Assessment of the effect of drought and anthropogenic liquid pollution on the physicochemical quality of the waters of Oued Inaouene using the Water Quality Index (Taza, Morocco)

Abstract

The Inaouene river, a tributary of the Oued Sebou, is subject to the effects of drought in the Mediterranean climate and pollution from raw wastewater. Assessment of water quality in this hydrosystem using the water quality index (WQI) calculated from 19 physico-chemical parameters (pH, T°, EC, DO, MES, NH4+, NTK, NO3-,SO4--, PO4-- ,PT, COD, BOD5, Cl-, Cr, Zn, Pb, Cu and Fe) over 3 hydrological cycles (May 2019 to June 2022) showed that upstream, water quality remains very poor, with no significant inter-annual variations, except for stations located on Oued Lahdar (WQI=35.11) and those downstream of Inaouène (WQI=43.71), where quality is good during the 2nd hydrological cycle. During the 1st and 3rd hydrological cycles, water quality deteriorated in the Inaouene (WQI>100), reflecting water quality unfit for consumption. Overall, the WQI values recorded are very high during the 3rd dry hydrological cycle. Moreover, the WQI varied significantly between the 3 cycles (p = 0.0006).