Identifying Homogeneous Water Quality Regions in the Nile River Using Multivariate Statistical Analysis

Detecting homogeneous regions in the Nile River is essential in carrying mathematical modelling. The aim of this paper is to indentify homogenous regions with respect to water quality. Eight years data were subjected to principal components analysis (PCA) to define the parameters responsible for the variability in water quality. The PCA produced three variates (or principal components). For the Nile stem, variates are related to bacterial pollution, organic pollution and then agricultural/nutrients. As for the Nile branches, variables group as coming from bacterial and organic sources, while the agricultural/nutrients stamp is more visible in summer. Then, cluster analysis (CA) was performed to verify whether the observations could be grouped into spatially coherent patterns. CA grouped sampling sites into three homogenous regions: upper, middle and lower Nile stem. To interpret the subdivision, CA was performed on municipal and demographic data coming from Nile governorates, such as potable water consumption, sewage collection, cultivated areas and population data. The cultivated areas group similarly to nutrients water quality data and the percentages of uncollected sewage group similarly to bacterial data. The consecutive use of PCA and CA enabled to determine the main sources of pollution and to identify homogeneous regions with respect to water quality variables.