Sediment transport modelling: effect of the coastal reservoirs development plan in the Cisadane estuary-Indonesia

National Capital Integrated Coastal Development (NCICD) aims to protect Jakarta from flooding. This project includes a coastal reservoir (CR) development plan at the Cisadane Estuary, Tangerang Regency, Indonesia. CR planning must consider the sedimentation process. With numerical modelling of sediment transport, the sedimentation pattern of bed load and suspended load sediments will be known. This study used the MIKE21/3 Integrated Models software that is coupled with Flow Model (FM) and Mud Transport (MT) for one year (August 1, 2020 - July 31, 2021). The validation result of surface elevation shows that the modelling results are valid with NRMSD 93.35%. Based on the simulation results, suspended sediment concentration in the west monsoon is higher than in the east. The sediment concentration around the coastal reservoir at the bottom layer of the water is slightly higher than the surface layer. There is an increase in the maximum bed thickness of 1.2 m in the northeast corner of CR. There is a reduction in the bottom thickness of about 0.5 m on the west side of the CR embankment. The results of this study can be used to develop the most optimal CR design to minimise the environmental impacts.