Sedimentation and Longshore Current Simulation with Delft3D Software in Rejoso Shoreline

Abstract

Rejoso estuary, located 3 kilometers from the center of Pasuruan, has an unstable river mouth that threatens the existence of residents in the surrounding area. During the rainy season, when high discharge in the river meets high tide from the ocean, flooding occured in residential areas located around the coast. It happens due to sediment deposits formed near the sea and ocean current that worsen the backwater. East Java Provincial Water Resources Agency plans to build a jetty in that area to reduce sediment deposition caused by longshore sediment transport and to protect the estuary from ocean currents. This study aims to look at the impact of jetty construction that is affected by wave and current activity by performing numerical modeling with Delft3D software. From the simulation results, jetty reduce the amount of ocean current with the biggest reduction at monitoring point A is 0.299 m/sec (94.05%) and decrease sedimentation with the biggest at monitoring point A by 91.37% in the east side of the estuary. In conditions without a jetty, the shape of the shoreline and the elevation follows the shape of the initial shoreline, while after one year with jetty the sedimentation occurred to the end of it.