Publication Details

Storm Surge Analysis Due to High Water Events and Sea Level Rise Impact (Kelantan - Negeri Sembilan - Melaka)

Being a country with almost all of it coastline is subjected to extreme marine climate conditions especially during monsoon periods, Malaysia is vulnerable to high waves and storm surges. There are two terms that need to be understood clearly when discussing storm surge which are storm surge and storm tide. Storm surge is the abnormal rise in level above normal water surface level generated by a storm, that is the difference between astronomical tidal level and the level recorded. It is therefore not an absolute water level, but a difference between expected water level and the level that actually occurs. Meanwhile, storm tide is the water level produced by the combined action of storm surge and astronomical tides. It is therefore an absolute water level as recorded. This report describes the development of storm surge risk evaluation with particular recurrence intervals along Kelantan, Negeri Sembilan and Malacca coasts. The analysis is based on sea level rise projection by year 2020, 2040, 2060, 2080 and 2100 using the statistical combination of storm surge and tidal information. Some aspects of the storm surge responses on the northern and southern coast of study sites are also considered since they are important for an overall assessment on neighbouring spatial impact. These evaluations provide a basis for the investigation of the possible repercussions of future climate change due to sea level rise and changes in weather conditions. In general, the analysis of more than 25 year’s sea-level data in East Coast and West Coast of Peninsular Malaysia indicates that storm surges occur year round, but in various magnitudes. In west coast, the variation of surges is much smaller and normally acknowledged as tide residual. In east coast, the surge magnitudes can reach up to a metre, and is more common in Northeast monsoon. About 75% of the surge belonged to above 0.5 m height category and the trends of higher surge is increasing parallel with the change in marine climate conditions globally. The peak surge throughout the 32-years tide level data in Geting, Kelantan recorded a surge height in a range from as low as 0.35 m up to almost 1.0 m in height. The surge height shown a decreasing trend in the first 17 years and later starts to increase steadily from year 2002 onwards. Meanwhile, the trend in Tg. Keling tide station residuals (for Negeri Sembilan and Malacca coast) shown an increasing pattern of surge height with residual heights recorded a level of above 0.37 m. In Kelantan, five locations along the study area are selected for sea bed profile extraction via the model bathymetry to investigate the SLR impact while six profile in Negeri Sembilan and Malacca are selected. The calculated Design Water Level (DWL) for year 2100 SLR and 25yr RP storm surge is plotted for each profile to identify whether the selected coastal area is prone to inundation. Calculation on the PVI at each profile indicated a variety of risk level, from Moderate to Very Low risk of inundation.