long profile/cross profile and details of upper, middle, lower course of river

Question 1

what are the features of a river in its upper course?

9

Answer 1

upper course of river is its source (where river starts)
- vertical erosion is dominant so, river travelling through mountains creates a v-shaped valley
- very steep gradient
- narrow and shallow channel
- low velocity
small discharge (river discharge is the volume of water flowing through a river channel)
- large bed load as not much erosion eg. attrition takes place here instead its more rough, more turbulence and more friction
- In upper course of river, the river erodes its bed by hydraulic and abrasive action
- As the river travels downstream it is joined by a no. of tributaries, theses increase the volume of water which gives the river more kinetic energy and a higher velocity and more erosive power.
-Upper course river features include steep-sided V-shaped valleys, interlocking spurs, rapids, waterfalls and gorges.

Question 2

middle course of river

Answer 2

• Middle course river features include wider, shallower valleys, meanders, and oxbow lakes.
• Channel become wider than in upper course
• U-shaped valley as valley widens
• Has a small floodplain
• Valley sides are not as steep, have vertical erosion, channel is deeper and wider as a result
  Gradient is less steep , river begins to meander(bend) and erode laterally (sideways) into the valley sides, and broadens out valley
• The rate of weathering (Weathering is the breakdown of rocks at the Earth’s surface, by the action of rainwater, extremes of temperature, and biological activity. It does not involve the removal of rock material.) increases on the softer rocks of valleys sides
• uses more lateral erosion, its not able to remove all weathered material
• fairly high velocity
• quite high discharge
• river bed less rough than ion upper course
  river bed sediments smaller and smoother

Question 3

lower course

Answer 3

• river bed levels out and becomes a flood plain (flat land)
• Can get levees
• Less erosion, only some later erosion
• Channel is at its widest and deepest
• Highest hydraulic radius, greatest velocity
• Channel is much deeper
• Found at where river meets at sea
• River passes through low-lying country.
• Deposition from floods build up on flood plan and meanders migrate so it widens valley
• gently gradient
• wide valley
• mostly deposition (process where material is being transported and then deposited, deposition occurs when river loses energy eg. river enters a shallow area/floods/on flood plain or towards its mouth)
• high velocity and discharge
• smooth river bed covered in alluvium

Question 4

erosion in upper course ?

transport ?

deposition?

Answer 4

vertical erosion by hydraulic action

traction(large boulders)

large boulders deposited

Question 5

erosion in middle course?

transport ?

deposition ?

Answer 5

less vertical erosion but more vertical erosion due to abrasion, attrition and solution

suspension and increase traction (load become smaller and less angular, less sharps and angles)

more deposition especially in inside bend of meanders

Question 6

erosion in lower course?

transport?

deposition?

Answer 6

very little erosion, only some lateral erosion

suspension and solution (very small particles of load but a great quantity of it)

deposition now the main fluvial process (fine material deposited)