SMT201 AY2019-20G1 EX2 Kok Jim Meng

Part 1: Map Layouts of Extractions

Target Roads

There is a higher number of target road networks in the central and eastern part of the Gombak study area. To build the quarantine centre, it is suitable to build at these areas due to the transportation of the materials for the construction of the quarantine centre.

Buildings

By using Master Plan 2014 Land Use and OSM’s buildings layer, I intersect them and classify them according to the building types. Residential buildings are saturated in the western side and northern side of the study area. Furthermore, military buildings (i.e. Bukit Panjang Camp) are at the central of the study area. In addition, train stations are at the eastern side of the study area. Hence, it is ideal to set up the quarantine centre at the southern side of the study area to stay away from those stated buildings.

Target Natural Features

According to the three types of nature features namely forest, parks, and water, the proposed quarantine centre needs to stay away from these nature features. Hence, it is ideal to set up the quarantine centre at the southern side of the study area.

Digital Elevation

The colours of the elevation are represented where green means flat land, orange-yellow means mid-level land, and red means high-level land. To fulfill the economic factor of building at gentle slope, it is suitable to build the quarantine centre at the green areas of the slope according to the raster.

Part 2: Map Layouts of Proximity

Proximity to Target Roads

The darker the values, the more suitable for the proposed quarantine centre to be constructed. Hence, this allows the accessibility of the transportation of the materials to construct the quarantine centre. With 5 metres by 5 metres resolution, the nearest road within the study area of Gombak is 0 metres. The furthest distance from the buildings is 743.303 metres.

Proximity to Buildings

The lighter the values, the more suitable for the proposed quarantine centre to be constructed. Hence, this is to ensure the quarantine centre to be built is staying away from the buildings. With 5 metres by 5 metres resolution, the nearest road within the study area of Gombak is 0 metres. The furthest distance from the roads is 838.466 metres.

Proximity to Target Natural Features

The lighter the values, the more suitable for the proposed quarantine centre to be constructed. Hence, this is to ensure the quarantine centre to be built is staying away from the nature features. With 5 metres by 5 metres resolution, the nearest road within the study area of Gombak is 0 metres. The furthest distance from the roads is 863.669 metres.

Slope

As mentioned earlier in first part of this Take Home Exercise, slopes are based on the elevation. The darker the values, the flatter the land is. Hence, the darker values are considered suitable for the quarantine centre to be constructed. With 30 metres by 30 metres resolution, the maximum steepness is approximately 36.419 degrees. As shown in the map, most areas of the study area are flat.

Part 3: Map Layouts of Criterion Scores

To standardize the criteria scores, I have used the min-max function. To get the minimum and maximum of the proximity layers, we can find out in the properties of the layers in the information section. The following shows an example of the minimum and maximum values of the proximity to roads layer.

Figure 1: Maximum and Minimum values of Proximity to Roads Layer

Thereafter, I have applied the min-max formula ((DN-min value)/(max value – min value)) to get the standardized criterion score by using the Raster Calculator.

Figure 2: Doing Standardisation formula by applying Min-Max for Proximity to Roads Layer

After standardization, the value is range from 0 to 1.

Accessibility Score

The Accessibility factor is to make sure that the site of the proposed quarantine centre is as close as possible to the roads. Hence, the lower the value the better.

Health Risk Score

The Health Risk factor is to make sure that the site of the proposed quarantine centre is as far as possible to the buildings. Hence, the higher the value the better.

Natural Conservation Score

The Natural Conservation factor is to make sure that the site of the proposed quarantine centre is far as possible to the natural sites. Hence, the higher the value the better.

Economic Score

The Economic factor is to make sure that the site of the proposed quarantine centre is at lower elevation of the slope. Hence, the lower the value the better.

Part 4: Analytical Hierarchical Process (AHP)

Figure 3: Jim Meng's AHP Hierarchy

After standardization, the value is range from 0 to 1. Before computing AHP and to find out the suitability of building Communicable Disease Quarantine Centre, we have to decide criteria relevant to our goal which I have identified and arranged in the hierarchy illustrated in the above figure. This allows the incorporation and accommodation of both qualitative and quantitative criteria for assessing the suitability of building Communicable Disease Quarantine Centre. So, let’s start computing AHP.

Figure 4: AHP Scoring Framework

AHP provides a framework where it helps us to prioritise on the different factors in decision making. It requires evaluation of the pair-wise comparison matrices using measurement theory. The parameter that is used to check this is called the Consistency Ratio. The consistency ratio is a measure of how much variation is allowed and must be less than 10%.

Based on my assumption of the analysis hierarchy figure, I have prioritised the factors in the following from top to bottom:

1. Health Risk: People are greatest assets. Best is to prevent the disease spread to people living or working nearby, especially the military personnel
2. Natural Conservation: Climate, environmental, and heritage issue
3. Accessibility: Convenience for transporting patients and materials for building the centre
4. Economic: A country with stable governance, money can be earned back.

I have constructed the AHP as follows and I got 7% of the consistency check which fulfills the criteria of the consistency ratio. This indicates that the comparisons of criteria were perfectly consistent. Moreover, I have also gotten the derived weights.

Figure 5: Jim Meng's computed Pairwise Comparison Matrix

Figure 6: Weightage and Consistency Check computed after computing Pairwise Comparison Matrix

Part 5: Suitability Analysis

Based on the weights computed in AHP (which are equal to 1), we use Raster Calculator to calculate the suitability by applying the following formulas of using the criterion scores (Note: Both Economic Factor and Accessibility Factor need to be inverse):

Figure 7: Using Raster Calculator to compute Criteria Raster

When visualized with single pseudocolour, the output is as follows:

Figure 8: The output of Criteria Raster after computing it in Raster Calculator

Hence, we will reclassify them into based on this condition by using Reclassify Values (simple):

Low Value	High Value	Replace with	Remark
0	0.31	3	Not Suitable Site
0.31	0.49	2	Good Suitable Site
0.49	0.85	1	Best Suitable Site

Figure 9: Using Reclassify Values (simple) to reclassify the values to compute the Suitability Zones

Thereafter, we visualise using single pseudocolour where the best suitable site (metric value of 1) is indicated by white zone and the good suitable site (metric value of 2) was indicated by the bright green pixels. Hence, the map is output as follows.

Next, we transform the suitability raster into a polygon using the Polygonize (raster to vector) function. Thereafter, we removed the metric value of 3 from the polygon’s attribute table as it is not a suitable site metric value.

Furthermore, it is considered as a valid location due to that it lies at the mid-steep areas of the elevation between 43m to 130m.

Hence, we will digitise suitable sites in the tint and pale orange regions where natural features, road accessibility and nearby houses which are outside Gombak subzone are taken into consideration in the following figure where it shows the zoomed overview of the are using Google Satellite base.

In the following figure show the digitised suitable sites and its areas where they fulfilled the criteria of at least 10,000m².

Figure 9: Jim Meng's digitised suitable sites and their areas which fulfilled at least 10,000m²

All the suitable sites are digitized in that way is because we can allow accessibility comes into play and maintain the natural conservation where we can link the road network to the proposed sites and construct the quarantine centre without affecting the natural feature (i.e. park). Furthermore, these suitable sites are staying away from buildings and are laying on the mid-level lands based on the elevation as explained earlier and in the following map.