Translated into english by Mr.TEMZI Mehdi

STUDY OF WATER QUALITY IN NORTH-WEST (CASE OF UPPER CHELIFF BASIN)

TOUHARI FADHILA **

Higher National School for Hydraulics Blida-ALGERIA

Abstract Surface water and groundwater are important and essential resources in many countries and often play a key role in water supply both for drinking and irrigation. During the last decades, water demand has significantly increased, especially in developing countries, because of population growth, improvements in standard of living, development of industry, agriculture and because of urbanization. This has led to increasing pressures on groundwater resources. Excessive abstractions of groundwater over the past decades to meet these demands have resulted in serious troubles: decrease in the level of water-table, groundwater quality degradation and ecosystems deterioration.

It is, therefore, essential to quantify and analyze the quantity and quality of water reserves and to find ways to manage this resource in order to ensure sustainability thereof. The main aim searched for in this context is to get to study the quality of groundwater and surface water in the Upper Cheliff region.

The aims of our study are as follows:  Give an overview into quality parameters and into methodology of the study for underground and surface water.  Location and presentation of the study area and its characteristics as well as analysis of the key climate and hydrologic conditions.  Stress the natural geologic and hydrologic setting and the piezometry with regard to the chemical quality.  Assess then the quality of surface water through quality charts achieved and their interpretations for each dam.  The study of chemical parameters evolution in the time and space, by addressing mechanisms of the acquisition of the groundwater mineralization.  Our efforts will also concern the dependencies and relationships between the various physical and chemical parameters of the water and origins thereof.  Identify the pollution sources and their impacts on the Upper Cheliff underground water * D o c t o r a l thesis of Sciences. ** Thesis advisor: Mr.MEDDI Mohamed, Professor – E.N.S.H BLIDA.

Introduction Water can be scarce in some places, such as arid and semi-arid, or may be quite simply of poor quality in other places. It is certain that the increase in water demand for human activities will 1 Translated into english by Mr.TEMZI Mehdi accentuate the constraint on this resource. In addition, natural factors such as drought or geological constraints affect the drinking water supply and distribution. In this context, this study adds to earlier researches, and this to provide a scientific overview, qualitatively and quantitatively, of the current state of the upper Cheliff area. The quality of waters of this region has undergone, in recent years some, deterioration because of uncontrolled urban waste, intensive use of artificial manures and fertilizers in agriculture and its disorderly utilisation. These elements alter the chemistry of the water and make it unsuitable for desired uses. It is in this context that this study was conducted in order to analyze the quality of water at the aforesaid region.

I. Presentation of the study area The study area corresponds to the Upper Cheliff basin, and is located 110 km South-West of , and is part of the Cheliff drainage basin (Figure 01).

The upper Cheliff area is an agricultural vocation requiring sprinkler irrigation due to a semi-arid continental climate with very dry summers (interannual temperature fluctuates from 13 to 19°C, with a monthly maximum of more than 30 °C recorded in July) and rainfall winter episodes sometimes causing spectacular flooding of Cheliff wadi. The building of dams (Ghrib, Deurdeur, Harreza and Sidi Mhamed Ben Taiba and Ouled Mellouk) enabled the control of the wadis’s flows and the provision of irrigation water from April to September.

Interannual average pluviometry varies between 300 and 500 mm. It is more concentrated in altitudes on the south slopes of Zaccar and on the north slopes of the Ouarsenis. Across the Upper Cheliff basin, annual potential evapotranspiration ranges from 1,200 to 1,500 mm according to the map of potential evapotranspiration in northern Algeria

Figure 1: Location map of the Upper Cheliff catchment basin.

II. Geology and Hydrogeology of the Upper Cheliff area

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The Upper Cheliff plain is located between 36° 12' and 36° 30' North latitude and 02° 02' and 2° 44' East longitude. It is bordered to the North by the dolomitic limestone of Jebel Zaccar (1,578 m altitude) and the sandstones of Jebel Gantas, to the South by the first foothills of the clayey-marly and sandstone Ouarsenis massif (figure 02). One enters the plain at the East by the sill at 308 m and comes out at the West by the Doui sill at 248 m a.s.l. (Mania, 1990). The plain of Upper Cheliff corresponds to a vast depressed and subsiding area with East-West orientation where Miocene, Pliocene and Quaternary sediments have accumulated. The cross lithological sections done in the plain of Upper Cheliff, show the synclinal attitude of different formations constituting the sub-soil.

M e d i t e r r e a n S e a

. T u n i s i a i i s n u T M o r o c c o A l g e r i a

Figure 02: Simplified geological map according to the 1/50.000 of .

Further to the piezometric campaigns conducted in high and low water in 2002 and 2008, we found that piezometric maps show the same morphology and the same attitude of piezometric curves. The groundwater flows are from the borders towards central axis of the valley before taking a East-West direction in a parallel to the main river of Cheliff wadi, but with a certain increase in piezometric level due to ground water recharge following a high annual pluviometry during 2008. However, we notice that there is a certain local disturbance at the central and southern area of the plain in 2008, due to the ground-water overdraft to ensure irrigation.

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Figure 03: Figure 03: Water-level map in period of High water and low water, 2002.

III. Quality of surface water This work will be the subject of a quality assessment study of dams’ waters on the basis of the monitoring of physical-chemical parameters, which is provided by the National Agency for Water Resources (ANRH) for a-10 year period (1999-2008). We give, first, the state of the dam’s water quality when the latter is equipped with a monitoring network, then, the origin and the amount of pollution received by each catchment area of the dam.

Monitoring and evaluation of the qualitative status of water require a measurement network of water quality, regular analyzes, interpretation of those analyzes and a comparison of results with accepted quality standards.

The study for the water quality of Upper Cheliff dam will deal with the five (05) operating dams Ghrib, Deurdeur, Harreza and Ouled Mellouk. These dams are monitored for water quality through the existence of ANRH monitoring stations.

Figure 04: Index of annual average quality of Ghrib Dam water (1999-2008)

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The importance and severity of pollution are confirmed by the results observed in the study of the surface water quality in the region of Upper Cheliff, namely: • Water quality records show a degradation of the aforementioned quality for all dams (an organic pollution expressed in COD) over time. In actual fact, the recorded quantity of COD often exceeds 50 mg / l, and that of the OM also exceeds 15 mg / l. This pollution is due to wastewater disposal and eutrophication process. • Water dams show a very high salinity (dry residue = 2,574 mg / l in 2008 for Ghrib dam waters, + - standard = 1,500 mg / l). The content of nitrogen substances in waters (NH4 , NO2 ) in 2008 is high in O. Mellouk dam. This pollution is due to oxidation of the nitrogenous organic material. • The polluting load reaching catchment areas of the dams is characterized by the polluting load of breeding establishments firstly and by its high value in almost all catchment areas secondly.

IV. Hydrogeochemical groundwater characterization This chapter deals with groundwater chemistry and will enable us trying to explain the behavior, the origin and the evolution of chemical elements described for the explanation of hydraulic functioning of geohydrologic unit.

The study is mainly based on information from four (04) sampling campaigns, achieved from 47 watering places in 2002, and 50 watering places in 2008, all the places are spread over the territory. As the plain of Upper Cheliff is agricultural, a particular interest will be given to the plain.

Figure 05: Ground-water inventory of the Upper Cheliff plain.

Pearson correlation matrix (Swan and Sandilands 1995) was used to find relationships between two or many elements. The analysis of the correlation matrix (Table 01) can retain the correlated elements in pairs with a significant correlation coefficient (r). It is noted that in 2002, the R.sec is perfectly correlated with calcium (R = 0.78), magnesium (R = 0.75), sodium (R = 0.85), chlorides (R = 0.94) and sulphate (R = 0.69). On the other hand, there was a slight increase in correlation coefficients in 2008 for calcium and magnesium ions.

Table 01: Correlation matrix between variables.

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2+ 2+ + + - -2 - - Variables Ca Mg Na +K Cl SO4 HCO3 NO3 R.Sec

Ca2+ 1

Mg2+ 0.79 1

Na++K+ 0.33 0.43 1

Cl- 0.77 0.76 0.80 1

-2 SO4 0.38 0.57 0.61 0.46 1

- HCO3 0.17 0.10 0.24 0.13 0.14 1

- NO3 0.04 -0.06 -0.32 -0.16 -0.40 -0.09 1

R.Sec 0.75 0.78 0.85 0.94 0.69 0.26 -0.20 1

The highest concentrations of these elements are found south of the plain, on the left bank of Cheliff wadi, and near the towns of Djendel, Bir Ouled Khelifa and .In fact, the discharging of domestic waste water from agglomerations which are situated in the plain (17 discharges points) and estimated at 15,000 m3 /d, without this water being treated beforehand, affects adversely the quality of groundwater. The location of high concentrations may be related, in a way, to these spills.

Figure 06: Map of chlorides, periods of high and low water 2002 and 2008 (mg/l).

The nitrate distribution is very different. The highest concentrations are found in the east, near Djendel, in south near Bir Ouled Khelifa, in north to Sidi lakhdar and in west at Djelida. These very high levels are due to the activity of orchards occupying a large part of the area benefiting from the excessive intake of fertilizers, pesticides, manure and communities’ waste. The projection of sampling units on the F1-F2 plane revealed that (see figure 07):

 The axis F1 shows opposition between lowly mineralized waters ( figure 07A) located to the northwest and west of the aquifer (in borders of Doui massif and Zaccar one in particular) and highly mineralized waters which are located to the south of the groundwater on the left bank of Cheliff wadi and this for the two years 2002 and 2008.

The axis F2 also shows an opposition between waters full of bicarbonates (figure 07B) and weakly loaded water with this element. The first waters become localized on the right bank of

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Cheliff wadi in the North and the Northwest of the groundwater in the proximity to the borders of Zaccar and Doui massifs. The seconds are located in the South of the groundwater.

Waters highly loaded with nitrates become localized in the East and South of the groundwater near the agglomerations of Djendel, Ouled Khelifa and Djelida.

Figure 07: sampling units projection on the factorial plane (F1-F2) in 2008

Examination of Table 2 shows that the most widespread chemical facies for 2002 are of Calcium chloride type; 17 samples out of 28 i.e. 61% in periods of high water and 08 samples out of 19 i.e. 42% in periods of low water. Followed by sodic oxychloride facies with 10 samples out of 28 or, i.e. 36% in high water and 6 samples out of 22 i.e. 27% in low water. The calcic bicarbonate facies represents 11% (3 samples) and 11% (2 samples), in high and low water respectively. Finally, the presence of a magnesian oxylchloride facies (4%) during the high water period and a sulfated calcic facies is reported (3% and 10% for the high and low water periods).

Table 2 : groundwater chemical facies in the Upper Cheliff aquifer in 2002.

A noticeable feature of phreatic table in the Upper Cheliff is, however, Cl- enrichment compared with Na+ (figure 08d). The excess of Cl- can be explained only by the existence of another origin of this ion than the dissolution of halite. There may also be an anthropogenic origin. Indeed, urban wastewater are discharged untreated in the environment and can reach groundwater by infiltration.

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The increase in C1- levels and which accompanied the low Na+ levels is due to base exchange phenomenon because substratum clays may release Ca2+ after having setting Na+.

2+ 2- 2+ - 2+ 2+ The relationship Ca vs SO4 (Fig. 08a), Ca vs HCO3 (Fig. 08b) and Ca vs Mg (Fig. 08c) however, show a large excess of Ca 2+, this indicates that the source of Ca2+ is not due to the sole fact of the dissolution of the calcite and gypsum, and thereby confirms the hypothesis of an entry of Ca2+ by ion exchange.

Figure 08: Relations between the main major elements 2002.

In this study, most points are on Ca2+ + Mg2+ side (Fig. 09), which suggests that the basic exchange is the major hydrochemical process that operates in this aquifer.

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2+ 2+ - 2- Figure 09: Relation between (Ca + Mg ) and (HCO3 +SO4 ) in 2002 (A) and 2008(B).

The calculation of the saturation index for carbonates and gypsiferous minerals showed that the first tend to precipitate before the second, this has allowed the chemical elements resulting from gypsum dissolution to acquire significant levels.

Figure 10: Variation of the minerals saturation index, April and September 2002.

The table 3 shows that almost all the water analyzed are very hard for both periods with a T.H (Total Hardness) above 54 °F. High magnesium and calcium contents exceeding the threshold set by the World Health Organization make this water very hard.

Table 3: Water classification according to their Total hardness.

T.H (°F) 0-7 7-14 14-22 22-32 32-54 >54

Water description Very soft Soft Relatively soft Rather soft Hard Very hard

April - - - - 18 82 (%) of samples 2002 September - - - 05 16 79

April - - - 04 07 89 2008 October - - - - 09 91

Domestic use Good potability Acceptable potability Poor to bad potability

The results of this study allowed improving in a significant way the understanding of aquifer which is an important resource for the development of this region. Urgent actions must be taken quickly by the authorities in order to face the serious degradation of this resource.

V. Pollution sources in the ground-water surface

The ground-water of Upper Cheliff includes several municipalities: Djendel, , Sidi Lakhdar, Bir Ouled Khelifa, Ain Soltane, Djelida and . Pollution sources that release more polluting load are mainly domestic and industrial waste, breeding, and uncontrolled public dumps. This is also true of slaughterhouses and hospital landfills but with less significant loads.

The figure (07) that the various pollutions with high loads are concentrated in the municipality of Khemis Miliana with 678,903 inh.eq., followed by the municipality of Ain Soltane with 403,578 9 Translated into english by Mr.TEMZI Mehdi inh.eq. and that of Sidi Lakhdar with 203,541 inh.eq. and finally the municipality of Djelida, Djendel and Bir Ouled Khelifa.

Figure 1: Polluting load in the Upper Cheliff ground-water

Conclusion

- Spatial distribution of chemical elements shows that chemism is highly linked to lithology of the ground-water, consequence of dissolution of the carbonate and evaporitic formations;

- The follow-up of water quality over time has shown the effect of rainfall and evaporation on the ground water mineralization.

- In the plain of the Upper Cheliff, most chemical elements analyzed exceed the standards set by WHO. In actual fact, high calcium and magnesium contents make this water very hard (91 % of water places are very hard in low water period 2008).

Understanding the groundwater hydrochemistry and quality is vital to preserve this resource and in so that it can meet the present and future water needs in many countries. In North West Algeria, groundwater resources in the Upper Cheliff plain play a vital role in potable water supply and in water use for agricultural purposes. However, the degradation of this valued resources increases, which reflects a lack of knowledge of the groundwater mineralization processes and an absence of rational management.

Application perspectives

In order to protect these water resources against pollution and in order to complete successfully the new developments projects, compliance with the map of water-vulnerable to pollution is recommended.

Proposal of a modeling of ground water run-off and a transfer of chemical pollutants in the plain will be useful in order to know their dispersion over the whole plain.

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Touhari F., Meddi M., Mehaiguene M. & Razack M. (2014): Hydrogeochemical assessment of the Upper Cheliff groundwater (North West Algeria). Environ Earth Sci ISSN 1866-6280 DOI 10.1007/s12665-014-3598- 6. 21p.

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