Sea Level Changes Along The Coast of Sandakan Town, Sabah, Malaysia: Projection and Inundation Coverage

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Pereira Dunstan, Ejria Saleh, Than H. Aung, Arshad Osman

Wednesday 1 july 2015

12:51 - 12:54h at North America (level 0)

Themes: (T) Extreme events, natural variability and climate change, (ST) Learning from disasters

Parallel session: Poster pitches: 9I. Extreme - Flood Drought

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Increase in the frequency and severity of extreme weather conditions witnessed in recent years are ostensibly linked to changing climate. Coastal areas are particularly bearing the brunt of this change. An issue that deserves serious study is the Sea Level Rise (SLR) in coastal districts, especially those with low lying areas such as Sandakan on the east coast of Sabah. Analysis of recent climate change scenario has indicated a great deal of uncertainty at global scale observation, requiring intensive examination at local level to understand vulnerability and develop adaptive capabilities. The Mean Sea Level (MSL) and sea level trends were determined from the 18 years Sandakan tidal data from the year 1994 to 2011. The analysis followed Pivot Table tools and trend line Analysis where daily average sea level trends were used to forecast the future sea level for the year 2100. MIKE 21 Flexible Mesh (FM) is the numerical model tools used to assess the hydrodynamic condition incorporated with the projected water level obtained from the regression model. Digital Terrain Model (DTM) with resolution of 30 m and approximate 300 m width from water edge was integrate with the model bathymetry to produce detail and updated bathymetry profile. The model also calibrated with measured water level data deployed at site from 10th to 22 May 2012. Geographic Information System (GIS) were used to draw the inundation map and calculate the area impacted. It is indicated MSL is at 2.706 m with sea level trends for daily is 5.3 mm/yr. The projected water level for the year 2040 and 2080 is estimated to be around 2983 mm and 3175 mm forecasted by regression model of Minitab 16 software. The numerical model simulation for the years 2020, 2040 and 2060 has indicated significant water level increment inside Sandakan Bay. Total potential inundated area for the year 2040 and 2080 are 2.41 km2 and 2.67 km2 respectively. The study pointed out the necessity of incorporating other factors of day- to- day influences and extreme events phenomenon with the inundation area based on tidal data analysis outcome to obtained more realistic flood inundation profiles in accordance to SLR. Evidently, sea level rise has severely creates potential future threats in term of inundation, possible flooding and erosion along the coastal area of Sandakan town. Keywords: Sea level trend, MSL, forecast, inundation map, Sandakan Bay