New simplification into NSF-WQI index to assess El Abid River water quality - Morocco

This research article comprises the calculation of the National Sanitation Foundation-water quality index (NSF-WQI) values for the El Abid River (Morocco) based on twelve physic-chemical and pollution parameters. Then, it defines a new simplified index WQI(min) based on parameters that are easy to measure in the laboratory or in the field. This simplification of the NSF-WQI parameters is based on principal component analysis, to reduce their associated analytical costs. Compared to NSF-WQI, similar spatiotemporal trends in water quality were obtained by WQI(min) (R-2 = 0.68). The WQI(min) reveals that during spring, autumn and winter (2016-2017) the quality in the Bin El Ouidane is good upstream, whilst it is undergoing a severe degradation into poor and very-poor-quality status in the downstream section, caused by high population rate and its pollution load coming from a polluted shallow aquifer. In summer when the flow discharge is low, the quality in the upper section is poor, whilst in the downstream section (from Bin El Ouidane to the outlet) it is decreasing to very-poor-quality status (WQI(min) = 89.57). In conclusion, the quality status in the downstream section is alarming and needs urgent intervention. The new simplified WQI(min) adequately reflects changes in El Abid River water quality using fewer parameters and reducing associated analytical charges.