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Power |
Telecom |
Transport |
Others
Least-cost pipelines path to the Langkawi Island, Malaysia using a geographical information system (GIS)
Result and analysis
Using the EXTRACT function in IDRISI, the lengths of the pipeline were determined (Tables 3 and 4). The EXTRACT developed the summary of statistics for the total pixels for the pipelines (Eastman, 1997) which were then converted to length by multiplying each pixel by 30 m. Table 3 and 4 show the result of pipelines for both scenarios 1 and 2 respectively.
In scenario 1, where friction surface values for paddy were lower than rubber, the least-cost pipeline distance from the Ulu Melaka reservoir to Kuah town was 6.57 km and from the Limbong reservoir to the Temoyong resort area, the distance was 9.12 km. In scenario 2, where friction surface values for rubber were lower than paddy, the least-cost pipeline distance was 6.3 km and 9.33 km respectively.
Table 3. Length of pipelines from reservoirs to the target areas in scenario 1.
| Management scenario |
Total pixels |
Total length (km)(1 pixel = 30 metres) |
| Ulu Melaka reservoir to Kuah town |
219 |
6.57 |
| Limbong reservoir to Temoyong |
304 |
9.12 |
Table 4. Length of pipelines from reservoirs to the target areas in scenario 2.
| Management scenario |
Total pixels |
Total length (km)(1 pixel = 30 metres) |
| Ulu Melaka reservoir to Kuah town |
210 |
6.3 |
| Limbong reservoir to Temoyong |
311 |
9.33 |
The effect of reducing friction surface values for rubber as in scenario 2, has decreased the pipeline length (from the Ulu Melaka reservoir to Kuah town) from 6.57 km to 6.33 km but the length (from the Limbong reservoir to Temoyong) has increased from 9.12 km to 9.33 km. This result suggested that reducing land use/cover type friction surface values may not necessarily decrease the pipeline length. It can also be deduced that other factors such as the position of each land use/cover types with respect to their adjacent land use/cover types may have influenced the least-cost pipeline distance.
Conclusion
The role of GIS for decision support for catchment management has been analysed. Several management scenarios are developed to provide alternatives to decision-makers. In the least-cost path analysis, two scenarios are presented; one based on a lesser value to paddy and the other based on a lesser value to rubber. Both scenarios produced similar results: the least-cost pipeline route to Temoyong was from the Limbong reservoir (9.12 km) for scenario 1 and to Kuah town was from the Ulu Melaka reservoir (6.3 km) from scenario 2. This study has shown that GIS can evaluate the suitable alternatives and visualise the results thus providing options to the decision-makers. Therefore, GIS, when reinforced by remotely sensed data, secondary data and field survey, can be a powerful tool for solving environmental problems in catchment management.
References
- Eastman J.R. (1997). Tutorial Exercises in IDRISI For Windows Version 2.0, Clark University, Worcester, MA, USA., pp77.
- Feldman, S. C., Pelletier, R. E., Walser, E., Smoot, J. C., and Ahl, D. (1996). Finding a least-cost path for pipeline siting. In S. Morain and S. L. Baros (eds.), Raster Imagery in Geographic Information Systems, Onward Press, Santa Fe, USA, 125-132.
- Janskowski, P. (1995). Integrating geographical information systems and multiple criteria decision-making methods. International Journal of Geographical Information Systems, 9 (3), 251-273.
- Jankowski, P. and Richard, L. (1994). Integration of GIS-based suitability analysis and multicriteria evaluation in a spatial decision support system for route selection, Environmental and Planning B: Planning and Design, 21, 323-340.
- Langkawi District Council. (1992). Langkawi Structure Plan 1990 - 2005. Prepared by Langkawi District Council in Co-operation with Federal Department of Town and Country Planning Peninsular Malaysia Northern Regional Office, Ministry of Housing and Local Government, State Department of Town and Country Planning Kedah Darulaman and French Consultant Team, Ministry of Foreign Affairs, France, Section 5, 1-22.
- Wan Yusof, K., and Baban S. M. J. (2000). Identifying Optimum Sites for Locating Reservoirs Employing Remotely Sensed Data and Geographical Information Systems, in the Proceedings of the 21st Asian Conference on Remote Sensing (ACRS 2000), Centre for Space and Remote Sensing Research, National Central University, Chung-Li, Taiwan, December 4-8, 2000, 35-40.
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