Assessment of Haraz River Water Quality Using IRWQI, NSFWQI, and CCMEWQI Indices and Optimization through Response Surface Methodology (RSM)

Articles in Press

Document Type : Research Paper

Authors

1 Civil, Water and Environmental Faculty, Shahid Beheshti University

2 Faculty of Civil, Water and Environmental- Shahid beheshti University

10.22059/jwim.2025.398878.1247

Abstract

Rivers as one of the primary sources of freshwater supply, play a vital role in meeting environmental, agricultural, and human needs. Assessing the water quality of these resources is essential for sustainable management and minimizing environmental risks. Selecting an appropriate index for surface water quality assessment remains a key challenge in water resources management. In this study, with the aim of comparing three widely used water quality indices—namely, the Iranian National Water Quality Index (IRWQI), the National Sanitation Foundation Water Quality Index (NSFWQI), and the Canadian Council of Ministers of the Environment Water Quality Index (CCMEWQI)—data collected from the Haraz River (nine stations in two seasons: winter and summer) were used as a case study. The results showed that all three indices were able to classify relative water quality, although differences were observed in their sensitivity and discriminatory power. Specifically, the NSFWQI tended to yield more optimistic results in most cases. In addition, the Response Surface Methodology (RSM) was applied to analyze the influence of different parameters on each index and to optimize the quality modeling process. Findings indicated that in summer, nitrate, phosphate, dissolved oxygen, and ammonium were the most influential parameters, accounting for a total contribution of 83 Percent, whereas in winter, biological oxygen demand, chemical oxygen demand, total hardness, and pH were most influential, accounting for 82 Percent. Water quality status based on the NSFWQI was lower in summer than in winter. During winter, 100 Percent of the stations were classified as having medium to good quality, while in summer only about 34 Percent of the stations fell within this range. Moreover, based on this index, a declining trend in water quality was observed along the river in both seasons. This study highlights that the choice of index can significantly affect the interpretation of water quality status and that integrating indices with statistical methods such as RSM can provide an effective tool for surface water quality management in other rivers as well.

Keywords

Main Subjects

Water and Irrigation Management

Articles in Press, Accepted Manuscript
Available Online from 18 October 2025

Files

Share

How to cite

Statistics