ASSESSMENT OF PROTECTION AGAINST SEA LEVEL RISE: A CASE STUDY OF A COASTAL AREA IN SINGAPORE

Abstract

The aim of this study was to assess the economic viability of constructing a seawall to protect a coastal area of Singapore against sea level rise. However, instead of relying on a traditional seawall design, this study investigated the introduction of biodiversity enhancing measures on the seawall design, as they are currently studied by the Department of Biological Sciences in NUS. Firstly, a review of sea level rise in the past years was examined for the whole world and also for the South East Asia region. Subsequently, the various predictions for future rates of sea level increase were studied. In the second chapter of this study, a detailed description of the study site area was conducted together with the different land uses. Furthermore, based on available topographic data for the area, a digital terrain model was created that represents the ground profile of the study area. Then, five different sea level rise scenarios were identified. All the scenarios assumed high tide conditions (spring tide) and different sea level rise rates were applied. In addition, extreme sea level increases, identified as sea level anomalies were also included. The resulting “inundation maps” allowed for an approximate estimation of the total area that will be inundated for the different sea level rise scenarios. In the third chapter there was a brief review of the various options that are currently being used around the world to protect coastline areas against sea level rise and coastal erosion. Methods, such as hard engineering structures, managed re-alignment techniques and bioengineering methods were briefly discussed, In addition, the approaches that have been followed in Singapore were highlighted. The method of protection chosen for this study was an enhanced biodiversity seawall that is comprised of a traditional seawall structure plus biodiversity enhancing concrete tiles. In the fourth chapter the construction and maintenance of the enhanced seawall was estimated using Net Present Values for 100 years. Two different assumptions were made: a) that the seawall shall be re-constructed after 50 years and b) that the seawall shall not be reconstructed. Also, in this chapter the losses in capital stock, if no protection from inundation is assumed, were calculated using the perpetual inventory method. Gross Capital Formation data for Singapore obtained by The World Bank, were used in this analysis and the capital stock for the whole of Singapore and also for inundated area was estimated. The losses in capital stock were then compared against the cost of the seawall construction. The result was that the seawall construction value is cheaper than the losses in capital stock. Therefore, the seawall construction may be a viable option for protection. In the fifth and final chapter, the conclusions from this study were crystallised and the limitations and the proposals for further work were identified.