THE ILORIN JOURNAL OF BUSINESS
AND SOCIAL SCIENCES
Sditor-in-Chief
J. FONSO OLORUNFEMI
Deputy Editor
JACKSON OLUJIDE
Associate Editors
A. G. FOLAYAN
S.0. OYEDELE
R.A. SENIYI
Business Sditor
C.F.
VOL. 4
OKOROSOBO
1994
C O N T E N T S
ARTICLES
Page
A decade of Economic crisis in
Nigeria: Analysis of strategies
and options - I.O. Taiwo
3
Climate and Mortality in Ilorin
(1983-1992) - J.F. Olorunfemi and
A.S. Adeyemi
33
Efficiency of the Health Care
Delivery System of the Oyun Loca]
Government of Kwara State T. Okorosobo
51
Labour Migration into a developing
industrial environment: A case study of
Ota, Ogun State, Nigeria - A.A. Adedibu
and G.A. Olude
69
Issues and Problems of Federalism in
a Multi-National society: The
Nigeria case - G. Xsij'olaA Sociological Analysis of Housing in
contemporary Nigeria - A.A. Mordi
Effects of Erosion on Foundation of
Houses in Okene and its Environs,
Nigeria - H.I. Jimoh
98
121
131
EFFECTS OF EROSION ON FOUNDATION OF
HOUSES IN OKENE AND ITS ENVIRONS, NIGERIA
H.I. Jimoh
Department of Geography
University of Ilorin
Ilorin, Kwara State
Abstract
This paper assesses the rate of soil erosion on
foundation of houses in Okene and its environ,
Nigeria. Direct measurement of depth of exposed
foundation of houses was carried out in the
field. The analysis revealed: (i) A significant
relationship between exposed foundations and
age; (ii) Erosion rates on aspects of
foundations of houses vary throughout the study
area; (iii)Type of foundation materials in
relation to age, slops angle and manner of house
renovations among others predisposes foundation
of houses to erosion risks, and, (iv) A
possibility of predicting soil erosion rates
from depth of exposed foundation of houses. The
various preventive measures suggested by erosion
threatened houses owners include the use of good
building materials, avoiding steep slope
surfaces in the course of house constructions,
carrying out stabilisation measures over problem
soil
surfaces
and
encouraging
house
constructions on concrete surfaces.
1.
Introduction
SOIL erosion occurs in many parts of Nigeria, but
it is most severe in Eastern Nigeria, Shendam and
Western Parkshin, Jos Plateau of Nigeria
(Ofomata, 1964: Udo, 1970).
Housing is the next most important human
basic need after food. The house types and
structures are decided by his culture, economy,
133
llorin Journal of Business and Social Sciences
history; ideas and Sangree, 'Richard, 1967 and
1977), but structure of the re cf -he type and
h: from erosional
his
of
dwelling and ether s because,
necessity
rcur.c.
surface
constructed or. the
which
is
tack
3ray,
subject to ercsicr.al
1S72).
Houses
arcund
are affected by ercstt
However, the severity their foundations. ;f the
foundation of houses erosion around the
varies with the type of foundation materials
used (Oyegun, 1987 and Jimoh, 1988) And the
ultimate result is that most of such houses
collapse. Thus, evaluating the rate of erosion on
the exposed foundation of houses,'examining the
factors responsible for the spatial variation and
the response of man to erosion threatened
foundation of houses constitutes the focus of
this investigation.
2. Study Area
Okene and its environs is in Kogi State,
Nigeria. It is located between latitude 7 15N and 7
BOW, and longitude 6.00 E and 6.47 E. The towns and
villages that make up the study area include
Arugu, Adogo and Achoze in the Southern part of
study area; Ajaokuta, Geregu and Ohunene in the
Eastern part, Ukpogoro, Agassa, Ogori and Magongo in
the Eastern part; while Okene is located in the
Northern part (fig. 1).
This area is characterised by tropical
seasonal climate with a mean rainfall of between
1,000mm to 1,250mm concentrated in the months of
March to November, with a double maximum in July
and September and a short dry spell in the month
of August. The topography is rough, steep and
Jagged, which tends to explain the peculiarity of
soil erosion ravages in this area of Kogi State,
Nigeria.
134
Effects of Erosion on Foundation
FIGURE 1: MAP OF OKENE AND ITS ENVIRON
6° 45'E
S O U R C E :
MINISTRY
OF
LANDS & SURVEY
OKENE
f\<?»
if 45'E
3. Study Method
This
study
utilised
data
estimated
directly from the field. These data ir.'-.lude:
denth of exposed foundations, foundation, raa:
erials, age of houses, slope angle of the si' e
o:: each sampled foundation, and response or.
man to erosion threats. In an attempt to
document these data, the study area was
divided into four parts of North, South, East
and West. This is because, it is hoped that
such exercise will ,•, ..EC in comparative
analysis.
In the course of the preliminary . tvey
it was observed that the foundations of one
hundred and fifty houses were severely
exposed; one hundred of these were selected
from the different aspects of the study area
representing 66.7
i'.v.v and Social Sciences
percenz cf the population of houses that have
been :--'-ged by erosion.
£.:; •-^rh sampled house, prismatic compass was
used r. : determine the cardinal direction of
houses _:;:d subsequently, a measuring tape
graduated in centimeters was used to measure the
depth cf r.he. exposed foundations. The measurement
was carried out at five points on each cardinal
direction of a house, and the mean value
recorded. At the same time, the slope angle over
which the house is located is taken with an abney
level mounted on a tripod (see Goudie, 1981) .
Questions relating to foundation materials used,
time when the house was built and soil erosion
control measures adopted were directed to the
landlord, landlady or an elderly person resident
in the house,
4.
Analysis and Observation: Relationship
Between Age and Depth of Exposed Foundation
of House,;
1 reveal that the relationship between
age and depth of exposed foundations in the
Northern, parr of the study area is 0.20, and have
been found insignificant. This is because, most
houses in this zone are construe:- , with concrete
materials (gravel mixed with sand and cement)
which offer considerable resistance to erosion
processes. In the Southern, Easter and Western
zones cf. the study area (Table 1) however,
relation.'.-'lips found between age and depth of
exposed i ounda'. icr- of riouses are 0.62, 0.62 and
0.50 resp'n.'ti'•;-•-j y. This is because mud has been
extens.ivt;:-.!" i: ; as fou3id.at.ion materials in these
zone?; rru thib foundation material offer little
resj.stanc-. to erosion attack. These results
further indicate that, the type of foundation
materials is a major determinant of the
relationship between age ai:d depth of exposed
foundation of houses. Thus, erosion rates vary
Effects of Erosion on Foundation
with the type of foundation materials and
increases with the age of the foundation.
Generally, it is possible to predict the
growth rate of erosion as foundation advances
in age given the regression models in Table 1.
TABLE 1:
CARDINAL
DIRECTIONS
IN THE
STUDY AREA
Okene
Okene
Okene
Okene
North
South
East
West
REGRESSION MODELS ON THE EFFECTS OF AGE
AND DEPTH OF EXPOSED FOUOKEECN OF
HOUSES ON EROSION RATES
SAMPLE REGRESSION
SIZES
MODELS
25
25
25
25
y
y
y
y
=24.6 + 1 . 34X
=15.55+ 0. 30x
=32.44+-C. 15X
=18.57+ 0.24X
•R'
0.20
0.62
0.62
0.50
R' 1
% EXPLA
NATION]
ON EROSION
RATES
0.04 4 . 0
0.38 38. 0*
0.38 38.0*
0.25 25.0*
COMMONEST
FOUNDATION MAT.
USED
Concrete
Mud
Mud
Mud
*significant at 0.05 level.
5.
Erosion Rates over Different Foundation
Materials
Over 80 percent of the sampled houses are
less than 50 years and about 60 percent of the
houses were erected on mud foundations, while 40
percent are on concrete foundation.
The mean rate of erosion on the exposed
foundations is 1.04cm/yr with a standard
deviation of 1.07. Mud foundations were the most
severely eroded. Erosion rates on this type of
foundation range from 0.28 to 8.41cm/yr, while
the erosion rates on concrete foundations range
from 0.29 to 2.75cm/yr. Thus, the severity of
erosion rates depends among others on the nature
of foundation materials used.
137
llorin Journal of Business and Social Sciences
6. Aspects and Rates of Erosion on Foundation of
Houses
In the northern part of the study area, it
was observed that, the severity of erosion on
foundations of houses is much on the east side of
houses. This is closely followed by west, south
and North aspects of foundation of houses. In the
southern part of area of study, impact of erosion
on foundation of houses is greatest on the west
side of foundation of houses. This is closely
followed by east, south and north. Erosion
severity is much on the south side of foundation
of houses in the eastern part of area of study.
This is followed by east, west and north side of
foundation of houses. Finally, in the western
part of study, the north side of foundation of
houses is the most affected. This is followed by
east, south and west sides (see Table 2) . The
variation in erosion rates on aspects of
foundation of houses is due to the fact that it
is common to plaster a house down to its
foundation and to erect embarkment on one side.
Thus, erosion is more severe on sides of
foundation of houses without such reinforcements.
Generally speaking, the ravages of soil
erosion on foundation of houses in the northern
part of area of study concentrated more on the
east and west aspects of foundation of houses.
While in the southern, eastern and western parts
of area of study, erosion is concentrated mainly
on the west and east, south and east and north
and east sides of foundation of houses
respectively. These variations in erosion
intensities are due to the type of foundation
materials used, age of foundations, the slope
angle over which each house is located and
ununiform attitudes towards renovating and
combating erosion on foundation of houses.
138
of Erosion on Foundatic.
TABLE 2: MEAN VALUE OF THE
ASPECTS OF F •
STUDY AREA
Cardinal
direction
of study
Area
Mean
age of
houses N D . E . E . R .
(yr)
S D.E.
^t OF EROSION ON
T-KMJ ->T?
IN
TM
E
«'
D.E.
W |
K.P. i :.S.
E.R
Mean
Slope
Houses
(0°)
E.R
(cm) cm/yr
Okene
Okene
Okene
Okene
North
South
East
West
36.64
29.28
37.0
28.16
(cm) cm/yr
14.41 0.39 20.62 0.63
15.37 0.74 '20.44 0 79
14.92 0.74 49.59 1.71
36.82 1.53 23 . 02 1 1 ':
cm
cm/yr
c.:.r ;
cm/yr
3S .73 < . :^r'i ?4 09 0-78
25 =3 l. . : ' 4 0 . 5 8 1 - £ 6
22.5J :" ::>! 19. 73 C . 92
r~ :-- - ' :• i n : . "3 o. 74
i
14.42
10.74
9. 85
8.41
Note: N,S,E and W are North, South. Ear-t ~,nd West sides of
foundation of houses. While, D.E. and E.R. are Depth of
erosion (cm) and erosion rate (cm/'yr} respectively.
7. Response to Threats of Eroded Fcnm d '• t j on of
Houses
measures have been suggested by the
indents fc
eating the menace of erosion
)undation •: r r 1 •-. -;s. These include;
Replastei .'.:.'• f
~ houses down to thei-1"
oundat lor.. v.~h. LCI: is a form of reinforcemen•against: ' rrche r --tosional attack; "
ii)
Construe
: • fN!vibarkment as props aroi1? ~? f f
eroded p_ •••*: s c ijundations ; of concrete
iii! Const.rr-uct i channels T-rland flows
divers ioi. f ' into them. ~he incidence
is to T'lri inns-:- of surface _endant
off and the c" problems; occurrence of
iv)
Minimising the overland flows rain water
from house roofs. The aim of this measure
the same with (iii) above;
Patching the eroded parts of foundation, r.
houses with good materials. The aim is t
halt further advances of erosion and
by collectinq drops at a point
v)
139
(// Business and Sochil
vi)
Di sccuraging
houses. This
mere to eros.;
Oyegun, 1.930
idea of hoeing around
.cause bare surface resoond
an vegetated surfaces (see
rimoh, 1994) .
-••:•••''. .;,• of erosion of foundation of
::-r Ohene and its environs in > ' -"' "• This work has therefore coo:oer:u the severity sectionally. co:
foundations to the point of becoming
dangerous, occurs over along period of time. It
is
often
imperceptible
especially
at
its
incipienc state. Hence; there is need to adopt a
preventive approach in combating it. The
suggested measures by the respondents include the
following:
i) Foundation of houses should be constructed
on ground surfaces that are problem free.
However, foundation of houses may equally
locate
over
problem
surface
after
stabilisation measures have been carried
out. The stabilisation measures range from
the application of lime over such problem
scii surface zc removal of such problem soil
surface and filling with laterites that are
ii
iii)
the ccosci
surface c
activities
usually s1974) aoo
Foundar.:. : o ;:;
with good
laterite or
because, ~hi
the strengtJ
forces of so.
owners should disemphasise
of houses on steep slope
-hills. This is because,
;sion in these places are
ce and Doornkamp,
houses should be constructed
uilding materials such as
concrete. This is necessary
cype of material reinforces
of foundation against the
erosion.
140
Effects of Erosion on Foundation
R E F E R E N C E S
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Geomorphology in environmental management an
introduction. Oxford University press Ltd.
Walton Street, Oxford. PP. 9 - 20.
Goudie, A et al (1981). Geomorphological
Techniques. George Allen and Unwin Ltd.,
Boston. P. 130 - 131.
Gray, D.H. (1972). "Soils and the City: In
urbanisation
and
environment.
(eds)
Detwyler and Marcus. Duxbuny Press Ltd., PP.
135-163.
Jimoh, H.I. 1(1988). Erosion of foundation of
houses: A case study of Okene Local
Government Area in Kwara State Nigeria.
An unpublished M.Sc. thesis submitted to
the Dept. of Geography, University of
Ilorin, Ilorin.. 116 pp.
Jimoh, H.I. (1994). "Response of land use
surfaces
to
erosion
during
intense
rainfall in Okun drainage basin of Ilorin
city, Nigeria" Occasional publications of
the Faculty of Business and Social
Sciences, University of Ilorin, Ilorin.
PP. 79 - 82.
Oromata, G.E.K. (1964). "Soil erosion in the
Enugu areas of Nigeria". Nigerian
Geographical Journal 8:45 - 59.
Oyegun, R.O. (1980). The effects of tropical
rainfall on sediment yield from different
landuse surfaces in sub-urban Ibadan. An
unpublished Ph.D. thesis submitted to
Department of Geography, University of
Ibadan. 324 PP.
Oyegun, R.O. (1987) . "Erosion of the
foundation of mud houses in a Nigerian
village". Ekistics (forthcoming).
Richard, A.V. (1967). Future Architectural
Design. Nigerian Magazine No. 93: 107-115.
Sangree, H.W.(1977). Irigwe shrine houses
(Robranyi) and Irigwo concepts of the sacred
141
llorin Journal of Business and Social Sciences
(Tede) . Journal of the environmental and
social sciences 6 (2): 113-117. Udo, R.K.
(1970). Geographical regions of
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Ltd., Ibadan. PP. 1-52.
142