Journal of Environmental Protection, 2014, 5, 60-64
Published Online January 2014 (
The Impact of Urban Flooding on Surface Water Quality
of Awka Town
Anthony C. Okoye1, Emma E. Ezenwaji2, Kabir A. Awopeju3
1Department of Environmental Management, Nnamdi Azikiwe University, Awka, Nigeria; 2Department of Geography and Meteor-
ology, Nnamdi Azikiwe University, Awka, Nigeria; 3Department of Statistics, Nnamdi Azikiwe University, Awka, Nigeria.
Email: emmaezenwaji@
Received May 31st, 2013; revised June 29th, 2013; accepted July 23rd, 2013
Copyright © 2014 Anthony C. Okoye et al. This is an open access article distributed under the Creative Commons Attribution Li-
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Some physico-chemical and bacteriological parameters were analyzed for in the water samples of four different
ponds loca ted in Awka tow n both prior and after the rain to ascertain the i mpact of flood in these ponds a nd to
establish w het her t he poll ut i on w as significant. Four samples were collected from each pond both before the rain
and after making it a total of thirty-two samples. Twenty-seven parameters were analyzed for in each of the
samples. The result revealed that twelve parameters exceeded WHO standard before the rain while fourteen ex-
ceeded after the rain. There was significant increment in the values of the analyzed parameters after the rain
when compared with the value before the rain as revealed by the Anova statistical tool. It was discovered that
there was a major increase in the bacteriological parameters after the rain which implied the serious health im-
pact. It was recommended that users who utilized these ponds for squeezing bitter leaf, processing cassava and
washing meats etc. should do so with the caution so as not to expose people to health problems.
Ponds; Flood; Pollution; Health Impact; WH O Standa r d
1. Introduction
Flooding is a localized hazard that generally results from
anthropogenic activities and moderately to large clirna-
tolo gic even ts suc h as the inte nse rainfall. It is one of the
most wide spread climatic hazards that poses multiple
risks to hu ma n hea lt h [ 1 ] . Urban areas especiall y those in
developing countries experience various types of disas-
ters in most periods of the rainy season as a result of
flooding. Ur banization aggra vates flooding b y restricting
where flood waters can go, covering large parts of the
ground wi th ro of s, ro ad s and p ave ments, ob str ucti ng se c-
tions of natural channels and building drains that ensure
that water moves to rivers faster than it does under natu-
ral conditions. As more and more people crowd into ci-
ties, the effects intensify. As a result, quite moderate
storms produce high flows in rivers because there are
more hard surfaces and drains.
Most studies in urban flooding have concentrated at-
tention in describing the nature of urban floods, listing
the causes of such floods and their destructive conse-
quences on life and property [2]. The destructive effects
of floods in urban areas have been widely recognized in
Nigeria [3-5]. The causes of such urban flooding has
been linked to climatic factors such as rainfall [6], topo-
graphy [7], urban sprawl [8], poor urban planning [9] and
other environmental factors [10]. Flooding is one of the
major causes of the surface water pollution. Flood was h-
es down all sorts of liquid and solid pollutants from the
city and deposits them into the surface water bodies.
People make use of these water bodies to process cassava,
squeeze bitter leaf and do other things that could expose
humans to health hazards. Most studies in the urban
flooding deal mainly with the nature and causes of the
floods and their general destructive consequences. There
is a need to assess the quality of these ponds and to investi-
gate the extent of the pollution so as to ascertain the sta-
tus of the pond s. This i s what this st udy seeks to address.
The Impact of Urban Flooding on Surface Water Quality of Awka Town
2. Materials and Methods
2.1. Study Area
Awka town is located between Latitude 6.24˚N and
6.28˚N and Longitudes 7.00˚F and 7.06˚F on the Sou-
theastern part of Nigeria (Figur e 1). The study area cov-
ers 144.5 hectares with a 2006 contested population of
116,208 persons [11]. This includes such outlying com-
munities as Amawbia, Okpuno and Amansea which are
fastiy being annexed to the town by urbanization. The
town’s topography presents a rugged relief as it lies
completely on Awka-Or1u upland. Generally, the aver-
age height of the town range from 91 m in the western
parts of the town to 160.2 M in the eastern zone, al-
though there are local variations within the town which
are drained by a number of streams. The climate is the
tropical wet and. dry type according to Koppen’s classi-
fication system with a clear cycle of season. The mean
daily maximum temperature is usually 27˚C all over the
year. This could reach 34˚C in March, and. lowest during
the hamartan months of December and January. The
mean annual rainfall according to the local meteorologi-
cal station reveals a mean rainfall of about 1600 mm wit h
a relative hu midity of 80% at dawn.
2.2. Site Selection and Sample Collection
This study was carried out during the rainy season of
2010. Samples were collected in May and September.
Four ponds were selected for this study as they are the
only ones available in Awka town. Pond 1 is located at
the back of Bishop Crowther seminary Aka Pond two is
along Obinagu road near Ejiofor bread Industry Pond 3 is
opposite Katta market while pond 4 is behind Crescent
Sprig Hotel Iyiagu (see Fig ur e 1) Four samples were
collected from each of the ponds using sterile 500 ml
glass sample bottles, with caps at different points before
the rain event and immediately after the rain event.
Another batch of samples were collected in September
making a total of thirty two samples for the four ponds.
The samples were stored at about 4˚C in a refrigerator
pri or t o t he analysis.
2.3. Sample Analysis
2.3.1. Physico-Chemical Analy sis
The temperature of the samples were measured with la-
The Impact of Urban Flooding on Surface Water Quality of Awka Town
Figure 1. M ap of Awka urban area, N igeria.
boratory mercury bulb thermometers calibrated in degree
centigrade. The colours were determined using the Pt-Co
method (Mamta, 1999). The pH of the samples were de-
termined using a pH meter (Model WTW Weiheim 88
68594) while the turbidity was determined by the forma-
zine Attenuation method [12]. Total hardness was deter-
mined by the EDTA titrating procedure. Total dissolved
solids (TDS) of samples were determined gravimetrically
after the samples were over dried to constant weight at
105˚C. Nitrates were determined through the colorimetric
diazotization method and the phosphates by persulfate
UV oxidation method [13]. The carbonates and bicarbo-
nates were determined by titrating 50 m1 of the samples
with 0.25 M solution of the tetraoxosulphate (vi) acid
using phenolphthalein and methyl orange as indicators.
The chloride content was determined by the Mohrs me-
thod [14]. The elements were determined using Unicam
SP 1700 Atomic Absorption Spectrophotometer.
2.3.2. Microbiological Analysis
The membrane filtration method (MF) was used to enu-
merate total coliforms and faecal coliform counts of the
water samples [15], while pour plate was used to deter-
mine the heter otr ophi c count.
2.3.3. Statistical Analy sis
Analysis of Variance (ANOVA) statistical technique was
the tool applied in the analysis of the data generated. The
H0 reads that there are significant differences between the
observed parameters after the rainfall while H1 reads that
there are no significant differences between the observed
parameters after the rain.
3. Result and Discussion
The result of the physico-chemical and bacteriological
parameters of the samples are presented in Table 1. The
Table 1. Phys ico-chemical and bacterological analyses of samples.
Paramet er s Before Rainfall After Ra infall
Pond 1 Po nd 2 Po nd 3 Po nd 4 P o nd 1 P o nd 2 P o nd 3 P o nd 4
Appearance muddy Slightly clear Slightly clear muddy muddy cloudy cloudy muddy
Temperature (˚C) 26 25 25 26 29 27 29 26
Colour (Ap-co) 120 110 115 120 200 150 180 190
Turbidity (FAU) 40 30 30 50 60 80 50 60
Odour 8.6 7.4 8 .1 6.9 8 .7 8.8 8 .6 7.4
PH 688 649 520 593 1286 1249 820 1130
Conductivity (μohms/cm) 510 500 500 721 910 840 860 940
TDS (mg/ l ) 2 2 2 4 4 3 4 5
BOD (mg/l) 22 18
Carbonate (mg /l) 60 54 33 40 87 63 48 60
Sality (mg/l) 24 33 35 32 83 107 94 102
Bicarbonate (mg/l) 44 40 31 70 120 60 48 10
Calcium ( mg/l) 112 94 119 102 184 138 193 171
Total Hardness (mg/l) 74 70 72 71 170 130 141 163
Magnessium (mg/ l) 5 3 5 5 10 5 8 6
Sodium (mg/l) 4.1 4 4 4 4.2 4.7 4.5 4
Pota ssium (mg/ l) 10 8 10 8 12 10 14 10
Sulphat e ( mg/l) 0.1 0 .1 0.1 0 .1 0.2 0 .2 0.4 0 .2
Nitrate (mg/l) 0.6 0.38 0.25 0.3 0.6 0.4 0 .3 0.4
Iron (mg/l) 0 0 0 0 0 0 0 0.2
Manganese (mg/l) 0 0 0.2 0.2 0.8 0.6 0 .6 0.4
Copper (m g/l) 1 1 0.3 2 3 3 1 5
Phosphate Chloride (mg/l) 0 0 0 0 0 0 0 0
Heterophic Count (cfu/100 ml) 320 300 301 310 410 360 320 4 00
Total Coliform (cfu/100 ml) 100 91 90 70 120 102 98 71
The Impact of Urban Flooding on Surface Water Quality of Awka Town
Feaca l Coliform c f u/100 ml 6 4 10 4 10 15 12 6
result showed that fifteen out of twenty seven parameters
measured before the rainfall in all the ponds fall within
WHO permissible limit and they include pH, salinity,
carbonate, bicarbonate, calcium, total hardness, magne-
sium, sodium, potassium, sulphate, nitrate, manganese,
copper, phosphate chloride and residual chlorine. These
parameters also fall within the WHO standards after the
rain event except for nitrate in all the ponds and pH in
ponds 1, 2 and 3. However, it was generally observed
that the values of the parameters increased after the rain
obviously because they constitute the pollutant load
which were washed off by the flood while passing
through various impurities such as industrial and com-
mercial solvents, metals and salts, radioactive materials,
pesticides, decaying materials and other contaminants
which end up in these ponds. The computation of the
average of the values of those parameters in the four
ponds during and after the rain (Table 2) confirms that.
Those parameters which were higher even before the rain
were probably so because of their accumulation over the
years. At 95% confidence level, the F critical (2.05963)
was greater than the F calculated (0.383372), hence we
accept the null hypothesis which is consistent with the
observation earlier made that the flood has significantly
affected the water quality of these ponds (Table 3).
4. Conclusion and Recommendation
The study showed that about 58% of the twenty-seven
parameters analyzed exceeded the WHO standard after
Table 2. Average values f or all ponds befor e and af ter rain.
Paramet er s Average before Rainf all WHO Averag e after Rainfall
Temperature (˚C) 25.5 25 26
Colour (P t-co) 116.25 50 190
Turbidity (FAU) 37.5 25 60
PH 7.75 6.5 - 8.5 8.375
Conductivity (μohms/cm) 612.5 500 1130
TDS (mg/ l ) 557.75 500 940
BOD (mg/l) 2.5 2 5
Carbonate (mg /l) Ni l 500 10
Sali nity (mg/l) 46.75 500 60
Bicarbonate (mg/l) 31 500 102
Calcium ( mg/l) 46.25 200 59.5
Total Hardness (mg/l) 106.75 5 00 171
Magnessium (mg/ l) 71.75 250 163
Sodium ( m g/l) 4.5 200 6
Pota ssium (mg/ l) 4.025 250 4.35
Sulphat e ( mg/l) 9 400 10
Nitrate (mg/l) 0.1 1 0.4
Iron (mg/l) 0.3825 0 .3 0.4
Manganese (mg/l) 0 0.1 0.2
Copper (m g/l) 0.1 1 0.4
Phosphate Chloride (mg/l) 1.075 10 5
Residual Choride (mg/l) 0 0.5 0
Heterotrophi c Count (cfu/100 ml) 307.75 300 400
Total Coliform (cfu/100 ml) 87.75 10 71
The Impact of Urban Flooding on Surface Water Quality of Awka Town
Feaca l Coliorm (c f u/100 ml) 6 0 10.75
Table 3. ANOVA statistical analysis.
Source of Va riat io n SS df MS F P-value F crit
Between Groups 147558.626 7 21079.8 0.383372 0.911281 2.059637
Within Groups 10117292 184 54985.28
Total 10264850.63 191
the rain event. All bacteriological parameters examined
exceeded the WHO standard both before and after the
rain. This implies that people that squeeze bitter leaf,
process cassava, wash meats and utilize these ponds for
other things most likely expose humans to all sorts of
health hazards. The increment in the values of the ana-
lyzed parameters after the rain and the statistical analysis
shows that the flood impacts significantly on the ponds
and the pollutant lo ad will continue to increase ad infini-
tum. It is recommended that people should be mindful of
what they use these ponds for. Government should en-
lighten people to desist from disposing their wastes into
the drains as this will reduce t he level of pollution.
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