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HB C in CM > HB RR > Flashcards

HB RR Flashcards

1
Q

River Processes include (3 stages)

A

Erosion, transportation and deposition

and all depend on the amount of energy in the river.

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2
Q

Erosion happens near its source. Surface run-off and throughflow cause erosion at the point where the water enters the valley head. This erosion is called

A

Headward erosion

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3
Q

Gravity and the weight of water flowing downhill – causes erosion of the bed and banks making the river wider, deeper and longer - erosion caused by

A

The energy in a river

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4
Q

Erosion that makes a river channel deeper. This happens more in the upper stages of a river

A

Vertical erosion

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5
Q

Erosion that makes a river wider. This occurs mostly in the middle and lower stages of a river.

A

Lateral erosion

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6
Q

There are four main processes of erosion that occur in rivers. These are:

A
  1. hydraulic action
  2. abrasion / corrasion
  3. attrition
  4. corrosion
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7
Q

The force of the water hits river banks and then pushes water into cracks. Air becomes compressed, pressure increases and the riverbank may, in time collapse breaking away rock particles from the river bed and banks

A

Hydraulic action

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8
Q

The sediment carried by a river scours the bed and banks. Where depressions exist in the channel floor the river can cause pebbles to spin around and turn hollows into potholes.

A

Abrasion / Corrasion

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9
Q

River water is swirled around in irregularities in the river bed creating

A

vertical eddies

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10
Q

Rocks get swept into small depressions and abrade the hollow. These rocks are called

A

Grinders

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11
Q

Eroded rocks collide and break into smaller fragments. The edges of these rocks become smoother and more rounded.

A

Attrition

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12
Q

Carbon dioxide dissolves in the water to form a weak acid which dissolves rock by chemical processes, particularly where carbonate rocks such as limestone and chalk are present in a channel. This can lead to characteristics like sink-holes, pot holes, caves and gorges.

A

Corrosion / Solution

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13
Q

Transportation of material in a river begins when it has been loosened by erosion is transported along the river. There are four main processes of transportation. These are:

A
  1. suspension
  2. solution
  3. saltation
  4. traction
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14
Q

Very fine particles of material such as clay and silt are lifted as the result of turbulence and transported by the river

A

Suspension

Faster-flowing, turbulent rivers carry more suspended material making the river appear muddy

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15
Q

Dissolved minerals are carried by a river.

A

Solution

This often happens in areas where the geology is limestone and is dissolved by slightly acidic water

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16
Q

Material like pebbles and gravel that are too heavy to be carried in suspension bounce along the river by the force of the water

A

Saltation

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17
Q

When large materials such as boulders are rolled and pushed along the river bed by the force of the river

A

Traction

Sometimes this only happens when the river is in spate or very full and not at other times.

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18
Q

The total load a river can transport at a given point

A

The capacity of a river

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19
Q

The process of the eroded material being dropped when a river loses energy

A

Deposition

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20
Q

A river can lose its energy when (5)

A
  1. Rainfall reduces
  2. Evaporation increases
  3. Friction close to river banks and shallow area
  4. Flatter areas
  5. Meets the Sea
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21
Q

The Hjulström curve shows the

A

relationship between river velocity and competence

It shows the velocities at which sediment will normally be eroded, transported or deposited

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22
Q

The maximum particle size of load a river is able to carry at a particular point

A

The competence

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23
Q

The total volume of material a river can transport

A

The capacity

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24
Q

Energy in a river is determined by three factors:

A
  1. mass of water
  2. the height of the river above sea level
  3. the gradient of the channel
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25
Q

Friction with the bed and banks and turbulence reduces

A

energy

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26
Q

Water with a more turbulent flow can transport more

A

sediment

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27
Q

Velocity is affected by three main factors:

A
  1. channel slope
  2. roughness of the channel’s bed and banks
  3. channel shape in cross-section (width)
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28
Q

canalise rivers with concrete walls to get them to move the water away from vulnerable areas quicker but this can actually cause other problems up or downstream such as (2)

A

siltation or flooding

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29
Q

A range of river elements can be measured. These include (5)

A
  1. changes in depth and width of rivers
  2. the type of bed load (size/roughness etc)
  3. stream gradient
  4. channel profiles
  5. channel and flow characteristics
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30
Q

The long profile of a river shows

A

changes in the height (altitude) of the course of a river from its source to its mouth

the slope becomes more gentle towards the mouth of the river. Long profiles usually have irregularities such as waterfalls or lakes.

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31
Q

The upper course is typified by what shaped valleys

A

V-shaped

The river usually occupies most of the narrow valley floor

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32
Q

The landforms of a V-Shaped valley are (5)

A
  1. Uneven
  2. Steep river bed
  3. Rapids
  4. Waterfalls
  5. Large boulders
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33
Q

The processes of a V-Shaped valley are (3)

A
  1. Vertical erosion
  2. Large boulders transported (heavy rain), some suspension and solution
  3. Large bedload deposited
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34
Q

The middle course or a river is typified by

A

the valley becoming wider (meandering). Flood plains are common

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35
Q

The landforms of a middle course are (3)

A
  1. Small meanders
  2. Small flood plains
  3. Rapids
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36
Q

The processes of a middle course are (3)

A
  1. Lateral erosion begins, mostly attrition, some hydraulic
  2. Traction and suspended load increases. Some solution
  3. Deposition on slip off slopes
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37
Q

The lower course of the river tends to carry

A

a large amount of sediment and large scale deposition occurs

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38
Q

The lower course of a river is typified by

A

it being very wide

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39
Q

The landforms of a lower course are (3)

A
  1. Levees
  2. Large meanders
  3. Floodplains
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40
Q

The processes of a lower course are (3)

A
  1. Small particles deposited, levees and slip off slopes formed
  2. Small bed load, most in suspension
  3. Erosion limited - lateral, outside of meanders
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41
Q

A meander is

A

a winding curve or bend in a river

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42
Q

River cliffs or bluffs form (where)

A

on the outside of meanders

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43
Q

Ox-bow lakes dry up to form

A

wetlands or other habitats

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44
Q

There are 5 stages in creating a meander

A
  1. Pathways cut in straight river, flow swings from side to side
  2. Undercutting and deposition - doesn’t get wider
  3. Continued erosion along outer bank - River cliff / bluff and point bars
  4. Meanders continue to form through helicoidal flow
  5. Erosion is greatest beyond the middle bend in the meander - migrate downstream over time.
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45
Q

Areas of much deeper water and lower current velocities

A

Pools

They provide species with deep-water protection and food owing to the organic matter that accumulates on the river bed. These are where to look for larger fish and otters and kingfishers seek out these areas.

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46
Q

Form where shallow water with high velocity flows over gravel or cobble material, creating a broken water surface

A

Riffles

home to animals that cling well and are favoured by fish as a feeding area, for shelter from predators because of the broken water surface, and by salmon, lamprey or trout as the sites of their egg nests (redds) due to the well-oxygenated water

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47
Q

A gently sloping deposit of sand, gravel and pebbles

A

Point bar

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48
Q

As the surface flow of water hits the outer bank it corkscrews, flows along the river bed then deposits eroded material on the inner bank

A

Helicoidal flow

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49
Q

Deposited load on the floodplain is known as

A

Alluvium

is rich in nutrients and leads to floodplains often being used for farming

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50
Q

Floodplains become wider when

A

there is a significant amount of meander migration as the width of the floodplain is determined by the sinuosity of the river and the amount of meander migration that takes place

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51
Q

A braided channel is one that is divided into smaller channels by temporary islands called

A

eyots

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52
Q

Braided channels tend to form in rivers that have a significant amount of (3)

A
  1. sedimentary load
  2. a steep profile
  3. where discharge regularly fluctuates
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53
Q

Deltas are landforms formed at the mouth of a river where

A

the river meets a body of water with a lower velocity than the river (e.g. a lake or sea), resulting in the reduction in the river’s capacity to transport sediment.

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54
Q

Deltas are dynamic areas that change quickly due to the

A

erosion of unstable land during storm and flood events and the creation of new land

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55
Q

Clay sediment particles stick together, gain in mass and sink so increasing the deposition of sediment

A

flocculation

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56
Q

River habitat includes

A

aquatic and terrestrial areas

often changing over short distances and timescales owing to the dynamic nature of rivers

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57
Q

Planning river conservation and restoration actions is influenced by the

A

river biodiversity and its value in the river system

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58
Q

Rivers are subject to a wide range of pressures including (4)

A
  1. point source and diffuse pollution
  2. water abstraction
  3. invasive plant and animal species
  4. physical modification
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59
Q

Rivers cover what % of the earths surface?

A

less than 1%
less than 0.01% of surface water, freshwater environments

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60
Q

The communities of plants and animals associated with rivers are rich and varied, owing to the

A

wide variety of shelter, breeding and feeding opportunities

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61
Q

River habitats are underpinned by the underlying (2)

A

geology and climate

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62
Q

A patchwork of linked habitats called a

A

habitat mosaic

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63
Q

Habitats intimately connected to rivers include (5)

A
  1. associated wetland areas
  2. swamps and fens
  3. bogs and mires
  4. floodplain meadows
  5. wet woodland
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64
Q

At a larger scale, a river reach can be defined as

A

a length of river that supports a characteristic assemblage of these habitat units

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65
Q

Succession in river-bank plant communities typically develops

A

scrub and woodland

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66
Q

Disturbance (e.g. due to floods) plays a vital role in structuring river communities and maintaining

A

high biodiversity

Disturbance can shift an ecosystem from one persistent state to another e.g. by restructuring an established vegetation community

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67
Q

Nutrient cycling is the reuse, transformation and movement of essential nutrients in the river system. The cycles of 3 nutrients are especially important

A

phosphorus, nitrogen and carbon

their relative scarcity in fresh waters and their influence on rates of algal growth

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68
Q

Nest digging by an individual salmon depending on the species and size, can disturb up to how much of the stream bed area, releasing sediment and nutrients that are deposited downstream

A

17 m2

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69
Q

Formed by vertical flow over bedrock, boulder or cobble river beds

A

Waterfalls

Spray creates wetland habitat favoured by organisms that need cool, damp conditions, such as mosses and lichens, as well as specialist beetle, stonefly and caddis species

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70
Q

Have a relatively steep gradient, with high water velocity creating torrential conditions. Large boulders provide shelter from high velocities for invertebrates and fish

A

Rapids and cascades

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71
Q

Areas of deep water with a smooth surface and intermediate flow velocities, often with gravel or sand river-beds

A

Glides

tend to have lower species richness and diversity than riffles, and are often occupied by aquatic plants

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72
Q

Wet areas linked to the main channel but with little or no flow during average weather conditions

A

Backwaters

shelter sites for adult fish, essential breeding habitat for dragonflies and important nursery areas for lampreys

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73
Q

Aquatic macrophyte (large plants) beds create complex habitats by forming physical structures that (3)

A
  1. affect flow patterns
  2. trap sediments
  3. raise nutrient and oxygen levels
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74
Q

Adding ….. Improves water quality, stabilise sediments and increase the diversity of physical habitat types within the stream.

A

Tree roots and in-stream woody material

Accumulations of wood slows the water flow, creating pools and eddies where fish can rest, hide from predators and avoid direct sunlight. They also provide a surface for algae, fungi, bacteria, plants and insects to colonise

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75
Q

Is important for plants and invertebrates (notably ground beetles, spiders and craneflies). This habitat is important for conservation because it supports a diverse range of species, including several specialists as well as many that are rare and endangered.

A

Exposed sediment

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76
Q

An important source of food and shelter for aquatic species and support many terrestrial organisms, including bats and a wide range of bird species. Many of the plants and trees specialise in living in damp ground.

A

River-bank (riparian) vegetation

Communities range from mature woodland to species-rich grasslands

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77
Q

Provide which specialist habitat that are scarce in the wider landscape

A

River banks

Steep banks are used by otters for their holts and water voles for their burrows. Nesting sand martin colonies also use eroded river banks.

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78
Q

Favoured by wading birds, amphibians and dragonflies, and provide an important source of food for bats and reptiles

A

Floodplain water features

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79
Q

Floodplain water features are (6)

A
  1. bogs
  2. flushes
  3. oxbow lakes
  4. wet woodland
  5. reedbeds
  6. permanent wetlands
80
Q

Evolved from hay pastures, a previously common feature of river valleys

A

Floodplain meadows

81
Q

Floodplain meadows have declined in the last 50 years due to (3)

A
  1. agricultural intensification
  2. building development
  3. lack of management
82
Q

Floodplain meadows are important as (4)

A
  1. flood storage areas
  2. high nature conservation value - floral diversity
  3. provide nectar for a range of insects
  4. important early indicators of environmental change
83
Q

A river or stream with a greater range of habitats generally supports

A

a greater diversity of organisms because it offers opportunities for different life stages and varied food and sheltering opportunities.

84
Q

A primary goal of many river restoration projects is

A

Developing a wide range of habitats.

ideally achieved by allowing the river to develop naturally its full characteristic habitat mosaic

85
Q

The region of sediment and porous space beneath and alongside a stream bed, where there is mixing of shallow groundwater and surface water

A

Hyporheic zone

86
Q

Species that specialise in water habitats (8)

A
  1. Daubenton’s bat
  2. Otter
  3. Dipper
  4. Emperor Dragonfly
  5. Fresh Pearl Mussel
  6. Atlantic Salmon
  7. White-clawed crayfish
  8. Caddis fly
87
Q

Rivers themselves are hard to conserve because (2)

A
  1. often the focus of so much human activity
  2. often cross many countries
88
Q

Rivers face direct impacts from man (modifications) such as (5)

A
  1. dredging
  2. damming
  3. channelising
  4. widening
  5. weirs

where the river features themselves are altered to suit man’s needs such as flood prevention, navigation, fishing and water abstraction

89
Q

Rivers face indirect impacts by man such as (3)

A
  1. pollution
  2. siltation from run-off from agriculture
  3. excessive run-off from human settlements
90
Q

Rivers are subject to a wide range of pressures including (4)

A
  1. physical modification
  2. water abstraction
  3. point source and diffuse pollution
  4. invasive plant and animal species
91
Q

Restoration actions aim to restore rivers to

A

their natural state, restore biodiversity and the key ecosystem services that society depends on such as the provision of clean drinking water and the natural management of flood risk

92
Q

The rivers of the UK and Republic of Ireland have a long history of alteration by humans for (6)

A
  1. navigation
  2. water and food supply
  3. waste disposal
  4. flood defence
  5. settlement
  6. power generation
93
Q

The first human influences can be traced back to Neolithic times - how many years ago

A

6,000 years ago

when vegetation clearance for agriculture accelerated water runoff and sediment input

94
Q

Based on River Habitat Survey (RHS) data in England and Wales combined, how much % of rivers have been physically modified through reshaping and reinforcement?

A

more than 50%

Scotland the figure is 17%
Northern Ireland more than 50% of lowland rivers

95
Q

Channelisation involves (2)

A
  1. the straightening, diversion and deepening of natural rivers
  2. the creation of artificial channels
96
Q

Channelisation aids (3)

A
  1. navigation
  2. improves drainage of agricultural land
  3. reduces the frequency of flooding locally
97
Q

Channelisation activities were accelerated in the last two centuries by mandates such as (2)

A
  1. the Arterial Drainage Act (1945) in the Republic of Ireland
  2. the Enclosure Acts of the mid-18th Century in England
98
Q

Channelisation activity reached its peak during the mid-20th Century resulting in how many km of channelised river network in England and Wales?

A

8,504 km

99
Q

Channelised rivers cannot sustain varied habitat for different invertebrate communities and juvenile fish because

A

they have uniform shapes and river-bed sediment that create a lack of flow variability.

100
Q

Channelised rivers can exacerbate flooding downstream because (2)

A
  1. Loss of temporary floodplain water storage,
  2. combined with the straight nature of channels that accelerate flow.

Disconnect rivers from their floodplains which reduces the frequency of water and matter exchange with the floodplain (e.g. nutrient rich sediment).

101
Q

Channelised rivers are maintained by

A

regular dredging

102
Q

What bad effects does dredging have? (3)

A
  1. immediate alteration of habitat
  2. Increased fine sediment loads - lead to the downstream siltation of substrates that can clog the redds (egg nests) of salmon and trout.
  3. deprive hyporheic macroinvertebrate communities of oxygen (e.g. white clawed crayfish)
103
Q

Gravel extraction from rivers is still widely practised to

A

reduce local flood risk

104
Q

What bad effects does gravel extraction have? (3)

A
  1. alter the natural sizes of sediment and shape of a river
  2. associated habitat can be slow to recover, depending on the flow and sediment supply regimes
  3. extraction can create conditions that erode the river bed and banks
105
Q

The practice of ‘de-snagging’ (removing wood from rivers) was used extensively in order to (4)

A
  1. improve navigation
  2. was thought to reduce flood risk
  3. aid fish migration
  4. assist drainage
106
Q

Rivers without large wood tend to be (3)

A
  1. wider
  2. straighter
  3. less biodiverse

Although accumulations of wood can increase local flood risk by redirecting water onto floodplains, this can reduce flood peaks downstream.

107
Q

Weirs were built to create ponds to supply water for (3)

A
  1. mills
  2. industry
  3. irrigation

Locks that are used to aid river navigation have a similar effect to weirs

108
Q

Weirs significantly alter the natural character of rivers, especially in England and Wales where there are how many impoundments?

A

25,000

Although a proportion of the flow is able to pass over such structures, the natural movement of water and sediment are disrupted.

109
Q

What are the impacts of weirs? (3)

A
  1. Upstream of weirs, uniformly deep water submerges exposed bar and riverbank habitat - reduces the abundance of certain aquatic plant communities
  2. create unnaturally ‘flat’ or stepped river profiles that lead to silt deposition and attendant problems such as heightened nutrient storage
  3. the obstruction of species movement upstream and downstream
110
Q

An estimated ?? km of Atlantic salmon spawning habitat is inaccessible due to weirs in Scotland?

A

5,400

111
Q

Flow deflectors and rubble mats designed to

A

improve habitat for fish

112
Q

Croys and groynes are no longer favoured measures because

A

they deflect the flow and alter the natural patterns of erosion and deposition which may degrade habitat

113
Q

In some steeper rivers with coarse beds, boulders have been removed to construct deflectors leading to a loss of (3)

A
  1. in-channel flow diversity
  2. shelter
  3. range of river-bed sediments

important for macroinvertebrate communities and fish

114
Q

Artificial reinforcement of banks are made using (4)

A
  1. boulders
  2. timber
  3. rubble
  4. concrete
115
Q

Artificial reinforcement of banks aim to (2)

A
  1. reduce channel movement to protect land, settlements or infrastructure (e.g. bridges and roads)
  2. to limit sediment input from eroding banks
116
Q

What % of all RHS sites in lowland areas of the UK, have banks been reinforced?

A

63%

117
Q

Negative effects of bank protection include (4)

A
  1. restricting a river’s natural ability to erode and shift in response to floods
  2. channel narrowing leading to increased water velocities that can in turn erode river beds
  3. construction can lead to immediate loss of bankside habitats for example those used by water vole, sand martin, kingfisher and juvenile fish
  4. a reduction in the channel and floodplain complexity needed to create diverse habitat
118
Q

Flood embankments or levees built using earth or concrete are designed to

A

prevent rivers naturally spilling onto their adjacent floodplains

119
Q

It is estimated that embankments reduced floodplain water storage and increased peak flows downstream by %

A

50-150%

120
Q

Owing to vegetation clearance it is estimated that what % of the total bank length of rivers in England and Wales has no or very little bankside tree cover

A

25%

121
Q

Species-rich floodplain meadows are also a very rare type of habitat with how many ha remaining in England?

A

1500

122
Q

Accelerated runoff from urban development can lead to

A

river channel erosion and enlargement creating unnatural river morphology and habitat

123
Q

The diversity of algal, invertebrate and fish communities can be adversely affected by (2)

A
  1. degraded water quality and unnatural flow regimes when the area of impervious surfaces approaches 10% of the catchment area
  2. Diffuse sediment input from areas used for agriculture, increases sediment yields leading to problems of river-bed siltation and altered morphology
124
Q

Common invasive plants that inhabit river banks are (3)

A
  1. Japanese Knotweed
  2. Himalayan Balsam
  3. Giant Hogweed
125
Q

Common invasive plants that inhabit river banks cause physical alteration to the river by (4)

A
  1. plants die in the winter
  2. bare earth is exposed
  3. more prone to erosion
  4. excessive deposition of fine sediment in rivers
126
Q

Invasive aquatic macrophytes are also highly damaging by

A

slowing flows and trapping sediment

127
Q

Invasive aquatic plant species include (3)

A
  1. Azolla
  2. Lemna
  3. Floating Pennywort
128
Q

Invasive aquatic plant species cause problems by (4)

A
  1. chokes waterways deterring angling
  2. boating/navigation
  3. obscuring light to the water below which affects the water life beneath it.
  4. Animals can mistake it for solid ground and risk drowning
129
Q

American signal crayfish cause problems by (2)

A
  1. spreading crayfish plague
  2. they can alter in-channel habitat by digging burrows that can undermine river banks, loosen substrate and in turn increase sediment loads downstream

The Chinese mitten crab is also highly disruptive and can destabilise river banks through burrowing

130
Q

Rivers are vulnerable to climate change as they are

A

highly sensitive to altered temperature and precipitation regimes

131
Q

Climate change will have what effects on rivers

A

more frequent extreme flows that could affect physical habitat stability as well as water quality.

These effects alter habitat, species abundance, composition and distribution and the connectivity between water bodies

132
Q

How many dams are there in UK and Ireland?

A

596 dams in the UK
16 in the Republic of Ireland

133
Q

The physical effects of Dam building are (3)

A
  1. fragment rivers and disrupt the natural movement of water, sediment and biota
  2. submerging upstream areas
  3. disruption of the natural flow variability needed to trigger certain ecological behaviour - river health is severely degraded
134
Q

A reduction in floods have what effects? (4)

A
  1. unable to transport sediment and re-generate habitat
  2. channel narrowing, reducing the habitat area available for spawning salmonids
  3. stabilise mobile gravel bars and increase riparian vegetation cover, but with a lower species diversity than an unregulated river
  4. reduction of sediment supply, that can lead to the development of ‘armoured’ river beds.
135
Q

How many dams are on the planet?

A

2.8 million

136
Q

Most of the remaining free-flowing rivers are confined to the less populated remote parts of the planet, including (3)

A
  1. the Arctic
  2. the Amazon
  3. the Congo basins
137
Q

The aim of river restoration is to

A

increase resilience and assist recovery by addressing hydrological, morphological, biological, chemical and societal issues within the catchment

138
Q

River ecosystem Services (5)

A
  1. Water supply
  2. Flood water & carbon storage
  3. Biodiversity
  4. Recreation
  5. Raw material and food supply
139
Q

River ecosystem pressures (5)

A
  1. Urbanisation
  2. Point source pollution
  3. Water abstraction
  4. Diffuse pollution
  5. Channelisation
140
Q

Benfefits to people of restoring rivers are (4)

A
  1. better water quality
  2. improved biodiversity
  3. water supply security
  4. reductions in flood risk and pollution
141
Q

The rehabilitation and restoration of floodplains and river wetlands… (6)

A
  1. improves water quality
  2. helps to retain and slowly release discharge from water bodies
  3. facilitates groundwater recharge
  4. seasonal aquatic habitats
  5. corridors of native riparian forests
  6. shaded riverine and terrestrial habitats
142
Q

River wetlands can also help in maintaining the functioning of estuarine and delta ecosystems and creating

A

natural land features that act as storm buffers

143
Q

NWRM

A

Natural Water Retention Measures

Retention areas are meant to receive the peak discharge of rivers and therefore to prevent flooding elsewhere

144
Q

The Water Framework Directive and the Habitats Directive are major drivers for

A

restoration and sustainable water management in the UK

145
Q

When planning river restoration we need to think on different scales: (4)

A
  1. Catchment scale – looking at the whole river system and all the issues such as pollution, siltation, flooding, canalization that have occurred within the whole catchment of the river.
  2. Reconnecting rivers with their floodplains – wetlands and floodplains are very rare habitats but they are also very valuable in preventing flooding upstream, slowing silt reaching the sea and allowing for rising sea levels due to climate change
  3. Restoring river meanders – straightened rivers are more prone to breaking their banks and flooding and have a lack of habitats and biodiversity
  4. In-stream enhancements – on a smaller scale things like woody debris, deflectors or bankside vegetation can be added. This might be all you can do in urban areas where major changes to the river cannot take place
146
Q

Connectivity is the

A

continuous flow of water, organisms and energy through a watershed

When connected, rivers function like superhighways, linking land, freshwater and ocean habitats and transporting water and nutrients between them

147
Q

Freshwater species populations have declined an average of how much % since 1970?

A

84%

fragmentation, pollution and over-extraction of water

148
Q

Anadromous fish move between

A

rivers and the ocean (Salmon)

149
Q

There are human consequences, too from river degradation and loss of biodiversity these are: (3)

A
  1. Freshwater fisheries - barriers reduce the water quantity and flow of nutrients these fisheries require.
  2. stagnation in larger reservoirs and the release of methane, a potent greenhouse gas
  3. stealing the ground from beneath their communities feet. Dams prevent the downstream flow of the sediments that build and replenish deltas
150
Q

River degradation and loss of biodiversity are caused by (4)

A
  1. hundreds of thousands of dams around the world
  2. overfishing
  3. climate crisis
  4. water pollution
151
Q

There are various ways that pollutants end up in rivers including (5)

A
  1. sewage plants
  2. storm drains
  3. agricultural run-off (silt, pesticides, herbicides, fertilisers, slurry)
  4. industrial effluent
  5. wastewater from urban development
152
Q

There are many steps we can take to improve the water quality of our streams, such as (9)

A
  1. Control farm contaminants – diffuse and direct
  2. Plant trees to reduce land run-off
  3. Remove or mitigate possible limiting factors, which will prevent natural recovery of the area e.g. point source discharges from factories etc
  4. Manage stock more efficiently e.g. by fencing off streams to reduce direct water contamination
  5. Take care when applying fertilisers and pesticides
  6. Be aware of water table depth and avoid overusing water in dry seasons
  7. Retire land from unsuitable uses or change land uses (e.g. pasture to forest)
  8. Careful planning of urban growth - minimal impact on neighbouring waterways.
  9. Continued control or removal of invasive species or pests
153
Q

NFM

A

Natural Flood Management

154
Q

WWNP

A

Working with Natural Processes

to reduce flood and coastal erosion risk involves implementing measures that help to protect, restore and emulate the natural functions of catchments, floodplains, rivers and the coast

155
Q

Natural Flood Management aims to

A

reduce the maximum water volume of a flood (the peak flood flow) and/or delay the arrival of the flood peak downstream increasing the time available to prepare for floods.

156
Q

Natural Flood Management uses 4 key, underlying physical mechanisms

A
  1. Increasing storage: creating temporary storage e.g. reconnecting functioning floodplains and creating storage ponds
  2. Increasing catchment and channel roughness: this ‘slows the flow’ e.g. planting trees and hedgerows, restoring meandering rivers and installing leaky dams
  3. Increasing losses: this increases the amount of water that drains (infiltrates) into the ground or is lost back into the atmosphere via evapo-transpiration (e.g. agricultural practices to improve soil structure and installing sustainable urban drainage systems
  4. De- synchronising peak flows from tributaries: Slowing down one tributary compared to another can significantly reduce flood peaks downstream.
157
Q

SUDS

A

Sustainable Urban Drainage Systems

158
Q

A successful natural stream restoration project requires following a multi-step process (4)

A
  1. to define the objectives - flood control, improving water quality, improving recreation, improving habitat and biodiversity, or reducing bank erosion
  2. assess current condition of the stream
  3. determining the best course of action - A potential solution is to allow the stream to fix itself. This option may include doing nothing or removing stressors such as livestock or mowed stream banks
  4. stream restoration design and construction involves reshaping the stream channel and floodplain, building in-stream structures, and protecting the bank
159
Q

Observations to assess current condition of the stream (4)

A
  1. noting any downcutting or widening
  2. the amount, type, and condition of bank vegetation
  3. changes in the watershed upstream
  4. features downstream that are constricting flow
160
Q

A re-vegetation plan for a river bank should include (3)

A
  1. a list of native plants to be used
  2. planting locations and timeline
  3. a monitoring and maintenance strategy
161
Q

In-stream structures that stabilize the stream slope to prevent erosion caused by downcutting and widening

A

Rock vanes

They also shift the flow of water away from the bank to the centre of the stream, where a scour pool is developed that dissipates energy and provides fish habitat

162
Q

Several variations of rock vanes exist (3)

A
  1. rock riffles (diagonally placed rocks that go less than halfway into the stream)
  2. cross-vanes (extends from bank to bank)
  3. J-hooks (rock structure built in the shape of a J)
163
Q

A rootwad / Toe wood consists of (4)

A
  1. a tree’s root mass and 10 to 15 feet of trunk
  2. placed on the outside bend of a meander installed with the trunk portion entrenched in the stream bank with the root ball exposed to the stream.
  3. Vegetation is added on top of the structure for erosion protection and habitat
  4. used when stream bank sloping is not an option, typically on vertical banks
164
Q

Benefits of large wood debris in a river include (10)

A
  1. Stabilises river banks and beds.
  2. Increases floodwater storage.
  3. Provides habitats for fish.
  4. Provides niche habitats – adds to the complexity of the river and the sediments creating new habitats.
  5. Provide splits and hollows for invertebrates to hide
  6. Supports up to 147 invertebrate species including dragonflies and mayflies
  7. Provided cover for mammals like otters and perches for birds like dippers and kingfishers.
  8. Improves water quality
  9. Improves recolonisation of species and protects against drying out or freezing
  10. Stores carbon in the wood itself as well as the sediments it traps
165
Q

Benefits of beaver dams (6)

A
  1. Increase in riparian vegetation
  2. Increase in channel aggradation
  3. Increase in Dam persistance
  4. Increase in fish habitat complexity - pools / gravels
  5. Increase in floodplain reconnection
  6. Decrease in stream temperature
166
Q

Paleochannels show the

A

historic location and form of the river

167
Q

An actively meandering channel will exhibit natural processes and features such as

A

erosion and deposition

168
Q

A passively meandering channel will show the form of a meandering river, but

A

none of the processes and forms of an active river

169
Q

The most suitable restoration option for a weir will depend on a number of factors these include (6)

A
  1. the structural make-up of the weir
  2. the condition of the river upstream and downstream
  3. the aims of the catchment plan
  4. the surrounding land use
  5. funding
  6. the presence of protected structures and habitats
170
Q

Hierarchy of actions to restore natural river processes high (best) to low (minimal action): (4)

A
  1. Re-meander
  2. Remove the weir
  3. Bypass / modify the weir
  4. Install a fish pass
171
Q

The degree to which a river can be free to adjust, or needs to be constrained, is heavily dependent on

A

site and catchment characteristics

172
Q

A weir is a barrier built-in river to (4)

A
  1. change the depth of flow
  2. alters the floor height of the river
  3. used to control the velocity of flow during high discharge
  4. also called a small-dam to store water in a small area
173
Q

The most suitable restoration option for a weir will depend on a number of factors: (7)

A
  1. the structural make-up of the weir
  2. the condition of the river upstream and downstream
  3. the aims of the catchment plan
  4. the surrounding land use
  5. funding
  6. the presence of protected structures and habitats
174
Q

Before selecting a bank protection technique, it is important to understand and identify the cause of the issue and type of bank erosion. This includes looking at (4)

A
  1. the energy of the river
  2. surrounding land use
  3. bank cohesion
  4. any structures or modifications that may be causing the problem
175
Q

Coir log is a natural fibre product designed to

A

provide soil stabilization and support along river banks, slopes, steams, hillsides, and other erosion prone areas

176
Q

Coir logs are versatile and can be used in many applications (9)

A
  1. Drain protection to slow water velocity
  2. Sediment control
  3. Riverbanks and toe protection
  4. Steep batters and sand dunes
  5. Building sites
  6. Wetland erosion
  7. Coastal wave erosion
  8. Sand bank regeneration
  9. Soil amendment
177
Q

Willow spiling is a

A

traditional technique used for the prevention of erosion to river and stream banks.

Live willow rods are woven between live willow upright stakes which have been driven into the river bank. The willows then grow and their roots help slow flows and stabilise the banks.

178
Q

Natural flood management measures within a river catchment aim to: (2)

A
  1. reduce the rate or amount of runoff; and/or
  2. improve the ability of rivers and their floodplains to manage flood water
179
Q

Natural Flood Management techniques include: (6)

A
  1. Breaching flood banks
  2. Floodplain wetland mosaic
  3. Floodplain spillways
  4. Land profiling
  5. Removing and setting back flood banks
  6. Floodplain scrapes
180
Q

Instream construction during the spring (March 15 to July 31) and Autumn (September 15 to November 30) may need to be restricted to

A

minimize impacts to fish spawning

181
Q

Broadly the process of river restoration involves the following stages: (6)

A
  1. Understanding the catchment
  2. Pressure and impact assessment
  3. Identify options
  4. Set catchment objectives
  5. Prioritise options
  6. Who to involve/permissions
182
Q

The starting point for planning any river restoration project is to understand your catchment using (3)

A
  1. River Habitat Survey
  2. MoRPH
  3. Fluvial Audit
183
Q

What is MoRPh?

A

a tool developed for citizen scientists to record information about local physical habitat conditions at a scale that complements biological monitoring

184
Q

What is the River Habitat Survey?

A

a methodology for recording habitat features for wildlife that was designed by the Environment Agency

is a systematic collection of data associated with the physical structure of watercourses. Data collection is based on a standard 500 m length of river channel. Map information is collected by doing a desk study for each site and includes grid reference (or latitude, longitude), altitude, slope, geology, height of source and distance from source

185
Q

What is a Fluvial Audit?

A

Fluvial Audit is a technique aimed at providing catchment wide geomorphological information to develop solutions to river management problems for a range of functions (e.g. water resources, flood risk management, fisheries). Fluvial Geomorphology is becoming an increasingly established discipline in managing river and floodplain form and behaviour.

186
Q

A river’s energy is a function of the discharge, channel slope and channel dimensions and is often expressed as

A

stream power

187
Q

A reference condition of a river is

A

the expected state of the river if modifications and impacts were not present. This is also known as the seminatural condition

188
Q

The main aspects that you need to consider for maping reference conditions are (6)

A
  1. Natural environmental processes (e.g. hydrological, geomorphological, ecological)
  2. Existing development, land ownership and future development plans
  3. Functional use (e.g. conservation, amenity, flood risk management, angling)
  4. Local site conditions (e.g. existing flora and fauna, river flows and levels, sediment movement, geotechnical)
  5. Operational window of opportunity (e.g. weather, funding budget, fishing, bird-nesting)
  6. Relevant policies, strategies, designations and regulation
189
Q

Pressure and Impact Assessment

A

A pressure is the cause of an issue (e.g. channel realignment), whilst an impact is the end result (e.g. poor habitats).

190
Q

SMART

A

Specific
Measurable
Attainable
Relevant
Time-Bound

191
Q

Making successive interventions to optimise or modify the restoration works is referred to as

A

adaptive management

192
Q

It is estimated that how much of global rivers are free-flowing?

A

around one-third

193
Q

The build-up of sediments and reduction in water flow can lead to

A

algal blooms and reductions in water quality

194
Q

In England and Wales, what % of freshwaters (excluding headwater streams, ditches, and ponds) fail to meet the minimum standards for Good ecological quality?

A

75%

195
Q

What % of our natural wetlands have we lost in Britain?

A

90%

196
Q

What ecosystem services do Beavers provide?

A
  1. reduce flooding
  2. lessen the impact of drought
  3. engineer a mosaic of habitats
  4. improve water quality

HB C in CM (9 decks)

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