Fuzzy Logic Application as A Tool for Classifying Water Quality Status in Gajahwong River, Yogyakarta, Indonesia

The growth of manufacturing and waste disposal in the Gajahwong River watershed has resulted in decreasing river water quality. Therefore this study aims to develop a fuzzy logic system in classifying water quality status in Gajahwong River. There are 11 parameters used for classifying water quality status, namely temperature, potential hydrogen (pH), dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), free chlorine, nitrate, nitrite, oil and fat, lead and Escherichia coli (E. Coli). These parameters are used to assess the Gajahwong River water quality at three different stations during the period of 2007 to 2017. The application process of fuzzy logic begins with the use of 11 parameters consisting of physical, chemical and biological parameters as input, with the Mamdani method as the fuzzy inference system. The output of this application is in the form of water quality status which is categorized as normal (N), lightly polluted (LP), moderately polluted (MP) and heavily polluted (HP). The classification is expected to facilitate the public in reading information about the quality of river water from the environmental agencies D.I. Yogyakarta, thus, the public can be aware of maintaining watersheds.