Introduction to soil resources and land degradation; soil erosion; Soil and water conservation; land degradation components: Loss of biodiversity, salinization, water erosion, range land degradation; degradation processes, ecosystem function and losses; Basic concept of hazards, risk, vulnerability and degradation; Type of degradation, their causes and impacts; Tools, model and methodologies for land degradation assessment and monitoring, Conservation concept and measures, Reconciling degradation and land resources management issues

1. Arsi University School of Agriculture
Department of Natural Resource
Management Stream of NRM
Land degradation & Rehabilitation
(NaRM2112)
Class day and Time: Th1Th2/W 2:00-5:00
By: Mohammed K.(MSc.)
October 2014

2. COURSE OBJECTIVE
The students will get the knowledge and skill to:
 Understand concept, type, Couse and impact of various
type of land resource degradation and rehabilitation
 Learn about the concerns, issue, types, tools, methodologies
and indicators to assess and monitor degradation extent and
severity
 Basic concept of good practices for conserving the important
LD on natural resource
 Poses complete knowledge of soil erosion, land degradation
and rehabilitation
 Assess land use /cover change
 Understand of land resource degradation for formulating
integrative and suitable conservation strategies to respond to
the challenge of sustainable food production and reversing
environmental problems
 Initiate projection land rehabilitation and conservation

3. CHAPTER 1: CONCEPTS AND DEFINITIONS
Definitions of Land
 Land and land resources refer to a
defined area on Earth's terrestrial
surface, encompassing biosphere
attributes such as
Climate,
Soil,
Terrain,
Hydrology,
Sedimentary layers,
Plant and animal
populations,
Human settlement
patterns, and
Physical results of human
activity.
Functions of land
 Land serves various functions in supporting
human and terrestrial ecosystems, includingas
:
A store of wealth,
Producer of food, and habitat for plants, animals,
and microorganisms.
Plays a role in the global energy balance and
hydrological cycle,
Regulates water storage and flow,
Stores minerals & raw materials,
Facilitates the movement of animals, plants, and
people.

4. What is land degradation?
The definitions and concept of land degradation (LD) are growing.
They have extended from a restricted focus on production to
encompass the full spectrum of goodsand services offered, and
From a concentration on the soil to include the ecosystemas a whole.

5. What is land degradation?
Here are several evolving definitions of land
degradation.
 The temporary or permanent lowering of the
productive capacity of land.
 Is a process which lowers the current/potential
capability of soils to produce (FAO, 1979).
 Is reduction of resource potential by a combination of
processes acting on land (UNEP, 1992).
 It is the reduction in the capacity of the land to perform
ecosystem goods, functions and services that support
society and development (MEA, 2005).

6. What is land degradation?----
 Land degradation is the Reduction or loss of the
biological or economic productivity and complexity of
rainfed cropland, irrigated cropland, or range, pasture,
forest and woodlands resulting from land uses or from a
process or combination of processes, including processes
arising from human activities and habitation patterns, such
as:
(i) Soil erosion caused by wind and/or water;
(ii) Deterioration of the physical, Chemical and biological or
economic properties of soil; and
(iii) Long-term loss of natural vegetation
 The reduction in the capacity of the land to provide ecosystem
goods and services and assure its functions over a period of
time for its beneficiaries (LADA, 2009).

7. 1.3. Trends in land degradation
LD may be as old as the beginning of pastoralism and
agriculture.
The trends of degradation can be explained using different
parameters. For instance,
 forest cover in Ethiopia constituted about :
 65% before 1950‘s,
 15% in 1950‘s and
 less than 3% in 2000.
 Land degradation has escalated in the 20th and 21st
centuries as a result of growing and combined
pressures from agricultural and animal output,
urbanisation, deforestation, and extreme meteorological
events such as droughts and coastal surges, which
salinate land.

8. 1.3. Trends in land degradation---
Results of the GLADIS technique, which is used to track the status
and trends of land degradation and the stresses placed on
ecosystem functioning, are shown in the Picture above.
It is based on six biophysical and socioeconomic factors, including
biomass, biodiversity, soil health, water resources, economic
conditions, and social and cultural factors, that affect the process
of land degradation (Nachtergaele et al., 2010).
However, due to the lack of comprehensive global level data, this
approach is constrained and must make a lot of generalisations in
its analysis, which reduces the applicability and reliability of its
outputs at the local scales.
Source: https://www.un-spider.org/links-and-resources/data-
sources/daotm-land-degradation

9. 1.3. Trends in land degradation---
Land Degradation Impact Index (GLADIS).
Image: Nachtergaele et al. 2010.

10. 1.4. Processes of land degradation
Land Degradation (LD) is a complex phenomenon resulting in a progressive
reduction in the capacity of providing ecosystem services (ES).
Landscape transformations promoting an unsustainable use of land often
reveal latent processes of LD.
It can be the loss of organic matter, decline in soil fertility, and structural
condition, erosion, adverse changes in salinity, acidity or alkalinity, and the
effects of toxic chemicals, pollutants or excessive flooding.
Land degradation can be categorized into three broad processes (physical,
chemical and biological) from which the following processes emanate
including:
 Acidification
 Salinizaton and alkalinization
 Compaction
 Water logging
 Soil erosion (gully, sheet, rill, tunnel, wind, gravity, coastal, stream bank,
glacial, land slide)
 Biodiversity loss
 Vegetation removal/deforestation
 Loss of water body (wet lands, lakes, rivers, springs, marshes)
 Pollution
 Desertification

11. 1.4. Processes of land degradation
 What are the biological processes of land degradation?
 Biological processes include reduction in total and biomass carbon, and decline in land
biodiversity.
 The latter comprises important concerns related to eutrophication of
surface water, contamination of groundwater, and emissions of trace
gases (CO2, CH4, N2O, NOx) from terrestrial/aquatic ecosystems to the
atmosphere.
 What is chemical degradation of land?
 Chemical deterioration as a type of soil degradation involves loss of
nutrients or organic matter, salinisation, acidification, soil pollution, and
fertility decline.
 The removal of nutrients reduces the capacity of soils to support plant
growth and crop production and causes acidification.
 What is Physical degradation of land?
 Physical processes include a decline in the soil structure, leading to
crusting, compaction, erosion, desertification, and environmental

12. 1.5. Hazards and disasters of land degradation
 What is Hazard?
 A ‘hazard ‘, by definition, is any event, phenomenon, or human activity that may cause
loss. Natural and human induced factors may act together to create a hazard.
 For example, earthquakes are normally considered to be natural hazards, but they can also
be triggered by mining activities or the impoundment of large dams.
 A landslide can be caused by a combination of heavy rains, light earth tremors, and
deforestation.
 What is Disaster?
 Is defined as an event that causes serious disruption, leading to widespread human,
material, or economic losses beyond the coping capacity of a given society.
 Disaster management requires a set of actions and processes that are designed to lessen
hazardous events before they become disasters.

13. 1.5. Hazards and disasters of land degradation
 There are different categories
of natural and human-induced
hazards and disasters
including:
A. Hydro-meteorological Hazards
Floods
Droughts Wildfires
Tropical cyclones and hurricanes
Severe storms
Dust storms
B. Geological Hazards Earthquakes
Tsunamis
Earthquakes
Tsunamis
Volcanoes and explosive crater lakes
Landslides, mudflows, erosion, and
siltation
D. Biological Hazards: epidemics and
insect infestations account for 36% of
all disasters in Africa
E. Human-induced Hazards and
Disasters
Air and water pollution
Gas flaring
Toxic waste disposal
Land degradation
Conflict-related hazards
E. Climate Change:
Global warming, may exacerbate many of
the hazards noted above. For example, sea-
level rise will cause coastal erosion and is an
especially serious threat to island states.

14. 1.6. Vulnerability
 Vulnerability is related to the exposure of an entity to the hazard, its
sensitivity to the hazard, and a lack of capacity to address the hazard.
 For example, people living in a zone characterized by high cyclone activity
(exposure) who have significant under-nutrition and health issues (sensitivity)
and who live in communities that do not have the means to prepare for, and
react to, the passing of a cyclone (capacity), are at high risk from a disaster.
 Demographic pressures, climate change and increased competition for land
and water are likely to increase vulnerability to land degradation and food
insecurity particularly in Africa and Asia.
Dry lands are especially vulnerable to LD because of their:
Soils‘coarse texture
Low organic matter content
Low water and nutrition retention capacities
Low inherent fertility, and
Low resilience.
•

15. 1.6. Vulnerability
 According to the recent state of the art, disaster risk
management has three components involving:
Hazard assessment,
Vulnerability analysis and
Improvement of managerial capacities.
 The risk can be diminished by the capacity of an entity
to recover from the adverse incidence.
 Risk is the product of hazard and vulnerability over the
recovery capacity of an entity (Risk = hazard x
vulnerability/recovery capacity).

16. 1.6. Vulnerability
 Risks can be defined easily in the case of some hazards but may be
complex in other hazards.
 For instance, In the case of floods and earthquakes, the risk implied can
be defined rather clearly.
 The analysis of slowly advancing hazards like desertification is much
more complex which implies that implementing risk management
strategies is not an easy task.
 The most important factors which determine disaster risk are:
Demographic factors (population increment and distribution, etc.)
Economic factors (agricultural production, standard of living, poverty
parameters, etc.)
Ecological factors (erosion, water management, deforestation,
climate, etc.) Political factors (political instability, decentralization,
etc.)
Cultural factors

17. 1.7. Rehabilitation
What Is Land Rehabilitation?
is a process of restoration to bring an area of land back to its
natural state after it has been damaged or degraded, making it
safe for wildlife and flora as well as humans.
is the process of returning the land in a given area to some
degree of its former state.
Many projects and developments may result in the land
becoming degraded. While it is rarely possible to restore the
land to its original condition, the rehabilitation process usually
attempts to bring some degree of restoration.

18. 1.7. Rehabilitation ….
Modern methods have in many cases not only restored degraded land but
actually improved it, depending on what criteria are used to measure
'improvement'.
What is the difference between land rehabilitation and restoration?
Restoration aims to return an ecosystem to a former natural condition,
Rehabilitation implies putting the landscape to a new or altered use to
serve a particular human purpose.