Hydrochemical and isotopic assessment for characterizing groundwater quality and recharge processes under a semi arid area: Case of the Haouz plain aquifer (Central Morocco)

Abstract

The Haouz plain aquifer is one of the most important aquifers in Morocco. It is supporting so many activities tightly connected to the local and national socioeconomic development (agriculture, tourism, industry). The recurrent drought the region has been experiencing, had led to a major mobilization of groundwater to meet human needs and socioeconomic objectives. A hydrogeochemical, isotopic and statistical study based on field data was conducted to understand the functioning of the aquifer, to characterize the processes controlling the groundwater's chemistry, as well as identify areas presenting water salinity anomalies. The objective of this study is to develop a conceptual model of functioning of the Haouz aquifer, leading to a better comprehension of the spatial evolution of mineralization regarding the geological frame and the current context of exploitation to evaluate groundwater suitability for domestic and agricultural use. The Plio-Quaternary aquifer water-table contours map showed a flow direction from the High Atlas Mountains, in the south (recharge zone) towards the Tensift bed river in the northwest part of the region. Physico-chemical analysis showed that electrical conductivity are essentially controlled by the chloride and sodium ions and varies over a wide range from 326 to 6800 μS/cm. Regarding irrigation, poor groundwater quality was defined specially near Tensift River in the north of the study area. Stable isotopes contents of water, range respectively from −8.35 to −5.26‰ for δ18O and from −54.4 to −32.4‰ for δD. The recharge altitude of the aquifer was estimated between 860 and 2110 m, following an altitudinal gradient of 0.25% per 100 m.