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Abstract

RESUMEParmi les aquireres régionaux importants de tres ?rande extension au Maroc, celui du Haouz qui s'étend sur une superficie de 6.000 km , circule au niveau du remplissage mioplioquatemaire issue du démantelement de la chaíne Atlasique. Ce demier présente un facies constitué de galets, graviers, argiles, mames et calcaires, dont la puissance atteint les 100 metres. Cet aquifere joue un role tres important dans l'alimentation en eau potable des habitants de la plaine du Haouz d'une population de plus de 4 millions d'habitants, en sus d'un complément al'irrigation de 80.000 ha.Le climat aride de type continental, qui y regne se caractérise par des amplitudes thermiques assez importantes entre 1'hiver et l'été. La pluviométrie présente une moyenne de 250 mm par ano La piézométrie de la zone étudiée est caractérisée par un écoulement général du sud vers le nord ouest en direction de l'oued Tensift, également principal colIecteur des eaux de surface de la région.Une traduit un régime atlantique des précipitations, sans évaporation, ce qui implique que la recharge se fait rapidement, probablement atravers les formations miocenes gréseuses largement fissurées al'affleurement de l'aquirere mio-plioquatemaire.Un gradient altitudinal moyen de -0,26 %0 par 100 metres est déterminé pour la plaine du Haouz, tres proche des autres valeurs trouvées pour d'autres régions au Maroc, confirmant la validité régionale de celui-ci.Les variations des teneurs en oxygene-8 peuvent etre interprétées en termes de diffé-rence d'altitude entre les altitudes de recharge et d'émergence.Mots c1és: Aquifere mio-plioquaternaire, isotopie, gradient altitudinal, Haouz de Marrakech. ABSTRACTThe study area «Haouz plain» is Located at the center of Morocco, it extend on a surface of 2800 km 2 , limited by the Jbilet hilIs in the North, the High-Atlas range in the South, R' dat wadi in the East and the Essaouira-Chichaoua plateau in the West. The area climate is semi-arid, characterized by low precipitations varying between 160 mm/year and 250mm/year and important variation in temperature between the winter and the summer with respectively 5°C and 45°C. Its hydrographic network is represented by the Tensift system which receives alI the affluents of central and Westem Haouz. These affluents are characterized by weak flows with important seasonal variations.The Haouz plain is a sedimentary basin, being along the northem edge of the high atlas, it presents a geologic succession going from the primary to the recent Quatemary. The mio-plioquatemary formations, stemming from the dismantling of the atlasic chain, refuge an important and generalized water table on alI the plain. This water table shows very variable hydrodynamic characteristics, reflecting the complexity of the deep structures of the plain, 1986) and also the lithological variability of the mio-plioquatemary formations. The Haouz plain includes also the deep reservoirs of the Jurassic, Cretaceous and Eocene which finish sorne meters at the north of the Atlas, thus having a very limited ex...

Chemical and Isotopic Tracers for Characterization of the Groundwater in the Heterogeneous System: Case from Chichaoua-Imin’tanout (Morocco)

“…Groundwater salinization was related to natural processes such as climate change [17], the interaction of water and geological layers [18][19][20][21][22][23], seawater intrusion [24][25][26][27][28][29][30], the ascent of fossil saline waters from deep layers [31], and the contamination by saline waters [32][33][34]. Man-made activities (septic tank effluent, synthetic fertilizer use) can also amplify the effect through intensive irrigation, reduction in the quality and usage of groundwater, and the development of landfills [35][36][37][38][39].…”

The Assessment of the Groundwater Quality in the Coastal Aquifers of the Essaouira Basin, Southwestern Morocco, Using Hydrogeochemistry and Isotopic Signatures

“…This approach is based on the assumption that groundwater's isotopic composition is related to precipitation at the time of recharge [84], which has a gradient of 0.25‰ per 100 m for δ 18 O. This value is consistent with that defined for the High Atlas (0.27‰ per 100 m) [85] and that of the Essaouira Basin our study area (−0.26‰ per 100 m) [86]; the projection (Figure 16) reveals that the waters originate from altitudes between 120 (E70) and 900 m (HT117).…”

Assessment of Groundwater Quality and the Main Controls on Its Hydrochemistry in a Changing Climate in Morocco (Essaouira Basin)

“…Isotopic analysis is a useful tool for deciphering the mechanisms that drive an aquifer system's hydrogeological and hydrochemical evolution [26,79,80]. Stable isotopes of oxygen (δ 18 O) and hydrogen (δ 2 H) are thought to be transported conservatively in shallow aquifers, according to Kim [81].…”

“…In the unsaturated zone, evaporation is likely to occur before water infiltration, or during sampling. The isotopic signature of rainwater and saltwater in the Atlantic Ocean has been used to draw the freshwater-saltwater boundary [25,79]. On the same plot, well 11/51, located near Cap Sim on the coastal edge, has high salinities and a drop in the piezometric level (since 2015).…”