Desert Landforms caused by water action
Sudden rainfall in deserts can be very destructive due to lack of vegetation cover on the surface. Water therefore becomes an agent of erosion in desert areas.
These heavy rain storms result into rushing torrents on steep slopes to sheet floods on gentle slopes. The run off on slopes is usually rills which connect with gullies. These lead to deep, steep sided valleys called Wadis – also called Chebka in Algeria.
During rush storms, flood waters run down the Wadis carrying large quantities of materials which seen turns into mudflows. The deposited material is known as alluvium. The Saharan uplands are all dissected by Wadis
Revision question 1
"Many parts of Africa lying on the desert fringes have reached land deterioration. The desert is expanding partly because of recurring cycles of drought, but also because of man." (source: J.M Pritchard; Africa Page 246)
(a) (i)What is a desert?
ii. Draw a map of Africa on it mark and name the major
deserts.
iii. Mention the African countries lying on the desert fringes.
(b) (i) State the causes of deserts.
(ii) State characteristics of desert surfaces.
(c) (i) Name the four types of desert surfaces.
(ii) Name the major landforms resulting from the wind
deflation process.
(iii)Choose two of these and explain how they were formed.
Question 2
(ii) Choose two of these and explain how they were formed.
(b)(i) Describe the major processes of wind erosion in arid areas.
(ii) Name the features resulting from water action.
(c) (i) Draw a diagram to show “Mesas and Buttes” landforms in desert.
(ii) Describe briefly how they are formed.
(iii) State the values of deserts and their landforms to man.
(d) Explain the steps taken to control the expansion of the desert by:-
(i) The effected areas.
ii) The International Community.
Question 3
Read the following passage and answer the questions that follow.
In the Central Sahara because of aridity, vegetation becomes extremely
rare, limited to the beds of quads (wadis). The lack of water and
chemical changes means an absence of soil. Nothing but pebbles and
sanddunes. A region entirely dead uninhabited and
uninhabitable.”(Adopted from Atlas Afrique)
(a)(i) State four characteristics of desert mentioned in the passage.
(ii) What factors are responsible for the formation of a desert.
(b)(i) For any two landforms mentioned in the passage, explain how they are formed.
(ii) Name a feature in the desert where life is possible. Give reasons for this.
(c)(i) Suppose you were a planner in one of Sahara countries (Algeria, Libya, Egypt, e.t.c).
(d) Suggest ways in which you would develop the area.