Assessment of oil spill vulnerability of Southwest Pulau Pinang shoreline

The island of Pulau Pinang is located at the northeastern sector of the Straits of Malacca. Oil spill vulnerability assessment was carried out at the southwestern Pulau Pinang shoreline. The study includes field mapping, GIS mapping and analysis of the vulnerability of the shoreline resources in various geomorphic and land-use types. The study aims to assess the relative vulnerability of different types of shoreline and prioritising the shoreline types for protection following a large oil spill. The oil spill vulnerability index (VI) was prepared following the Environmental Sensitivity Index (ESI) approach of National Oceanic and Atmospheric Administration (NOAA) with adaptation to include shoreline types not listed under the ESIs. A modified oil spill vulnerability index (MVI) is formulated by taking into account the environmental and socio-economic value of the shorelines. The vulnerability index is increased by 3 ranks for shorelines with high environmental and/or socio-economic value, by 2 ranks for medium value and by 1 rank for low value. The shoreline of southwest Pulau Pinang can be divided into nine natural and two units of man-made geomorphic units. The southern part of the shoreline is characterised by low to moderate oil spill vulnerability (MVI=1 to 6S), consisting mainly of exposed boulder beaches and exposed coarse sand beaches interspersed with lesser exposed cliffs and steep rocky shore, exposed mixed sand and gravel beaches and exposed fine sand beaches. In the north, the shoreline is highly vulnerable (MVI=8E to 10E), comprising largely of parallel strips of exposed tidal mudflat and mangrove.