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11 th International Symposium for GIS and Computer Cartography for Coastal Zones ManagementAdditionally, for the last four decades, the coastlines were generated in a semi-automated routine usingLANDSAT satellite images. Thus, a continuous coverage of the coastline development over the last century couldbe produced. Figure 1a shows the development of Singapore’s coastline over the last century.Simulation of past hydrodynamicsThe reconstructed bathymetries were used for hydrodynamic modelling. In all, 4 bathymetries were generated,including a pre-development stage (1909) as well as 1946, 2004 and 2012. The hydrodynamic conditions for theseperiods were simulated using MIKE 3 FM to analyze the impact of the coastline and bathymetry changes on thehydrodynamic conditions. The results show that in some areas, currents and water exchange have reduced substantially,while in the main Singapore Strait, the maximum current velocities increased due to narrowing of the channels.Coastline development and habitat distributionMuch of Singapore’s terrestrial biodiversity was lost historically due to extensive deforestation in the 19 th centuryto make way for cultivation of economic crops. Over 95 percent of native habitats have been lost in the past 190years (Tan, 1995). In this trend, around 60 percent of coral reef area has been lost due to near shore reclamation andthe accompanying sediment loads have triggered declines in coral cover since 1987 (Burke et al., 2002). Sedimentationeffects resulting from reclamation have hampered the ability for coral reefs to cope and recover.Development pressures and coastal modifications continue to be the main threat to Singapore’s remaining intertidalhabitats. Sedimentation and water clarity issues stemming from coastal works also threaten marine intertidalbiodiversity. The construction of the Kranji Dam possibly caused a reduction in sediment supply and consequentlyled to further erosion along much of the coastline, with the mangrove fringe having retreated up to 50 m in 2001.The damming up of rivers (to form reservoirs), could affect seawater input for the mangroves, hence enabling encroachmentby fresh water species or other potentially invasive species. This may affect the ecosystem balance bydriving out species dependent on the mangrove habitats for survival.An encouraging trend observed from some reclaimed areas is the re-colonisation of marine life, forming new habitats.An example of this can be found at Changi beach, where the new beach formed after reclamation was ideal forthe growth of seagrasses, forming a new habitat. The area now supports diverse marine life, which indicates thatwhere conditions are favourable, given time, new habitats can form on man-made landforms. Another showcase isPulau Semakau, an offshore island in Singapore waters, where costal habitats and a marine landfill co-exist in closeproximity.Coastal habitat mappingIn an effort to quantify the extent of Singapore’s coastal and marine habitats, a baseline map of these habitats inSingapore was generated for use in conservation management policy-making.Worldview-2 satellite images from 2010 and 2011 were used to map the extent of the habitats and were supplementedby GeoEye-1 satellite images, with four spectral bands and 2 m spatial resolution, when cloud freeWorldview-2 images could not be obtained.The images used are acquired at low tide when possible in order to increase the accuracy of the classificationstudy. Hierarchical unsupervised classification was applied on each image to group dominant statistically differentspectral clusters based on their spectral reflectance values. These clusters were then aggregated and assigned to thethematic categories based on visual interpretation and spectral signature. Coupled with filtering and contextual editing,all the classified images were then combined to produce a pan-sharpened 0.5 m multispectral image of thecoastal and marine habitats of Singapore.In addition, ground-truthing was conducted with randomized sampling points. GPS-tagged field photographs andvideos were also taken during low tide conditions in order to relate image data to real features on the ground andtherefore minimise errors in the classification. These surveys were done in offshore islands and patch reefs with avariety of inter-tidal habitats in order to evaluate the classification results.The final map consisted of 18 thematic categories and is broadly divided into two parts according to geographiclocations. The classification scheme was designed to categorise cover by both substrate type and habitat cover. As148
11 th International Symposium for GIS and Computer Cartography for Coastal Zones Managementthe focus of the project was on the coastal and marine areas, the classification of terrestrial areas included the followingcategories: built up land, rock bund, other vegetation (such as secondary forest, grassland, scrubland) etc.Some of the categories for the intertidal zones included, e.g.: sandy beach, mangroves, sandflat, mudflat, seagrassmeadows, rubble/sand, coral rubble with seagrass/algae.Figure 1a (top) shows Singapore’s changing coastline over time as part of the study to simulate changes in hydrodynamics.Figure 1b (bottom) shows the habitat map of Palau Semakau to collect baseline information on the coastal and marine habitats.Figure 1b presents a map of the habitats of Pulau Semakau in 2011. Some of the habitats that could be found inand around the island include seagrass meadows, mangroves, sandflat, etc. The results from the study are used ex-149
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CoastGIS Conference 2013: Monitorin
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Sponsors
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Steering Committee Secretariat main
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Santos Basin, BrazilA.F. Romero, R.
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Coastline development and associate
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Visual resource management system f
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11 th International Symposium for G
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Use of Terrestrial-LiDAR for quanti
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Community beach monitoring: utilisi
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Data policy implications arising fr
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Global ocean observing system for w
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ResultsMetadata11 th International
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Coastal vulnerability index to glob
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generating probabilities contours f
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maps, the most critical conditions
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Statistical and spatial toolbox for
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Global oceans and marine planning
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Analysis11 th International Symposi
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Building scenarios and visualizatio
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Using a 3D physics-based visualizat
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Documenting situated tsunami risk p
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SeaSketch11 th International Sympos
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A structured model to enable coasta
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Developing and testing approaches f
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A dynamic GIS as an efficient tool
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GIS spatio-temporal modeling of hum
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Acknowledgments11 th International
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Long-term continuous observations o
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Comparing endmember extraction meth
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Integration of scientific data as a
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Conclusions11 th International Symp
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