STUDY OF EROSION AND SEDIMENTATION DYNAMICS IN AYUNG ESTUARY WATERS

• Main Author: Indah Dianti Putri, Putu
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/49453
• Institution: Institut Teknologi Bandung

The estuary of Ayung River had sedimentation throughout the year, both in the wet and dry seasons. High sedimentation causes the area around river estuaries such as temples and several houses to be inundated, especially when the river discharge is high. The main cause of sedimentation at the estuary is the dominant down-shore current moving to the southwest and the dominant incoming waves from the southeast. The effect of river discharge is quite small because there is a weir which is about 4 km from the river mouth. Meanwhile, the beaches in the waters of the Ayung River Estuary had erosion or decline in the coastline. The rate of coastline erosion average 1.16 meters/year. Several coastal segments have been handled with revetment buildings, but there are coastal segments that have not been handled. Erosion along the coast is predominantly influenced by the currents along the coast. Current movements parallel to the shoreline carry sediment transport so that the coast is unstable. Based on these, this study aims to study sediment transport and coastal hydrodynamics in the waters of the Ayung River Estuary to find solutions to overcome these problems. The numerical method is used to determine the characteristics of the sediment distribution, the distribution pattern of the erosion, and sedimentation areas which are influenced by currents, waves, river flows, and tides. Simulations using hydrodynamic and sediment transport models from Delft 3D. In the dry season, there is a buildup of sediment at the mouth of the estuary which reaches 2.2 meters and erosion occurs along the coast of the northern river estuary reaching 1.5 meters. In the wet season, erosion occurs on the body of the river mouth to a depth of 2 meters in the southern section of the river mouth. Increasing the length of the jetty to 57.5 meters was carried out to solve the sedimentation problem of the estuary. Installation of groins along 70 meters in series with a distance between groins of about 300 meters was carried out to solve the problem of coastal erosion.