drainage basins and the river valley Flashcards
what is a drainage basin?
The area of land drained by a river
what type of system is a drainage basin?
a drainage basin is an open system
what is an open system?
an open system has inputs, flows, stores and outputs
what is the input of of a drainage system?
precipitation
name as many flows of the drainage basin as you can?
- surface run off
- channel flow
- infiltration
- through flow
- groundwater flow
- percolation
name as many stores of a drainage basin as possible?
- channel storage
- groundwater storage
- interception storage
- surface storage
name 3 outputs of the drainage basin?
- evaporation
- transpiration
- river flow into the sea
what is the boundary called that separates drainage basins?
a watershed
how does the watershed work?
the watershed is a high ridge of land, the water will run down both sides of the ridge into different drainage basins
what is a tributary?
a smaller river or stream that joins a main river
what is a source?
the source is where the river starts, usually in an upland area
what is a confluence?
a confluence is the point where two rivers join
what is a mouth?
a mouth is where the river flows into a river or lake
what is mechanical weathering?
is the breakdown of rock without changing its chemical composition
what is chemical weathering?
chemical weathering is the breakdown of rock by changing its chemical composition
what is biological weathering?
biological weathering is the break down of rock by living things, such as plant roots
what type of weathering is freeze thaw weathering?
mechanical weathering
how does freeze thaw weathering work?
the temperature drops to below freezing point, water gets into cracks in the rock, the water freezes and expands which puts pressure on the rock,when the ice thaws the pressure is released and the crack widens
what type of weathering is carbonation weathering?
chemical weathering
how does carbonation weathering work?
rainwater has carbon dioxide in it; therefore making it a weak carbonic acid, carbonic acid reacts with rocks that contain calcium carbonate (for example limestone) and the rocks are dissolved by the rainwater
what is the river’s course?
the path of a river as it flows downhill
what is the upper course of a river?
the part of the river closest to the source
what is the lower course of a river?
the part of the river closest to the mouth
what do rivers flow in?
channels and valleys
what causes the shape of the valley and channels to change?
erosion and deposition
what is deposition?
the material being carried being deposited
which course of the river has a steep gradient?
the upper course
which course of the river has a medium gradient?
the middle course
which course of the river has a gentle gradient?
the lower course
what is the shape of the valley like in the upper course?
the valley is V shaped with steep sides and a narrow, shallow channel
what is the shape of the valley like in the middle course?
gently sloping valley sides with a wider, deeper channel
what is the valley like in the lower course of the river?
it is a very wide, almost flat valley, with a wide deep channel
