## 6 Discussion  
As several studies report, the significance and predictive power of spring related factors that are used in groundwater spring potential assessments are controlled by the geological, morphological, hydrological, and climatic settings of the area [19; 22; 79; 80; 81]. According to [PERSON] [35], topographic \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Models** & **AUC** & **SE** & **95\% CI** \\ \hline KLR & 0.797 & 0.0591 & 0.691 to 0.879 \\ RF & 0.811 & 0.0526 & 0.707 to 0.890 \\ ADTree & 0.773 & 0.0578 & 0.665 to 0.860 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Parameters of AUC values using validation dataset. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Models** & **AUC** & **SE** & **95\% CI** \\ \hline KLR & 0.877 & 0.0294 & 0.821 to 0.921 \\ RF & 0.909 & 0.0225 & 0.858 to 0.946 \\ ADTree & 0.812 & 0.0341 & 0.748 to 0.866 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Parameters of AUC values using training dataset. SE: standard error; CI: confidence interval. Figure 9: ROC curves of the three models using a (**a**) training dataset and (**b**) validation dataset. features, such as elevation and slope, have a negative influence with groundwater spring potential, and on the other hand TWI and drainage density have a positive influence. Similar studies, report that topographic features along with the characteristics of the soil cover, tectonic features (fault density and distance to faults), and also hydrological features (drainage density) influence the rainfall-runoff rate and also the infiltration rate, thus possibly affecting the groundwater spring potential occurrence [19; 35]. [PERSON] et al. [43] reported that lithology, elevation, and distance to streams had a greater influence, whereas land use, NDVI, plan, and profile curvature appear to have the least influence. During the present study, the implementation of LSVM revealed that lithology had the highest predictive power, followed by elevation, SPI, and soil cover. Concerning the lithology factor, lithological and structural differences lead to variations in the durability and permeability of rock and soil formations, and thus the presence of springs [35]. Based on the FR analysis, groundwater springs are more probable to be found in southeast facing slopes, in areas with slopes angles ranging between 15 to 25 degrees and elevation lower than 1150 m. Concerning slope angles, the outcomes of the study are persistent with previous studies that report that areas with slopes greater than 35\({}^{\circ}\) are considered unfavorable since as the slope increases so too does runoff, having as a result reduced infiltration rates [82; 83]. Moreover, the most spring-probable areas are covered by Haplic Arenosols (ARh) soils, which are coarsely textured sandy soils, permeable to water, and Calcic Kastanozems (KSk) soils, which are characterized by a rather restricted water transmission with higher portions of clay particles. According to [PERSON] and [PERSON] [84], sandy soils and coarse sandy clays appear as potential favorable storage bodies due to their light texture and excellent rate of infiltration, which is persistent with the findings of our study. Within the research area, sand, mudstone, and sandstone formations appear to be more likely to contain springs. Similar findings were found by the authors in a previous study concerning the area of research [43]. Mudstone layers, which could be defined as formations with very low infiltration capacity, form an impermeable layer while sand and sandstone formations act as permeable layers allowing the concentration of surface water within their mass. The alternation of these layers permits the formation of groundwater springs as can be found in the area of research. An interesting point that should be mentioned is the high predictive value of the factor distance to roads.