Assessing the Ability of GIS Based MCDA Methods to Reveal the Geothermal Potential of the Büyük Menderes Graben

Abstract

More than 80% of the geothermal electricity production of Turkey is currently attained by the Büyük Menderes Graben with further potential yet to be revealed. The majority of the early development has been on the main plain of the graben, however in the recent years new sites with great geothermal potential have been discovered at the northern flank of the graben. The geothermal system in Western Anatolia is governed by a N-S extensional regime represented by high angle E-W trending normal faults. The heat transfer achieved through fault controlled convective system led to the formation of many low-to-high enthalpy geothermal areas at the northern flank of the graben. The general success rate of geothermal drilling tend to decrease away from the graben center thus every means that could guide the search for new geothermal sites should be made available prior to drilling exploratory wells accounting for the majority of the cost in geothermal exploration studies. The GIS based MCDA serves as an invaluable tool in an attempt to minimize the risks of geothermal exploration by revealing areas with high potential as an initial assessment. In this study, a knowledge-based MCDA method has been employed in order to determine the geothermal potential map of the Büyük Menderes Graben. Criteria including geological, seismo-tectonic, topographic, surface temperature and vegetation data have been used for the spatial assessment of the geothermal potential of the Büyük Menderes Graben. The ability of MCDA to reveal the true geothermal potential of the area was evaluated by comparing the generated favorability map with the known locations of producing geothermal wells. As a result, 95% of the producing wells corresponded to the classes identified as most favorable (76%) and favorable (19%).