River Landscapes and Processes Flashcards
(42 cards)
What are the four ways in which rivers transport materials?
Traction, Saltation, Suspension and Solution.
What is Traction?
Large sediment roll along the river bed.
What is saltation?
Where small pieces of shingle or large grains of sand are bounced along the river bed.
What is suspension?
Where small particles like sand or clay are carried by the water stream. This can make water look cloudy.
What is solution?
Where minerals are dissolved in river water and carried downstream.
What is the stream like in the upper course?
Since the gradient is greater it has more power to erode downwardly, forming a V-shaped valley.
What is a stream like in the mid course?
As gradient had decreased, the river begins to erode laterally and widening, forming meanders and ox-bow lakes.
What is a stream like in the lower course?
The gradient is very shallow and thus the stream is increasingly wide, forming floodplains and levees.
What is a river mouth?
Where a river ends, either when it joins another river or the sea.
What is a long profile?
A slice through the river from source to mouth showing elevation changes throughout its course.
What is the river source?
The start of the river, normally found at high elevation in areas glaciated or of high rainfall.
What is river channel shape?
The width and depth of the river.
What is the river discharge?
The amount of water passing a specific point at a given time, measured in cubic metres per second.
What is river volume?
The amount of water in a river.
What is river velocity?
The speed of the river.
What is a valley profile?
A slice across the river showing changes in height across the valley.
What is a river confluence?
The place where two rivers meet.
How does a levee form?
A levee is a raised bank formed on the banks of a river when sediment is deposited on the sides during repeated flooding.
What is a floodplain?
A low-lying area of land that frequently floods due to its close proximity to a river.
What are interlocking spurs and how do rivers move through them.
Interlocking spurs are outcroppings in a valley which form in areas of high altitude in the upper course. In this region, the river is shallow and there is a lot of friction, thus erosion occurs a lot. Due to the steep gradient a V-shaped valley forms and the rover path winds through the interlocking spurs.
How do waterfalls form?
They form due to erosion and the local geology. Less resistant, softer rock is eroded faster, leaving an overhang of more resistant, harder rock. In time this heavy rock becomes too heavy and falls.
How do meanders form?
The point of fastest flow erodes on one side, and material is deposited on the other side, so the highest erosive power moves to the other side diagonally, so the material is now deposited on the other side.
How does an oxbow lake form?
At certain points in meanders there id a faster route that the river can take, instead of winding around the usual path, so during times of flooding more water from the stream cuts through this path. Over time the old route has sediment deposited on it, cutting it off from the old stream, forming a lake cut off from the river called an oxbow lake.
What is interception?
When trees stop precipitation hitting the ground.
