River Landscapes Flashcards
What is the source of a River?
Where the river begins
Usually in Upland areas
What is a watershed?
The edge of the drainage basin
What is a tributary?
A small river that meets the main channel
What is a river channel?
The name of the place where the water flows
What is a confluence?
Where the tributary meets the main channel
What is a river mouth?
Where the River meets the Sea
What is a drainage basin?
The area that the river and its tributaries covers
Sometimes called the river catchment
Why does the depth and width increase in a river?
More water is added from the tributaries at confluences
Hydraulic action and abrasion erode the channel vertically and laterally
Why does the load/sediment size get smaller?
Attrition happens as the pebbles are carried downstream
Why does the channel bed and banks get less rough/smoother
Abrasion, smooth, the banks
Why does the velocity increase in a river?
In the upper course, it is slower because the channel is rough and stones are angular so there is lots of action
Discharge measured in cubic metres per second/cumecs is calculated by
velocity X cross-section
why does discharge increase?
The bed and banks are smoother due to abrasion, so the water flows faster
The amount of water in the channel increases has tributaries Joiner, so there is more hydraulic action enlarging the channel
Why does the gradient decrease in rivers?
In The upper course they’re mountain, so it’s deep, but it’s flat by the sea
More vertical erosion a planned as the water tries to get to sea level
Why does the valley shape change from V shaped to widen flat?
In the other course, there is vertical erosion, but there is more lateral erosion near the mouth of the River
Interlocking spurs
Where are they found?
What are they?
The upper course of a river
Water and material at Currys cut into the riverbed, creating a steep V shaped valley
River, not powerful enough to a road lottery through areas of hard rock, so wines and bends around the rocks
Waterfalls and gorges
What are they?
Why do they exist?
The river flows down the cliff face
The softer rock is eroded easily by the hydraulic action and abrasion, enabling the river to cut down into the channel
Over lots of time, the river continues to erode the soft rock and a plunge pool develops
The overlaying hard rock is undercut and left unsupported until it collapses
The falling hard rocks cause further erosion and abrasion, and the waterfall begins to retreat upstream
Slip off slope
Disposition takes place on the inside bend where the river flows slowly
Vishali channel, create greater friction, slows the river down
Sand and shingle are deposited on the inside bend, forming slip of slips
Oxbow lakes
How do you they form?
Erosion on the outside, bend of a meander, causes the neck to become narrower
The neck of the meander continues to narrow until the river eventually breaks through to form a new river channel
The river flows along the shortest path bypassing the loop
Sediment is deposited on the river banks the meander becomes sealed off
An oxbow lake form
Levees
When the river floods over its banks of the water spreads out and slows down
As it, does, it loses energy and deposits, the material it was carrying
Heavy material is deposited first close to the channel
Repeated flooding and deposition form, raise levees along the edges of the channel
What is lag time?
The time between peak rainfall and peak discharge
Peak discharge is the amount of water in a river when it’s fullest may cause flood 
Who is lag time longer, or shorter in urban over rural areas
Shorter
Concrete and drains
Lots of run-off
Short lag time
Is the lag time shorter, or longer in a deep valley sided
Shorter
Water runs over surface rapidly
No time to infiltrate
Is the lag time shorter or longer in areas of forest rather than open land
Both are long
Forest longer
Trees intercept the rain and store it
Causes of river, flooding
Climate change - more extreme events
Urbanisation - drains shorts, lag, time, -impermeable concrete, run-off
Deforestation - less trees to store water - high peak discharge, short lag time
Winter snow ice - frozen, ground, -impermeable - rapid run-off - -snowmelts - short lag time increase -run off
