Caractéristiques de ressources en eau des plateaux de Akkar au Nord du Liban

Characteristics of water resources in Akkar plateaus in north Lebanon

¹ Université Libanaise, Faculté de Santé Publique, B. P. 246, Tripoli, Liban
² Université des Sciences et Technologies de Lille, Laboratoire de Chimie Analytique et Marine, (EP 1750 CNRS), 59655 Villeneuve d'Ascq cedex, France
³ Université Libanaise, Faculté des Lettres et des Sciences Humaines, B. P. 246, Tripoli, Liban

Résumé

L'analyse chimique de 20 ressources en eau des plateaux de Akkar au Nord du Liban a été effectuée avec une recherche des éléments à l'état de trace par ICP-AES. Les résultats obtenus révèlent l'absence d'une pollution chimique, le caractère doux des eaux et la diversité chimique des sources étudiées. Confrontées avec les connaissances sur les aquifères de la région, les sources se regroupent en fonction de la formation géologique des plateaux. Néanmoins certaines sont uniques ; c'est le cas de la source de Ain Al-Jaouzé à Hrar que se caractérise par son aspect très faiblement minéralisé (conductivité 63 µ/cm), par la quasi absence des ions majeurs (Na, Ca, K, Mg) et la présence à l'état de trace des oligo-éléments (Fe, Mn, Si, Al) ; la source de Ain Al-Aarbit à Barqayel qui se distingue par son pH légèrement acide (5.6), par la faible teneur en Mg et par la présence du Ba et du Cr à l'État de trace, alors que la source de Ain El-Helzane à Jebrayel est la plus fortement minéralisée (conductivité 310 µ/cm), c'est elle qui contient le plus de Ca, K, Na, Mg, Ni, B, quant à la source de Ain El-Delbet à El-Qamouaa, elle se caractérise par sa pureté exceptionnelle et son pH légèrement basique (8.13). Cette première étude sur la caractérisation des sources en eau à Akkar pourrait servir de base à l'exploitation de certaines de ces sources.

Abstract

The chemical analysis of 20 water resources of the Akkar plateau's in North Lebanon, was performed by ICP-AES with a research on the trace elements. In spite of the high content in water of this area, the majority of the inhabitants consume polluted water. Indeed, fault of good management of these resources, and the quasi absence of sewerage systems, the majority of the natural sources is polluted from the microbiological point of view. Indeed, the first microbiological study carried out on the mountainous sources [Hamze, 1996] showed that 75% of them were polluted. Although a chloration was introduced into the majority of the sources forming part of the existing network of adduction which serves less than one third of the population of the area ; the Ministry for Health indicated [Baltagi, 1997] that ouf of 55 samples analysed in 1996 by the Health Central Laboratory, 27 of them (47%) are polluted from the microbiological point of view. On another side, the study of the quality of underground water of the plain of Akkar [Halwani, 1998] had revealed a significant microbiological pollution (63%), a worrying contamination by nitrates the (86%) and a salinity excessive.

The obtained results proved the absence of chemical pollution, the soft characters as well as the diversity of resources were studied. Confronted with the knowledge of the aquifers of the region, the resources are grouped on the geological formation of the plateau. Some of these resources were unique, such as the case of "Ain Al-Jaouze" spring in Hrar, which is characterised by its weakening minerals (conductivity 63 µ/cm), by the near absence of major ions (Na, Ca, K, Mg); the presence of some trace elements (Fe, Mn, Si, Al); the "Ain Al-Aarbit" spring in Barqayel which is distinguished by its nearly acid pH (5.6), weak presence of Mg & the presence of Ba & Cr in significant concentrations. The highly mineralised is "Ain El-Helzane" in Jebrayel (conductivity 310 µ/cm), this spring contains the highest Ca, K, Na, Mg, Ni, B; while "Ain El-Delbet" in El-Qamouaa, ls especially characteri sed by its purity & its nearly basic pH (8.13). This general feasibility study could start later on from the dynamic point of view at the sameness in time and space, an appreciation of modifications of the variation of the physicochemical composition of water of the sources of Akkar during one year, in connection with varied factors; pluviometry, lithological, hydrological and morphological, in order to have a global vision of the characteristics of the sources out of water with Akkar for the exploitation of some of them. It is quite obvious that this study does not only suffice for it to make the final observation, but it is the first stone in a more general study, it would be necessary initially, fo found a perimeter of protection around these sources in order to back up them faecal pollution (human or animal), then, to look further into hydrological knowledge and to study the total colony count of these sources, to carry out clinical studies, and finally to check the stability of biological and chemical qualities during the year.

This first study on the characteristics of water resources in Akkar plateau's is considered a head start which can help as a basis for future investigation of springs.