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Coastline development and associated changes in coastal habitats in SingaporeNhung Nguyen 1 , Elimar Precht 2 & Rachel Lim 11 National Biodiversity Centre, National Park Board, 1 Cluny Park, SingaporeNguyen_nhung@nparks.gov.sg, Lim_Li-feng@nparks.gov.sg2 DHI Water & Environment, 1 Cleantech Loop, #03-05 CleanTech One, Singaporeepr@dhi.com.sgAbstractSingapore’s geographical shape has changed substantially over the past decades due to reclamation and coastaldevelopment. Land reclamation alongside the development of Singapore into the world’s busiest port has alsocaused substantial changes to the seascape, hydrodynamic regime, and coastal habitat distribution in the watersaround Singapore. For the last decade, reclamation and the state of the coastal and marine environment in Singaporehave been well documented, monitored and managed. However, data on coastal works before the 1990s, whichcaused substantial changes in Singapore’s seascape, are much less readily available. This paper presents the changesin coastline and bathymetry reconstructed through the use of historical topographic maps and navigational charts andremote sensing data. Past hydrodynamics are modeled to show changes in the flow pattern, tidal cycles, which subsequentlyaffect sedimentology and habitat distribution. Understanding the natural habitat distribution in Singaporehas an important implication in coastal and marine environments, especially in habitat restoration and rehabilitationefforts.IntroductionThe present coastline of Singapore is an impressive showcase of the rapid development Singapore has made inthe past 50 years. Being a small island state facing land scarcity, reclamation works were undertaken extensively toexpand the country’s land area. This impacted Singapore’s coast in many aspects, particularly conversion and loss ofcoastal habitats (Hilton and Manning, 1995). On a broader term, the changes in both the coastline and bathymetriesare believed to have also altered the hydrodynamic regime and the habitat distribution in the waters around Singapore.An example of this is the construction of the causeway to Malaysia in 1922, which may have caused a seawardincrease of the Sungei Buloh Wetland Reserve mangroves nearby (Bird et al., 2004).Since the pre-colonial era, the Singapore Strait has always been an important navigation route serving the tradersfrom the Middle East, India, the Indonesian archipelago, China, and Japan. Maps and navigational tools thus weredeveloped very early in Singapore’s history. European archives hold a sizable collection of nautical charts of Singaporewaters from as early as the 17 th century. However, it was only after the late 19 th century, that cartography wasadvanced enough to generate maps that can be used with confidence today and European archives contain theseuseful maps from the early 1900s. The changes along the coasts of Singapore can be generated from past topographicmaps and navigational charts. However, they are not always easily accessible.Data sourcing and map reconstructionThe project sourced maps from various sources in Singapore and in Europe. A clear focus has been on navigationalcharts that allowed a reconstruction of the past bathymetry and some habitats in very early development stage.For the purpose of this project, maps were acquired from 14 sources within and outside of Singapore. These mapswere georeferenced and entered into ArcGIS to be used for analysis and modelling. Due to a large number of mapsacquired, the discrepancy in map projections, units, scales, and topological survey technology posed a challenge tointegrate them into one map displaying platform. Particularly, some early maps could not be matched with mapsmade later, mostly due to different projections used. These maps were rectified using unchanged and recognisablefeatures on the coastline. Coastlines, isobaths, and depth soundings were digitalised manually, which amounted to40163 datapoints. A web-GIS was created which allows data to be easily presented on an interactive interface.147