GIS as Decision Support Tool for Landfills Siting

GIS as Decision Support Tool for Landfills Siting

3) Distance from environmentally sensitive or protected areas
The location of a landfill in close proximity to sensitive areas such as fish sanctuaries must be avoided, and mangrove areas and areas gazetted for special protection would be excluded. Apart from the area being excluded, a 3,000 meters buffer would also be created surrounding the environmentally sensitive area. The 3,000-meter buffer is in line with the guidelines produced by the Department of Environment, Sabah.

4) Distance from urban areas
Landfills should not be placed too close to high-density urban areas in order to mitigate conflicts relating to the Not in My Back Yard syndrome (NIMBY). This guards against health problems, noise complaints, odour complaints, decreased property values and mischief due to scavenging animals. For this reason, population density was then generated based on the 1991 and 2000 Census in GIS ready format produced by the Department of Statistic, Malaysia.

5) Distance from rural settlements areas
Due to the same conflicts relating to the NIMBY syndrome, development of landfills shall be prohibited within 3000 meters from village settlements. The rural settlement area was designated either by point location or by polygons in the Sabah map and a 3000-metre buffer shall be created around it. There is no pre-qualification of the use of 3,000-metre buffer but such a distance should be sufficient to guard the interests of the rural settlement area

6) Landform and Soil Type
The permeability of the underlying soils and bedrock will greatly influence how much leachate is escaping a landfill site; therefore, preference is given to a landform that is somewhat located in flat or undulating land.

7) Land use/land cover
The Land use and Land cover must be known in order to determine which areas are more suitable for a landfill. Land use types such as grassland, forests and cultivated land would be considered and assigned an appropriate index of land use suitability. The Department of Agriculture, Sabah has identified several classes of land cover and for the purpose of this research seven (7) classes were used.

8) Haul distance
Whilst a landfill should not be located within 100 meters of a road it would be more cost efficient for landfills to be located not too far away in order to avoid high transportation costs. From the discussions with the Sandakan Municipal Council and Spatial Plan Working Group, it was decided that a sanitary landfill for Sandakan District shall be located within 25km from the town centre.

Methodology
This particular research applied Constraint Mapping Technique to reduce the search area over vast land coverage and to leave only those areas that are suitable for siting a landfill. The exact operation of the research methodology is presented in the following sequences: -

Problem Identification,
Research Objective,
Choose a Study Area,
Decide on the Criteria,
Acquire Data,
Convert Criteria into GIS Layer,
Perform Spatial Operation,
Analyze Results and
Identification of Potential Search Area.

This research began with problem identification and thereby establishing the objective, which was tied to a specific study area. In step 4, the input criteria have to be discussed and agreed by the proponent or the owner of the project. This particular study has taken the advantage of the “The Spatial Plan Working Group” for Sandakan District, which at the same time of this research was in the process of preparing the overall district physical planning in collaboration with DANCED and Town and Regional Planning Department. Figure 1 present the summary of the methodology for this research.

Figure 1: Sequence for Constraint Mapping Technique

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