Chapter 1

Soil and Water Conservation Engineering
course code WRIE5162
Mengistu Zantet (MSc in Hydraulic Engineering )
Lecturer @ Hydraulic and Water Resources Engineering department
Mizan Tepi university
Email: mengistu.zantet@gmail.com
P.O.Box: 260
Tepi, Ethiopia
7/15/2021 1
mengistu.zantet@gmail.com .
lecturer@ Hydraulic and water
resources Engineering Department

Outline of Chapter 1
General aspects of soil
conservation
History of soil erosion
Problems of soil erosion
Types of soil erosion
.Geological erosion
. Accelerated
erosion
Water
Conservation
Importance of soil
and water
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resources Engineering Department 2

INTRODUCTION
The different resources reside in our environment
may include:
 Soil
 Water
 Minerals
 Solar power (Energy)
 Any more…….
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Soil
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Water
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Minerals
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Solar power
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Natural Resources
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Enough to human
need if production
is increased
It will degrade due
to over
exploitation
Population growth…

Environmental degradation
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Conservation
It is a wise use of the available resource base.
Utilization of a natural resource without
waste to make a continuous high level of
production possible from it while improving or
maintaining environmental quality.
 Wise use of a resource requires knowledge /
skill of different disciplines for understanding
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Conservation
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• It is a strategy to balance the demand and
supply using expert approaches.
Why conservation?
Due to population growth there are problems of
: decline in resource base owing to increased
consumption, pollution, and land degradation
and so on…
• When demand for products from natural
resources base exceeds sustainable production,
and if stable situation of living is bypassed the
sustainable interest from the natural resources
base, then we pass to the unstable downward
spiral where we use up capital resources to
meet the demand.
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•Soil and Water are such resources to
be conserved.
•Knowledge can be acquired through
soil and water conservation
Engineering
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EROSION

Soil conservation
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Water conservation
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What is soil and water conservation?
•Defined as the application of engineering,
agronomic and other fields’ principles for
the solution of soil and water management
problems
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History of soil Erosion
• Soil erosion was given less attention till
the late ninetieth (19) and the first 20th
century.
• Surprisingly, the problem of erosion is
attached firmly with agricultural
development which was counted from
antiquities.
• There are also many articles which
mention the threat of soil erosion in the
centuries past .
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• A major cause of the downfall of many
flourishing empires was soil degradation
(Lowdermilk, 1953).
• So, why not erosion problem not given
attention in early times?????
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Soil Erosion image
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• The earliest civilizations all arose on
irrigated alluvial plains, and were
dependent up on flood deposits of silt
for continued fertility. Examples:-
• The civilizations of the valleys of Nile,
the Tigris and the Euphrates, which
their existence to erosion to the head
waters, could hardly be expected to
see erosion in the same light as a
modern agricultural community.
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alluvial plains image
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General Aspects of Soil and Water Conservation
Engineering
Soil and water conservation engineering is multi-
disciplinary subject which requires the knowledge
of
Soil science,
Engineering, plant science,
Economics,
Geology,
Environmental sciences,
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Necessity of soil and water conservation
 For years there has been concern about
whether the natural resources of the world are
able to feed, clothe, and provide shelter for the
present and future population.
 There are two different opinions about
exploitation of natural resources
 The optimists view and The pessimists
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The optimists view
•They believe that the available natural
resource is enough to feed the present and
future generation.
•To justify their opinion these group says
that the potential to increase food supplies
are ample through use of improved
technologies and farming methods.
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The pessimists View
 They believe that the world’s natural resource is
inadequate to satisfy the needs/demands of present and
future generation unless some suitable conservation
measures are implemented.
 Anyhow, the pessimists are now getting stronger voice in
current debate, and hence their idea necessitates the
conservation of natural resources.
 This is because recent studies show that there is rapid
growth of population but there is decline in precious
natural resource base such as soil and water because of
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Activity 1.1
Which argument do you support? Why?
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Causes of soil degradation or depletion
Several causes can be named for the problem of soil
degradation.
The common one are:
Erosion
Acidification
Salinization and
Other chemical soil contamination.
Out of the above listed problems Erosion is the main
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Ocean acidification
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Soil Salinization
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chemical soil contamination
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Soil Erosion
 Soil erosion refers to the detachment,
transport and deposition of soil and soil
material from their original place to another
place by water, wind and ice or gravity.
 It also can be defined as the wearing away of
topsoil.
 The main causative agents of soil erosion are
water and wind.
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Types of Soil Erosion
Based on the disturbance
A)Geological Erosion
• Refers to erosion that results from forces of nature only i.e. without
intervention of human activity. Since activities of man that speed up
up erosion process are not expected the process of geological erosion is
erosion is very slow process.
B) Accelerated Erosion
• This refers to erosion which results from human activity that influences
influences the process of erosion. For instance cutting of trees and tillage
tillage can speed up the process of erosion many folds. Accelerated
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A)Geological Erosion
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B) Accelerated Erosion
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Based on the agents
1) Water Erosion
•Water erosion refers to the detaching and transporting
of the top soil by runoff.
•Runoff is basically caused due to rainfall. Therefore,
water erosion is linked to the rainfall event in an area.
2) Wind Erosion
There are two main conditions which must exist before
wind erosion can be a serious problem
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A) Water Erosion
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B) Wind Erosion
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 Firstly, only dry soil blows, so the vulnerable
regions are those with mean annual rainfall,
particularly less than about 250 to 300mm.
 Secondly, large scale movements can occur
only where there are steady prevailing winds
at all levels from the upper air down to
ground level, and these are associated with
large fairly level land mass.
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Problems of Soil Erosion
 Loss of upper part of the soil
 Damage to sea coast and formation of sand dunes
 Outbreak of disease and public health hazards
 Spent of money on water purification work
 Siltation of irrigation channels and reservoirs (small to
large)
 Silting of rivers and lakes
 Problems in crop irrigation and consequent need of
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Loss of upper part of the soil
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Damage to sea coast and formation of sand
dunes
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Outbreak of disease and public health
hazards
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Spent of money on water purification
work
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Siltation of irrigation channels and reservoirs (sma
to large)
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Silting of rivers and lakes
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Problems in crop irrigation and consequent
need of conserving the water.
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Activity1.2. Which damage is serious?
Why?
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Soil conservation
is a set of management strategies for
prevention of soil being eroded from
the earth’s surface or becoming
chemically altered by overuse,
salinization, acidification, or other
chemical soil contamination.
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Soil conservation
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The principal approaches of these strategies are
Choice of vegetative cover
Erosion prevention
Salinity management
Acidity control
Encouraging health of beneficial soil organisms
Prevention and remediation of soil contamination
Mineralization
• Other ways are: no till farming, contour
ploughing, wind rows, crop rotation, the use of
natural and man-made fertilizer and
fallowing/resting the land.
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Water Conservation
refers to reducing use of fresh water, through
technological or social methods.
Any beneficial reduction in water loss, waste, or use;
A reduction in water use accomplished by
implementation of water conservation or water efficiency
measures; or,
Improved water management practices that reduce or
enhance the beneficial use of water.
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Water Conservation
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The goals of water conservation efforts include:
 Sustainability - To ensure availability for future
generations, the withdrawal of fresh water from an
ecosystem should not exceed its natural replacement
rate.
 Energy conservation - Water pumping, delivery, and
wastewater treatment facilities consume a significant
amount of energy.
 Habitat conservation - Minimizing human water use
helps to preserve fresh water habitats for local wildlife
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Sustainability
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Energy conservation
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Habitat conservation
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Activity 1. 3
• What is the Importance of Soil and
Water Conservation ???
1)-------
2)-----
3)---
4)--
5)------
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Chapter 1

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Chapter 1