Cohesive Sediment Transport Modeling: Application to the Madura Strait, Indonesia

Abstract

Madura Strait is located in East Java province, about 800 km east of Jakarta, the capital city of Indonesia. The Madura Strait is subject to ocean waves of less than 1 m height due to its position in semi-enclosed Java Sea in Indonesian archipelago. There are 2 major rivers that carry sediment to Madura strait namely Bengawan Solo River and Brantas River. In the last years sediment transport from Brantas river has been increasing significantly through one of its branch namely Porong River. The development of Suramadu Bridge between Surabaya (at Java Island) and Bangkalan (at Madura Island) contributed to sedimentation pattern in Madura Strait. The shallow bathymetries in major part of Madura Strait threat an environmental problem in the area. Therefore sedimentation model is necessary on attempt to anticipate serious environmental problem in Madura Strait. This study is about mud transport simulation in Madura Strait due to increasing sediment discharge from Porong River. The analysis was carried out by using MIKE-21 model software developed by DHI Water and Environment. In hydrodynamic simulation, water level boundary conditions were generated using global tide model from MIKE21 Toolbox at the boundary. The simulated water level and velocity were compared with observed data at calibration stations. In the calibration, the bed roughness parameter was adjusted by trial and error until the most satisfactory results were obtained. The root mean square error between computed and observed parameters in calibration was satisfied. In mud transport simulation, sediment concentration boundary conditions were generated using observation data. The simulated suspended sediment concentration was compared with observed data at calibration stations. Calibration parameters (critical shear stress for deposition, critical shear stress for erosion and erosion coefficient) were adjusted to get satisfaction results. After the calibrated mud transport model was achieved, simulation of several scenarios was applied to predict future behavior of sedimentation in Madura Strait.