Assessment of Water Quality in the Middle Section of Shatt Al-Arab River Using Principal Component Analysis: A Temporal and Spatial Study

Nuha Mohsen

Authors

Mohsen et al., 2026 Department of Ecology, College of Science, University of Basrah https://orcid.org/0000-0003-1350-741X

Keywords:

Water quality, Shatt Al-Arab River, Middle section, PCA.

Abstract

The current study aimed to use principal component analysis to assessment Spatio-temporal changes in water quality in the middle section of the Shatt Al-Arab River, southern Iraq. Seasonal surface water samples (autumn, winter, spring and summer) were collected from four stations (Abu-Flous, Al-Baradeyea, Al-Maqal, and Al-Muhammadiyat) to measure 12 physicochemical and biological variables, including water temperature (WT), pH, electrical conductivity (EC), total dissolved solids (TDS), total suspended solids (TSS), turbidity, dissolved oxygen (DO), biochemical oxygen demand (BOD5), chemical oxygen demand (COD), nitrates (NO3), phosphates (PO4) and fecal coliform bacteria (FCB) from October 2024 to July 2025. Summer exhibited the poorest water quality associated with reduced flow, increased organic pollution, and saline intrusion from the Arabian Gulf. Principal component analysis identified three principal components (eigenvalues >1) explaining the greatest variance, linked to dissolved salts and organic pollution, nutrients (nitrates, phosphates), and fecal coliforms. This confirms the substantial influence of saline waters advancing from the Arabian Gulf toward the study area due to the sharp decline in freshwater inflows to Shatt Al-Arab River, compounded by domestic, agricultural and industrial discharges.

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