Estimating groundwater resources in remote desert environments by coupling geographic information systems with groundwater modeling (Erg Chebbi, Morocco)

摘要

Groundwater resources are essential to underpin the daily life of communities in remote regions. Hydrogeological studies in these areas are complex, largely due to the absence of long water table records and to the difficulties involved in accessing some relevant locations. This hampers attempts to manage local resources. Devising cost-effective methods to explore these aquifers is important to understand how they work and to come up with adequate protection strategies. This paper deals with the joint application of Geographic Information Systems (G1S) tools and numerical groundwater models to explore groundwater resources in desert areas. The method is illustrated through its application to Erg Chebbi, a water table aquifer located in southern Morocco, which supplies drinking and irrigation water for local communities while also underpinning agriculture and tourism. The geometry of the aquifer was established based on existing cartography, CIS and a field survey. This led to the development of a steady-state numerical model. Modeling results suggest that the aquifer has been depleted by almost 30% due to groundwater extractions in less than 50 years. The average drawdown was found to be in the order of three meters. This corresponds to a total depletion in the order of 20-60 Mm~3.