rivers Flashcards
name the four main proccesses of erosion [4]
-hydrolic action
-attrition
-solution
-abrasion
name the four main proccesses of transportation [4]
-suspension
-solution
-saltation
-traction
hydrolic action [1]
the force of water on the bed and banks of a river removes material
attrition [1]
the load that is carried by the river bumps together and wears down into smaller smoother pieces
abrasion [1]
material carried by the river rubs against the bed and banks and wears them away
solution [1]
some rock minerals dissolve in river water (e.g. calcium carbonate in limestone)
traction [1]
large boulders roll along the river bed
saltation [1]
smaller pebbles are bounced along the river bed, picked up and then dropped as the flow of the river changes
suspension [1]
finer sand and silt particles are carried along in the flow, giving the river a brown appearence
solution [1]
minerals from rocks such as limestone and chalk are dissolved in the water and carried along in the flow, although they cannot be seen
name the three types of weathering [3]
-chemical
-physical
-biological
Explain how both the processes of erosion and deposition create river meanders. [4]
Firstly, meanders form as lateral erosion naturally makes the outside bend of the river faster, meaning it gets more curvy through erosion, such as Hydraulic Action.
Secondly, a meander continues to form as the inside bend is slower, causing deposition, this also enhances the rivers curve.
Explain two differences between upper course and lower course river landscapes. [4]
-The upper course landscape is narrower and steeper, because of vertical erosion, making landforms such as Waterfalls.
-The lower course landscape is often used for agriculture, such as farming, this is due to the presence of floodplains making the land more fertile.
list the causes of flooding (human) [4]
- impermeable roads
-built up areas
-building on floodplains
-loss of trees due to deforestation
list the causes of flooding (physical) [4]
-heavy/prolonged rainfall
-impermeable rock (e.g. granite)
-tributaries running into river
-snowmelt
explain what river proccesses occur at the upper course of a river [2]
the river is fast flowing and eroding downwards and very quickly
explain what river proccesses occur at the lower course of a river [2]
here there is high discharge and some deposition and erosion, though the erosion is reduced, due to the slowed flow of the river.
explain what river proccesses occur at the middle course of a river [2]
lateral erosion becomes more significant, often creating meanders, and as the river slows down and loses some energy, deposition begins to occur
the water cycle is a ____ system
closed
Evaporation
liquid to gas
condensation
gas to liquid
percolation
water goes into the ground
groundwater flow
water that flows in the soil
interception
water is stopped from reaching the ground
transpiration
water leaving a plant as a gas
run off
flows over the surface
precipitation
rain snow and ice
what is a storm hydrograph?
shows the change in discharge caused by a period of rainfall
hydrograph
recod of river discharge over a period of time
river discharge
cross sectional area x rivers mean velocity
positives of flood barriers/storm surge barriers
can protect large areas from storm surges
positives of flood warning and preperation
people have time to prepare their properties e.g sandbags
negatives of flood barriers/storm surge barriers
regular maintenance needed
negatives of flood warning and preperation
some people may not be able to access the warnings
positives of floodplaining zoning
less damage is caused, leading to fewer insurance claims
positives of river restoration
restoring meanders help to slow down rivers
negatives of floodplaining zoning
not always possible to change existing land uses
negatives of river restoration
flooding still likely
positives of dams and reservoirs
can be used to produce electricity
negetives of dams and reservoirs
traps sediment
positives of river straightening and dredging
more water can be held in the channel
negatives of river straightening and dredging
speeds up river increasing flood risk
positives of embankments
allows flood water to be contined in the river
negatives of embankments
looks unnatural
positives of flood relief channels
removes excess water from the river channel
negatives of flood relief channels
if water levels continue to rise the relief channel may also rise
positives of demountable flood barriers
good for places where a permanent sea wall would look ugly
negatives of demountable flood barriers
needs 24 hours warning to set up the barriers so there is a risk that they wouldnt be set up in time
list the soft engineering river managments [5]
-flood relief channels
-demountable flood barriers
-flood warnings/preperation
-floodplaining zoning
-river restoration
list the hard engineering river managments [4]
-flood barriers/storm surge barriers
-dams+reservoirs
-river straightening and dredging
-embankments
hard engineering
man made structures
soft engineering
works with natural processes
