Rivers

Question 2

national levees

Answer 2

these are raised banks of sedinment parallel to a river channel formed by deposition of coarser sediment during floods §

Question 3

draingage basin

Answer 3

also known as watershed is the highest land bordering the basin. rivers are the main features of a drainage basin

Question 4

processes- drainage basin

Answer 4

interception- precipitation falling into the drainage basin can be intercepted by leaves and ground vegetation
infiltration- some of the precipitation that reaches the ground continues downward through soil
overland flow- some of the precipitation reaching the ground flows over the surface until it reaches a river channel
evaporation- water on vegetation or in river channel get evaporated back into the atmosphere
through flow- infiltrating water continues down slopes through the soil towards the river channel
groundwater flow - some infiltrating water continues into pores and cracks in the underlying rock and cracks in the underlying rock and flows towards the river as groundwater.

Question 5

river processes

Answer 5

source- upper
–> highland- middle
—> lowland- lower
—> mouth

Question 6

transportation

Answer 6

rivers carry eroded material :boulders, pebbles, sand, silt. this is caller a river’s load this can be don in several processes:
- traction
- saltation
- suspension
- solution

Question 7

traction

Answer 7

rolling large particles along the riverbed

Question 8

saltation

Answer 8

bouncing of smaller particles along the riverbed

Question 9

suspension

Answer 9

carrying fine particles in the water collumn

Question 10

solution

Answer 10

dissolving soluble materials

Question 11

alluvial plains

Answer 11

these are flat areas of land adjacent to rivers, fomred by the deposition of sediment carried by the river overtime.

Question 12

deltas

Answer 12

form at the mouth of a river where it meets a body of water, such as a sea or lake. sediment carried by the river is deposited, creating a fan-shaped landforms with multiple distributions

Question 13

meanders

Answer 13

are bends or curves in a river’s course, formed through the lateral erosion of the riverbanks and the deposition of sediment on the inside of bends

Question 14

hydraulic action

Answer 14

force of the water knocks particles off the sides

Question 15

corrasion

Answer 15

wearing down of rock by the river’s load(abrasion)

Question 16

attrition

Answer 16

waering down of big rocks by colliding together and breaking in the river

Question 17

solution/corrosion

Answer 17

acids in the river dissolve the rocks that make up the bed + banks

Question 18

erosion and speed

Answer 18

as the speed of the river increases, so does the amount of erosion and load in a river

Question 19

river deltas

Answer 19

formed at the mouth of a river where sediment is deposited, creating a network of distributariesfl

Question 20

floodplanes

Answer 20

are flat area of land adjacent to rivers, periodically inundated to the formation and replenishment of floodplains

Question 21

river course

Answer 21

goes through three stages : upper, middle, lower
length of these depends on type of rock, landscape, climate
refers to its journey from source to mouth

Question 22

upper course

Answer 22

river has a V-shaped valley with a steep gradient, water in river channel occupies most of the valley floor
load is large bc not enough time to erode
load found at bottom
lots of friction between water and bed-load = decease velocity
common features: waterfalls, rapids, potholes

Question 23

waterfalls

Answer 23

occur where the river crosses resistent rock and the softer rock downstream is eroded more rapidly
under waterfall is plunge pool is formed when erosion by hydraulic action and abrasion is greatest.

Question 24

potholes

Answer 24

if riverbed is uneven, pebbles become trapped and swirl currents cause pebbles to rotate and erode circular holes in riverbeds
alternating hard and soft rock forms uneven bends and areas of rapids

Question 25

features of the middle course

Answer 25

river cchannel is wide and deeper w/ gentler valley sides and a wide flood plain
river ahs joined by its tributaries at points of confluence
lateral erosion - more important than verticle erosion so, meanders are formed
bedload size decreases, more chance of depostion
main features- meanders, oxbow lakes and waterfalls

Question 26

meanders

Answer 26

more erosion on side where velocity is greatest
on fast-flowing side, river cuts into bank and becomes deeper
increasing deposition forms slip-off slope

Question 27

oxbow lakes

Answer 27

as meander get bigger outsides bend closer together
in times of flood, river might erode to find a straight way and cut of meanders neck
old channel becomes an oxbow lake, may dry out and vegetation will grow in its place

Question 28

features of the lower course

Answer 28

river is broad and deep
bedload transported in suspension/solution and deposition
fast-flowing = very little friction
common landforms- floodplains, alluviun, levees and mouth

Question 29

flood plains

Answer 29

area either side of channel which floods if river bursts in its banks
covered in clay, salt and sand from flooding (alluviun)

Question 30

levees

Answer 30

river’s edge have natural ridges

Question 31

mouth of a river

Answer 31

estuary- wide deep end of river
narrow mouth
delta- mark the end of river’s long profile

Question 32

Mississippi river in USA

Answer 32

biggest river in USA
source 446m at lake itasca, Minnesota
has a waterfall (falls of st.anthony)
many tributaries add to river
—> increasing load
different type of rocks means 60m gorges and meanders
influenced development in US
silt, deposits make for fertile land
sugarcane, rice, tabacco, cotton
transport route
500mil tonnes of stuff transported along river
92% of US’s agriculture comes from there
recreational opportunities
tourism (11mil each year)
sport, fishing, waterfowl
29 power plants
flooding

Question 33

types of river management

Answer 33

hard engineering
soft engineering

Question 34

hard engineering

Answer 34

is when artificial structures are constructed to change the shape of the river channel or manage the way that a river flows.​

Question 35

soft engineering

Answer 35

is when engineers work with nature to try to reduce the likelihood of river flooding

Question 36

what do soft engineering strategies allow

Answer 36

Soft engineering strategies allow a river to flow more naturally. The river is managed so that: ​
it slows down​
is able to store water and release it slowly.​

Question 37

soft engineering strategies

Answer 37

planting trees in the upper catchment to soak up water​
blocking up old field drains so that rainwater takes longer to get into the river​
felling trees across small tributaries so that the flow of water down these streams is slowed down​
replacing artificial straight sections of river with more natural meandering sections.

Question 38

what do hard engineering strategies allow

Answer 38

Hard engineering strategies are used to artificially manage rivers to reduce the risk of erosion or flooding.

Question 39

hard engineering strategies

Answer 39

dredging the river to make it deeper. This increases the capacity of the river.​
widening or straightening the river so that it flows more quickly​
building embankments or walls to prevent water spilling over the top of the bank.​