Modelling the optimum routes for linking potential reservoir sites to demand area in mountainous tropical islands

Identifying efficient pathways for linking potential reservoir sites to demand areas can be a difficult task in mountainous tropical regions. Options for locating optimum water pipe routes to link two proposed reservoir sites to future demand areas in the Langkawi Island, Malaysia, were developed and simulated. A basic water pipe locating criteria was developed based on land use, terrain, geological, and environmental factors. A raster based GIS, IDRISI was used to geographically associate this information with individual land use/cover types on the island. Then, a friction surface cost-value and a friction surface were created. Subsequently, two alternative scenarios were established and implemented. The results from both scenarios show that the paths will pass through the lowest friction surface value, i.e., grassland and mixed horticulture. The results from both scenarios were evaluated against straight-line paths. The analysis shows that a straight-line path may not necessarily be the cheapest distance in mountainous tropical environments. This study has demonstrated the advantages of using GIS in developing and simulating different options for finding optimum paths and providing reliable management options for decision makers.