A long profile is a line representing the river from its source (where it starts) to its mouth (where it meets the sea). It shows how the river changes over its course.
What is the upper course of a river like?
Upper course - in the upper course, where the river starts, there is often an upland area. The river's load is large in the upper course, as it hasn't been broken down by erosion yet.
What is the middle course of a river like?
A mixture of erosion and deposition
Meanders and Gorges
What is the lower course like?
Lower course - in the lower course, the land is a lot flatter. The river's load is fine sediment, as erosion has broken down the rocks. Erosion predominant force.
What are interlocking spurs?
These are rocks where the river isn't strong enough to erode so instead the river bends around.
What erodes quicker, soft or hard rock?
Soft
What is the first step to how a waterfall forms?
In an area where the river flows over hard and soft rock, the soft rock erodes at a faster rate.
What is the second step of a waterfall forming?
The soft rock erodes around the harder rock over time forming a step.
What is the third step of a waterfall forming?
The soft rock further erodes, undercutting the harder rock, the hard rock is left suspended in the air, as an overhang. The rotational movement of water increases and quickens erosion creating a deep plunge pool.
What is the fourth step of a waterfall eroding?
Due to the force of gravity, the unsupported overhang collapses. The broken-up rocks fall into the plunge pool and act as tools for erosion which further deepens the plunge pool.
What is the fifth step of a waterfall eroding?
Erosion continues to undercut underneath the hard rock, creating an overhang further upstream.
What is the sixth step of a waterfall forming?
The continual process of the overhang collapsing causes the water to retreat upstream over time, forming a gorge.
What is a meander?
A bend in the river
Which course of the river are meanders found?
Middle Course
What is lateral erosion?
The sideways erosion of a river or stream.
What is a thalweg?
Fastest flowing part of a river
Where do thalwegs occur?
Outside bend of a river.
Formation of an ox-bow lake:
Initially, a river with meanders forms based on water speed
Thalweg erosion widens the river while sediment deposition narrows it
Meanders move together due to erosion
The river breaks the neck of the meander to create a straight river, leaving the bend stationary
Deposition separates the old meander, forming an ox-bow lake
Name all human factors that lead to flooding
Urbanisation
Deforestation
The capacity of the river
Name all the physical factors which lead to floods
The rate and volume of rain
Geology
Relief of the land
How does urbanisation contribute to flooding?
Paving, buildings, and drainage systems reduce natural absorption of water, leading to increased runoff and flooding.
How does deforestation increase flooding?
Trees intercept the rain and so it takes longer for the rain to travel through the leaves into the river. Therefore, cutting down trees will speed up the time taken for rainwater to flow into the river, increasing the risk of flash flooding.
How does the capacity of the river affect flooding?
If the river becomes filled with rubbish and debris, the channel's sizewill decrease. This means the river can carry less water and so is more likely to flood. Topography- The shape of the landwill determine how quickly rainwater flows into the river.
How does the geology of the land lead to flooding?
Soil and rock type can also influence what happens to precipitation when it reaches the ground. Impermeable soils and rocks such as clay or shale do not allow water to infiltrate, this forces water to run off reducing river lag times and increasing flood risk. Permeable rocks allow water to infiltrate into them.