Water Quality Index Assessment using GIS Case study: Tigris River in Baghdad City

Abstract

In this study water quality index (WQI) was calculated to classify the flowing water in the Tigris River in Baghdad city. GIS was used to develop colored water quality maps indicating the classification of the river for drinking water purposes. Water quality parameters including: Turbidity, pH, Alkalinity, Total hardness, Calcium, Magnesium, Iron, Chloride, Sulfate, Nitrite, Nitrate, Ammonia, Orthophosphate and Total dissolved solids were used for WQI determination. These parameters were recorded at the intakes of the WTPs in Baghdad for the period 2004 to 2011. The results from the annual average WQI analysis classified the Tigris River very poor to polluted at the north of Baghdad (Alkarkh WTP) while it was very poor to very polluted in the south (Alrasheed WTP). WQI reached a maximum value of 912 at Alwathba WTP in 2011and 602 at Alqadisia in 2009 (WTPs at the center part of Baghdad). This classification considers the river unfit for drinking water purposes. Eight color maps of the river were constructed by GIS all gave clear images of the water quality along the river. GIS helped to join the calculated WQI in such an organized and scientific allowing decision making easier to solve pollution problems.