Assessment of surface water quality: Case study of Oued Fez catchment areas (Morocco)

Abstract

Under sustainable development conditions, water quality and quantity play a crucial role in meeting basic human needs. To meet the growing demand for water, surface water quality management is an important aspect. Consequently, water quality must be monitored and assessed via the use of innovative techniques, such as water quality index (SEQ-Water).For that purpose, water quality of Oued Fez catchment areas was evaluated according to Moroccan water quality guidelines by using the weighted quality index (SEQ-Water), physicochemical parameters, trace elements and bacteriological characterization. Five Sites were chosen after a diagnosis based on different criteria such as activity and density of population. These sites were Amont oued Fez (S1), Oued Fez (S2), Oued Ljawahir (S3), Oued Tgat (S4) and Oued Ain Smen (S5). Physicochemical quality was determined by evaluating Chemical Oxygen Demand (COD), total Kjeldhal nitrogen (NTK), suspended solids (SS), nitrates (NO3-), nitrites (NO2-), ammonium (NH4+), sulphates (SO42-), total phosphorus (TP) and trace elements (Cr, Cd, Cu, Ni, Co, Pb and Zn). Bacteriological analyses were carried out by testing enumeration of total coliforms (TC) and fecal coliforms (FC).Except Oued Ain Smen, physico-chemical parameters exceed by far the Moroccan standards of surface water quality. High concentrations of Se, Cd, Pb and As were detected. Fecal and total coliforms were also present at all sites, and varied from 1150 CF/100 mL to 100,000 CF/100 mL. All results were statistically validated with a p value < 0.05. Overall quality of the water sites assessed basing on the concept of the weight quality index, showed high pollution of the Oued Fez catchments. System based on the concept of the weighted quality index (SEQ-Water) is a suitable method to monitor point sources of pollution in surface water, and could provide a crude guideline for selecting the priorities of possible preventative measures in the proper management of the surface water resources.To summarize, it would be dangerous to use water from these rivers for domestic and agricultural purposes without some form of physical and chemical treatment. Sensitization of the authorities on the extent of water pollution of this Oued and the harmful consequences for man and the ecosystem should be urgent and mandatory.

Keywords

• Bacteriological quality
• Physicochemical quality
• Surface water
• Fez city
• Quality SEQ-Water