GEOTHERMAL RESOURCE PROSPECTING USING GIS

This paper presents the applications of remote sensing and Geographical Information System (GIS) as a Decision Support System (DSS) in geothermal exploration and environmental management. The project aim is to find out the best location for drill sites in the Namafjall geothermal area in North Iceland. GIS was used in this work not only as a tool in mapping and spatial visualization but also as a DSS tool for suitability analysis. Decision about the location of wells in analogue methods has been made mostly using geological, hydrological, geochemical and geophysical data, and thus human errors are unavoidable during complex decision making process for well site locating.In geological studies three data layers including geothermal manifestations, volcanic craters and faults and fractures were overlain and intersected, then the common area was selected as a geologically suitable area. This area was overlain by the weighted geophysical and fractures distance raster maps and a weighted cell base raster calculation were carried out, and the suitable area based on exploration data were selected.In environmental suitability analysis, the vegetation cover and its density maps are first overlain and suitable area is selected. This map was overlain by the weighted protected area, slope and elevation maps with predefined criteria and a special weighting for each one, and a suitable area was selected. In final well site selection the exploration suitability map and environmental suitability map were overlain and a weighted cell based raster analysis were carried out. Based on the final analysis the suitable area has been ranked at three different levels of suitability and the first priority sites were selected as wellfields for the first phase of geothermal exploration drilling.