Mohammed IGOUZAL¹, Jean Marie MOUCHEL², KARIM TAMOH¹ & ABDELLATIF MASLOUHI¹

Abstract In this study, a first attempt is performed to study and to model the hydraulic regime and water quality of the Sebou River in the Gharb agricultural zone. A 90 km long reach situated upstream a reservoir dam is studied during the base flow period. During this period, water resources are scarce and much solicited by agriculture while water quality is very problematic. The dynamic water quality model WASP5 is used. Results give more information about the hydraulic regime which is influenced by a variable morphology. Water depth, flow and velocity evolution along the river and the water reserve available in the dam reservoir are simulated. In the water quality modelling, scenarios of excessive salinity propagation were first simulated. The time of arriving and the amplitude of the salinity were estimated at agricultural pumping stations. This model can play the role of an alert system against this natural phenomenon. Dissolved oxygen (DO) and biological oxygen demand (BOD) were then simulated. The impact on the oxygen depletion of sugar production plant wastewater was estimated. This information gives more suggestions for the envisaged waste load treatment programmes.