Abstract | Full Paper | PDF | Printer Friendly Format

A least-cost pipeline path simulation was performed on the two selected reservoir sites to selected targeted demand areas in the Langkawi Island, Malaysia. The selected reservoir sites were Ulu Melaka and Limbong. These sites were selected because first, these reservoirs will provide sufficient water supply until 2015 and, secondly, their locations were verified by a field study as amongst the potential reservoir sites recommended for the Langkawi Island (Syed, 1992).

In the development planning, future water supply requirement in the Langkawi Island will be targeted to major towns and new tourist areas. In this study, the work concentrated on finding the least-cost path to a major town (Kuah) and a new tourist area (Temoyong). An analysis of the relationship between physical factors and land use/cover types for the whole of the Langkawi Island was performed. Land use/cover types under considerations were inland forest, rubber, mangrove, mixed horticulture, paddy and grassland. Information regarding their physical factors such as height, slope and geology and the percentage coverage for each factor were extracted from the digitised maps available for the Island. The results of this analysis were used as the basis for determining a friction surface factor for the least-cost pipeline routes. A friction surface which defined the costs associated with moving through different land use/cover types in the Langkawi Island was created. Using the COST function in IDRISI, a raster-based GIS, a friction surface was then created for Kuah town. Consequently, using the PATHWAY function, the computation of the least-cost path was completed.

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 as has been demonstrated by the simulation of the least-cost pipelines path studies.