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Abstract
The rapid expansion of extensive brackishwater aquaculture (BA) in Southeast Asia, particularly in Indonesia, has created an urgent need to develop reliable methods for site selection and evaluation. A lack of proper site selection criteria and poor understanding of spatial assessment of environmental factors are two major constraints on the development of the extensive aquaculture system in Indonesia. Multi-criteria evaluation methods (MCEs) currently developed for Indonesia have been unsuccessful due to the lack of supporting spatial data at appropriate scales. This study presents small-scale and finer-scale GIS approaches using key environmental spatial datasets to handle the complexity. This case study employed spatial datasets, including land use-cover maps, elevation data and soil data, for coastal areas in Barru District, South Sulawesi Province, Indonesia. Data analysis involved GIS-based spatial analysis, fuzzy logic or fuzzy set techniques, univariate and multivariate statistical analyses. The research successfully produced an overall suitability map at the scale of 1: 50,000 for the whole regency. This small scale GIS approach effectively excluded more than 95% of the total areas as not being suitable area for BA. This study also discovered the model integration of spatial and multivariate statistics to aid in-depth understanding of the relationships between soil chemical variables and its influence on pond suitability level. This combined spatial and multivariate statistical model suggested a suite of key soil variables that were applied for the finer-scale pond suitability mapping. At the finer scale approach (1: 5,000), this study found interesting local soil variability at the selected study region and only discovered 21% of the total 506 ha farming areas, as highly suitable class for extensive BA. Overall this study will enable farmers and decision makers to select methods and information of assessment relevant to different scales and goals for BA development and management. Increased awareness of the need for improved pond engineering techniques is specially highlighted in this study to safeguard the economic and environmental sustainability of Indonesia s valuable aquaculture industry. The problems identified by the study are not unique to Barru; they also occur in other extensive aquaculture areas in Indonesia.