2.2 Rivers Flashcards

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1
Q

Tributary?

A

A stream which joins a larger river

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2
Q

Drainage basin

A

The area of land drained by a river system (a river and its tributaries).

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3
Q

Watershed

A

A ridge or other line of separation between two river systems.

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4
Q

Confluence

A

The point at which two rivers meet

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5
Q

Interception

A

The precipitation that is collected and stored by vegetation

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6
Q

Infiltration

A

The movement of water into the soil. The rate at which water enters the soil (the infiltration rate) depends on the intensity of rainfall, the permeability of the soil, and the extent to which it is already saturated with water

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7
Q

Throughflow

A

The downslope movement of water in the subsoil

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8
Q

Evaporation

A

The process in which liquid turns into a vapour

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9
Q

Overland flow

A

Overland movement of water after rainfall. It is the fastest way in which water reaches a river. The amount of overland runoff increases with heavy and prolonged rainfall, steep gradients, lack of veg, and saturated or frozen soil

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10
Q

what is CASH

A

Corrasion, attrition, solution, hydraulic action

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11
Q

what is corrasion

A

The wearing away of the bed and bank by the load carried by a river

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12
Q

Attrition?

A

The wearing away of the load carried by a river. It creates smaller, rounder particles

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13
Q

Hydraulic action

A

The forces of air and water on the sides of rivers in cracks

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14
Q

Groundwater flow

A

The movement of water from land to river through rock. It is the slowest form of such water movement, and accounts for the constant flow of water in rivers during times of low rainfall

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15
Q

Suspension

A

Small particles are held up by turbulent flow in the river

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16
Q

Saltation

A

Heavier particles are bounced or bumped along the bed of the river.

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17
Q

Solution?

A

The removal of chemical ions, especially calcium, which cause rocks to dissolve.
The chemical load is carried dissolved in the water.

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18
Q

Traction?

A

The heaviest material is dragged or rolled along the bed of the river.

19
Q

Drainage basin cycle

A
20
Q

What is the hydrological cycle

A

The movement of water between air, land and sea. It varies in scale from the global hydrological mode to a small-scale drainage basin hydrological model.

21
Q

What factors affect erosion

A

Greater velocity and discharge
increased gradient increases rate of erosion
solution can be increased when water is more acidic

22
Q

Transport

A
Suspension 
Saltation 
Solution 
Traction 
Flotation
23
Q

How does deposition occur

A

Decline in energy or velocity - river becoming more shallow. For example

When a flood spills onto a floodplain; the river gets trapped behind a dam or enters a lake or the sea; vegetation. slows down the river; or gradient becomes gentler

24
Q

How does the shape of a river generally change

A

From being steep and V-shaped in its upper course, to bring much flatter and wider in its lower course.

25
Q

Why do river generally change shape.

A

Tributary streams, changes in climate and vegetation, human impacts and river processes- erosion, transport, deposition

26
Q

How are waterfalls, gorges and potholes created?

A

Rivers erode softer rock and undercut harder rock.
This causes harder rock to collapse and turn into a waterfall.
If water retreats it may form a gorge of recession

27
Q

Landforms caused by erosion and deposition?

A

Meanders and oxbow lakes.

28
Q

What causes the landforms caused by erosion and deposition

A

Erosion occurs on the outer bank of a meander whereas deposition occurs on the inner bank. This produces a river cliff in the outer bank and a slip-off slope (river beach) on the inner bank, the meanders may become so exaggerated that successive meanders touch. In time of flood, the river may break through the meander to form an oxbow lake or meander cut off

29
Q

What landforms are created by deposition

A

Levees and floodplains

30
Q

How is a levee formed

A

They occur in the lower course of the river.
The finer clays and silts are carried further away from river. This coarser sand and gravel may build up a small bar by the edge of the river.

31
Q

How is a delta formed

A

When a river entered a lake or the sea where there is very little current, river slows down and deposits it’s load, forming a delta

32
Q

briefly explain how waterfalls and gorges are formed (4)

A

Waterfalls frequently occur on horizontal bedded rocks. The soft rock is undercut by hydraulic action and abrasion, to form a plunge pool. The softer rock is eroded by fragments of the harder rock that break off. The weight of the water and the lack of support cause the waterfall to collapse and retreat. Over thousands of years the waterfall may retreat enough to form a gorge of recession

33
Q

draw an annotated diagram to show the formation of an oxbow lake

A
34
Q

How are settlements built to prevent loss of possessions and lives

A

building settlements on raised ground

35
Q

Hazards of rivers

A

Erosion of their river banks thereby making some people vulnerable to losing their home and fields
loss of lives + possessions

36
Q

What physicality’s cause a flood (Climatological)

A

Rain
Ice melting
Snow melting

37
Q

What physicalitys cause a flood (part climatological)

A

Estuarine interactions between steam flow and tide

Coastal storm surges

38
Q

What physicalitys cause of a flood (other)

A

Earthquakes
Landslides
Dam failure

39
Q

Human causes for a flood

A
Urban growth
Floodplain developments 
Obstruction of dams
change in vegetation cover
Human-induced climate change
River engineering work
40
Q

What opportunities do rivers present

A
A source of drinking water
Fertile silt for farming 
a line of communication 
a source of power
fishing
41
Q

What do dams do to rivers

A
reduce speed of water flow 
control amount of water in a river
cause deposition behind the dam 
change ecosystems 
can cause earthquakes
42
Q

What do dams provide us

A
reliable water throughout the year 
navigation
hydro-electric power
water for irrigation
safety from flooding
43
Q

how can you reduce impacts of river flooding

A

raising river bank
building dams
using sandbags to prevent water getting into house
having insure me to cover valuables
diverting the steam
land use planning (building only on land free from flooding)

44
Q

CASE STUDY FOR RIVER: NILE DELTA

A

oldest intensively cultivated areas in the word. Heavily populated and has population density of 16k people per km2.
only 2.5% of egypt is usable for agriculture.
95% of produce comes from Nile valley and delta
Long been a source of freshwater and fertile silt, excellent for import and export. Flat land makes it building easy.

PROBLEMS

Delta covers 25k km2 and home to 66% of growing population.
Provides 60% of food supply.
increase of just 1m would flood 20% population. Excessive irrigation led to pesticides and salt in water delta.