A physico-chemical characterisation of urban wet weather discharges (UWWDs) was carried out on a residential catchment of Riviera Palmeraie in the Abidjan District. This neighborhood is characterised by periodic drainage channel overflows, which have caused several floods in recent years. In order to determine the temporal variability of pollutant concentrations and their transfer dynamics, 5 floods were sampled between November 2021 and April 2023. Physico-chemical parameters such as pH, electrical conductivity (EC), total suspended solids (TSS), chemical oxygen demand (COD), ammonium, nitrite, nitrate, total nitrogen (TN), total phosphorus (TP), and phosphate were determined. Descriptive analysis of these parameters and the associated statistical tests showed that urban wet weather discharges are alkaline (pH 9.92), highly loaded with TSS (19.3 g.L-1) and moderately mineralised (EC 698 µS cm-1). While construction sites and soil erosion in the catchment are the main sources of TSS, the high values for electrical conductivity and concentrations of ammonium, total nitrogen and total phosphorus are directly related to wastewater discharges into the drainage system and leaching from the urban areas as a whole. Nitrogen and phosphorus pollution is predominantly in particulate form and is strongly correlated with TSS (r = 0.86) for most floods. For all the sampled floods, discharge and electrical conductivity appear to be good descriptors of ammonium dynamics. Suspended solids also appear to be good descriptors of total nitrogen and total phosphorus dynamics.

The study investigates the spatial and temporal variation in water quality parameters at nine different locations in Mé, Bété and Djibi Rivers as well as Aghien Lagoon near Abidjan city for twelve consecutive months. Physicochemical parameters concerned are pH, temperature, electrical conductivity, dissolved oxygen, chlorophyll-a, total phosphorus and total nitrogen. Dissolved heavy metals analyzed are Ni, Cu, Zn, Pb, Cd and As. The assessment of physicochemical parameters shown the deteriorate of water quality with significant changes particularly in the Djibi River with high mean concentrations of total phosphorus (0.51 mgP.L-1) and total nitrogen (7.60 mgN.L-1). Nevertheless, the overall mean concentrations of heavy metals in water Cu (1.43 µg.L-1), Cd (0.06 µg.L-1), Pb (0.2 µg.L-1), Zn (9.16 µg.L-1), As (0.3 µg.L-1), Ni (2.77 µg.L-1) were lower than WHO Standard for Drinking Water Quality. Dissolved heavy metal percentage indicates that the order of concentrations was Zn>Ni>Cu>Pb>As>Cd. Multivariate analysis of variance (ANOVA) was used to group the different sampling sites on the basis of spatial similarities and classification, based on contamination sources and origin of pollutants in rivers and lagoon. In conclusion, this study clearly infers the fact that the cause of pollution in this region is mainly due to domestic and industrial effluents, agriculture and finally natural source.