of urban areas increases the risk of flooding.

Question 30

What is the effect of vegetation on water flow?

Answer 30

Vegetation slows water flow and can store water through interception.

Question 31

What is interception?

Answer 31

The process where some water is caught and stored on leaves.

Question 32

What is transpiration?

Answer 32

The process of water being returned to the atmosphere through the pores of leaves.

Question 33

How does deforestation affect flood risk?

Answer 33

Cutting down trees or leaving fields bare can reduce interception, increasing flood risk.

Question 34

What is one way to reduce flood risk downstream?

Answer 34

Planting trees in upland areas.

Question 35

What type of rocks are mainly found in the drainage basin of the River Valency?

Answer 35

Slates These rocks are impermeable.

Question 36

What is the gradient of the River Valency due to its high source and short length?

Answer 36

Steep

Question 37

What natural feature helps to remove some water from the soil before it reaches the river?

Answer 37

Trees, via interception

Question 38

What happens to tree branches during flood events?

Answer 38

They can break off and restrict the flow of water

Question 39

Define mouth in the context of rivers

Answer 39

where the river meets the sea/lake

Question 40

Define watershed

Answer 40

where the water falls into two different drainage basins

Question 41

Define confluence

Answer 41

where two rivers meet

Question 42

Define tributary

Answer 42

a small stream that joins the main river

Question 43

Define source in the context of rivers

Answer 43

where the river starts

Question 44

Define catchment area

Answer 44

the drainage basin

Question 45

What changes were made to the river channel downstream of Boscastle?

Answer 45

Widened, deepened, and straightened

Question 46

Why was the river widened?

Answer 46

The wider, deeper channel has a greater capacity so it holds more water.

Question 47

Why was the river straightened?

Answer 47

Water moves quickly through a straight channel. By straightening the channel it means that flood water would flow away from the town much more quickly.

Question 48

Why was the river bed deepened?

Answer 48

As it allows for a greater capacity of water

Question 49

What type of engineering uses natural features of a river to reduce flood risk?

Answer 49

Soft engineering

Question 50

What would happen to the Somerset Levels without flood defences?

Answer 50

They would be flooded twice a month by high spring tides

Question 51

How have people managed this landscape?

Answer 51

People have managed this landscape by dredging the rivers - removing silt and mud so the river channel can carry more water.

Question 52

What caused the 2014 floods in the Somerset Levels?

Answer 52

High rainfall that saturated soils Rivers backing up at high tide

Question 53

What is land use zoning?

Answer 53

When low-value land uses are not protected by flood walls These zones provide safe areas for water to be stored during a flood event so that water is kept away from more valuable land uses such as homes.

Question 54

What was the purpose of the demountable flood barriers in Shrewsbury?

Answer 54

To hold back flood water during flood events