rivers

Question 1

characteristics of rivers

Answer 1

• width
• depth
• speed of flow
• discharge`

Question 2

width of river

Answer 2

the distance between to banks

Question 3

depth of river

Answer 3

the distance between the surface of water and the riverbed

Question 4

speed of flow of river

Answer 4

the velocity of water in the river

Question 5

discharge of river

Answer 5

the volume of water in the river

Question 6

characteristics of drainage basin

Answer 6

• watershed
• tributary
• confluence

Question 7

watershed

Answer 7

marks the boundary of the drainage basin

Question 8

tributary

Answer 8

small rivers joining into the main river

Question 9

confluence

Answer 9

the point where the tributary joins the main river

Question 10

process of erosion

Answer 10

• abrasion
• hydraulic action
• attrition
• solution (corrosion)

Question 11

abrasion river

Answer 11

where sand and pebbles are dragged along the river bed, wearing it away

Question 12

hydraulic action river

Answer 12

where fast-flowing water is forced into cracks, breaking up the bank over time

Question 13

attrition river

Answer 13

where rocks and stones wear each other away as they knock together, becoming smaller and more rounded

Question 14

solution river

Answer 14

where rocks such as limestone are dissolved in acid rainwater

Question 15

process of transportation in a river

Answer 15

• traction
• saltation
• suspension
• solution

Question 16

traction river

Answer 16

large stones are dragged along the river bed

Question 17

saltation river

Answer 17

smaller stones or pebbles are picked up then dropped again in a “leapfrog motion”

Question 18

suspension river

Answer 18

tiny particles of sediment are carried as a suspension in the river water making it look murky

Question 19

solution river

Answer 19

dissolved salts and minerals are carried by the river water

Question 20

what is a drainage basin

Answer 20

area of land drained by a river and its tributaries

Question 21

what is interception in a drainage basin

Answer 21

leaves and branches of trees catch rainwater

Question 22

what is infiltration in a drainage basin

Answer 22

rain soaks into the ground

Question 23

what is throughflow in a drainage basin

Answer 23

some water flows through the soil

Question 24

what is groundwater flow in a drainage basin

Answer 24

some water continues into solid rock to form groundwater

Question 25

what is evaporation in a drainage basin

Answer 25

due to the sun's heat. some river water evaporates

Question 26

what is overland flow in a drainage basin

Answer 26

if the ground is very hard or very wet rain flows overground

Question 27

upper course of the river characteristics

Answer 27

steep long profile with a steep and v-shaped cross profile (water flow is fastest here)

Question 28

middle course of river

Answer 28

gentler long profile and cross profile

Question 29

lower course of river

Answer 29

gentle long profile and almost flat cross profile (water flow is slowest here)

Question 30

formation of waterfalls process

Answer 30

- alternating layers of hard and soft rock present - hard rock resists erosion whereas softer rock is eroded rapidly - plunge pool forms - overhang develops - plunge pool deepens - process repeats causing waterfall to retreat - gorge forms

Question 31

formation of potholes process

Answer 31

- smooth rounded hollows formed in the river bed by vertical erosion - formed by stones trapped in hollows on the river bed - eddies in the water swirl the trapped stones around, causing abrasion - this causes the stone to drill down into the riverbed - hollows become deeper and wider and may join together to form larger potholes

Question 32

formation of oxbow lake process

Answer 32

- river flows around a meander - erosion on outer bends due to faster flowing water - hydraulic action and abrasion involved - helical flow of water adds to the faster erosion - deposition on inside bends due to slower flowing water - river becomes more sinuous, winding around meanders - neck of meander reduced in thickness - eventually river erodes across neck and river flows straight on - during time of flood, deposition seals former meander - oxbow lake formed

Question 33

formation of delta process

Answer 33

- large amounts of sediment brought downstream - deposition in lower course as speed of flow is reduced - flocculation occurs due to salt in water - deposited silt blocks course of river which splits into distributaries to reach the sea - deposited materials are not washed away due to lack of current - colonization by vegetation occurs and delta is formed

Question 34

what are floodplains

Answer 34

- a wide and flat piece of land found on both sides of a river - covered in alluvium (rock particles such as sand, clay and silt) deposited by the river

Question 35

what are levees

Answer 35

naturally raised banks by the riversides made up of deposited coarser materials

Question 36

hazards of living near rivers

Answer 36

- erosion - marsh lands not suitable for firm houses - mosquitoes contaminate and spread diseases - difficulty to get to other side of river - roads cant be built on rivers - flooding

Question 37

managing river flooding

Answer 37

- reservoirs/dams built upstream - increase height of banks - artificial levees - afforestation - overflow channels - straighten channel - dredging - widening river - warning systems - land zoning

Question 38

managing river erosion

Answer 38

- strengthen banks by adding hard rocks to banks or placing rock barriers infront of banks - use gablons - concrete river channel