Isotopic and Chemical Tracers for the Sustainable Management of Water Resources in Semi-arid Area: Case of Massa Catchment, Morocco

Abstract

The Massa region is an important agricultural area in south-western Morocco. The climate in this region is semi-arid to arid with an average precipitation of 150-200 mm/y. Thus, the region suffers from water scarcity and water quality degradation. Hence, in this study we aim to assess the influence of human activity and climate change on the quality and quantity of water resources in the Massa catchment. An approach combining chemical and isotopic tracers is adopted to achieve this objective. About 54 water samples were taken from river, dam, spring and wells through the Massa catchment. Preliminary results show different water types and large variability of NO3 -, Electrical Conductivity (EC) with high contents mainly in the downstream. Stable isotopes indicate a large variability of isotopic signatures with values falling close to the global and local meteoric water lines. River water shows an enrichment of oxygen-18 along a line of evaporation and groundwater indicate a recharge from Anti Atlas Mountains with elevation ranging from 500 to 3300 m.a.s.l. The quality of water is impacted mainly by water-rock interaction, marine intrusion and anthropic activity. These results could be useful for the decision makers to more improve water resources management in this area suffering from water crisis.