rivers

Question 1

What are the stores in the hydrological cycle?

Answer 1

• ocean
• ice
• reservoir
• groundwater

Question 2

What are the Flows in the hydrological cycle?

Answer 2

• run-off
• through flow
• ground water flow
• rivers

Question 3

What are the Processes in the hydrological cycle?

Answer 3

• evapouration
• condensation
• interception
• transpiration
• precipitation
• percolation

Question 4

What is the source?

Answer 4

Where the river begins

Question 5

What is the watershed?

Answer 5

separates 2 drainage baisins

Question 6

What is a confluence?

Answer 6

where 2 rivers meet

Question 7

What is a tributary?

Answer 7

small rivers that join the main river

Question 8

What is the mouth?

Answer 8

where the river flows into a sea or lake

Question 9

What are the characteristics of the upper course?

Answer 9

• steep sided ‘v’ shaped valley
• hilly and barren
• not much human activity
• small channel
• small discharge

Question 10

What are the characteristics of the middle course?

Answer 10

• meanders along a flat flood plain with lots of vegetation and fertile land
• wide deep channel
• larger discharge

Question 11

What is are the characteristics of the lower course?

Answer 11

• very large channel
• fast flowing and high energy
• used for transport
• flat surrounding land
• large discharge

Question 12

Why do rivers deposit their load?

Answer 12

because they lose energy

Question 13

What is the discharge of a river?

Answer 13

volume of water flowing through through a river channel

Question 14

How is river discharge effected?

Answer 14

• rock and soil type
• land use
• rainfall
• relief

Question 15

How is river erosion effected?

Answer 15

• gradient
• rock resistance
• velocity
• discharge

Question 16

On a storm hydrograph what shows the rainfall and what shows the discharge?

Answer 16

• rainfall bar chart

- discharge line graph

Question 17

What is base flow?

Answer 17

starting and finishing flow of the river either side of the increased discharge

Question 18

What is the erosional process of Hydraulic action?

Answer 18

the force of the river against the banks can cause air to be trapped in cracks and crevices. The pressure weakens the banks and gradually wears it away.

Question 19

What is the erosional process of Abrasion?

Answer 19

rocks carried along by the river wear down the river bed and banks.

Question 20

What is the erosional process of Attrition?

Answer 20

rocks being carried by the river smash together and break into smaller, smoother and rounder particles.

Question 21

What is the erosional process of Solution?

Answer 21

soluble particles are dissolved into the river.

Question 22

What is the Transportation process of Solution?

Answer 22

minerals are dissolved in the water and carried along in solution.

Question 23

What is the Transportation process of saltation?

Answer 23

small pebbles and stones are bounced along the river bed.

Question 24

What is the Transportation process of suspension?

Answer 24

fine light material is carried along in the water.

Question 25

What is the Transportation process of Traction?

Answer 25

large boulders and rocks are rolled along the river bed.

Question 26

What is deposition?

Answer 26

drop or deposit some of the material the river was carrying when it loses energy

Question 27

What are the physical causes of floods?

Answer 27

- heavy/long periods of rain - snowmelt - steep slopes - impermeable rock (doesn't allow water through) - very wet, saturated soils - compacted or dry soil

Question 28

What is peak discharge?

Answer 28

maximum discharge following rainfall event

Question 29

What is peak rainfall?

Answer 29

maximum rainfall following rainfall event

Question 30

What is the lag time?

Answer 30

the time between peak rainfall and peak discharge

Question 31

What is the rising limb?

Answer 31

increasing discharge as storm water enters the river channel

Question 32

What is the receding limb?

Answer 32

fall in discharge back to base level

Question 33

What is channelisation (hard)?

Answer 33

reduces water friction with the bed and banks speeding up water flow and allowing the water to get away from an area quickly

Question 34

What are retention ponds (soft/hard)?

Answer 34

Allows runoff to be temporarily stored and in turn lessens the risk of flooding

Question 35

What is a flood warning system(soft)?

Answer 35

Allows evacuation of areas likely to flood and therefore reduction in damage by warning people in advance

Question 36

What is a Dam (hard)?

Answer 36

Built to control discharge it hoilds back water allowing i to be released in a controlled way

Question 37

What is a Afforestation (soft)?

Answer 37

Trees slow down the flow of water towards the river channel and also allow more interception

Question 38

What are Levees (hard)?

Answer 38

Increases the potential maximum area of the river channel allowing it to hold more water before bursting its banks

Question 39

What is flood plain zoning (soft)?

Answer 39

consider the floodplain and avoid building on the areas which are most regularly flooded.

Question 40

What are the human causes of floods?

Answer 40

- urbanisation, because towns and cities have more impermeable surfaces - deforestation, because removing trees reduces the amount of water intercepted and increases runoff

Question 41

How is a waterfall formed?

Answer 41

When there are alternating layers of rock( Hard rock on top). The softer rock is eroded more quickly therefore undercutting occurs., eventually this leaves an overhang which collapses into the plunge pool.

Question 42

How is a gorge formed?

Answer 42

The waterfall formation continues and it begins to retreat upstream leaving behind a steep sided gorge.

Question 43

How is a meander formed?

Answer 43

Lateral erosion causes kinks in the river. The water on the outside bend moving more quickly meaning it has more energy to erode the river bank on the inside the water travels more slowly causes depostion. after time the bend get tighter and tighter.

Question 44

How is an oxbow-lake formed?

Answer 44

When the water level is high (or during a flood) the meander is cut off and the river takes the easiest route. The ox-bow lake often drys up.

Question 45

How are levees formed?

Answer 45

when a river flood it deposits the material its transporting, due it having less energy. The heaviest material is deposited closest to the river and over many flood this material builds up into levees.

Question 46

How are deltas formed?

Answer 46

only under certain conditions at the mouth of a river. deltas are built up over time as sediment s are deposited at the mouth of the river causing the river to be split into 100's of different channels.

Question 47

How is a "v" shaped valley formed?

Answer 47

vertical erosion causes a narrow gorge the sides are weathered making it less steep and more of a "v" shape.