Fuzzy Logic-Based Evaluation of Physicochemical Water Quality Parameters in the Gökırmak River (Türkiye)

Year 2025, Volume: 56 Issue: 3, 234 - 242, 26.09.2025

Adem Yavuz Sönmez , Semih Kale , Yiğit Taştan , Rahmi Can Özdemir , Ali Eslem Kadak

https://doi.org/10.17097/agricultureatauni.1693998

Abstract

Traditional water quality classification methods rely on fixed threshold values, which limits their ability to reflect the degree of deviation from these boundaries. This rigid approach often results in uncertainties when assessing the ecological status of rivers. Fuzzy logic, in contrast, provides a more flexible framework by incorporating gradual transitions between classes and accounting for the relative importance of parameters. In this study, a fuzzy logic-based classification system was developed to evaluate the water quality of the Gökırmak River (Türkiye) and was compared with the conventional water quality index defined by national standards. Ten physicochemical parameters (temperature, pH, dissolved oxygen, electrical conductivity, nitrate, nitrite, ammonium, phosphate, biochemical oxygen demand, and chemical oxygen demand) were monitored monthly at six stations for one year. The fuzzy logic model was constructed using triangular membership functions and a Mamdani inference system. Model performance was assessed by comparing fuzzy classification results with expert evaluations based on the Surface Water Regulation. The system achieved 90% agreement, calculated as the ratio of consistent classifications to the total number of cases, demonstrating that fuzzy logic can serve as a reliable tool in water quality assessment. The findings highlight that fuzzy logic-based approaches not only reduce classification uncertainties but also provide a decision support framework for sustainable water resource management. Further research should expand the dataset across longer time periods and incorporate retrospective records to improve generalizability.

Keywords

Decision support system , Environmental monitoring , Fuzzy logic , Water pollution , Water quality assessment

Supporting Institution

Kastamonu University

Project Number

KÜ-BAP01/2020-9

Thanks

The study was financially supported by the Kastamonu University, Coordination Unit of Scientific Research Projects (Project no: KÜ-BAP01/2020-9).

Gökırmak Nehri'nin (Türkiye) Fizikokimyasal Su Kalitesinin Bulanık Mantık ile Değerlendirilmesi

Abstract

Geleneksel su kalitesi sınıflandırma yöntemleri sabit eşik değerlerine dayanmaktadır ve bu durum ölçüm değerlerinin bu sınırların ne kadar uzağında veya yakınında olduğunu yansıtamamaktadır. Bu katı yaklaşım, nehirlerin ekolojik durumunun değerlendirilmesinde belirsizliklere yol açmaktadır. Buna karşılık, bulanık mantık, sınıflar arasında kademeli geçişlere izin vererek ve parametrelerin göreli önemini dikkate alarak daha esnek bir değerlendirme çerçevesi sunmaktadır. Bu çalışmada, Türkiye’deki Gökırmak Nehri’nin su kalitesini değerlendirmek amacıyla bulanık mantık tabanlı bir sınıflandırma sistemi geliştirilmiş ve ulusal standartlarda tanımlanan klasik su kalite indeksi ile karşılaştırılmıştır. On farklı fizikokimyasal parametre (sıcaklık, pH, çözünmüş oksijen, elektriksel iletkenlik, nitrat, nitrit, amonyum, fosfat, biyokimyasal oksijen ihtiyacı ve kimyasal oksijen ihtiyacı) bir yıl boyunca altı istasyonda aylık olarak izlenmiştir. Bulanık mantık modeli üçgensel üyelik fonksiyonları ve Mamdani çıkarım sistemi ile oluşturulmuştur. Modelin performansı, Yüzey Suları Yönetmeliği’ne göre uzman değerlendirmeleri ile karşılaştırılarak test edilmiştir. Sistem, toplam sınıflandırmaların %90’ında uyum sağlamış olup bu oran, bulanık mantık yaklaşımının su kalitesi değerlendirmesinde güvenilir bir araç olduğunu göstermektedir. Bulgular, bulanık mantık tabanlı yöntemlerin sınıflandırma belirsizliklerini azaltmanın yanı sıra sürdürülebilir su kaynakları yönetimi için karar destek aracı sağlayabileceğini ortaya koymaktadır. Daha geniş veri setlerinin ve geçmiş yıllara ait kayıtların dahil edilmesi, yöntemin genellenebilirliğini artırmak için önerilmektedir.

Keywords

Karar destek sistemi , Çevresel İzleme , Bulanık mantık , Su kirliliği , Su kalite değerlendirmesi

Supporting Institution

Kastamonu Üniversitesi

Project Number

KÜ-BAP01/2020-9

Thanks

Çalışma Kastamonu Üniversitesi Bilimsel Araştırma Projeleri Koordinasyon Birimi tarafından finansal olarak desteklenmiştir (Proje no: KÜ-BAP01/2020-9).

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