Global Journal of Engineering Sciences (GJES)
Impact
of Climate Change and Anthropic Activity on The Water Quality of Babar Dam in
Algeria
Authored by Aissam Gaagai
Abstract
The
quality of surface water has deteriorated in recent years, mainly due to
climate change. The objective of this work is to assess the impact of a long
drought and anthropic action on the water quality of a dam in eastern Algeria,
called Babar. To achieve this objective, a study of the water composition of
this dam, using the trend method was carried out. The results demonstrated that
the waters have a sulfate-calcium to magnesium facies. They show also that most
of the parameters follow negative trends, with the exception of K (41.56%), NO2
(5%) and NO3 (35.62%). The use of potassium fertilizers and the dumping of
village waste directly into the basin of the dam without any prior treatment,
leads to an increase in K. The increase in NO3 is mainly due to the
contribution by fertilizers and the nitrification of the ‘ammonium (-61%) which
was accompanied by the drop in dissolved oxygen levels (-7.5%). The drop-in
orthophosphate content (-80%) is due to its low mobility on the first hand, and
to the elimination of phosphorus on the other hand, by mechanical erosion
processes from adsorption of the latter by soil colloids. This approach has
shown that drought and anthropogenic action have a negative impact on the
quality of surface water
Keywords: Dam; Trend method; Anthropic;
Nitrification; Algeria
Introduction
Given
the climate change that has hit the world in recent years, the quality of
surface water has deteriorated significantly due to agricultural, urban and
industrial development. Many variables in water quality are subject to large
fluctuations in space and time and understanding these fluctuations in the
environment can be a difficult task [1]. The natural influence factors can be
due to changes in precipitation, erosion, weathering of the earth’s crust
materials or they are due to anthropogenic action such as urban, industrial and
agricultural activities as well that the excessive exploitation of water
resources [2]. These factors work together to create a type of water whose
chemical composition varies in space and time [3]. In addition, in river
monitoring, it is often necessary to determine whether a variable should be
assigned to natural or anthropogenic causes [4,5], knowledge of the geochemical
evolution of water qual ity could lead to efficient management of water
resources. Water quality is just as important as quantity. Several studies around
the world [6-10]. As for Algeria [11-16] are reported on the effects of
agricultural, industrial and urban effluents on the quality of surface water.
Oued El Arab controlled by the Babar dam, was built for the supply of drinking
water and the supply of industrial and irrigation water. The water stored in
the basin of this dam experiences a deterioration in its quality due to
different types of pollution, in addition to the natural processes of erosion
and leaching of various toxic elements. A program of physico-chemical analyzes
which made it possible to establish a database, which should be analyzed, and
to detect significant trends. This study therefore presents details on the
fluctuations in the chemical composition of the water in the Babar dam between January
2013 and March 2016. This work makes it possible both to understand the
hydrochemical behavior of the surface waters of the dam reservoir. The trend
analysis applied here is determined by linear regression, using the following
least squares method to the time series of water quality parameters, it is a
fairly simple and easy to implement method.
Material & Methods
Study area
The
study area is located in southeastern Algeria, in the eastern reaches of the
Saharan Atlas and precisely at the level of the Djebel Djehfa mountain range
belonging to the Nememtcha mountains. Most of the inhabitants (more than 20,000
inhabitants) are concentrated in the city of Babar. The surface of the sub
watershed is 567 km2, the Babar dam has a capacity of 42 Mm3, built to retain
the waters of Oued Tamagra in the West and Oued El Htiba in the East. The Babar
dam is located at 35° 10 ‘10’’N and 7° 01’41’’E and the city of Babar is
located at 35° 10’4’’N and 7° 06’7’’E (Figure 1). An increase in population and
inadequate domestic sewage systems have the potential to influence the quality
of the dam water. Oued El Arab provides water for neighboring towns and
irrigates thousands of hectares of agricultural land. The increased demand for
water at the development stage, including agriculture, could lead to a bleak
future for the water quality of the dam.
Analytical methods
The trend method was applied
to the data from the physico- chemical analyzes of the surface waters of the
Babar dam during the period spanning 39 months, in this case from January 2013
to March 2016. This method allows acquire representative data on the spatial
and temporal variability of the surface water quality of the Babar dam on Oued
El Arab. For this, we used the data from physico- chemical analyzes, carried
out by the National Agency for Water Resources (ANRH) of Constantine.
The measured parameters are
determined by the ANRH, such as:
pH, suspended matter (MES),
electrical conductivity of water (CE), temperature of surface water in the
Babar dam reservoir (Teau), turbidity (gross), organic matter (MO), calcium (Ca2+),
magnesium (Mg2+),
sodium (Na+), potassium (K+), chlorides (Cl-), sulfates (SO42-), bicarbonates (HCO3-), nitrates (NO3-), nitrites (NO2-), ammonium (NH4+), orthophosphates (PO4 3-). Biological oxygen demand in five days (BOD5), chemical
demand in oxygen (COD), dissolved oxygen (O2dis), the variation of the water
reserve at the level of the reservoir (Vr).
This technique was applied to
the instantaneous monthly physico- chemical data from the Babar dam, during the
period from January 2013 to March 2016 using Excel 2007, which constitute a
time series of 39 analyzes and 21 variables (Table 1).
In this study, we will
effectively present the trends in physico- chemical parameters using a linear
regression method. It is a model based on linear trend least squares equations.
Whatever the case, three classes of trends have been defined: ‘+’ if a positive
trend is detected; ‘0’ if no significant trend is detected; and ‘-‘ if a
negative sible to highlight the possible effects of pollution of anthropic
origin in the long term [17]. This goal is also achieved using the moving
average which makes it possible to make a smoothing which removes seasonality
and to reduce background noise as much as possible. The method in question will
consist in calculating the moving averages by choosing as length the period of
the seasonal variations, so that they will disappear.
Results & Discussion
Characterization of dam water
Table
1:Statistical characteristics of the Babar Dam chemical data in
the long term.
Examination of the
standard deviation and the coefficient of variation shows that (Table 1):
• Twater, pH,
DCO, NO2, NO3, HCO3, Ca
et O2dis are affected by a small variation (< 20%);
• MES, MO, DBO5, NH4, SO4, Cl
et Na show a variation around the mean oscillated between 20 and 40%.
• The rest of the elements
(Turbidity, CE, PO4,, Mg
et K) show a large variation around the average (> 40%).
These strong variations
resulting from effluents and leaching of land following torrential
precipitation, poorly distributed especially over time.
Examination of these data also
shows that the concentrations of the various elements are below Algerian
standards with the exception of:
• SO4 where
66.6% of the data exceeds the standard during the study period.
• NO2 where
5.12% of the data exceeds the standard.
• Turbidity where 36.46% of
the data exceeds the standard. With maximum values recorded during the year
2013.
• MES where 35.89% of the data
exceeds the standard. It has a similar evolution as turbidity.
The Piper diagram applied to
these waters shows that the samples have a sulfate-calcium to magnesium facies
(Figure 2). The first thing noticed between the first campaign (October 2007 to
April 2008) and the second campaign (January 2013 to March 2016), no change was
seen in the chemical characteristics of the dam waters. According to [18] and
[19], calcium can come from nitrogen fertilizers, which participate in the
dissolution of carbonates.
Variation in the chemistry of
the dam water
The linear trend was determined
using instantaneous concentrations and time (Table 1). The initial and final
average values for the period considered made it possible to calculate these
variations. We notice that for most parameters, the slope differs significantly
from zero with the exception of pH, O2dis, T° C, Ca and NO2, where the slope is
respectively equal to -1.24, -7.5, + 2.69, +5 and -4.29. All the other
parameters display a positive slope which varies between +10 and + 108%.
The temperature trend line is
stable with a very slight slope of 2.96%. This small increase is probably due
to climate change. The slope of the pH trend line is slightly negative
(-1.24%). This reflects the presence of low concentrations of organic matter,
where the increase in CO2 pressure leads to a decrease in pH according to the
formula proposed by Kempe (5). The salinity of the water represented by the
electrical conductivity, it registers a negative trend of (-17.57%), this is
due to the increase in the volume of water in the dam during the sampling
period.
The carbonate elements
have a slope, which differs significantly from zero. They recorded negative
trends ranging from -4.29% for (Ca2 +), -18.95% for (HCO3-) and - 44.37% for
(Mg2+). These trends are related to the equilibrium state of the various minerals
in the water and the increase in the volume of water in the dam. These
variations in the carbonate parameters contributed to the drop in overall
salinity (EC) by -17.57% and a drop in pH by -1.24% (Figure 3).
For most of the salt
elements, the trend analysis showed a negative slope ranging from -34.21% for
(Cl-), -22.04% for (Na+2), -13.10% for (SO4-2). On the other hand, a positive
trend was recorded for the K+ (+ 41.56%) (Figure 4). These trends are related
to the increase in the volume of water in the dam, which allows the different
chemical elements to be diluted. On the other hand, the use of potassium
fertilizers and the discharge of village wastewater discharges directly into
the main river, lead to an increase in K+.
The salinity of water
is represented by the electrical conductivity and the variation of this
parameter makes it possible to follow the evolution of the overall salinity and
of the chemistry of the water. In the long term, there was a decrease of
-17.54%, following the increase in the volume of water in the dam. Salinity can
have two origins, either carbonate or saliferous. To determine this origin, we
established the Ca2 + + Mg2 + + HCO3- / Na + + Cl- + SO42- vs CE ratio. The Ca2 + + Mg2 + + HCO3- / Na + + Cl- + SO42- <1 ratio. This reflects the influence of salt minerals on
salinity (Figure 5). The increase in the content of salt elements allows the
increase in salinity. This resulted in a negative trend in the relationship Ca2
+ + Mg2 + + HCO3- / Na + + Cl- + SO42- vs CE.
The
electrical conductivity of the different samples shows a good correlation with
the elements (Na, Ca, Mg, SO4, Cl) with a respective correlation coefficient of
(0.34, 0.27, 0.43, 0.68, 0.4). These strong correlations indicate the direct
contribution of these elements in the salinity of the surface water of the dam.
In contrast, potassium (R = -0.1) and bicarbonates (-0.11) do not seem to
influence the salinity of the water too much. The dissolution of carbonated and
evaporated minerals takes place according to reactions.
This positive trend is
also related to the use of fertilizers on these agricultural soils, this has
been highlighted throughout the world by [25,26] and in Algeria by several
authors such as [15]. Indeed, the form of nutrient is very toxic for both
humans and the aquatic world. This explains why the release of nitrogen in this
form constitutes a potential risk for the environment [27].
The phosphorus trend (-80%)
does not follow the same trend as nitrates and nitrites, this situation can be
explained by the immobility of this element on the one hand, and on the other
hand, the elimination of phosphorus by mechanical erosion processes starting
from adsorption of the latter by soil colloids [20]. It can also relate to the regulation
of phosphorus concentrations in wadis waters by several biogeochemical
processes such as precipitation in the form of apatite [(PO4)3 (F, Cl, OH) Ca5]
[28] and consumption by aquatic plants [29].
Principal without any prior
treatment. Furthermore, this gradual increase in the concentration of NO3-,
corresponds to the yield of nitrification, in the presence of oxygen
aerobically according to reactions (14) and (15) [24]. This oxidation resulted
in a decrease of oxygen of -7.5%.
Influence of water volume
Examination of the trend line
shows a positive trend (+3.41%), since the inputs represented by precipitation
are greater than the outputs represented by evaporation (Figure 8). Analysis of
the evolution of the water volume according to the different hydrochemical
parameters highlights a very significant linear correlation between the water
volume and the parameters with a stronger negative bond (-0.35 to -0.81) for:
(MES, CE, BOD5, SO4, COD,
Mg), a weak negative bond (-0.001 to -0.21) for (pH, MO, NO3, Na,
Ca, NH4, PO4, Cl).
In addition, for the rest we have recorded positive bonds such as HCO3 (0.129),
NO2 (0.22), K (0.51), O2 (0.06).On this basis, we note that most of the bonds
are significant at the 10% threshold, except (pH, NO3, Na, O2) which highlights
either a phenomenon of dilution or concentration depending on the case.
Conclusion
In this case study, the trend
method was used to assess the temporal variations of surface water in the Ouel
El Arab watershed controlled by the Oued El Arab dam. Sources of water
pollution in this watershed could derive from industrial and urban wastewater,
irrigation activities and inclement weather. The temporal evolution of the
physico-chemical parameters was followed during the period of 39 months. The
results obtained showed that most of the parameters followed negative trends,
with the exception of K (41.56%), NO2 (5%) and NO3 (35.62%). The use of
potassium fertilizers and the dumping of village waste directly into the basin
of the dam without any prior treatment, leads to an increase in K. The increase
in NO3 is mainly due to the contribution by fertilizers and the nitrification
of the ‘ammonium (-61%) which was accompanied by the drop in dissolved oxygen
levels (-7.5%). The drop-in orthophosphate content (-80%) is due to its low
mobility on the one hand, and the elimination of phosphorus on the other hand,
by the processes of mechanical erosion from adsorption of this the latter by
soil colloids.
For
more about Iris Publishers
please click on: http://irispublishersgroup.com/submit-manuscript.php.
To read more about this article - https://irispublishers.com/gjes/fulltext/impact-of-climate-change-and-anthropic-activity-on-the-water-quality-of-babar-dam-in-algeria.ID.000643.php
Indexing List of Iris Publishers: https://medium.com/@irispublishers/what-is-the-indexing-list-of-iris-publishers-4ace353e4eee
Iris publishers google scholar citations: https://scholar.google.co.in/scholar?hl=en&as_sdt=0%2C5&q=irispublishers&btnG=
Comments
Post a Comment