Preparation of Groundwater Potential Map (Springs) of Sierra Watershed Using Bivariate Statistical Model and Frequency Ratio

In this study, using the frequency ratio (FR) model, an attempt has been made to identify areas with high groundwater potential of the Sira catchment. Effective factors for preparing groundwater potential map including slope aspect, slope percentage, slope length (LS), Elevation, stream power index (SPI), topographic wetness index (TWI), plan curvature, distance to rivers, distance to roads, distance to faults, lithology, land use, soil hydrological groups and drainage density considered for groundwater potential zone mapping. In the GIS environment, the maps of factors were prepared and overlapped. There are 83 springs in the region, of which 58 were used for modeling and 25 for validation in the FR model. Finally, using the model output, the potential map of groundwater resources was created. The ‌ROC curve was used to validate and evaluate the groundwater potential maps. Validation results showed that the area under the curve (AUC) in the frequency ratio model is 81.21percent, which has a good performance in the potential of groundwater resources in the region. Based on the results of spring potential, 5.07, 13.59, 42.85, and 38.48 percent of the region were in low, medium, high, and very high classes, respectively.