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Flashcards in Rivers Deck (35):
1

Stages of a river

Upper course/youthful stage

Middle course/mature stage

Lower course/old stage

2

Course

Rout a river takes as it flows into the sea

3

Tributary

River which joins a larger one

4

Confluence

Place where rivers join

5

Mouth

Place where a river enters a sea or lake

6

Estuary

Part of a river's course which is tidal

7

Basin

Entire area drained by a river and it's tributaries

8

Watershed

High ground which separates one river basin from another

9

Youthful/upper stage

River has steep gradient

10

Mature/middle stage

River has a gentler gradient

11

Old/lower stage

River has an almost flat gradient

12

Youthful stage explanation

As river moves through upper/youthful stage, cuts downwards

Gradient is steep, river narrow

Vertical erosion in this highland part helps to creat steep sided v-shaped valleys, interlocking spurs, rapids, waterfalls, gorges

13

Erosion

Hydraulic action, abrasion, attrition

14

Hydraulic action

Force of moving water breaks off material from banks + bed of river

15

Abrasion

Load of material carried along by river hits banks * bed of river, wearing them away

16

Attrition

Load is itself worn down smoothed, rounded

17

Solution

Some rocks dissolved by acids in water

18

Landforms of youthful stage

V-shaped valley
Interlocking spurs
Waterfalls & gorges

19

Transportation in a river

Traction/rolling

Bouncing

Suspension

Solution

20

Traction/rolling

When large objects (pebbles, stones) are rolled along bed of river

21

Bouncing

Smaller objects, eg. small pebles, bounced along bed of river

22

Suspension

Lightest objects, eg. slit + clay, carried along suspended in water

23

Solution (transportation)

Dissolved material (eg. limestone) is carried in solution

24

Mature river

River has a greater volume, now that many tributaries joined it

Flows over gentler gradient (slope)

River has large load of material to transport

Flows slower

25

Landforms of mature river

Wider valley

Meander

Flood plains

26

Meander

Feature of erosion + deposition

River's volume increased but slope is gentler in middle course.

River slows down on inside of bend - deposition

River speeds up on outside of bend - erosion

27

Flood plains

Area at either side of river is called flood plain

When river floods it deposits fine fertile clay called alluvium

28

Old river

River starts to slow down bc gradient is flat

Has large load (sand, rock, etc.) & starts to deposit it

29

Landforms of old river

Oxbow lakes

Leeves

Deltas

30

Oxbow lake

1. Formed by erosion + deposition

2. Begins life as meander

3. Outer curve - river moves fast + erodes.

4. Load of river increases

5. At inner curve - river moves slowly as load is deposited

6. Dloely, open end of curve closes

7. River now flows straight through instead of following meander

8. Sediment is deposited, seals ends and creates oxbow lake

31

Leeves

Raised banks of alluvium found along banks of some rivers in old age

When river floods, deposits load

After many periods of flooding, deposits build up to form leeves

32

Deltas

Triangular areas of land formed by deposition

When mouth of river becomes clogged become of deposition of load, river splits into smaller channels called distributaries

Deposits build up above sea level, form delta

Examples - river Nile, Missisipi, Amazon

33

Advantages of dams

Can be used to hold back water

Used for production of hydroelectric power

Can be used for water based activities

34

Disadvantages of dams

Farm land may be flooded

destruction of people's proprty

People's homes destroyed, had to be relocated

Large build up of alluvium behind dams

35

Source

Where river begins