Study of Rivers - Main Information Flashcards
how are highland areas usually composed
they are usually composed of hard igneous rocks, which are ideal for forming a river’s usual uneven features
where is the source of a river often found
often, but not always, in an upland area
what does the river flow over near the source
steep slopes with an uneven surface, often also flowing over a series of waterfalls and rapids
what happens when a river flows down steep slopes
the water performs vertical erosion
what does vertical erosion do
it cuts down towards the river bed and carves out steep-sided V-shaped valleys
what happens as the river flows towards the river mouth
the slopes become less steep and eventually the river will flow over flat land as it approaches the sea
what happens to the amount of water flowing
this is called the discharge, it will increase as the river approaches the sea
the upper part of the river
the upper part of a river has a larger bed load, more roughness, turbulence and friction
the lower part of the river
the lower part of the river has the greatest cross-section, highest hydraulic radius, the greatest velocity and discharge
what creates turbulence and friction in the river
the sediment
how does vertical erosion affect the river channels
as a result, the channels are narrow and shallow and may contain large boulders and angular fragments eroded and weathered from the steep valley sides.
what happens as the river approaches the mouth
velocity and energy increase due to increased discharge
what happens when the river forms more lateral erosion
this makes the channel wider and smoother, there is less turbulence and friction which makes the flow of water more efficient
