Comparative Assessment of Physicochemical and Biological Indicies of Otamiri and Nworie River Using a Piper Diagram Model

The Surface Water Resources of Otamiri-Nworie Watershed within the Owerri Metropolis were studied with the prime aim of developing a Non-Point Source Event-Based Model to Contamination of the water bodies. Clean, safe, and sufficient water is essential for both human existence and the health of ecosystems, communities, and economies (Fubara and Kpormon, 2023). As human populations increase, industrial and agricultural production increases, and climate change pose a threat of significant disruption of the hydrologic cycle, and as such, declining water quality has emerged as a major global problem (Ogbonna and Orinya, 2023). Human-drinking water must be free of organisms and chemical substances, as high amounts might be harmful to one’s health (Adeyi et al., 2021). This study aimed at comparatively assessing the physicochemical and biological indices of Otamiri and Nworie Rivers, and the Piper diagram model was employed for the analysis. Fifteen water samples were collected along the course of the two rivers and analyzed for physical, chemical and microbial parameters. Physical, chemical, and biological parameters were analyzed. The analytical results of the samples were compared with notable standards like the World Health Organization WHO, etc. It was observed that all the parameters analyzed for the rivers fall below the acceptable standards except for pH (6.5-8.5) indicating the acidic nature of these water bodies. Similarly, the colour value of the two rivers ranges between 21.5 to 229 PCU and observed to be decreasing downstream within Nworie and Otamiri rivers. Within the river Nworie axis, both the total dissolved solids (TDS) and the total suspended solids (TSS) were observed to be increasing downstream. Along Otamiri river before confluence, total dissolved solids increased downstream whereas the reverse was the case for the total suspended solids, just after the confluence. There is a noticeable increase in dissolved oxygen (DO) downstream within the Nworie axis. The biological oxygen demand (BOD) values for the rivers were below the WHO standard. Finally, the major sources of contamination within the study area revealed that they are mainly from agricultural practices, dumpsites, and human defecation. The quality can be improved by applying appropriate treatment to the water before its use for various purposes.