## 3 Results  
The preliminary phase for the groundwater simulation carried out for the investigated aquifer allowed us to get a possible scenario of the mean hydraulic head. It was deduced by model calibration, assuming the abovementioned conceptual model boundary conditions.  
Figure 9 highlights the maximum and minimum groundwater levels for TSZ values of 100 m and 2000 m, respectively, considering the mean hydraulic conductivity K\({}_{\text{mean}}\) = 0.0048 m/s obtained for all calibrations, Figure 10 shows the Caposele aquifer fluctuation for different depths, considering a mean recharge amount (R = 1.06 m/y); then, the simulation was also carried out considering high recharge (2 \(\times\) R) and low recharge periods (0.5 \(\times\) R).  
Figure 8: The simulated hydraulic head in the P1 borehole, using different values of the hydraulic conductivity, which was found based on the mean hydraulic head observed in the P1 borehole (422.16 m) and different values of TSZ: (**a**) 100 m, (**b**) 200 m, (**c**) 500 m, (**d**) 1000 m and (**e**) 2000 m.  
Figure 9: Plan-view of the Caposele unconfined aquifer under steady-state conditions during the mean recharge period (R = 1.06 m/y), cell size \(100\times 100\) m, K\({}_{\rm mean}\) = \(4.8\times 10^{-3}\) m/s and thickness of the saturated zone of the aquifer (TS2): (a) 100 m, equipotential lines spaced at 0.5 m; and (b) 2000 m, equipotential lines spaced at 0.1 m. (1) spring (2) active cell; (3) inactive cell and (4) flow net.  
The simulation points out that the hydraulic head of the recharge area drops when TSZ increases, fixing the K\({}_{\text{mean}}\) value as being constant for all the proposed scenarios (Figure 10). This preliminary result allows one to obtain a relationship between the groundwater level fluctuation and aquifer depth, providing details on the water table slope. According to the proposed scenarios, thicker aquifers are characterized by a flat water table, while conversely, a high slope of the water table can be considered an indicator of a saturated zone with less thickness; this also allows one to claim that aquifers characterized by a flat water table are affected by deep groundwater circulation, whereas a higher water table slope is a marker of shallow flow paths.  
The flow simulation provided hydraulic head arrays as the output parameters for the model, leading us to hypothesize a possible scenario of the Caposele unconfined aquifer's hydraulic behavior under a steady state condition. Based on the conceptual model assumptions, the hydraulic head, \(h\), estimated by simulation, ranges between the lowest value at the spring (h\({}_{\text{min}}\) = 417 m a.s.l.) and the mean of the maximum values reached in all simulations, h\({}_{\text{max}}\)\(\approx\) 427.5 m a.s.l. in the recharge area, estimated for the mean recharge condition. Considering the hydraulic head difference between the recharge area and the Caposele spring, \(\Delta\)h \(\approx\) 10.5 m, the water table slope has a mean value of about 0.001, which is in agreement with the slope found for other karst aquifers of central-southern Italy [30, 43]. However, due to its non-linearity, the slope of the water table progressively increases toward the spring [43, 44]; in particular, it has a mean value of 0.008 between the P1 borehole and the spring, and it is almost flat when far from the spring.  
The hydraulic head difference that was found, \(\Delta\)h \(\approx\) 10.5 m, between the maximum recharge area and the Caposele spring, was proven considering the n.5 groundwater level scenarios proposed for different aquifer TSZs. However, the hydraulic head difference that was estimated is a mean value because it can fluctuate during the hydrological year, reaching values that are higher and lower than the mean value.