2.2 Rivers

Question 1

Tributary?

Answer 1

A stream which joins a larger river

Question 2

Drainage basin

Answer 2

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

Question 3

Watershed

Answer 3

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

Question 4

Confluence

Answer 4

The point at which two rivers meet

Question 5

Interception

Answer 5

The precipitation that is collected and stored by vegetation

Question 6

Infiltration

Answer 6

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

Question 7

Throughflow

Answer 7

The downslope movement of water in the subsoil

Question 8

Evaporation

Answer 8

The process in which liquid turns into a vapour

Question 9

Overland flow

Answer 9

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

Question 10

what is CASH

Answer 10

Corrasion, attrition, solution, hydraulic action

Question 11

what is corrasion

Answer 11

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

Question 12

Attrition?

Answer 12

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

Question 13

Hydraulic action

Answer 13

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

Question 14

Groundwater flow

Answer 14

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

Question 15

Suspension

Answer 15

Small particles are held up by turbulent flow in the river

Question 16

Saltation

Answer 16

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

Question 17

Solution?

Answer 17

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

Question 18

Traction?

Answer 18

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

Question 19

Drainage basin cycle

Answer 19

Question 20

What is the hydrological cycle

Answer 20

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.

Question 21

What factors affect erosion

Answer 21

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

Question 22

Transport

Answer 22

Suspension 
Saltation 
Solution 
Traction 
Flotation

Question 23

How does deposition occur

Answer 23

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

Question 24

How does the shape of a river generally change

Answer 24

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

Question 25

Why do river generally change shape.

Answer 25

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

Question 26

How are waterfalls, gorges and potholes created?

Answer 26

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

Question 27

Landforms caused by erosion and deposition?

Answer 27

Meanders and oxbow lakes.

Question 28

What causes the landforms caused by erosion and deposition

Answer 28

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

Question 29

What landforms are created by deposition

Answer 29

Levees and floodplains

Question 30

How is a levee formed

Answer 30

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.

Question 31

How is a delta formed

Answer 31

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

Question 32

briefly explain how waterfalls and gorges are formed (4)

Answer 32

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

Question 33

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

Answer 33

Question 34

How are settlements built to prevent loss of possessions and lives

Answer 34

building settlements on raised ground

Question 35

Hazards of rivers

Answer 35

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

Question 36

What physicality’s cause a flood (Climatological)

Answer 36

Rain Ice melting Snow melting

Question 37

What physicalitys cause a flood (part climatological)

Answer 37

Estuarine interactions between steam flow and tide | Coastal storm surges

Question 38

What physicalitys cause of a flood (other)

Answer 38

Earthquakes Landslides Dam failure

Question 39

Human causes for a flood

Answer 39

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

Question 40

What opportunities do rivers present

Answer 40

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

Question 41

What do dams do to rivers

Answer 41

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

Question 42

What do dams provide us

Answer 42

``` reliable water throughout the year navigation hydro-electric power water for irrigation safety from flooding ```

Question 43

how can you reduce impacts of river flooding

Answer 43

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)

Question 44

CASE STUDY FOR RIVER: NILE DELTA

Answer 44

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.