[A-HW33] Prediction of water and sediment dynamics from small to large scales

[AHW33-09] Characteristics of Discharge and Tidal Asymmetry over Two Inlets Lagoon: A Case Study on Segara Anakan Lagoon, Central Java, Indonesia

*Faruq Khadami^1,2, Kiyoshi Kawanishi¹ (1.Department of Civil and Environmental Engineering, Hiroshima University, 2.Oceanography Study Group, Faculty of Earth Science and Technology, Institut Teknologi Bandung)

Keywords:Tidal Assymetry, Discharge, Two Inlets Lagoon, Tidal Dynamics

Segara Anakan Lagoon is a two-inlet lagoon with high sedimentation rate. Tides from the two inlets can be main factor that leads to the sedimentation pattern. A two-dimensional hydrodynamic model was used to investigate the tidal asymmetry and discharge in the inlets of the Segara Anakan Lagoon. The model results of water elevation and discharge were acceptable compared with the observation. The results show that the tidal wave propagates to the lagoon from both inlets and amasses in the central of lagoon. The type of tides in the Segara Anakan Lagoon is a mixed semi-diurnal tide which M2 component is dominant by having 0.5 m in amplitude. Analysis of the result of the water elevation model shows the tidal duration asymmetry in both inlets is flood dominance, while the tidal duration asymmetry around the amassing area is ebb dominance. Furthermore, the peak discharge asymmetry in both inlets is ebb dominance while the slack water asymmetry is ebb dominance. The slack water and peak discharge asymmetry indicates that the ebb flow in both inlets have shorter duration than the flood flow. However, the flood discharge is larger than the ebb discharge. The asymmetries of the tides duration and peak discharge may affect the sediment flux in both inlets and distribution of sediment in the lagoon.