Water Quality Zoning Based on Water Quality Index and Wilcox Index Using Geographic Information System

Background: Due to the limited fresh water resources and its important role in life and progress of nations, maintaining the water quality is necessary. Objectives: The purpose of this study was to evaluate quality of Khorramrood River water using Indexes of water quality including water quality index (WQI) and Wilcox and zoning with geographical information systems (GIS). Patients and Methods: In this cross-sectional study, the quality parameters required for the calculation of quality indicators, i. e. WQI and Wilcox index, were measured by using standard methods at six selected stations during six months in 2012. This Parameters consisted of pH, dissolved oxygen, total dissolved solids, electrical conductivity, biochemical oxygen demand, turbidity, temperature, phosphate, nitrate, fecal coliform, calcium, magnesium, and sodium. River zonation was done using the software GIS. Results: By using WQI, the best water quality was reported in station number one with the scalar quantity of 71.11 (water with best quality) and the worst water quality was in station number six with scalar quality of 42.77 (water with bad quality). By using a Wilcox index for agricultural consumption, the river water based on EC classified in C2 and C3, and based on SAR it classified in S4. The quality parameters concerning the total dissolved solids, turbidity, nitrate, phosphate, and BOD5 in some sampling stations were higher than standard limit of surface water. Conclusions: According to the average of WQI index, quality of water was good in station number one, medium in station number two, and bad in the rest of stations. According to the WILCOX Index, qualities of water in third station were medium and in the rest were good.