Physical- Rivers Flashcards

Question

What is equilibrium?

Answer 1

The volume of the liquid stays the same as does its state and energy.

Answer 2

No overall change in the store of energy and matter.

Answer 3

A system that is balanced but is constantly changing e.g. erosion. It is a sate of stability that changes through time. e.g. river

Answer 4

A closed system.

Answer 5

Geothermal energy | Short wave radiations of heat and light.

Answer 6

``` Ice and Snow Lakes Groundwater Atmosphere Oceans and Seas ```

Answer 7

Precipitation Advection Rivers Evaporation

Answer 8

Heat, light and sound.

Answer 9

A graph which shows variations in river discharge over a particular period of time and shows the response of a drainage basin and over a year may be called its river regime.

Answer 10

A graph showing how the discharge of a river at a particular point responded to a specific rainfall event.

Answer 11

The maximum flow of the river often in response to rainfall.

Answer 12

The length of time between peak precipitation and peak discharge.

Answer 13

The rapid increase in river discharge due to overland flow and throughflow.

Answer 14

The fall in river discharge due to the decline of overland flow and throughflow.

Answer 15

The normal discharge for a discharge which reflects seasonal changes. It is part of the river's discharge that is produced by groundwater seeping slowly into the river bed.

Answer 16

Highest amount of precipitation at a certain time.

Answer 17

The volume of flow of water passing a gauging station in a river at a particular time.

Answer 18

cumecs m3/s

Answer 19

meters/ second (m/s-1)

Answer 20

Velocity of water

Answer 21

Cross sectional area of a river.

Answer 22

1) Basin size, shape and relief 2) Precipitation 3) Temperature 4) Land use 5) Geology 6) Soil type 7) Drainage basin 8) Tides and storm surges

Answer 23

Small... Rainfall reaches channel quickly, so lag time will be short and the hydrograph will rise rapidly. Large...

Answer 24

Circular... Shorter lag time and higher peak flow because the points on the watershed are equidistant from the gauging station. Elongated...

Answer 25

Flooding often occurs following a long period of rainfall and the ground has become saturated and infiltration has been replaced by surface run-off. The effect on the hydrograph will be over a period of time.

Answer 26

When heavy rainfall occurs, the rainfall intensity may be greater than the storage capacity of the soil. As a result, surface runoff is likely to produce rapid rises (flash floods)

Answer 27

Convectional thunderstorms

Answer 28

Heavy snowfall means that water is held in storage and the river levels drop. When temperatures rise rapidly, meltwater soon reaches the river and if the ground is frozen infiltration will be impeded. If melting occurs over a longer period the response will be more subdued.

Answer 29

Extremes of temperature restrict infiltration and increase surface runoff. If evapotranspiration rates are high, then there will be less water available to flow into the main river.

Answer 30

Come BACK LATER!

Answer 31

A rock which contains numerous pores which can be stored with water e.g. sandstone or chalk

Answer 32

Pervious rock allows water to flow along bedding planes and down joints within the rock, although the rock itself is impervious

Answer 33

Carboniferous Limestone

Answer 34

Porous and pervious

Answer 35

Impermeable rocks e.g. granite do not allow water to pass through them so there is more surface run-off and a higher discharge

Answer 36

Soil type controls the speed of infiltration, amount of soil moisture storage and the rate of throughflow.

Answer 37

Sandy soils have large pore spaces and allow rapid infiltration preventing flooding.

Answer 38

Clay has much smaller pore spaces which reduces infiltration and throughflow, but encourages surface runoff and increases the risk of flooding.

Answer 39

This refers to the number of surface streams in a given area. The density is higher on impermeable rocks and lower on permeable ones. A higher density means a greater chance of flash flooding.

Answer 40

Shorter lag time and a higher peak flow in relation to normal discharge.

Answer 41

High spring tides prevent river flood from escaping to the sea and water therefore builds up. If high tide coincides with gale force winds, the result may be a storm surge.

Answer 42

South-East England in 1953 prompting the construction of the Thames Barrier

Answer 43

- Basin size - Basin shape - Basin density - Rock type

Answer 44

- Rainfall amount - Rainfall duration - Type of precipitation - Soil moisture levels

Answer 45

- River use- Industrial/ domestic - Land use- Rural/ urban - Surface water stores

Answer 46

1) Less rainfall interception 2) Low transpiration rates 3) Throughflow unimpeded by the shallow roots 4) Little impact on surface runoff 5) Higher discharge likely.

Answer 47

Industrial extraction/ Irrigation/ Domestic water supply extraction reduce water volume lowering the discharge

Answer 48

1) Increased impermeable surfaces and drains increase surface runoff. 2) Less vegetation means less interception 3) Higher discharge likely

Answer 49

- Steep rising limb | - High peak discharge

Answer 50

Gentle rising limb | Long lag time

Answer 51

A hydrograph showing the years worth of discharge

Answer 52

Potential energy and kinetic energy

Answer 53

Stored energy fixed by the altitude of the source of the stream in relation to base level

Answer 54

Energy due to movement , and is generated by the flow of the river which converts PE into movement.

Answer 55

- Discharge - Channel gradient - Average velocity

Answer 56

- The maximum size of particles that a river can transport - When velocity and energy levels are low the river can only transport smaller particles e.g. clay and silt. - When river levels are high, rivers can transport larger particles e.g. pebbles and boulders

Answer 57

- The total load (material) that the river actually transports at a particular discharge or energy level. - The capacity increases as the discharge increases. - The river is capable of carrying more sediment

Answer 58

- V shaped - Channel profile is approximately 1.5m across - Interlocking spurs

Answer 59

U shaped valley | Channel profile 5m

Answer 60

Wide and deep | 20m across

Answer 61

- Weathering - Vertical erosion - Headward erosion

Answer 62

- Lateral erosion | - Transportation

Answer 63

Deposition- flooding | Transportation

Answer 64

Rapids | Waterfalls and gorges

Answer 65

Levee Ox-bow lakes Delta Braided channel

Answer 66

The long profile

Answer 67

The breakdown and removal of the river bed and banks

Answer 68

Downwards erosion found in the upper course where rivers have large angular bedload.

Answer 69

Most common at the source and in the formation of gorges.

Answer 70

Dominate in the middle course where rivers meander from side to side.

Answer 71

1) River picks up material and rubs it along the beds and banks.

Answer 72

1) As bed load moves downstream, boulders collide with other material making the load smoother and rounder.

Answer 73

1) Force of the water

Answer 74

Rocks dissolve due to the acidity of the water e.g. Limestone and chalk

Answer 75

Diagram showing how the river changes as it moves downstream

Answer 76

Large particles such as pebbles and boulders are rolled along the river bed.

Answer 77

- Dissolved minerals carried in the body of the water e.g. Calcium and Sodium - Particles are invisible

Answer 78

Large particles like gravel are bounced along the river bed.

Answer 79

- Smaller particles such as silt, clay or fine sand are carried along in the body of the water without making contact with the beds or banks.

Answer 80

1) Velocity decreases 2) Less energy 3) Doesn't have competence or capacity to carry all its load. 4) Heaviest material deposited first

Answer 81

- Delta - Flooding - Levee - Snow

Answer 82

A diagram showing the relationship between erosion, transportation and deposition.

Answer 83

In winter particles stick together due to electromagnetic forces meaning they are heavier and require a higher velocity to move them (flocculation).

Answer 84

The energy available to overcome friction and move sediment.

Answer 85

When the river has just enough energy to transport the sediment available.

Answer 86

Deposition

Answer 87

Competence is size of the load. | Capacity is amount of load that the river can actually carry.

Answer 88

1) River widens and deepens 2) Capacity increases 3) Tributaries 4) Increased velocity

Answer 89

1) Lateral erosion 2) Potential energy- kinetic energy 3) Tributaries 4) Velocity

Answer 90

1) Tributaries 2) Velocity 3) Vertical erosion

Answer 91

1) Potential energy- kinetic energy

Answer 92

1) More velocity 2) Energy 3) Capacity

Answer 93

1) More energy=more erosion

Answer 94

1) Smoother and rounder rocks-erosion | 2) Efficiency increased

Answer 95

1) River meanders across land rather than erode it.

Answer 96

- Particles stick together due to electromagnetic forces meaning they are heavier and require a higher velocity to move them- FLOCEULATION

Answer 97

... very low

Answer 98

Rapidly as velocity falls

Answer 99

Only at high flows

Answer 100

The settling velocity

Answer 101

Internal friction due to the turbulence of the river itself.

Answer 102

Calculated by width x mean depth | Area of water

Answer 103

The perimeter of a rivers channel cross-section that is in contact with the water.

Answer 104

The ratio of the cross-sectional area of the channel and the length of its wetted perimeter. Calculated by Area/ wetted perimeter

Answer 105

There is less water in contact with the beds and banks therefore there is less frictional drag and a higher velocity.

Answer 106

More water in contact with the beds and banks results in more frictional drag and a lower velocity.

Answer 107

1) Formed when a small hollow or depression is created and pebbles or rocks become trapped inside them. 2) Material is swirled around the hole causing it to become larger due to abrasion- pothole drilling. 3) Hydraulic action and the force of the water also contribute to increase in size. 4) Over time, they may join together to create sudden drops in the channel gradient.

Answer 108

L- Bedrock of a river E- Upper course, Afon Glaslyn River S- 1cm-2m diameter S- Smooth and rounded

Answer 109

L- Sudden increase in channel gradient E- Aysgarth Falls, Yorkshire- 30m- 1 mile S- 1-2m in height, several hundred in length S- Series of small waterfalls

Answer 110

1) Small terraces of water 1-2m in height 2) Alternating hard and soft rock, occur when stream stream flow is restricted which increases the velocity of the water. 3) As water flows over boulders, the river can flow back on itself in the form of underwater currents and HA forms some deeper pools. 4) Turbulent flow also creates eddy currents in sheltered areas away from the main river channel. 5) Water depth is shallow near rock lips where velocity is fastest with deep pools below the resistant rock ledges.

Answer 111

1) Top section is made from a hard rock called Whinstone but underneath is a soft rock called carboniferous limestone. This is undercut as it erodes faster leaving an overhang at the top. 2) Plunge pool deepened over time by HA and abrasion 3) The continuous undercutting results in the collapse of the whinstone overhang. 4) Over time the process is repeated but because of headward erosion gradually retreats further upstream leaving a narrow, deep gorge in front of it. 5) Durham gorge 700m

Answer 112

L- Upper course, Durham E- High Force, River Tee S- 21m high, gorge 700m

Answer 113

1) Periods of high discharge= greater capacity and competence meaning more material is eroded and transported 2) Discharge decreases, material deposited, river develops a sequence of deep pools and shallow riffles 3) Water flows inefficiently over riffles, HR decreases as there is a high amount of friction which slows the river down. 4) To avoid areas of higher frictional contact the river goes around them. 5) The water becomes deeper as the HR is higher so there is less friction, increasing the speed, giving greater erosive power and forming pools.

Answer 114

6) At high flow the water flowing around the riffle will be propelled by centripetal force directing maximum velocity at one bank, resulting in undercutting due to abrasion and HA. 7) Outer, concave bank, which having been undercut forms a river cliff. At the same time deposition occurs on inside, convex bank where the water is slowest. This forms a slip-off slope giving an asymmetrical channel slope and causing the thalweg to move to the outside of the bend. 8) Doesn't become wider because erosion and deposition occur simultaneously but the sinuosity of the bend increases 9) Corkscrew like motion of water is known as the helicoidal flow. 10) Eroded material transported downstream, and deposited on the slip off slope on the inside of the next meander bend.

Answer 115

L- Middle/lower course e.g. Snowdonia E- Afon Glaslyn S- Asymmetrical channel S- Sinuous

Answer 116

1) River floods and water spills onto the floodplain increasing wetted perimeter. 2) Consequently, HR decreases as the river is less efficient due to friction. 3) Heavier sediment is deposited close to the channel; finer material further away. 4) During a dry spell, river slows and deposits material on the bed. 5) After many floods and dry spells, material builds up while also raising the river bed. Subsequently, the river can flow above the floodplain as it is contained by the levees.

Answer 117

L- Floodplains E- Mississippi river S- 3,200Km and up to 15m high with an average of 7m S- Raised parallel banks

Answer 118

1) River loses energy as it meets a area of slow-moving water e.g. the sea 2) The combination of fresh and salt water result in an electric charge which cause clay particles to coagulate and settle on the seabed, a process known as flocculation. 3) Deposits are laid on the sea bed in a three-fold sequence- Heaviest first on the topset beds, medium on the forest beds and finest on the bottomsets last.

Answer 119

Arcurate... Nile, Egypt Cuspate... Tiber, Italy Birds foot... Mississippi, USA

Answer 120

1) During periods of high discharge the river erodes easily 2) Sediment from banks is transported downstream due to high competence and capacity. 3) Water levels fall and energy decreases, coarsest material is deposited and begins to block the river channel. 4) Doesn't have the competence to move it so the channel subdivides into a series of smaller and diverging channels, seeking the easiest route past obstruction.

Answer 121

L- Rivers with high sediment and a variable discharge E- Afon Glaslyn river- 5Km before it reaches the sea S- Wide in relation to depth S- Split into several channels by islands of sediment

Answer 122

Wide, flat area of land surrounding a river in its lower course e.g. Afon Glaslyn river

Answer 123

1) Erosion and decomposition. Meanders laterally erode and widen the floodplain. The width of the floodplain is determined by the amount of meander migration and lateral erosion occurring. 2) Decomposition on the slip-off slopes provide sediment to build up valley floor and this is added to during flooding when the river overflows. 3) River carries its load and as water spills onto floodplain there is lots of friction because of the large wetted perimeter and the water being shallow. As a result, velocity decreases and the river deposits. 4) Over thousands of years these deposits build up.

Answer 124

When there is either a fall in sea level relative to the level of the land (fall in base level) or a rise of the land relative to the sea. This causes an increase in the rivers potential energy.

Answer 125

1) Sea level could fall due to climate change e.g. in a glacial period more water will be stored as ice and sea levels will lower- EUSTATIC 2) The land could rise up due to glacial rebound- Isostatic change

Answer 126

1) Knick point 2) River terraces 3) Incised meanders

Answer 127

1) The drop in base level gives the river greater potential energy, increasing its vertical erosion potential 2) The long profile of the river is extended and a knick point will form marking the junction between the original long profile and the new one. 3) Adjustments to the new base level start at the sea and gradually work their way up the rivers course. As the river is eroding it will erode the knick point gradually and it will recede upstream. 4) The rate at which it erodes depends on the resistance of the rock.

Answer 128

A sudden break or irregularity in the gradient along the long profile of a river.

Answer 129

A narrow, flat piece of ground that runs parallel to the river on either side, above the level of the floodplain.

Answer 130

1) As the water level drops relative to the land the river's capacity to erode increases and it begins to erode vertically leaving the old floodplain above the present level of the river. 2) Lateral erosion also occurs and widens the new valley. 3) It rejuvenation takes place again the process is repeated and a new pair of terraces is formed beneath the original.

Answer 131

A meander that has deeply cut into the floodplain, creating steep cliff like banks.

Answer 132

1) As the water level drops relative to the land the river's capacity to erode increases and it begins to erode vertically- the meander becomes deepened/incised 2) When incision is slow, lateral erosion is dominant and an ingrown meander may be produced- valley becomes asymmetrical, with steep cliffs on the outer bend and more gentle slip off slopes on the inner bend. 3) When incision is rapid, vertical erosion dominates- valley becomes more symmetrical with steep sides and a gorge like appearance, these are described as entrenched meanders.

Answer 133

1) Excessive or intense precipitation 2) Snowmelt 3) Climatic hazards 4) Relief 5) Vegetation 6) Soil type and depth 7) Geology 8) Drainage density

Answer 134

1) Urbanisation 2) Forestation 3) River management 4) Climate change

Answer 135

- Cyclones and hurricanes and low pressure systems lead to increased precipitation.

Answer 136

- Steeper slopes mean less water can infiltrate the soil resulting in increased runoff which decreases the lag-time and leads to river exceeding bank full.

Answer 137

- Interception, storage and evapotranspiration

Answer 138

- Clay soils retain a greater amount of water, thus becoming saturated more quickly than free-draining sandy soil - Deeper soil absorbs more water and results in less runoff

Answer 139

- Impermeable rock impedes percolation and ground storage, and results in soils becoming saturated more quickly.

Answer 140

- When drainage density is high there is a shorter lag-time and an increased risk of flooding and the hydrograph is flashy and bank full may be exceeded.

Answer 141

- Construction on floodplains - Impermeable surfaces - Removal of vegetated surfaces - Drains and sewer channels increase discharge

Answer 142

- Soil erosion - Sediment finds its way into the river, blocking it - Decreases interception and evapotranspiration

Answer 143

- Embankments can prevent floodwater returning to the river - Inappropriate use of floodgates on dams, flooding downstream - Levees may be breached River straightening increases flooding downstream

Answer 144

- Increasing sea temperatures leads to greater frequency and severity of tropical storms. - Increased temperatures result in greater evaporation and rainfall. - Rise in sea levels

Answer 145

- The size of the flood often measured in disacharge

Answer 146

The number of times you would expect to see a flood of a given magnitude.

Answer 147

Sheffield floods 2007

Answer 148

- Heavy and prolonged rainfall - 1 in 200 year flood - Intense depressions due to a stronger than normal jet stream - 285mm in June - 25th June- 100mm in 24 hours - s fast-flowing rivers

Answer 149

- Construction on floodplain - Insufficient drainage and impermeable surfaces- 5% damage from surface water - Culverts built- failed - Failure of flood defences- wall collapse of river Don

Answer 150

- Crack in dam wall at Ulley reservoir - 95% flooding= direct fluvial flooding - 1400 residential properties flooded - Railway station and 41 road closures - 2 dead - Meadowhall and Hillsborough stadium flooded - 1000 businesses affected - £15 million for roads

Answer 151

- MET office warnings - Ulley reservoir- firemen to lower water level, 700 evacuated, part of M1 closed - 20,000 sandbags prepared - RAF helicopters for rescue - Emergency aid from government to help with clear-up - All gullies cleared once a year by council.

Answer 152

- Review of flood management strategies - Environmental agency spent £4 million on flood prevention from 2007-10 in Sheffield. - SCC must work with EA by not allowing development in high risk areas. - Over 200 businesses balloted for a £1.4 million improvement in flood defences.

Answer 153

The construction of artificial structures that through science, technology and force prevent a river from flooding- work against nature

Answer 154

Use natural resources and local people's knowledge of the river to reduce the risk posed by a flood- work with nature.

Answer 155

1) Large impact on the river | 2) Vital for cities such as London protected by the Thames flood barrier.

Answer 156

1) Disrupt ecological systems in the drainage basin. 2) Failure would be catastrophic 3) High cost, technological requirements and maintenance 4) Rare in LEDCs

Answer 157

1) Reduce impact of flooding 2) Significantly cheaper 3) Suitable for developing countries 4) Lower education and technology requirements so can be implemented by local people. 5) More sustainable 6) Don't disturb natural processes and ecological systems

Answer 158

A giant wall built across a channel to impede its flow. Water builds up behind the dam and forms a reservoir which can then be controlled. This helps keep discharge downstream of the dam low even during prolonged heavy rainfall.

Answer 159

1) Controls discharge 2) Generates HEP 3) Reservoir water supply 4) Recreational activities 5) Prevents flooding downstream 6) Irrigation for farmland.

Answer 160

1) Huge amount of flooding which destroys habitats, displaces people and prevents fish migrating. 2) Expensive to build and maintain. 3) Terrorist target

Answer 161

- An artificial version of their natural counterparts - Extend the channel's height and increases its bankfull discharge - Concrete resistant to erosion

Answer 162

Three Gorges dam

Answer 163

Mississippi River

Answer 164

- Allows development of floodplain | - Larger than normal levees and resistant to erosion

Answer 165

- Expensive - If water overflows flooding can be worse - Constant maintenance - Sedimentation reduces capacity

Answer 166

- Blocks off meanders and constructs alternate, straighter routes allowing the river to flow faster preventing pooling and reducing risk of flooding.

Answer 167

Mississippi river

Answer 168

- Provide alternative route increases efficiency - Reduce risk of flooding - Aids navigation (transport) - Habitats may survive - Allows the control of where the river goes

Answer 169

- Expensive - Unnatural - Destruction of habitats - Flooding risk downstream

Answer 170

- Artificial channels that a river can flow into when its discharge rises. - Channels move water around and either send it back into the river downstream or another river. - Generally have floodgates on them that can be used to control the volume of water in the spillway.

Answer 171

Windsor area on Thames

Answer 172

- Alternate route - Straighter and shorter - Reduces flood risk

Answer 173

- Habitats completely destroyed - Expensive - Flood gates maintained - Flooding downstream - If the spillway failed it could cause widespread damage

Answer 174

- Placing restrictions on land usage on areas surrounding the river. - Construction is unlimited outside the floodplain but the floodplain itself is linked to outdoor facilities like playing fields and parks.

Answer 175

- Reduces damage when the river floods | - Floodplain isn't urbanised so infiltration can occur and surface runoff is reduced.

Answer 176

- Limits development to certain areas | - If floodplain is already developed then this is ineffective

Answer 177

A61 River Donne

Answer 178

- Planting trees to increase interception and reduce through flow.

Answer 179

- New habitats - Very effective when combined with floodplain zoning - Prevents soil erosion reducing the amount of soil entering the river and keeping capacity high - Cheap

Answer 180

- Requires a large amount of space - Unpopular among farmers as trees use nutrients from the soil. - Takes 40 years for trees to grow.

Answer 181

Pickering, North Yorkshire

Answer 182

- Restoring a river that has undergone hard engineering back to its original course. - Used when land is no longer valuable, and can help reduce teh risk of flooding in other areas.

Answer 183

- Prevents and reverts environmental and ecological damage introduced by hard engineering projects. - Maintenance costs are zero making it cheap

Answer 184

- Conflict in areas that are still being used by people. - What defines valuable? This decision is left to the local environmental agency and if they make the wrong one, it can cause a lot of damage.

Answer 185

1) Monsoon rains more than 200mm were recorded in 4 days in several provinces. 2) Deforestation- Only 5% of Pakistan is covered by forest 3) Federal flood commission (FFC) was set up following previous floods, and received $900 million with documents showing that projects were initiated, funded and completed but little work was done to corruption.

Answer 186

- 7 million homeless - 2,500 highways and 3,500 railways destroyed. - 500,000 tonnes of wheat lost - Taliban gaining support and social unrest - 5,000 schools destroyed - Food shortages - Disease

Answer 187

- 20% requested aid given by end of August - 10 million forced to drink unsafe water - Pakistani government blamed

Physical- Rivers Flashcards

(220 cards)