Assessing Water Quality for Al-Diwaniyah River, Iraq Using GIS Technique

Abstract

In this study, Al-Diwaniyah River within Al-Diwaniyah Governorate was monitored for a set of chemical, physical, and bacteriological parameters for the assessment of water quality during January to July 2018. Water quality maps for this river were plotted to represent the change in each parameter during the study period using GIS program. Three sampling stations along the river and eighteen parameters were selected: air temperature, water temperature, turbidity, pH value, electrical conductivity (EC), biochemical oxygen demand (BOD), dissolved oxygen (DO), alkalinity, chloride, Sulfate, total suspended solids (TSS), total dissolved solids (TDS), calcium, magnesium, total hardness, lead, total coliform, and Escherichia coli bacteria. The results explained that the water temperature varied between (15-31) °C. pH values ranged between (7.4-8.2) and river water was considered as slightly alkaline with alkalinity concentrations between (124-176) mg/L. Most water of the river was very hard according to the values of hardness that varied between (384-531) mg/L. The turbidity values of the river ranged between (1.5-35.2) NTU. Electrical conductivity was between (998-1380) µs/cm. Total dissolved solids and total suspended solids were their values varied between (620-932) mg/L and (2-28) mg/L respectively. It was found that among measured positive ions, calcium concentrations were higher than the magnesium concentrations, ranging between (71-175) mg/L and (21-67) mg/L respectively. On the other hand, when studying Anions, sulfate concentrations were higher than chloride concentrations with values ranging from (152-339) mg/L and (101-167) mg/L respectively. River water contained dissolved oxygen concentrations ranging (6.3-10.1) mg/L while concentrations of biochemical oxygen demand varied between (0.6-7.6) mg/L. Lead ranged in values between (0.001-0.017) mg/L. The study found that bacteriological parameters, including total coliform and E. coli, ranged between (500-1600) MPN/100ml and (30-1600) MPN/100ml respectively. In general, the parameters of Turbidity, SO4, BOD5, TC and E. coli have exceeded Iraqi standards for drinking water IQS: 417 while the rest of the parameters were within these limits. It revealed that station 2 which was located only at a short distance from the site of the wastewater treatment plant was more polluted than the other two stations. The results showed that the water of the river is neither suitable for drinking, nor suitable for swimming according to the high bacterial pollution in addition to the danger and threat to aquatic life but can be used for irrigation purposes.