Review of water quality index models as river quality evaluation tool: insight from various rivers in Indonesia

As industrial activities grow and increase, it is directly proportional to the wastewater produced, which is disposed of into the river. One of the calculation models commonly used for evaluating surface water quality is the water quality index (WQI). The method produces uncertainty in the conversion and is site specific dependent. The data collected for the last five years used a comparative method to assess the status classification of those rivers’ quality. In addition, this study also aims to classify the river quality status and evaluate the WQI model in determining the impact of industrial activities on Sumatra Island and Kalimantan Island, the five longest rivers in Indonesia. This paper uses the WQI to review the water quality condition of Indonesia’s five longest rivers, i.e., Kapuas River, Mahakam River, Barito River, Batanghari River, and Musi River, where the community heavily uses these rivers for their daily needs. This review study concluded that the WQI of a river could vary depending on the measurement data used in calculating the WQI value. The data describing the WQI of a river is a momentary WQI or periodic WQI. The study is expected to be used as a basis for developing a sustainable water pollution control strategy to maintain the grade status of a river according to its classification.