Journal of Water Resource and Protection, 2012, 4, 663-673 Published Online August 2012 (
Attempts to Answer on the Origin of the High Nitrates
Concentrations in Groundwaters of the Sourou Valley
in Burkina Faso
Francis Rosillon1*, Boubacar Savadogo2, Aminata Kabore3, Hortense Bado-Sama4, Dayeri Dianou2
1Water, Environment, Development Unit, Arlon Campus, University of Liège, Arlon, Belgique
2Research Institute for Health Sciences, Ouagadougou, Burkina Faso
3Research Center for Biological, Alimentary and Nutritional Sciences, Research and Training Unit, Life and Earth Sciences,
University of Ouagadougou, Ouagadougou, Burkina Faso
4Convention for the Promotion of a Sustainable Development, Non Governmental Organization, Ouagadougou, Burkina Faso
Email: *
Received June 3, 2012; revised July 12, 2012; accepted July 21, 2012
Within the framework of the contract of Sourou River, a survey of the groundwater quality was performed through 7
campaigns of water sampling and analysis from 2006 till 2012. The water samples resulted from 23 drillings and 9
wells located in the Sourou Valley. Among the analyzed physico-chemical parameters, the nitrates concentrations ob-
served were worrisome. Out of 32 water sources, 14 (44%) supplied a nitrates content superior to the WHO threshold
value for drinking water (50 mg NO3/L). Very high concentrations, superior to 500 mg NO3/L with a peak in 860 mg /L,
were observed. Given the important variations observed from a sampling point to another, a generalized contamination
of the total aquifer was not possible. An individual diagnosis allowed to identify the possible causes of this degradation.
Several sources of contamination , in connection with the anth ropological activities, were ob served near the water facili-
ties (drillings/wells): animal and human wild defecation, presence of nontight latrines, solid waste, wastewater dis-
charges. It is also advisable to wonder about the impact of the dynamite use for digging wells, this one being able to
leave nitrates in the water. With regard to the intensive use of water from the strong ly contaminated wells and drillings
by the rural populations of Sourou, implementing protection areas within which would be eliminated the sources of
contamination in addition to health education among populations could improve the situation. Care should also be taken
in the use of nitrates explosives for digg ing new wells or drillings.
Keywords: Burkina Faso; Sourou; Groundwaters; Nitrates; Pollution
1. Introduction
According to the United Nations Development Program
[1], access to safe drinking water in Burkina Faso clearly
improved these years with a national rate of water access
passed from 18.3% in 1993 to 66.3% in 2007. These
good performances are the consequence of the efforts
undertaken by the country to achieve the Millenium De-
velopment Goals (MDG) knowing that water access con-
stitutes a lever of development and a mean to fight
against poverty. According to the United Nations, the
measures taken led to the reinforcement of the infra-
structures of water supply. The network of drinking wa-
ter adduction which was of 881 kilometers in 1986
reached 3129 kilometers in 2004 while between 2006
and 2007, th e projects and programs allowed the realiza-
tion of approximately 1882 drillings. The situation is
undoubtedly variable from one place to another of the
country, urban environment being privileged compared
to rural environment.
Although Burkina Faso already reached the MDG for
the access to safe drinking water [1], the situation is not
therefore satisfactory, in particular in rural environment
where the populations are confronted with the optimal
management of the water supply poin ts. Who has not met
these drillings installed within the framework of coop-
erative projects and which, after a few years of operation,
break down and aren’t repaired?
But beyond the quantitativ e aspect, it is also advisable
to remain vigilant on the level of the water quality con-
sumed by the populations. If in urban environment, dis-
tributed water is the object of regular con trol, it is not the
same in rural environment where the indicators of drink-
ing water quality are missing due to the lack of analytical
data. An improvement of knowledge is ho wever essential
to make the water services more powerful and to rein-
*Corresponding a uthor.
opyright © 2012 SciRes. JWARP
force the policy for the access to safe water in the coun-
try. It is in this direction that in the Nation al Action Plan
for Integrated Water Management Resources (APIWRM,
2003), one of measurements relates to the installation of
networks for wa te r analy si s [2 ,3] .
The present contribution is devoted to the investiga-
tion on nitrates, an important physicochemical parameter
which characterizes the quality of drinking water for
which World Health Organization (WHO) fixed the
threshold value of 50 mg/L. This study was conducted
from 2006 to 2012 in the Sour ou Valley in Burk ina Faso.
It consisted in evaluating the nitrates contents of water
samples from wells and drillings located primarily in the
Sourou Province. This survey of groundwaters nitrates
contents is part of the data produced by the network of
surface and groundwaters quality survey which was initi-
ated within the framework of the contract of the Sourou
River [4]. After a first restitution related to the general
quality of surface water [5] and of groundwaters [6], it
appeared important to examine the problems related to
the high nitrates concentrations observed for wells and
drillings in this zone.
After the presentation of the context of the study and
the methodology used, the results obtained will be pre-
sented. We will particularly be interested in the results
exceeding the standard of the WHO and more specifi-
cally through three case studies in the villages of Yaba,
Diouroum and Kiembara. We will try to understand the
causes of these raised concentrations of nitrates before
proposing some reflections as regards to good practices
of management to be implemented in order to solve the
2. Context of the Study
2.1. One Action of the Sourou River’s Contract
This study was realized within the framework of the im-
plementation of a project of river contract in the Sourou’s
watershed. It constitutes one of the activities reg istered in
the action program of this river contract.
In 2003, through cooperation with the Walloon Re-
gion of Belgium, a river contract based on the Walloon
model was initiated [4]. This model is an approach of
integrated and participatory management which aims at
gathering within a river committee of the representatives
of all the users of water. This committee has essential
mission to define and implement a restoration actions
program of the water resources, waterways and their ac-
cesses. This program is elaborate according to a consen-
sual approach which takes care to integrate the concerns
of each user while improving the environment protection.
In Burkina Faso, it was proved that the river contract
could also be an issue to fight against desertification and
This project which has been developed on nearly ten
years was framed locally by a Burkinabè NGO, the
COPROD (Convention for the promotion of a sustainable
development) which dealt with the animation and the
coordination of the activities. The Department of Envi-
ronment of the University of Liege in Belgium ensured
the general coordination and the scientific expertise for
the account of the Walloon Region in collaboration with
the Institute for Health Sciences Research (IRSS) of the
Scientific and Technological National Research Center
(CNRST) of Ouagadougou.
Considering the operational characteristic of the river
contract, many activities were performed at the field [7].
The activities were divided into five sets of themes:
1) Coordination, animation and dialog between actors
of water;
2) Improvement of knowledge through the data acqui-
sition and the organization of many formations for the
users of water and the local collectivities;
3) Communication, information and sensitization of
schools and water users;
4) Restoration of the water resources and the environ-
ment which is concretized by an improvement of water
access and environment protection (waterways protection
and fight against desertification;
5) Income-generating activities in a context of fighting
against povert y .
The present study is in line with an improvement of
knowledge related to the quality of water resources in the
Sourou basin. It also meets one of measures recom-
mended by the APIWRM in the actions field No. 2 “wa-
ter information system”: action 2.2, the implementation
of national networks to monitor the water quality, water
uses, water requests and the risks. However, it is sur-
prising that the National System on Water Information
does not mention nitrates on the list of the basic parame-
ters to consider for the groundwaters quality [8].
2.2. The Zone of Study
The Sourou valley is located in the North-West of Burk-
ina Faso, in the area of the Mouhoun loop. The Sourou
River takes its source in Mali at the level of Baye. It
makes border between Burkina Faso and Mali, by then
crossing the Burkina Faso from north to south before
joining Mouhoun River at Léri. The Sourou’s watershed
occupies a surface of 16,200 km2 but it is primarily the
central part of the watershed located on the left bank of
the river (approximately 5000 km2) which is the object of
this study (see Figure 1).
The Sourou valley is especially known for its hydro-
agricultural installations following the erection of dam
valves at the junction of Sourou and Mouhoun rivers in
1984. The realization allowed to increase significantly
the level of water of the Sourou River, the river draining
Copyright © 2012 SciRes. JWARP
Copyright © 2012 SciRes. JWARP
Catchment area of Sourou
Area covered by the river contract
0 100 200km
Figure 1. Zone covered by the contract of Sourou River, Burkina Faso.
important quantities of water (600,000,000 m3) through
the valley [5]. This availab ility of water thus allowed the
creation of irrigated perimeters, making the Sourou Val-
ley an important agricultural production zone.
Currently, the irrigated perimeters extend on a surface
of 3200 ha and are managed under the direction of the
Sourou Valley Development Authority (SVDA). The
SVDA also envisages to extend the irrigated perimeters
area with a new additional zone of 2033 ha. The Sourou
valley thus constitutes an important agrarian production
zone benefitting the whole country. Onion, tomato, rice,
corn, cabbages, lettuces, … are produced in Sourou. Irri-
gated wheat cultures were also developed within the
framework of cooperation with Morocco. Unfortunately
the collected quantities not reaching the envisaged out-
puts, the culture of wheat was abandoned. The slopes of
sprinkling to after the abandonment can still be ob-
served at the field. The activities in the valley are thus
directed towards the exploitation of the irrigated perime-
ters. Elsewhere, they are traditional cultures (millet, sor-
ghum, niebe, …) not irrigated which are installed. The
farmers also supplement their incomes through activities
of cattle, sheep and goats breeding, from some heads of
cattle per family to herds which can be very important.
Water access for Sourou populations is possible, from
various sources of supply, primarily from groundwaters
but certain insular villages or close to the river use sur-
face water. Except for some more important localities
like Tougan, chief town of the Sourou Province, which
profits from a partial system of water adduction, the rural
populations generally feed on from water tanks or tradi-
tional wells to a relatively dense network of drillings
installed by NGO within the framework of cooperative
projects or programs supported by the State, in particular
by the second Soils Management National Plan (SMNP
The availability of groundwater is rather stable. The
Sourou aquifer system is located in a sedimentary zone
and consists of hard stones represented by sandstones
and limestone-dolomites which can be crossed by faults.
The thickness of the aquiferous sandstones is estimated
to a hundred meters [9]. The de pth of drillings is about a
sixty meters in the zone of this study. The water level in
the traditional wells is variable from one site to another,
the depth being of approximately 10 to 20 m. The refill
of the aquifer can be established through a slow infiltra-
tion in the subsoil. This diffuse refill, could be supple-
mented by a preferential water flow through fractured
Within the framework of the Sourou river contract, an
inventory of wells and drillings were carried out. This
inventory identified many nonfunctional works which
were the object of repair within the framework of this
river contract. More than 100 works were thus given
back in activity. Once repairs carried out, it appeared
convenient to check the distributed water quality. If ini-
tially, the repaired drillings were the object of analysis,
thereafter, directed by the nitrates problem, other sam-
plings were carried out.
3. Material and Methods
3.1. Sampling and Field Information Gathering
The network of groun dwater resources analysis consisted
of 32 control points along with 23 drillings and 9 wells
(traditional or modern, large diameter wells). Seven sam-
plings campaigns were carried out from 2006 to 2012
(see Table 1). Six of the campaigns were conducted in
dry season, and one in rain season. A total of 95 samples
were taken and analyzed during the campaigns. Samples
collected at the field were preserved at 4˚C in cool boxes,
carried to the National Laboratory for Water Analysis in
Ouagadoug ou and stor ed in a refrigerator before analysis.
Some samples were blocked by the addition of mercuric
chloride and analysed in Belgium at the laboratory of
water resources of the Department of Environment, Uni-
versity of Liege. In addition to nitrates, the samples were
also analyzed for other physicochemical parameters (pH,
conductivity, turb idity, hardness, ions, NH4, P O4) and for
microbiological indicators (fecal contamination indica-
tors: Escherichia coli, Fecal coliforms and Fecal en-
terocoques) [6].
During sampling, ground observations, supplemented
by information collected from water users and local au-
thorities, fed the reflection in order to try to identify the
potential sources of contamination.
3.2. Analysis Method
The analyses were carried out by the National Laboratory
for Water Analysis of the Ministry of Environment in
Ouagadougou, in the 2 - 3 days following sampling.
Meanwhile, the samples were preserved at 4˚. Propor-
tioning is carried out by molecular absorption spectro-
photometry through nitrates reduction in nitrites by cad-
mium (spectro Hach DR2400 method 8171). The nitrites
formed are proportioned by diazotization of the sulpha-
nilamide which in the presence of N-ethylenediamine
forms a coloured complex [10].
At the laboratory of the Environment Department of
the University of Liege in Belgium, the standard NF IN
ISO 13395 by analysis in flow and spectrophotometric
detection after diazotization was the metho d applied.
In addition, a rapid semi-quantitative test nitrates was
carried out at the field by the use of Merckoquant strips.
This test provided a rather good estimate of the nitrates
concentrations in water [11].
4. Results and Discussion
The average nitrates contents observed during the whole
campaigns are presented in Tables 2 and 3 for drillings
and wells. A great variation in the values obtained can be
observed which ranged from 1 to 860 mg NO3/L. Impor-
tant variations can also be observed between two works
very closely located. Sometimes for less than one kilo-
meter between two works, important differences can be
noted. It does not appear to be a generalized contamina-
tion of the Sourou aquifer but localized situations. For a
same work, the nitrates concentration is generally stable
from one campaign to another, except where the values
are high (see the studies of typical cases hereafter).
Whereas many wells and drillings respect the WHO
standard of 50 mg NO3/L, very high nitrates concentra-
tions were recorded at certain places. Thus, the quality of
Table 1. Campaigns of water sampling and samples collected.
No. campaign Period Season Number of samples Number of well sample Number of drilling sample
1 18/10/2006 Rain (end) 3 3
2 25-30/11/2007 Dry 15 5 10
3 24-28/02/2008 Dry 14 4 10
4 6-9/06/2008 Rain 14 4 10
5 12-13/12/2009 Dry 18 5 13
6 17-18/01/2011 Dry 15 4 11
7 19-21/01/2012 Dry 16 7 9
Total 95 29 (9 controls) 66 (23 contro ls)
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Table 2. Nitrates content in drillings samples (average results).
Locality Drilling name Number of samples Nitrates contents (mg NO3/L)
Kouy COPROD 3 18
Sono Dispensaire 4 8
Kassoum CEG 6 4.5
Wawara COPROD 6 4
Dioroum COPROD 5 648
Dioroum Mosquée 1 1
Kassoum Ecole 3 14
Niassan Dispensaire 4 15
Niassan AMVS 4 13.5
Di Caisse populaire 6 119
Yaba Dispensaire 4 115
Bassan Bassan 1 45
Diélé Dièlé 1 20
Bonro Bonro 1 3
Bourgou COPROD 1 1 150
Bourgou COPROD 2 1 309
Dian Dian 2 74
Guiédougou Ecole 3 19
Boaré Ecole 2 11.5
Kiembara PNGT 2 3 137
Kiembara AEP 2 69
Lankoé Ecole A 2 84
Lankoé Rimaélé 1 17
Total 23 drillings 66 samples
Table 3. Nitrates content in wells samples (average results).
Locality Well name Number of sample Nitrates content (mg NO3/L)
Kouy Mosquée 6 22.5
Kouy Mission 1 263
Sono Sono centre 4 44.5
Kassoum Marché 4 15
Diouroum Diouroum 1 1 205
Diouroum PNGT 2 6 61
Yaba Dispensaire 3 143
Kiembara Mongolo 3 201
Bouaré Ecole 1 25
Total 9 wells 29 samples
Copyright © 2012 SciRes. JWARP
water from the COPROD drilling in Diouroum is particu-
larly worrying with a peak of 860 mg NO3/L observed
during campaign No. 3 (February 2008). To a lesser extent,
but however with always raised concentrations, drillings
of Di, Yaba, Bourgou and Kiembara presented values
ranging from 100 to 200 mg NO3/L. Out of the 23 ana-
lyzed drillings, the WHO threshold value was exceeded
for 9, which corresponds to 39% of nonconformity (see
Figure 2).
yright © 2012 SciRes.
Concerning the wells, the maximum concentrations
seem less lower than in drillings. However, raised con-
centrations were observed at Kouy, Yaba, Kiembara and
Diouroum. 5 wells out of 9 delivered water with nitrates
exceeding the WHO standard, which corresponded to
55% of nonconfo rmity (see Figure 3).
Other parameters were analyzed in the framework of
the contract of Sourou river activities [6] and nitrates did
not appear to be the only factor of disturbance. Whereas
the ammonium (NH4) contents were relatively low for all
the works, with concentrations generally lower than 0.5
mg NH4/L, high concentrations of fecal contamination
indicators (100 to more than 1000 Escherichia coli/100
ml) were observed for wells samples. On the other hand,
drillings globally respected the WHO standard for this
indicator (0 Escherichia coli/100 ml). We could not
connect the nitrates contents with these fecal contamina-
High percentages of nitrates in groundwaters were
previously observed in the subregion and in Burkina
Faso. In the subregion , Mali is also confron ted to nitrates
concentrations much higher than the WHO standard,
according to the Ministry of Energy, Mines and Water
[12] of this country, the situation indicates a local pollu-
tion of the water supply points. In Senegal, concentra-
tions exceeding 500 mg NO3/L were observed for the
aquifer of quaternary sands in the area of Dakar at the
time of campaigns conducted in 1987, 1988, 1995 and
1996 [13]. According to the authors of the study, the
contamination of the aquifer by nitrates results primarily
from horizontal and vertical flows related to nontight
family latrines and organic waste deposits. Moreover,
Fall [14] reported values from 165 to 873 mg NO3/L in 7
mg NO3/L
+de 500
251 - 500
101 - 250
51 - 100
26 - 50
11 - 25
0 - 10
umber of drillings
0 2 4 6 8 10
Figure 2. Nitrates contents (per classes) in drillings water samples.
mg NO
0 1 2 3 4
+de 500
251 - 500
101 - 250
51 - 100
26 - 50
11 - 25
0 - 10
umber of wells
Figure 3. Nitrates contents (per classes) in wells water samples.
private wells of the town of Pikine, these analyses having
been realized in 1992 by the Institute of Sciences of the
Environment of Dakar.
At the country level, the National Water Information
System (NWIS) of the DGIRH [15] through the fol-
low-up network of water quality evoked raised nitrates
concentrations, particularly in the urban centres. Ac-
cording to the design and implementation plan of the
NWIS, these results could due to the insufficiency of
sanitation and sewerage systems, but we are here in rural
Concerning the Sourou zone, concentrations higher
than 100 mg of nitrates per liter were announced by the
information system AQUASTAT of FAO [16] in the
areas of Mouhoun and Sourou. In addition, two cam-
paigns of water analysis were carried out in May and
August 2006 by Nabayaogo [17] within the framework
of a study on the impact of the Sourou valley agricultur al
management on the water resources and the ecosystems.
Only some drillings and wells located in the village of
Niassan and on the riverside were subjected to analysis.
Nitrates contents from 2.7 to 37.2 mg NO3/L were ob-
served in Niassan village by the author and correspond
approximately to the range of values recorded in this
same village during the present study (10 to 23.4 mg
A study of the CIRAD [18] concludes that the pollu-
tion risk of the aquifer by nitrates of agricultural origin is
nearly zero in the Sourou valley (zone of Di). On the
other hand, concentrations reaching 41 mg NO3/L were
evidenced at the beginn ing of rainy season in the Sourou
river, particularly downstream Di village, within the
framework of this project. These nitrates could be due to
the cultivation practices related to the production of to-
mato and onions at this place [5].
For the nitrates concentrations in groundwater ex-
ceeding sometimes at a large extent the WHO threshold
value of 50 mg NO3/L, what could be the sources of
contamination in the Sourou valley? After rejecting the
possibility of a natural origin, we tried to identify the
anthropic causes which could explain these high rates of
nitrates through field investigations at the respective sites.
Globally, at the selected sites, various potential sources
of nitrates can be observed. Concerning diffuse pollution,
the important cattle near the water supply points leads to
deposits of defecation pro ducts in abundance, in addition
to that of human origin. It is particularly the case at Di-
ouroum village where the ground is strewn with excre-
ments. In addition, specific organic matter deposits such
as dunghills and composting areas can also generate re-
jections of nutrients. Latrines, although not very wide-
spread in the Sourou villages can also punctually influ-
ence the quality of water (case of Yaba village), particu-
larly in fractured zones where a fast contaminatio n of the
aquifer is possible.
Concerning nitrates coming from agricultural inputs
cultures, since most of the water supply points are far
away from the hydro-agricultural perimeters, we could
not establish a connection between the fertilizers used
and the contamination of groundwaters. Moreover, sam-
ples collected from Niassan village, next to the irrigated
perimeters presented nitrates concentrations lower than
the WHO standard.
It has also been announced that the digging of certain
drillings and wells in hard sandston e made up required at
certain places the use of dynamite (case of the village of
Diouroum hereafter) which could be a source of nitrates
release in water.
From the tracks evoked above, it appears difficult to
generalize the situation to the whole area in which the
variations are very important from one point to another.
Within a few kilometers distance, we observed very dif-
ferent nitrates contents, sometimes even within the same
village with concentrations varying from one point to
another in significant proportions. In order to better un-
derstand the origin of these nitrates, we carried out three
case studies in three problematic villages where an
in-depth survey was carried out, namely Diouroum and
Kiembara in the Sourou Province and Yaba in the Nayala
Province. The investigations were performed on several
periods from 2007 to 2012.
4.1. Three Case Studies
4.1.1. YA B A Village
The village of Yaba (Province of Nayala, Commune of
Yaba) counts 6618 inhabitants according to the 2006
INSD census [19]. This village has a dispensary and a
maternity equipped with a drilling and a well with large
diameter selected for this study.
The water able in the well was at eight meters depth
(measured in January 2012). The well located at a few
meters of the dispensary presented nitrates concentra-
tions from 93 to 240 mg NO3/L between 2007 and 2012.
An average nitrates content of 115 mg/L was observed in
the water of the drilling of about sixty meters of depth
(see Tabl e 4).
Within a radius of 10 to 20 meters around these water
supply points, beside the dispensary and the maternity,
two buildings occupied by nontight latrines were identi-
fied (see Figure 4). In addition to the function of latrines,
these pits collect also the biological liquids coming from
the maternity.
The first building located at 15 m of the well was
abandoned since a few years. A new block including two
latrines is today in activity. To approximately 100 m of
the well and drilling, is an aban doned cemetery. No wild
defecation was observed near the works.
Copyright © 2012 SciRes. JWARP
Table 4. Nitrates concentrations in water samples of Yaba dispensary’s drilling and well during the 2007, 2008, 2009 and
2012 campaigns.
Sampling source Period Nitrates concentration (mg NO3/L) Average (mg NO3/L)
November 2007 122
February 2008 116
June 2008 143
January 2012 80
November 2007 240
December 2009 93 Yaba—Well
January 2012 97
In this case, the latrines can be responsible for these
the raised concentrations of nitrates. A hydrogeological
study should be able to determine the protection zone to
set up and in which the activities should be regulated. It
is of great importance to have near the health facility a
source of water supply and latrines. However, the pits
should be perfectly tight and subjected to a frequent
draining under control far away the perimeter of protec-
tion of the well and the drilling .
4.1.2. DI OU ROUM Vill a ge
The village of Diouroum (Province of Sourou, Commune
of Tougan) counts in 2006 2048 inhabitants, essentially
farmers and stockbreeders. The three analyzed water
supply points are localized in a maximum radius of 1 km
(see Figure 5). The drilling broken down for several
years has been restored by the COPROD within the
framework of the application of the contract of Sourou
river. In 2010, again broken down, it was repaired by the
inhabitants of the village. Th e nitrates concentrations are
particularly high, a peak of 860 mg/L was observed in
June 2008. In Januar y 2012, the concentr ations remained
high but in clear reduction compared to the previous
years. The two other points presented low but still wor-
rying nitrates concen trations (see Table 5).
In the neighborhoods of these water supply points, the
first observation relates to the important animal defeca-
tion, the animals coming to water itself into the basin
next to the drilling. At a few hundred meters, one can
observed butts, relics of old districts given up with their
waste for a hundred years. A nontight dunghill is local-
ised near the well No. 1.
Drilling would have been dug at the beginning of the
Nineties. Work was particularly painful and idles be-
cause of the hardness of the rock to be bored, dynamite
has been employed to come to end from this resistance.
The depth of water is about 60 m. Well PNGT 2 was dug
in 2005, its depth is of 10 m (measured in January 2012 ).
Cemetery N
100 m
Figure 4. Localization of the water supply points within the
health facility/medical center of Yaba and brief description
of the close environment. W: Well with large diameter; D:
Drilling; L: Latrines; C: Dispensary; Ma: Maternity; - - -:
Village; —: Road.
Du Tougan
500 m
Figure 5. Localization of the three water supply points at
Diouroum and description of the close environment; W1:
Well with large diameter; W PNGT: Well PNGT 2; D:
Drilling; Du: Dunghill; X: Defecation zone; : Old aban-
doned districts; - - -: Village; —: Road.
Copyright © 2012 SciRes. JWARP
Table 5. Nitrates concentrations in groundwate r s at Diour o um.
Sampling source Period Nitr ates concentration (mg NO3/L) Average (mg NO3/L)
November 2007 750
February 2008 610
June 2008 860
December 2009 703
Diouroum—COPROD Drilling
January 2012 315
Diouroum—Well 1 January 2012 205 205
November 2007 45
February 2008 100
June 2008 37
September 2009 5 8
January 2011 72
Diouroum—Well PNGT 2
January 2012 54
Except for the problems of breeding (defecation, ma-
nure), we did not observe near these water supply points
other elements being able to disturb the quality of water.
But what can be the contribution of the use of dynamite
(nitroglycerin: C3H5(NO3)3 obtained by nitration with the
nitric acid of glycerin)? One can suppose that the nitrates
left by dynamite should grow blurred in the course of
time. One should ke ep in mind that the drilling ha s more
than 20 years and that the wells are also contaminated.
However, this probable source of contamination should
be taken seriously in consideration by avoiding the use
nitrated explosives during the operations of drilling.
In addition, if the breeding also contributes to the de-
terioration of water quality, how to solve this problem?
Knowing that the animals need water, is it not appropri-
ate in this precise case to differentiate the water supply
points? Some could be dedicated to human consumption,
and the others to cattle watering with a sufficient dis-
tance in between to avoid disturbances. In this case, a
better knowledge of the perimeters to be protected is es-
4.1.3. KIEM BARA Vil l age
The third case of study relates to the commun e of Kiem-
bara (Province of Sourou) located on the axis Tougan-
Ouahigouya, halfway between these two cities. In 2006,
the village counted 4605 inhabitants whose activities
were varied: farmers, stockbreeders, truck farming, small
shops. Three water supply points were analyzed: a drill-
ing carried out within the framework of the PNGT 2, a
traditional well, a fountain supplied with a drilling out-
side the village. In all the three cases, the nitrates con-
centrations were higher than the WHO standard (see Ta-
ble 6).
PNGT 2 drilling is much attended. Near this drilling,
in a radius of 10 to 20 m, du nghills, nontight latrines and
wild defecation are observed. Two traditional wells close
to the city hall are particularly vulnerab le. The immediate
surroundings of the wells are soiled by wastewaters and
solid wastes. Located on the ground, they directly receive
surface waters coming from the surface of the ground.
Following the first results communicated to the city hall,
a concrete curbstone was installed in 2011. The fountain
is fed by a drilling with water tower (see Figure 6) and
presents a water of better quality but not respecting
however the WHO standard.
Notwithstanding the problem of distances to cover and
the crossing of the road Tougan-Ouahigouya, is it not
more appropriate to keep the water of the fountain for
human consumption and the drilling or traditional wells
one for other uses? Is it not also possible to extend the
network of water adduction while placing equitably addi-
tional fountains th roughout the village?
These three cases illustrate the complexity but also the
specificity of each situation. They show also the interest
of a local analysis, the variations being able to be impor-
tant within the same village, within a sh ort distance.
4.2. Impact on Health
The information obtained from the City hall o f Kiembara,
the dispensary of Yaba and the hospital of Tougan did
not allow to establish a direct relation between the con-
sumption of water with high nitrates concentrations and
the consumers’ health status.Even if cases of cancers are
Copyright © 2012 SciRes. JWARP
Table 6. Nitrates concentrations in groundwaters at Kiembara.
Sampling source Period Nitrates concentration (mg NO3/L) Average (mg NO3/L)
December 2009 106
Jannuary 2011 179
Kiembara—PNGT 2 Drilling
January 2012 125
December 2009 171
January 2011 259 Kiembara—Traditionnel well
January 2012 174
December 2009 71
Kiembara—Fountain January 2011 66
500 m
Figure 6. Localization of the three water supply points at
Kiembara and brief description of the close environment;
W: Traditional well; Du: Dunghill; D: Drilling; CH: City
Hall; F: Fountain; ----: Village; L: Latrines; —: Road.
evoked, the patients are transferred towards more impor-
tant centers for a better assump tion of responsibility.
4.3. Conclusions and Prospects
From the analysis of the nitrates concentrations in ground-
waters of Sourou, it was thus observed that on 32 ana-
lyzed water supply points, 14 provided water with ni-
trates exceeding the WHO threshold value of 50 mg
NO3/L. This proportion corresponds to 44% of noncom-
formity. Very high nitrates contents were revealed in
some sampling sites.
We tried to understand the origin of these worrying
concentrations. Several tracks of contamination were
thus evoked near the works, in relation with the anthropic
activities: animal and human wild defecation, presence of
nontight latrines, presence of pits with dunghill, surfaces
of composting, waste deposits, wastewaters rejections, …
To these possible causes of nitrates pollution, it is appro-
priate to wonder about th e impact of the use of dynamite
for digging on the groundwater quality. Many explosives
contain in their structure a nitrate radical which could
remain in water after drilling. However, the precise di-
agnosis is not obvious to establish and it requires to be
examined case-by-case since the fluctuations of the ni-
trates contents can be important from one work to an-
other, even if they are very close. The situation is not
related to a general contamination of the aquifer of
Sourou but born to punctual specific effects which de-
serve specific observations. Therefore, we examined
three typical cases to try to better understand the origin
of these nitrates.
The processes of nitrates transfer in the aquifer how-
ever deserve to be better documented from an aquifer
susceptible to be fractured and sensitive to direct contri-
butions of contaminants. It would be useful to follow
nitrate flows from the sources of contamination and to
define in particular the transfer times. A refined knowl-
edge of hydrogeology near the works would be also nec-
essary in order to specify the sensitive areas.
But beyond this expertise, it is the rural populations
that are confronted to the access to non-safe water. In the
case, could it not be advisable to relate water uses to the
quality of available water? But that may require longer
displacements for certain families towards not contami-
nated water supply points. Given the difficulty in setting
up denitrification processes, could it not be appropriate to
define perimeters of protection in which the water
sources could be preserved from contamination? In the
future, could it not be required to show prudence for the
use of nitrated explosives during the digging of new
Copyright © 2012 SciRes. JWARP
This contribution which aims at improving knowledge
on the quality of water resources in Burkina Faso Regis-
ters to the policy of integrated water management to
which Burkina Faso subscribed through the APIWRM.
These advances in knowledge must be provided to the
institutions in charge of the water policy and to the local
collectivities, which within the framework of the decen-
tralization, were seen entrusted the responsibility for the
natural resources management. It is also appropriate that
local participating structures as the Local Water Com-
mittees (LWC) catch these problems in order to improve
the water services in response to the populations needs.
Not to forget that in addition to the quantitative aspect
related to water access, water to be provide to popula-
tions should be of good quality, with respect to the inter-
national standards of drinking water .
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