Sediment Propagation in the Porong River below the Sidoardjo Mud Volcano Diversion in Indonesia

The Sidoardjo Mud Volcano in East Java, Indonesia, started on May 29, 2006. The average daily discharge of the mud volcano is 50,000 m(3)/day, with a 35% average concentration of sand, silt, and clay. Since 2017, the finer fractions have been diverted to the Madura Strait through the Porong River. The Ginonjo Outlet serves as a point source with a constant discharge of 45 m(3)/s and an average sediment concentration of 57,000 mg/L. The settling and transport of fine sediments were studied through field measurements at 106 cross sections over 16 km of the Porong River. At low flow, maximum concentrations decreased from 4,200 to 90 mg/L in the study reach. The two-dimensional mixing and settling model with flocculation resulted in better agreement with the observed data than did models without flocculation. Flocculation tests showed an increase in settling velocity from 0.013 to 0.028 mm/s. Flocculation affected settling of approximately 38% of the total sediment load. The fractions coarser than 92 mu m settled within the first 4 km from the point source. (C) 2021 American Society of Civil Engineers.