Analysis of Reservoir Sedimentation Impact on Water Transfer Systems for Water Scarcity Alleviation in Arid and Semi-arid Zones: Case Studies from Morocco

In arid and semi-arid countries, reservoirs and water transfer systems are increasingly used to alleviate water scarcity and take advantage of rare extreme rainfall events. However, sediments can progress rapidly during major floods toward dams at the minimum operating level and flushed through the bottom outlets. Hence, accumulation of fine suspended particles is generated in the course of downstream water transfer channels. This phenomenon adversely affects operational water transfer systems causing many dysfunctions in delivered water in terms of quantity and quality. In this paper, the issue of reservoir sedimentation impact on two water transfer systems, namely Rocade canal and Doukkala irrigation systems in central and southernMoroccois investigated. Analysis of available data shows that nearly 20% of Sidi Driss reservoir sediments are transported to downstream water transfer systems of the Rocade canal, while 70% of Imfout reservoir sediments are accumulated in the course ofDoukkala water irrigation system. Siltation of these water transfer systems affects distributed water quality, reduces flow discharge that crops need and increases maintenance operation costs.More studies and monitoring campaigns need to be carried out to gain a deeper insight into the temporal and spatial evolution of sediment transportand deposition from reservoirs to their downstream operational water transfer systems to improve their performances and ensure their sustainability.