Most of the third world countries having rivers passing through them suffer from the water contaminant problem. This problem is considered so difficult to get the water quality within the standard allowable limits for drinking, as well as for industrial and agricultural purposes. This research aims to assess the water quality of the Tigris River using the water quality index method and GIS software. Twelve parameters (Ca, Mg, Na, K, Cl, SO₄, HCO₃, TH, TDS, BOD₅, NO₃, and EC) were taken from 14 stations along the river. The weighted arithmetic method was applied to compute the water quality index (WQI). The interpolation method (IDW) was applied in ArcGIS 10.5 to produce the prediction maps for 12 parameters at 11 stations along the Tigris River during the wet and dry seasons in 2016. The regression prediction was applied on three stations in the Tigris River between observed values and predicted values, from the prediction maps, in both seasons. The results showed that the regression prediction for all parameters was given the acceptable values of the determination coefficient (R²). Furthermore, the state of water quality for the Tigris River was degraded downstream of the Tigris River, especially at the station (8) in Aziziyah in the wet and dry seasons and increase degradation clearly at Qurnah (Basrah province) in the south of Iraq. This paper considers the whole length of the Tigris River for the study. This is important to give comprehensive knowledge about the contamination reality of the river. Such that it becomes easier to understand the problem of contamination, analyze it, and then find the suitable treatments and solutions.

中文翻译：

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使用水质指数（WQI）和GIS软件对底格里斯河（伊拉克）的水质进行评估

大多数第三世界国家都有河流经过，因此遭受了水污染问题的困扰。人们认为很难使该水质达到标准允许饮用范围以及工业和农业目的的水质。本研究旨在使用水质指数法和GIS软件评估底格里斯河的水质。十二个参数（Ca，Mg，Na，K，Cl，SO ₄，HCO ₃，TH，TDS，BOD ₅，NO ₃和EC）来自沿河的14个站点。应用加权算术方法计算水质指数（WQI）。插值方法（IDW）已在ArcGIS 10.5中应用，以生成2016年干季和湿季沿底格里斯河的11个站点的12个参数的预测图。对底格里斯河中的三个站点的观测值之间进行了回归预测以及两个季节中来自预测图的预测值。结果表明，对所有参数的回归预测均获得了确定系数的可接受值（R ²）。此外，底格里斯河的水质状况在底格里斯河的下游特别是在湿季和干季的阿齐兹耶（8）站（8）退化，并且明显加剧了伊拉克南部库尔纳（巴士拉省）的退化。本文考虑了底格里斯河的全长进行研究。重要的是要全面了解河流的污染状况。这样就更容易理解污染问题，对其进行分析，然后找到合适的处理方法和解决方案。