## 5 Discussion
Results obtained with the 3D ERTs show how important it is to define the best electrode setting; therefore, the simulated approaches in full-scale laboratory experiments help to evaluate the best solution for each kind of detection aims. In our experiments, the results highlight the capability of the loop-loop array to detect the structures buried in the subsoil is greater than the classical dipolar approach. Therefore, these results show the potentiality of this approach for the investigation in areas where obstacles can reduce the possibility to perform electrical analyses with 2D and 3D ERTs based on conventional approaches. Moreover, 2D ERTs acquired with electrodes located on the water surface show that the high conductive environment and the depth of investigation of the methodology do not allow to easily identify the buried structures. On the contrary, the use of floor embedded electrodes allows to improve the depth of investigation for supporting the detection of the buried structures. Therefore, 2D ERTs can be a suitable contribution for the shallower structures, but the limitations mainly related to the problem of resolution at depth require further efforts to apply in contexts similar to the analyzed ones. In order to overcome the limits of the single methodology used, the best approach is the integration of electrical resistivity and GPR data. In detail, through a simplified geophysical integration of the GPR and ERT 3D data, based on the model co-rendered image process [101], the integration of the methodologies provides good information for  
Figure 16: Frequency spectra of the mean trace related to the radargram acquired in S2 for WL3 (**a**), WL2 (**b**), and WL1 (**c**). the localization of the archaeological buried remains as shown in Figure 17. 3D ERTs have provided acceptable results only in the drier conditions (WL2 and WL3). The cause is due to the low resolution of the method when the water table was shallower (WL1) and the electrical contrasts were weak. However, the strong reflections are generally correspondent to the higher electrical anomalies, and where one of the two methodology struggles, the other one can support the detection of the structure. This is the case of the capuchin tomb (F), which is not clearly detectable by the GPR data due to its orientation with respect to the acquisition direction, whereas ERT data clearly identify the presence of a strong electrical anomaly where the tomb is expected. On the contrary, the rectangular tomb (B) is well detectable with the GPR, while it is not visible for the ERT because its position too marginal within the acquisition scheme. Moreover, GPR radargrams and ERTs acquired along S1 and S2 during WP2 (underwater conditions) are model co-rendered and the results are plotted in Figure 18. The first level of integration highlights the capability of both the methods to detect electric and em anomalies in correspondence of the buried structures despite the different resolution. Generally, the presence of strong reflections implies anomalies of the electrical behaviour of the subsoil related to the presence of archaeological remains. The results are in good agreement, especially in the upper layer where the ERTs, acquired with the electrodes fixed into the floor, have the better resolution and all the structures are distinguishable. A further quantitative consideration can be realized comparing the geophysical detected anomalies both with the GPR and the ERTs with the real sizes and depths of the various objects buried in the subsoil. As previously shown, the used geophysical methods were able to detect the buried structures and the GPR was the best one in the different scenarios.