Rivers

Question 1

define drainage basin

Answer 1

an area of land drained by a river and its tributaries

Question 2

define watershed

Answer 2

the border between drainage basins E.g hills

Question 3

source of a river

Answer 3

the beginning of the river

Question 4

mouth of a river

Answer 4

the end of the river
where it meets the sea

Question 5

what is a confluence

Answer 5

where 2 rivers meet

Question 6

what is a tributary

Answer 6

when a smaller river joins a larger river

Question 7

river channel

Answer 7

the area the water takes up

Question 8

where does vertical erosion occur and what does it form

Answer 8

occurs in the upper course
forms V-shaped valleys

Question 9

where does lateral erosion occur and what does it form

Answer 9

occurs in the middle & lower course
forms wide valleys

Question 10

when does a river deposit material

Answer 10

• going around a bend- material deposited on inside bend
• during flooding
• at the mouth when freshwater meets seawater- mudflats are formed
  -at the end of the river

Question 11

what is a long profile
describe the long profile of a river

Answer 11

shows changes in the height of the course of a river from its source to its mouth

Upper course - river’s load is large as it hasn’t been broken down by erosion yet. narrow valley sides

Lower course - land is flatter. river’s load is fine sediment, as erosion has broken down the rocks.

Question 12

what is a cross profile
describe the cross profile of a river

Answer 12

show a river’s cross section as it changes with distance downstream

upper course- narrow and steep-sided river channel due to vertical erosion

middle course- wider valley floor due to more lateral erosion than vertical erosion

lower course- almost flat valley floor, only some lateral erosion, river at its widest

Question 13

fluvial processes

Answer 13

processes found in a river

Question 14

what is erosion

describe the 4 types of erosion

Answer 14

erosion is the process which wears away the river bed and bank

1. hydraulic action- power of water as it smashes against river banks. Air gets trapped in cracks of river bank and bed, causing the rock to break apart

2.abrasion- pebbles grind along the river bank and bed in a sand-papering effect.

3.attrition- rocks carried by the river hit each other. They break apart to become smaller and more rounded

4.solution- the water dissolves certain types of rocks, eg limestone

Question 15

what is transportation

describe the 4 types of transportation

Answer 15

transportation is when the river picks up sediment and carries it downstream.

1. traction- large, heavy pebbles are rolled along the river bed- most common near source of a river as load is larger.
2. saltation- pebbles bounce along the river bed, most common near source
3. suspension- lighter sediment is carried within the water, most common near mouth of the river.
4. solution- transporting dissolved chemicals

Question 16

define load

Answer 16

the particles of rock carried by a river

Question 17

describe deposition
when does deposition occur

Answer 17

deposition is when the river loses energy and drops material

-shallow water
-at the river’s mouth
-when volume of the water decreases
-areas of low velocity

Question 18

what landforms result from erosion

Answer 18

waterfalls
gorges
interlocking spurs

Question 19

what landforms result from erosion and deposition

Answer 19

meanders
oxbow lakes

Question 20

what landforms result from deposition

Answer 20

levées
floodplains
estuaries

Question 21

explain the formation of a waterfall and gorge

where are waterfalls found

Answer 21

found in upper course

1. soft rock is eroded quicker than hard rock
2. hard rock is undercut by erosion (hydraulic action & abrasion), forming an overhang
3. this forms a plunge pool

4.plunge pool gets bigger and overhang collapses

5.process continues and waterfall retreats upstream

6. A steep-sided valley is left where the waterfall was. This is a gorge.

Question 22

explain the formation of interlocking spurs

where are interlocking spurs found

Answer 22

found in upper course

In upper course there’s more vertical erosion.

the river bends round areas of hard rock instead of eroding them

This creates interlocking spurs of land which link together

Question 23

explain the formation of a meander
where are meanders found

Answer 23

in middle & lower course

As river goes around bends, water is pushed towards the outside.

This increases speed and increases erosion (hydraulic action and abrasion).

lateral erosion on outside bend undercuts the bank  to form a river cliff.

Water on inner bend is slower, so water slows down and deposits material,
creates a slope of sand and shingle.

The build-up of deposited sediment is a slip-off slope/river beach.

Question 24

explain the formation of an oxbow lake

Answer 24

in middle and lower course

meander neck narrows due to lateral erosion

during high river discharge, meander neck breaks.
river takes the shorter, straight route

deposition at the edges cuts off the old meander

the old meander forms an oxbow lake, is horseshoe shaped- separate to river

oxbow lake silts up to form marshland

Question 25

explain the formation of a levée where are levees found

Answer 25

found in lower course during high river discharge and flooding Sediment eroded upstream is transported downstream. during floods, the river loses energy. large material is deposited first on the sides of the river banks and small material deposited further away. After many floods, sediment builds up to increase height of the river banks, the channel can carry a greater discharge flooding is less likely to occur in the future

Question 26

explain the formation of floodplain

Answer 26

in middle and lower course A floodplain is an area of land covered in water when a river bursts its banks. Erosion removes interlocking spurs, creating a wide, flat area on both sides of the river. During a flood, material carried by the river is deposited (as the river loses its speed and energy). Over time, the height of the floodplain increases as material is deposited on either side of the river. Floodplains are agricultural land, as the area is fertile because it's made up of alluvium (deposited silt from a river flood).

Question 27

explain the formation of a estuary

Answer 27

lower course An estuary is where the river meets the sea. (mouth) The river here is tidal and when the sea retreats, the volume of the water in the estuary is reduced. When there is less water, the river deposits silt to form mudflats which are habitats for wildlife.

Question 28

3 physical factors of floods

Answer 28

precipitation- heavy rainfall saturates soil so water cannot infiltrate into the soil = surface runoff geology- impermeable rocks don't let water infiltrate into them =surface runoff steep slopes- causes rapid water transfer which means a SHORT LAG TIME

Question 29

define lag time

Answer 29

the time taken between peak rainfall and peak discharge.

Question 30

3 human factors of floods

Answer 30

farming- bare soils transfer water quickly, short lag time urbanisation- construction using impermeable surfaces such as concrete, water cannot infiltrate deforestation- trees intercept rainfall and reduce flood risk. if there are less trees, less rain is intercepted= higher flood risk

Question 31

define peak discharge

Answer 31

the maximum amount of water held in the channel

Question 32

define peak rainfall

Answer 32

the maximum amount of rainfall (mm)

Question 33

define rising limb

Answer 33

the increase in discharge on a hydrograph

Question 34

define falling limb

Answer 34

the return of discharge to normal/base flow on a hydrograph.

Question 35

define base flow

Answer 35

the normal discharge of a river

Question 36

what factors decrease lag time

Answer 36

large drainage basin little vegetation steep valley sides impermeable soil type

Question 37

what are hard engineering strategies list the 4 hard engineering strategies

Answer 37

building artificial structures which try to control rivers. -dams & reservoirs -river straightening & dredging -embankments -flood relief channels

Question 38

what are soft engineering strategies list the 4 soft engineering strategies

Answer 38

takes a more sustainable & natural approach to managing river flooding -flood warnings and preparations -floodplain zoning -planting trees -river restoration

Question 39

explain dams/reservoirs gives advantages give disadvantages

Answer 39

dam traps water, which builds up behind it, forming a reservoir. Water is released in a controlled way. Advantages: -Hydro-electric power -water sports attract tourists -creates wetland habitats Disadvantages: -Very expensive -reservoir silts up which reduces storage capacity -locals are displaced -Habitats destroyed

Question 40

explain river dredging/straightening gives advantages give disadvantages

Answer 40

Straightening the river speeds up water so high volumes of water can pass through an area quickly. Dredging deepens the river so it holds more water. Advantages: -More water held in the channel It can be used to reduce flood risk in built-up areas. Disadvantages: -expensive -faster water flow increases flood risk

Question 41

explain embankments gives advantages of give disadvantages of

Answer 41

Raising the banks of a river means that it can hold more water. Advantages: -more water can be hold -create walkways for locals . Disadvantages: -expensive -Looks unnatural

Question 42

explain flood relief channels gives advantages give disadvantages

Answer 42

The floodwater flows into the relief channel is taken to an area where it's absorbed, or re-enters the river Advantages: -Removes excess water from the river channel -recreation-walking, fishing -aquatic habitats created Disadvantages: -Expensive to build -can look unattractive -regular maintenance needed

Question 43

explain flood plain zoning gives advantages give disadvantages

Answer 43

restricts land uses in high-risk areas, high-value land uses away from flood-prone areas. Advantages: -expensive buildings & land uses are far from the river, so have a reduced flood risk. -so less damage is caused, leading to fewer insurance claims. Disadvantages: -restricts economic development in areas as land use is prohibited

Question 44

explain flood warnings and preparation gives advantages give disadvantages

Answer 44

EA issues online warnings about floods so people can evacuate Advantages: -gives time to evacuate and prepare -possessions can be saved, fewer insurance claims. Disadvantages: -Some people may not be able to access the warnings. -Flash floods- too quick too prepare for -does not stop floods

Question 45

explain planting trees gives advantages give disadvantages

Answer 45

trees intercept rainfall, reduces runoff advantages: -creates habitats -reduces carbon emissions -inexpensive disadvantages: -reduces biodiversity -loss of farmland

Question 46

explain river restoration gives advantages give disadvantages

Answer 46

restores straightened channels to meandering pattern to slow water flow. advantages: -restores wetland areas -reduces downstream flooding disadvantages: -expensive to construct and maintain

Question 47

Jubilee river

Answer 47

a flood relief channel on the River Thames, built in 2002 12km in length 50m wide low flow conditions removes excess water from thames

Question 48

Jubilee river social issues

Answer 48

-protection of wealthy properties such as windsor, but not less affluent towns downstream -paddle boaters are disrupted by weirs

Question 49

Jubilee river economic issues

Answer 49

- cost £110 million -floods damaged weirs- high maintenance cost

Question 50

Jubilee river environmental issues

Answer 50

-flooding in 2014 damaged habitats -concrete weirs are unattractive -algae collects above weirs

Question 51

describe the path of the river tees

Answer 51

River Tees is located in north of England. The source of the River is located in the Pennines river flows east to its mouth where it joins the North Sea

Question 52

describe the upper course of the river tees

Answer 52

-Hard, impermeable rocks. -interlocking spurs (cauldron snout) -Vertical erosion formed a V-shaped valley. -High Force (UK's largest waterfall) -area of hard rock, called Whinstone is located above soft rock (limestone)

Question 53

describe the middle course of the river tees

Answer 53

As the River Tees erodes sideways (lateral erosion), it forms meanders. These are seen in the middle course near Barnard Castle.

Question 54

describe the lower course of the river tees

Answer 54

-Near Yarm, meanders are larger, oxbow lakes have formed. -levees have formed when the river has flooded. -a very large estuary with mudflats and sandbanks which supports wildlife in the area. Sites such as Seal Sands are protected areas.

Question 55

define relief

Answer 55

the difference in heights of land's surfaces