Abstract
ABSTRACT
Soil erosion is the systematic removal of soil including plant
nutrients from the land surface by various agents of denudation.
This paper highlights the social and economic impacts of gulling in
the area. Social effects include; loss of ancestral homes, loss of
school building, loss of church building and loss of sources of water
supply. Economic effects studied are loss of farmland, loss of
planted crops, loss of shop/business premises and loss of economic
trees. The study intends to identify the percentage of the residents
according to localities that have suffered socially and economically
from gully incidents. It also intend to determine the relationship
between adverse social and economic effects suffered by the
affected people in the various localities of the study area. The
loacalities studied include, Isiakpuenu-Nanka, Engwu-Nanka,
Ududo-Nanka, Madonna-Agulu and Agulu – road cut areas. Data for
the study was collected from two major sources; primary
s
INTRODUCTION
1.1 Background to the Study
Erosion is the process by which the agents of soil erosion wear
away, eat into, loosen, or carry away soil material and transport it
from one locality to another where it is eventually deposited
(Egboka, 1991). Soil erosion is a complex process caused by wind,
water and physical disturbances, encompassing detachment,
transport and deposition of weathered rock. Soil erosion reduces
land productivity, challenges agricultural sustainability and degrades
environmental quality through contaminants attached to the
sediments.
Soil erosion is caused and complexed by a variety of factors
such as natural phenomena of neotectonics and paleotectonics,
soil/rock features (pedology/geology), wind/water dynamics; and
human phenomena such as population density, anthropogenic
activities including engihanic effects (Egboka and Nwankwor, 1985).
In the execution of colossal or small scale projects of Industrial or
engineering nature, the textural, coherence and plasticity
characteristics of the soil are not considered. Irrigation schemes,
major road network, small and large dams, urbanization,
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deforestation, sand and laterite mining are carried out without
cognizance of the warnings of environmental experts and/or
professionals. Similarly, sensitive drainage areas, wetlands and flood
channels are encroached upon by hungry land developers. In view of
these activities, sheet, rill and gully erosion are known to
progressively develop over several years. All over the world man is a
more important agent of environmental change than Nature (Press,
1990). Soil erosion problems are now endemic in many parts of
southeastern Nigeria (Egboka, 1991). Increased awareness of
erosion impacts on land, air, water quality and global climate, raises
new challenges for erosion researchers. In some conditions, these
impacts are so severe that they reduce the quality of life and
economic well-being, and can threaten survival.
Chemical and physical deterioration of soil have major
implication on agricultural productivity and housing development. In
Nigeria agricultural production is the most important source of
income to the people. Soil quality has a major impact on the capacity
of the rural farmers to achieve food security. Soil erosion increment
results in an unsustainable development of the living standard of the
people. Sustainable development is the positive socio-economic
change that does not undermine the ecological and social systems
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upon which communities and social systems are dependent. Land
provides services to humans and other life forms as well as providing
raw materials in production process. Land provides waste
assimilation services as well as other ecosystem functions. Land
provides utilities for recreation, health, cultural and ecological cycles
and functions.
The quality of available land determines its production potential
and real value. Land owned by families in Agulu-Nanka is mainly
used for cultivation and housing development. Soil degradation
resulting from gully erosion in the area, economically results in loss
of its potentials (Values) for food production and housing
development. This is because the eroded soil is not naturally
replaced without costs. This process leads to material loss and
reduction of economic base overtime and may have long term
consequences on the living standard of the people affected. AguluNanka erosion remain a local problem for a long time, which later
gained attention on an isolated and adhoc basis from affected
communities and relevant Government agencies, hence the silence
on the documentation of losses sustained by the affected people:
There is therefore, need for study on the social impact and economic
losses sustained by affected people.
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1.2 Statement of the Problem
Soil erosion is one of the most striking features on the land
surface of southeastern Nigeria, especially in Anambra State. Several
non-responsive human activities by both the Government and the
inhabitants have culminated in the devastating gully erosion in this
area. Some of these activities include, excavation of red earth
(laterite) and sand in the process of sand/regolith mining,
construction of roads without drainage channels, uncontrolled
population growth and poor agricultural practices. Buildings are
congested on top of groundwater recharge areas. The geology of
the area (Nanka Sandstone) is composed of weak, friable soils which
are poorly consolidated.
At Agulu-Nanka, each rainy season is associated with
nightmares, particularly for inhabitants living at the proximity of
erosion sites. Each gully incidence is accompanied by landslides and
slumping, leaving at the end of each event inhabitants crying and
mourning for loss of agricultural lands, ancestral lands, homes and
economic trees. The cumulative effect is that the affected inhabitants
are left homeless and/or jobless. The threats posed by gaping and
daunting large gullies to farmlands, settlements, roads and human
are enormous. Most communities in Anambra State have been
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ravaged by soil erosion of different dimensions. Sheet erosion is
common and it has resulted in the reduction of soil fertility. Rill
erosion is also common in many communities. However, in these
areas they have graduated into gully erosion. The incidence of gully
erosion is a common phenomenon in Agulu-Nanka communities. The
inhabitants of gully ravaged sites have suffered mishaps ranging
from psychological trauma to loss of property and life. Observations
show that gullies in Agulu-Nanka are allowed to advance without
adequate control efforts by Government, hence, the affected people
watch helplessly while their farmland and homes are destroyed.
The incidence of gully erosion in Agulu-Nanka is not new, as it
has formed a subject for research. Unfortunately, until now, most
researchers are confined only to the factors causing gulling and
control measures, keeping the losses sustained and other social and
economic effects suffered by the affected people aside. It is of
utmost importance to study and document the losses suffered by soil
erosion victims in terms of social disruption, psychological effects and
economic effects with a view to attracting Government, (State and
Federal) to bring lasting solution to Agulu-Nanka erosion ravaged
areas.
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1.3 Research Questions
The following research questions inform the aim and objectives
of the study:
1. What are the adverse social effects that are consequent on
Agulu-Nanka gully erosion?
2. What are the adverse economic effects that resulted from gully
erosion in Agulu-Nanka areas?
3. What percentage of the residents of various localities of AguluNanka have suffered as a result of gully erosion?
4. What is the relationship between the social and economic
effects that resulted from gully erosion in Agulu-Nanka areas?
5. How effective are the measures to contain the menace?
1.4 Aim and Objectives of the Study
The aim of this study is to assess the adverse social and
economic implications of gully erosion hazards in Agulu-Nanka
Communities of Anambra State, Southeastern Nigeria. The
specific-objectives of this study include:
1. To identify the adverse social effects that resulted from gully
erosion in Agulu-Nanka.
2. To identify the adverse economic effects that is consequent o
gully erosion in the Agulu-Nanka
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3. To determine the size of residents in various localities of AguluNanka that has suffered adverse social and economic effects
resulting from gully erosion.
4. To determine the relationship between the social and economic
effects of gully erosion in the area.
5. To determine the common adaptive measures and their
sustainability
1.5 Research Hypotheses
The research questions and objectives translate to the
following research hypotheses that are applied to this study.
1. H0: The adverse social effects of Agulu-Nanka Erosion on the
Residents in the Erosion affected areas do not differ
Significantly from the social situation in the unaffected
Areas.
2. Ho: There is no significant difference between the economic
effects of gully erosion in the various erosion ravaged
localities of Agulu-Nanka and the other areas.
3. Ho: There is no significant relationship between the social
And the economic effects of gully erosion in Agulu-
Nanka areas.
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1.6 Significance of the Study
The study is significant for two reasons. First, the study intends
to identify the percentage of the residents according to localities that
have suffered socially and economically from gully erosion incidence
irrespective of the dimension of the gully occurrence. Adverse social
effects include loss of ancestral home; loss of school building, loss of
church buildings and loss of sources of water supply. On the other
hand, adverse economic effects include loss of farmland, loss of
crops, loss of shop/business premises, loss of economic trees; palm
trees, Ukwa trees (Bread fruit tree), Udara trees (African apple tree),
kola trees, etc. Secondly, this study intends to determine the
relationship the social and economic effects of gully erosion in the
area. The study should enable decision makers, policy makers and
environmental managers to evolve sustainable procedures for
managing human activities like farming, road construction practices,
stone and sand quarrying and harvesting in line with the
characteristics of the lithology in the gully erosion prone areas.
Hitherto, the studies on gully erosion have established the
general factors that cause gully erosion in the area. This study
intends to move in another direction, it assesses the social and
economic losses to the residents in Agulu-Nanka..
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1.7 Scope of the study.
This section will be discussed under two categories, namely
area coverage of the study and content. The coverage include
erosion sites in Agulu-Nanka. Content of the research will include a
study of the social and economic implications of gully erosion on the
inhabitants of areas devastated by gully erosion.
Social characteristics that will be studied include, destruction of
ancestral homeland resulting to forced relocation and hence refugee
in Own-Land; loss of source of water supply, experience of trauma
and frightful Scenic environment. On the other hand economic
characteristics that form the crux of the study will include loss of
building and furniture, farmland, planted crops, economic trees and
monetary contributions to gully control works.
1.8 Theoretical framework
The Davison theory is the earliest cause and effect oriented
theory on soil erosion. It holds that steep slopes are faster eroded
than gentle slopes and that stream or runoff velocities are solely
dependent on bed slopes, which got their derivation from this axiom.
This law is tantamount to an obvious conclusion by Davis (1990) that
the rate of change of landforms as well as other geometric impact
magnitudes are functions of local relief. It therefore implies that the
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progressive changes on the terrain by the effects (impacts) of soil
erosion are accepted to be universally associated with a progressive
landscape evolution where the geometry of individual landforms and
the rate of their erosion changes are both subject to sequential
transformation through time.
The Ofomata’s (1987) Soil Erosion Model for humid tropics
incorporates both the biophysical and human components in soil
erosion cause and impact. The two major purposes that the Model
addressed are firstly, the clarification of the relative importance of
the numerous factors (causes) of soil erosion in southeastern
Nigeria. Secondly, the advancing of a guide for uniformity of soil
erosion research in all parts of the world in consonance with the
second purpose. The Model explains comparative study and
assessment of soil erosion in the entire humid tropical regions such
that necessary variants in the major components of the Model can be
introduced by specific local conditions. The model did not address
the human impacts of erosion.
The 1969 passage of the National Environmental Policy Act in
USA gave birth to the Environmental Impact Assessment. It was
earlier known as cost-Benefit-Analysis (CBA). Its effect on human
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being or the human component of the environment was not at the
centre focus. In other words, it has no human dimension.
Interaction Matrix Approach (IMA) has been earlier put
forwards by Leopold, Clar, Hansaw and Ralsley (1971) as the first
environmental impact assessment approach. It consist of ten (10)
general categories of action on the abscissa or horizontal axis. This
consist of about eight hundred and eighty eight (888) environmental
factors or characteristic such as soil, flora and land uses. The vertical
axis or ordinate has four (4) general categories with many impact
characteristics. There are eight thousand eight hundred (8800) cells
(that is 100 x 88) on a full matrix. It is denoted by (M
/I) where M is
the magnitude of interaction and I is the importance of Interaction.
Burton, Kates and White (1978) Model, opines that natural
hazards are best viewed as ecological framework. This clearly
explains that natural hazards occur from conflicts between what can
be referred to as the natural event system and the human use
system. The human (socio-economic environment) is given a central
role from this interpretation of natural hazards. In the first place,
through location. Secondly, through human perception.
Consequently, Kates (1971) concluded that hazard occurrences
merely represent the extreme of natural processes and their
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distributions and in a slightly different context would often be
regarded as natural resource. The study is based on this theory.
Figure 1. shows the ecological framework of natural hazard.
Fig.1. Natural Hazard as an Ecological Framework.
Source: Burton, Kates and White (1978).
This study is mainly on the assessment of gully erosion effect
on the inhabitants of Agulu-Nanka. Burton et al (1978) utilizes
questionnaire as a tool for psychological enquiries into hazards. This
will be employed in this study. This model gives man a central role
and it is armed with ecological frameworks that involve the use of
psychological enquiries.
1.9 Study Area.
The study area will be discussed under three characteristics,
namely location, physiographic and human characteristics
Natural Use System
Hazards (Flood,
Soil erosion,storm)
Resources
Human use System
Resources
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1.9.1 Location
Agulu and Nanka are towns in Anambra State, Nigeria. AguluNanka lies between latitude 60
001
– 6
0
101N and longitude 70
001
E –
7
0
091
E (Fig.3). Anambra State is one of the thirty six states of
Nigeria (Fig.2)
The area is bounded on the North by Nise and Mbaukwu, on
the South by Ekwulobia, on the East by Oko, Amaokpala and Ogbu
(Awgbu) and on the West Akwaeze, Neni and Adazi. A major tarred
road running from Amawbia-Awka to Ekwulobia with other minor
untarred roads and footpaths help to connect the gully complex.