GIS maps of
intertidal zones in Singapore

Methods involved in preparing the maps
The method involves the following steps

1. Preparation of base maps using topographic sheets and also also in consultation with tide charts.

2. Demarcation of low tide coastal landforms from aerial photographs using tone and texture variations.

3. Extensive field verifications of landforms during low tide and generation of thematic maps.

4. Digital conversion of base maps and derived thematic maps .
(a) Digitization (scan to raster and convert to vector or trace the maps using a digitizer table)
(b) Error removal, feature labeling and attribute indexing

5. Transect surveys were determined across these landforms to study their fauna/flora distribution.

6. The results of the transect survey were organized in spread sheets.

7. The transect survey results( spread sheets) linked with maps using common attributes.

8. Developing a Geographic Information System (GIS) database by integrating the thematic maps and the survey results.

Some of the maps in this study were prepared using Global Positioning System (GPS)

In this system the device uses triangulation method to calculate the real time position using measure distance through radio signal from satellites. This system is quite expensive but very accurate. GPS system found to be very useful and also helpful in preparing accurate intertidal maps.

Advantages of Intertidal maps

  • The maps can show the overall distribution of habitats over large areas of shoreline and can be invaluable
  • Entering field data directly to a PC has several advantages. As well as being quick, it cuts out sources of error which can be created by in-between paper stages.
  • The maps can highlight and help quantify large-scale changes in habitat, fauna/flora distribution.
  • Data stored in a GIS are more flexible and can be interrogated

by Dr. D. Kumaran Raju,
Research Fellow, Marine Information Technology Laboratory
Tropical Marine Science Institute
hosted by