Why does cross sectional area increase downstream?
Why does cross sectional area increase downstream?
As the river flows downstream it is joined by tributaries, increasing the volume of water, velocity and therefore its erosive power. This enables it to cut a deeper channel as it flows downstream. Downstream, the channel becomes wider as the gradient becomes more gentle leading to less vertical erosion.
What is cross profiling?
Cross-Profile – The side to side cross-section of a river channel and/or valley. CROSS – Think ACROSS. Across this section of the river is the profile (cross profile) she needed. If she knew it was shallow, she might be able to cross this section of the river.
What is Cross river profile?
A cross profile shows a cross-section of a river’s channel and valley at a certain point along the river’s course. A – as the river flows downhill there is an increase in vertical erosion . The channel is shallow and narrow because there is not a lot of water in the channel.
How does a river valley change downstream?
As a river flows down steep slopes, the water performs vertical erosion . This form of erosion cuts down towards the river bed and carves out steep-sided V-shaped valleys. As the river flows towards the mouth, the gradient of the slope becomes less steep.
How and why does sediment size change along the cross profile of a river?
When discharge is high vertical erosion erodes the river bed and larger sediments are transported by traction. Mid-course – here the gradient becomes less steep. The river channel gets deeper and wider as the bed and banks are eroded. The sediment load of the river gets smaller in size.
Why does the river channel become wider and deeper with distance downstream?
Why does the river channel become wider and deeper with distance downstream? The river channel becomes deeper due to the increase in discharge and wider due to lateral erosion.
What is the need of drawing cross profile and long profile across the river?
River cross profiles show you a cross-section of a river’s channel and valley at certain points in the river’s course. The cross profile of a river changes as it moves from the upper to lower course as a result of changes in the river’s energy and the processes that the river carries out.
How does the cross profile of a river change?
The cross profile of a river changes as it moves from the upper to lower course as a result of changes in the river’s energy and the processes that the river carries out. In the upper course, the valley and channel are narrow and deep as a result of the large amount of vertical erosion and little lateral erosion.
How rejuvenation affects the cross profile of rivers?
Typically a river will always try to form a concave shaped profile. From time to time something can occur that changes and de-stabilises this equilibrium. This causes the river to vertically erode its channel to re-establish the its long, smooth concave profile. This renewed period is known as rejuvenation.
Why does the cross profile change?
How does a river change along its long profile?
The long profile of a river shows changes in the height (altitude) of the course of a river from its source to its mouth. A long profile is usually concave and the slope becomes more gentle towards the mouth of the river. Long profiles usually have irregularities such as waterfalls or lakes.
