# Innovative Hydrogeophysical Approaches as Aids to Assess Hungarian Groundwater Bodies
## 4 Discussion and Conclusions  
In this paper, advanced surface geophysical and well-logging techniques were presented as effective tools to solve hydrogeological and groundwater management problems. It was shown that these techniques could give more detailed images and petrophysical characterization about the subsurface than traditional techniques. Detection and characterization of faults, fractures and fracture zones were demonstrated in the case of studies in Hungary (and India). In order to understand hydrogeological processes in Hungarian groundwater bodies, it is essential to see such features well and determine the petrophysical properties of the hosting formations. In Sopron, West Hungary, in studying a step-like structure, the joint application of the Dp and the newly developed \(\gamma_{11\text{n}}\) arrays seemed to be an optimal choice. Their joint interpretation enabled the determination of all important details, that is, the number, position, width and depth of the steps and the fracture zones. In Kadarta, North-West Hungary, the WS array displayed a fault in the dolomite basement; the \(\gamma_{11\text{n}}\) arrays enabled its accurate localization and the detection of the most-likely water-rich fracture zone. While the WS array gave a robust image of the subsurface, the \(\gamma_{11\text{n}}\) arrays could enrich it by separating two anomalies and by delineating more accurately the most fractured zone. In  
Figure 14: Result of multivariate statistical analysis of wireline logs in Baktalórántháżza-1 well in Baktalórántháza-1 well, northeast Hungary. the Indian example, the set of Dp ERT, \(\gamma_{116}\) ERT and the \(\gamma_{116}\) shallowest profile enabled the delineation of a fault fracture zone accurately and the localization of two other significant fractures. Furthermore, the water-bearing zones could be well described by this set of methods. The members of this set complete and verify each other's results well. Conclusions of precedent numerical and analog studies--according to which the choice of two \(\gamma_{11n}\) arrays between whose \(n\) values the difference is two or three is optimal--were verified by field studies in the Sopron (Section 3.1.1) and Kadarta (Section 3.1.2) study sites. Thus, e.g., the application of the \(\gamma_{112}\) and \(\gamma_{114}\), or \(\gamma_{112}\) and \(\gamma_{115}\), or \(\gamma_{113}\) and \(\gamma_{115}\) arrays is recommended in field studies. The application of only two \(\gamma_{11n}\) arrays completed with the Dp array is very economic, and it seems to be the best solution to follow horizontal resistivity variations. Although the joint application of traditional-, and \(\gamma_{11n}\) geoelectric arrays was presented in Hungarian examples, this set is applicable anywhere independently on the geomorphology conditions. Local climatic conditions may, however, severely influence the results. Fracture zones and especially narrow individual fractures may easily become \"invisible\" for this method if their water-saturation is not very high or low, thus not providing sufficient difference in the electrical resistivity between them and the host. In such a situation, the choice of the date of the measurement may become extremely important. The time and quantity of the last precipitation and infiltration rate must be taken into account to get the best possible results. In small-scale studies, especially if displaying lateral variations is required, application of the presented \(\gamma_{11n}\) arrays together with the traditional Dp array seems to be the best geophysical method. GPR, VLF and seismic studies did not prove to be successful in the study sites. The Dp array moreover gives a robust image, which can further be refined using \(\gamma_{11n}\) arrays. In Baktaloranthaza, northeast Hungary, multivariate statistical interpretation of wire-line logs using robust cluster analysis allowed a reliable lithological separation of potential aquifers.