Innovative Hydrogeophysical Approaches as Aids to Assess Hungarian Groundwater Bodies

Abstract

The Hungarian water management plan has lately identified 185 groundwater bodies based on the concepts given by the European Water Framework Directive. Achieving and maintaining the good quantitative and chemical status of these groundwater bodies is of primary importance. It is demonstrated how innovative hydrogeophysical methods can be applied successfully to assess the Hungarian or other international groundwater bodies. By applying geoelectric methods, horizontal layering or large uniform rock units can be well characterized by Wenner–Schlumberger array, also enabling accurate depth determination of the shallow groundwater table. Horizontal variations in the rock type or its state can be well described by dipole–dipole array or, even better, by the newly developed quasi-null arrays. Their joint application may be very straightforward to investigate different aquifer types by giving high-resolution resistivity images as input for hydrogeological modeling. In the identification of porous formations, multivariate statistical interpretation of wireline logs using cluster analysis allows reliable lithological separation of potential aquifers. Their clay content is estimated by robust factor analysis, while their hydraulic properties are directly derived from the resistivity log. For a more effective interpretation, a combination of surface and borehole geophysical methods can be recommended for meeting challenges in hydrogeology and groundwater management.

Assessing heterogeneous groundwater systems: Geostatistical interpretation of well logging data for estimating essential hydrogeological parameters

“…The observations have unveiled the existence of two distinct hydraulic systems in the study area. In the upper system, groundwater flow is predominantly governed by gravitational forces, while the lower system experiences overpressure 10 . Hydraulic interaction between these two systems frequently occurs, particularly in areas where low-permeability layers exert outward pressure 52 .…”

“…Traditional geological and hydrogeological methods can provide valuable insights, but they often fall short of capturing the full lithological variability within the aquifers 7 – 9 . On the other hand, Geophysical well logging offers a unique opportunity to attain a more comprehensive understanding of the aquifer system as it gives a continuous estimation of the aquifer characteristics 10 – 13 . The petrophysical and hydraulic parameters can be obtained by analyzing well-logging data using deterministic and inverse modeling 14 – 17 .…”

Meta-algorithm assisted interval inversion for petrophysical properties prediction

“…To formalize the interval inversion in the layer-wise homogeneous layers sequence model can be represented using the step function or the Heaviside function. The Heaviside function divides the model into homogeneous segments (Szabó, 2018b;Szűcs et al, 2021), and (Dobróka et al, 2009). The layerwise interval inversion can be expressed as:…”

“…The stable data distance of the conventional interval inversion and the GSS-based interval inversion is around 9.75%. Figure (13) shows the difference between the data distance behavior in the case of the conventional interval inversion and the GSS-based interval inversion. The stopping criterion of the algorithms is a threshold number of iterations, which have been chosen to be 60 iterations.…”

Investigation of petrophysical and hydrogeological parameters of the transboundary Nubian Aquifer system using geophysical methods

“…VES is the most popular resistivity technique for defining potential groundwater zones and calculating hydraulic parameters such as transmissivity and hydraulic conductivity (Arétouyap et al, 2019;Mohammed et al, 2023e;Omeiza et al, 2023). This technique was efficiently used to quickly and affordably determine the depth of the water table, aquifer thickness, and vertical and horizontal geological variation (Szűcs et al, 2021).…”