River processes

Question 1

River patterns - dendretic

Answer 1

Looks like a tree
tribituaries meet main river at acute angles
Gentle slopes w uniform rock types

Question 2

River patterns - Trellis

Answer 2

Looks like an phone tower
Tribituaries meet river at 90 degree angles
Large river eroded downwards into softer rocl
Harder rock left elevated above it

Question 3

River patterns - Radial

Answer 3

Tribituaries flow from a circle or oval shaped mountain.
Tribituaries flow out like wheel spokes

Question 4

River patterns - Parallel

Answer 4

Rivers flow parallel + don’t join. Straight course separated by steep slopes

Question 5

River patterns - Deranged

Answer 5

Disorganised + chotic tribituaries. Swamp or marsh

Question 6

River basin - Source

Answer 6

Where a river begins, usually high ground

Question 7

River basin - Tribituary

Answer 7

Small river that joins a bigger one

Question 8

River basin - Confluence

Answer 8

The point where 2 or more rivers join together

Question 9

River basin - Mouth

Answer 9

Where the river meets the sea

Question 10

River basin - Course

Answer 10

Path a river flows along

Question 11

River basin - Watershed

Answer 11

Highland area that separates 1 drainage basin from another

Question 12

River basin - Estuary

Answer 12

Tidal part of the river mouth, where the river water meets the sea

Question 13

River erosion - hydraulic action

Answer 13

Water hits off riverbed and bank, breaks off rocks

Question 14

River erosion - Abrasion

Answer 14

Eroded materials hit off the bed and banks, loosening other rocks + soil

Question 15

River erosion -Attrition

Answer 15

Rocks and pebbles hit off eachother gradually wearing eachother down

Question 16

River erosion -Solution

Answer 16

Soluble rock particles disaloved by weak acids in the water

Question 17

River transportation - Suspension

Answer 17

Particles lifted off the riverbed + carried

Question 18

River transportation - Saltation

Answer 18

Pebbles + stones bounced off the riverbed

Question 19

River transportation - Traction

Answer 19

Heavy rocks rolled along the riverbed

Question 20

River deposition causes

Answer 20

Loss of velocity - old age stage + dams
Loses volume - distributaries, heat + irrigation
Increased load - heavy rainfall = more erosion = more load

Question 21

Waterfalls - Eg

Answer 21

Powerscourt, Co. Wicklow

Question 22

Waterfalls - Description

Answer 22

Vedrtical drop in a riverbed formed in the youthful stage due to vertical erosion

Question 23

Waterfalls - Explanation

Answer 23

Hard rock lies (granite) upstream of soft rock (limestone)
Differential erosion from hydraulic action - soft rock eroded
Hydraulic action + abrasion create plungepool below where soft rock was eroded
Rock undercut by solution creating an overhand
The overhang eventually collapses causing upstream erosion

Question 24

Meanders - eg

Answer 24

River Liffey

Question 25

Meanders - description

Answer 25

S shapped curves in a river from erosion + deposition

Question 26

Meanders - explanation

Answer 26

Hydraulic action + abrasion laterally erode the river River loses volume , losing energy + depositing silt Uneven river bed w shallow riffles + deep pools Water flows fastest on the outer bend - lateral erosion + undercutting Cavitation causes bank to collapse - river cliff Water on the inside bank slowed by friction, deposition + creation of a point bar

Question 27

bluff line

Answer 27

Meander erodes interlocking spurs

Question 28

Delta - eg

Answer 28

Shannon Estuary

Question 29

Delta description

Answer 29

An area of sediment deposited at the mouth of a river

Question 30

Lake delta is called a

Answer 30

Lacustrine delta

Question 31

Sea delta is called a

Answer 31

Marine delta

Question 32

Delta explanation

Answer 32

River slows down + loses energy at the mouth meeting the water, depositing sediment Flocculation occurs Rate of deposition > than rate of erosion. Tides + currents must be week

Question 33

Deltas - flocculation

Answer 33

Chemical reaction where saltwater glues sediment together causing it to sink to river bed. Less likely to be removed from river

Question 34

Delta layers/beds

Answer 34

Topset - heaviest + closest to the mouth Foreset - coarse meterial further from the river mouth Bottomset - finest + lightest material furthest from the mouth

Question 35

Marine delta shapes

Answer 35

Arcuate deltas Birds foot Cuspate

Question 36

Bow shaped delta is a..

Answer 36

Arcuate delta - made of alluvium + gravel. Current + sea's tide are the same strenght

Question 37

decomposing leaf shaped delta is a ...

Answer 37

Birds foot delta. River current is stronger than incoming waves. Deposition around tribituaries

Question 38

V shaped delta is called a ...

Answer 38

Cuspate delta - powerful waves hit the river mouth head on. Spreads sediment evenly

Question 39

HEP - dam defintion

Answer 39

Tall concrete barrier built across a river to block the flow of water

Question 40

HEP - reservoir

Answer 40

water is kept upstream by a dam, increasing the water level upstream

Question 41

HEP - negative effects

Answer 41

Dams slow waterflow, sediment builds up behind dam + needs dredging Less deposition downstream prevents formation of natural landforms. Increased erosion from increased velocitity - clearwater erosion

Question 42

River Shannon + HEP - background

Answer 42

Ardnacrusha Hydroelectric powerplant built along the lower course of the Shannon river. Weir + canal built to divert 60% of Shannon's water to power plant

Question 43

River Shannon + HEP - impacts

Answer 43

Waterflow downstream reduced as water diverted, more deposition. Some parts of riverbed dried up. Winter floods worsened

Question 44

River Shannon + HEP - Floods

Answer 44

more severe from artificially high loughs + increased ersoion when excess water bursts the banks. Eg Dec 2015