Evaluation of the surface quality in the Kebir-Rhumel catchment area (northeast Algeria) using biotic indices and physico-chemical analyses

Assessing the water quality of the Kebir-Rhumel watershed by the use of benthic macroinvertebrates and physico-chemical analysis is the aim of this work. Thirteen physicochemical parameters and macroinvertebrates fauna were collected monthly in 15 stations located along the catchment area in the two principal wadis: El Kebir and Rhumel. Canonical correspondence analysis was used to study the relationships between physico-chemical parameters and macroinvertebrates. Biotic indices Biological Monitoring Working Party (BMWP '), Global Biological Normalized Index (IBGN), EPT index (Ephemeroptera, Plecoptera, Trichoptera), and %EPT/Chironomidae, based on benthic macroinvertebrates, have been applied in assessing the biological water quality. According to the results, a majority of the physicochemical parameters measured during the study period show spatial heterogeneity (Kruskal-Wallis,Pvalue < 0.05), indicating that Rhumel wadi is more polluted compared with El Kebir wadi; the NO2-, NO3-, PO4-3, Cl-, and SM contents are very high consequences of human and industrial anthropogenic actions. Canonical correspondence analysis has shown that the environmental parameters measured during this study influence the dynamics of macroinvertebrates, and the polluo-resistant taxa (Chironomidae) predominate in sites very rich in organic matter with low oxygen conditions. Sensitive taxa have a vulnerability to pollution. The biotic indices used confirm the diagnosis of the physicochemical analysis demonstrating a very degraded quality at Rhumel wadi. The EPT index and %EPT/Chironomidae results are closer to the scores of the BMWP ' index.

Automated summary

Assessing water quality in the Kebir-Rhumel watershed using benthic macroinvertebrates and physico-chemical analysis revealed spatial heterogeneity, with higher pollution levels in the Rhumel wadi compared to the El Kebir wadi. Elevated levels of NO2-, NO3-, PO4-3, Cl-, and SM were attributed to human and industrial activities. Canonical correspondence analysis showed that environmental parameters influence macroinvertebrate dynamics, with pollution-resistant taxa dominating in organically rich, low-oxygen conditions. The results from biotic indices confirmed degraded water quality in the Rhumel wadi.