Evaluation of Darbandikhan Lake and its tributaries' water quality in the Sulaymaniyah Province in Iraqi Kurdistan, using the water quality index model and multivariate statistical analysis.

This study evaluated the characteristics of the water in Darbandikhan Lake and its rivers in the Kurdistan Region of Iraq. For this purpose, 25 samples were collected seasonally and analysed for 36 physiochemical parameters. The proportions of physiochemical parameters exceeding the WHO standards in the samples with their highest exceedances were 9894% for Al, 198% for Mn, 40% for Pb, 1.6% for pH, 3250% for PO₄, 11.8% for Sr, 155% for T.Alk, 7813% for turbidity, 1188% for Ti, 1033% for Tl and 1293% for V in the river water and 120% for Co, 74% for Cr, 4485% for Fe and 9% for K in the lake water. The pollution sources were designated by multivariate statistical analysis as being related to industrial and domestic waste, solid waste disposal, fertilisers and organic contamination from agricultural and natural sources. The water quality index (WQI) results were 22.3 to 721.3 for drinking, 13.9 to 86.2 for irrigation, 1.4 to 299.5 for livestock, 71.5 to 1754.4 for the textile industry, 20.7 to 237.9 for recreation and 64.6 to 1867.4 for aquatic life. The irrigation water quality index (IWQI) results were excellent for sodium adsorption ratio (SAR), and for the US salinity scale, all water samples fell into the medium salinity-low sodium category (C2-S1) in all seasons, except for all Chaqan River samples. The Tanjaro River sample in spring fell in the relatively high salinity-low sodium category (C3-S1), excellent and good for sodium percentage (Na%), suitable to moderate for permeability index (PI%), suitable to unsuitable for magnesium hazard percentage (MH%), suitable for Kelly Index (KI) and safe to unsuitable for residual sodium carbonates (RSC). The Sirwan River, Tanjaro River and Zmkan River took first to third place in both the annual average pollution share ratio and the discharge. While the Zalm River ranked fourth in discharge and fifth in pollution share ratio, the Chaqan River was the reverse. The highest pollution share ratio was 64.3 for the Sirwan River in summer, and the lowest was 0.7 for the Zalm River in autumn. [ABSTRACT FROM AUTHOR]