Latar Belakang: Sungai Bedadung hilir berada di Kabupaten Jember dan merupakan bagian sungai utama di DAS Bedadung. Sungai ini berperan penting bagi kehidupan masyarakat Jember. Kegiatan pengunaan lahan mengubah fungsi sungai menjadi saluran pembuang limbah. Limbah organik masuk ke badan air Sungai Bedadung dan menurunkan oksigen terlarut di perairan.Metode: Penelitian ini merupakan penelitian deskriptif. Data primer diperoleh dengan melakukan pengukuran debit dan kualitas air (Temperatur, DO dan BOD) sungai di lima titik pantau. Data tersebut kemudian diolah dan digunakan sebagai input variabel persamaan Streeter-Phelps.Hasil: Berdasarkan penelitian yang dilakukan laju deoksigenasi dan reoksigenasi Sungai Bedadung hilir tertinggi berada pada BDG02 masing-masing 7.997 mg/L.hari dan 19.168 mg/L/hari. Purifikasi alami yang dimodelkan dengan persamaan Streeter-Phelps, pada BDG02 tidak menunjukkan tren penurunan oksigen terlarut, sedangkan empat titik yang lain cenderung turun, mencapai kondisi kritis dan saturai di waktu yang berbeda. Hasil pembuktian model menunjukkan terjadi perbedaan nilai DO model terhadap kondisi lapangan (DO aktual).Simpulan: Aplikasi pemodelan Streeter-Phelps untuk menganalisis purifikasi alami Sungai Bedadung tidak dapat menunjukkan kesesuaian dengan kondisi lapang, karena proses deoksigenasi dan reoksigenasi di sepanjang sungai selalu berbeda dengan model bergantung pada tambahan pencemar dan hidraulik sungai. ABSTRACTTitle :Background: Bedadung Downstream, at Jember Region, is the primary river of Bedadung basin. The river has its meaningful advantages to public activities. Change of land uses the stream functions to a big drainage channel. Organic pollutants entrance to the water body and decrease the concentration of dissolved oxygen.Methods: This research was descriptive. The primary data was obtained by measuring stream flows and water quality (Temperature, DO, and BOD) at five observed stations. The data were processed and used as variable inputs to the Streeter-Phelps equation.Results: Based on the research conducted, BDG02 had the highest values of deoxygenation and reoxygenation rates, which were 7.997 mg/L.day and 19.168 mg/L.day respectively. DOmod at BDG02 tends to line up, whereas DOmod at four stations had a tendency to declined to critical conditions and rise to the saturation condition at different times. DO sag model was different from actual DO, which measured directly in the water body.Conclusions: The use of the Streeter-Phelps equation to analyze the self-purification of Bedadung downstream wasn’t appropriate with the field conditions. Deoxygenation and reoxygenation process in the river body was typically difference with the model applied, which were affected by organic pollutants and stream hydraulics.
Approaches for assessing riverine scour