Derivation of tidal constituents from satellite altimetry data for coastal vulnerability assessment in Malaysia

Abstract

Sea level rise has posed a serious threat particularly to the coastal environment due to its prominent association to the land inundation. The rise of global sea level might be inevitable, however the assessment of the impending impacts of the sea level rise is a vital approach to mitigate the incoming impacts. This study is an initiative to assist coastal vulnerability assessment due to the sea level rise impacts specifically across Malaysian coastal regions by using Mean Tidal Range parameter derived from tidal models. The tidal models were generated from merged along-track TOPEX and Jason-1 sea level anomalies (SLA) data retrieved in Radar Altimeter Database System (RADS) for South China Sea region covering latitude 0° N to 13° N and longitude 98° E to 120° E. Tidal harmonic analysis was performed by using t-tide Matlab programme to estimate amplitude and phase for tidal constituents M2, S2, K1 and O1 from altimetry data. The corresponding tidal constituents were subsequently interpolated into 0.25° square grids. The overall accuracy of the tidal models is Root Sum Square (RSS) whose value is 8.59 cm, while the Root Mean Square (RMS) of Mean Tidal Range values derived from the tidal models is 17.12 cm. Subsequent to the derivation of Mean Tidal Range from the corresponding tidal models, it can be inferred that Mean Tidal Range values for Malaysian coastal regions vary from 81.95 cm to 158.97 cm. There is a consensus in various coastal vulnerability studies that a region whose Mean Tidal Range value less than 2 meters is the most susceptible region to the sea level rise impacts. Therefore, Malaysian coastal regions can be generally categorized as vulnerable due to the sea level rise threats. The use of tidal models are expected to complement the existing coastal management system in order to monitor level of coastal severity caused by the sea level rise impacts especially for Malaysian coastal region.