Enhanced Representation of Java Sea Tidal Propagation through Sensitivity Analysis

Chiranjeevi Rambabu A; Sibtey Hasan
Java Sea is a very complex tidal region due to its associated intrinsic geometrical characteristics which include coastline geometry, small islands and sharply varying bottom topography. Several numerical modelling studies have been conducted to evaluate the tidal characteristics of Java Sea. The present modelling study is an attempt to enhance the representation of tidal propagation of Java Sea by performing sensitivity analysis using Delft3D. Several simulations were done with Manning (0.015, 0.018 0.02, 0.03, 0.032 and 0.035) and Chezy (50, 55, 60, 65 and 70) bottom roughness coefficients in order to enhance the model performance. In general Java Sea is shallow in nature however based on sensitivity analysis with different bottom roughness coefficients, bottom roughness coefficients map was created and applied in combination with varying spatial wind to understand its effect on tidal propagation. The model performance has been verified by comparing with observed amplitudes and phases of M2, S2, K1, O1 tidal constituents at several locations on southern and northern coast of Java Sea. The root mean square error (RMSE) between observed and modelled amplitudes were 0.05, 0.04, 0.06, 0.04 calculated for M2, S2, K1 and O1 tidal constituents respectively at northern coast. Similarly, the maximum RMS error between observed and modelled phase of 34.07 was calculated for S2 tidal constituent. Most importantly, model results clearly indicated bottom roughness coefficients of 0.02, 0.03, 0.032 and 0.035 largely influencing the semi-diurnal tidal harmonic constituents compared to diurnal tidal constituents. However, the spatial varying wind had minimal effect on amplitude and phase. The present study clearly indicates that the assessment of tidal propagation in such a shallow water environment could be enhanced through detailed sensitivity analysis.
Java Sea; Numerical Model; Sensitivity Analysis; Tidal Propagation; Bottom Roughness; Spatial Wind
Download | Back to Issue| Archive