Environmental Modeling and Assessment 6: 57–65, 2001.  2001 Kluwer Academic Publishers. Printed in the Netherlands. Distributed process modeling for regional assessment of coastal vulnerability to sea-level rise Brett Bryan a , Nick Harvey b , Tony Belperio c and Bob Bourman b a Department of Geographical and Environmental Studies and GISCA, National Key Centre for Social Applications of GIS, University of Adelaide, South Australia, Australia b Department of Geographical and Environmental Studies, University of Adelaide, South Australia, Australia c Minotaur Gold, South Australia, Australia Sea-level rise involves increases in the coastal processes of inundation and erosion which are affected by a complex interplay of physical environmental parameters at the coast. Many assessments of coastal vulnerability to sea-level rise have been detailed and localised in extent. There is a need for regional assessment techniques which identify areas vulnerable to sea-level rise. Four physical environmental parameters – elevation, exposure, aspect and slope, are modeled on a regional scale for the Northern Spencer Gulf (NSG) study area using commonly available low-resolution elevation data of 10 m contour interval and GIS-based spatial modeling techniques. For comparison, the same parameters are modeled on a fine-scale for the False Bay area within the NSG using high-resolution elevation data. Physical environmental parameters on the two scales are statistically compared to coastal vulnerability classes as identified by Harvey et al. [1] using the Spearman rank-correlation test and stepwise linear regression. Coastal vulnerability is strongly correlated with elevation and exposure at both scales and this relationship is only slightly stronger for the high resolution False Bay data. The results of this study suggest that regional scale distributed coastal process modeling may be suitable as a “first cut” in assessing coastal vulnerability to sea-level rise in tide-dominated, sedimentary coastal regions. Distributed coastal process modeling provides a suitable basis for the assessment of coastal vulnerability to sea-level rise of sufficient accuracy for on-ground management and priority-setting on a regional scale. Keywords: coastal vulnerability assessment, environmental modeling, GIS, regional, sea-level rise 1. Introduction Potential accelerated sea-level rise (hereafter referred to as sea-level rise) is a ubiquitous hazard facing coastal ar- eas and is of great economic and ecological significance considering the intensive nature of both biological and hu- man activity in the coastal zone. The necessity of assess- ment of the vulnerability of coastal areas to sea-level rise has been recognised by the Intergovernmental Panel on Climate Change [2]. The impact of sea-level rise involves increases in the coastal processes of inundation, and wave attack and erosion [3,4]. Coastal vulnerability assessment must incor- porate the complex interaction of physical environmental factors at the coast which affect these coastal processes and hence, coastal vulnerability to sea-level rise. The best estimate for projected sea-level rise is 49 cm to the year 2100 [5]. Assessing the vulnerability of coastal areas to sea-level rise of such magnitude and even earlier projections which were closer to 1 m [6] has demanded the use of specialised techniques and data. Many different tech- niques have been employed in quantifying coastal vulnera- bility to sea-level rise including ground survey, engineering and high-resolution topographic mapping. Several studies have also assessed coastal vulnerability to sea-level rise us- ing Geographic Information Systems (GIS) [4,7–14]. Many of these have relied upon detailed and precise data such as storm-flood data [13], high-resolution topographic data [4], or detailed coastal profiles and long-term beach monitoring data [14]. As a result, these studies are generally expensive, time consuming, and only cover localised areas often of high economic importance [4,13,14]. Whilst the importance of localised and detailed studies re- mains for areas of particular significance, there is a real need for techniques suitable for assessing regional-scale (coast- lines in the order of hundreds of kilometres) coastal vulner- ability to sea-level rise that do not have intensive data re- quirements. Regional assessments are required so that areas vulnerable to sea-level rise can be identified within coastal regions and priorities can be set for fine-scale studies and management. Harvey et al. [1] propose a method of coastal geologic mapping in combination with ground survey that is suitable for this kind of regional assessment of coastal vulnerability to sea-level rise. This technique involves the mapping of ho- mogeneous coastal geological units from aerial photography and extensive field verification on a regional scale and was implemented in the Northern Spencer Gulf, South Australia. The units are used as surrogate indicators of the complex in- teraction of the coastal processes affecting vulnerability to sea-level rise. Vulnerability classes are based on the eleva- tion of the geological units derived from two coast-normal transect surveys [1]. In this study, we assess the potential of GIS-based dis- tributed coastal process modeling for providing an alter- native yet compatible technique for the regional assess- ment of coastal vulnerability to sea-level rise. Distributed coastal process modeling involves modeling the spatial dis- tribution of physical environmental parameters which influ-