Describe three ways by which a river transports its load

15/1/2021

Geography Paper 1 1996 Qn 2

a)
- i) What is river divide? (6mks)
- ii) Describe three ways by which a river transports its load (6mks)
b) Describe the characteristics of a river in its old age (7mks)
c) Describe each of the following drainage patterns
- i) Superimposed drainage pattern (3mks)
- ii) Centripetal drainage pattern (2mks)
d) You have planned to carry out a study of a river in its youthful stage
- i) State two ways in which you would prepare for the study (2mks)
- ii) Name two feature you are likely to study (2mks)
- iii) List two problems you are likely to experience during the study (2mks)

Expected Response

2. a)

i) A river dived
- It is a ridge / high ground that separates two or more rivers basins
- The highest line of an interflose (1mks)
ii) Describe three ways by which a river transports its load
- Traction process / rolling / sliding – The large and heavy particles of the river load are rolled / dragged along the river bed.
- Saltation process – particles that are not too heavy but cannot remain suspended in water are momentarily lifted by the water turbulence and at times dropped onto the river bed.
- Solution – soluble minerals are dissolved in the river water and carried away in solution.
- Suspension – light particles of the load are carried and maintained within the turbulence of flowing water. (any 3 x2 = (6 mks)
  NB: Correct description can earn marks without process.

b) The characteristics of a river in its old stage

The widening of the valley through lateral erosion creates an extensive area where the river deposits its load, the gradient of the plain is low.
The speed of flow is low, the gradient of the plain is low.
Due to the slow speed and the high rate of deposition, the river forms pronounced meanders.
Due to the slow speed, the main work of the river is deposition
Meanders become more pronounced with narrow neck which are eventually blocked by deposits to form meander cut off / ox –bow lakes.
Increased deposition along the channel raises the river bed may eventually form small islands / braided channel / river braids
Deposition along the banks of the river channel leads to formation of leaves.
The reduced speed and increased deposition blocks the river mouth forcing the river to form distributaries / delta.
(any 7 points = 7 marks)

c) Description of drainage patterns / systems.

i) Superimposed
- The drainage system develops on a rock structure that overlay a totally different one.
- The river valley cuts through the surface rock layer onto the underlying rocks.
- Gradually the surface rocks are removed ad the underlying rocks now become exposed.
- The superimposed drainage system bears on relationship to the existing rock structure / discordant with the rock structure (3mks)
ii) Centripetal
- The pattern develops in an area with a central basin
- River drain into the depression from different directions(2mks)