GIS mapping of regional probabilistic groundwater potential in the area of Pohang City, Korea

This study analyzed the relationships between groundwater specific capacity (SPC) and its related hydrological factors to assess the sensitivity of each factor and map the regional groundwater potential for the area of Pohang City, Korea, using a geographic information system (GIS) and a probability model. All related factors including topography, geology, lineament, and soil data were collected and entered into a spatial database. SPC data were collected from well locations, and SPC values of ≥6.25 m3/d/m, corresponding to a yield of 500 m3/d, were input to a spatial database. SPC data were then randomly selected in a 66/34 ratio to train and validate the model. A frequency-ratio model and sensitivity analysis were used to determine the relationships between SPC and its related factors and the importance of SPC-related factors. Sensitivity analysis allows for comparison of the combined effects of all factors except for one. The validation of the groundwater potential map overlain by all factors showed 77.78% accuracy. In the sensitivity analysis, the best accuracy was obtained by omitting ground elevation data (78.64%), and the worst accuracy resulted when soil texture was not included (76.64%). The results show that soil texture had the greatest effect on the groundwater potential and ground elevation had the least effect. Such information and the maps generated from it can be applied to groundwater management and groundwater resource exploration.