Rivers Flashcards
(29 cards)
what is a source
the origin of the river
what is a tributary
a small stream joining a bigger stream
what is a confluence
the place where two rivers join
what is a waterfall
a step in a river
what are rapids
a steep section of a river but not vertical
what is a weir
a small dam to deepen the part of the river
what is a flood plain
a flat area next to a river which can fload
what is braiding
when the river divides and forms an island
what is an oxbow lake
a cut off meander
what is a levee
mud pilled up at the side of a river
what is a mouth
the place where the river flows into the sea or lake
what is an estuary
a signal river mouth
what is a delta
multiple river mouths
draw a long river profile
source
upper= erosion > deposition
middle= erosion = deposition
lower=erosion < deposition
describe the process of a waterfall
For a waterfall to form there must be hard rock on top of soft rock at a cliff. Over time the soft rock will erode leaving a ledge of hard rock and a plunge pool beneath. With time the ledge will erode as well and eventually collapse, moving the waterfall upstream.
draw a diagram of a waterfall
hard rock
soft rock
water
describe the process of a oxbow lake
For an oxbow lake to form there must be a strongly curved meander. Over time the river will erode on the outside forming a narrow neck. With time it will cut off and with deposition the river will straighten and will leave an oxbow lake.
draw a diagram of an oxbow lake
meander
river
oxbow lake
what are the causes of flooding
1) heavy rain: if there is heavy rain the tree will not be able to intercept much water so it reaches the ground. There is not enough time for infiltration so the water leaves the area as runoff.
2) steep land: if there is steep land then the runoff reaches the river very quickly causing increase in discharge.
3) impermeable rock: if there is impermeable rock then all of the water will reach the ground as runoff.
4) many tributaries: if there are many tributaries then the main river receives a lot of discharge all at once. the main river then quickly reaches bank full discharge.
5) deforestation: if there is deforestation then there is no interception so water becomes runoff.
6) urbanisation: if there is urbanisation there will be no infiltration and no interception.
what is attrition
- erosional process
- rocks and pebbles and carried in the river flow and repeatedly collide with each other, this causes them to erode and eventually become sediment
what is corrasion
mechanical/ physical erosion of the earths surface caused when materials are transported by waves, wind water etc
what is corrosion
- chemical erosion
- when water or acid rain enters a rocks through cracks and through chemical reactions it caused erosion.
what is hydraulic action
when the force of water crashes against the coastline and dislodges materials, carrying them away
what is traction
method of transporting rocks / large stones. The stones are rolled along the river bottom by water.
