Multi-tracer approach for assessing complex aquifer systems under arid climate: Case study of the River Tata catchment in the Moroccan Anti-Atlas Mountains

Abstract

Within the arid Tata River catchment of the Moroccan Anti-Atlas Mountains groundwater is the only source for drinking and irrigation water supply. Nevertheless, the hydrogeological and hydrogeochemical setting of the area is understudied. In order to develop sustainable groundwater management strategies a profound understanding of the region's groundwater system is essential. In terms of comprehensive field surveys, aquifer structure and properties as well as water composition were evaluated. The Lower Cambrian Limestone and Dolomite Series as well as the Quaternary sediments were identified to be the major aquifer systems. Isotopic signatures of groundwater indicate direct groundwater recharge trough fractures and a major flow direction similar to the drainage system of the Tata River. Hydrochemical composition mainly reflects the mineralogy. The primary processes are calcite and bassanite dissolution as well as dedolomitization and feldspar weathering. Water of irrigation return flow drains downstream and is pumped repeatedly, with each cycle contributing to contamination and water loss through evaporation, while the water is used for irrigation and daily needs. In turn, groundwater quality decreases along its flow path from N to S. The hydrogeological conceptual model, visualizing all results, can be used by stakeholders to integrate groundwater related aspects into site-specific agricultural practices as well as to set up numerical flow and transport models.