Sinkhole Susceptibility Mapping Using a Frequency Ratio Method and GIS Technology Near Karapınar, Konya-Turkey

The purpose of this study is to produce a sinkhole susceptibility map of the Obruk Plateau in central Turkey, based on a frequency ratio method within a Geographic Information System environment. Using field surveys, the locations of the 182 sinkholes were determined in the study area. In this study, 30 sinkhole-related factors were determined and used in the analysis. The values of the frequency ratio were estimated using frequency ratio analysis and were used to calculate the sinkhole potential for the entire study area. For model validation, the constructed sinkhole occurrence potential map was overlaid onto the 182 observed sinkholes, showing that 169 sinkholes (93% of all sinkholes) were determined to be in the high and moderate sinkhole occurrence potential areas. In addition, the predictive capabilities of the models were determined by the area under the relative operating characteristic (ROC) curve. The area value under the ROC curve was 0.953. These results indicate that the model is a good estimator of the sinkhole potential in the study area. The sinkhole potential map shows that the areas of very low or no, low, moderate and high sinkhole potential classes are 712.31 km2; 641.15 km2, 572.45 km2; and 438.01 km2, respectively. The interpretations of the potential map showed that geology (lithology), elevation, aspect, fault density, distance to fault, and decline of the groundwater level play major roles in sinkhole occurrence and distribution in the Obruk Plateau. The resulting sinkhole potential map can aid planners and engineers in development plans and land-use planning.