Vízügyi Közlemények, 2000 (82. évfolyam)

2. füzet - Ujfaludi László: Felszín alatti víztartók szivárgási együtthatójának becslése elektromos mérések alapján

Felszín alatti víztartók szivárgási együtthatójának becslése elektromos mérések alapján 3 321 Masac, O-Kelly, W. E.-Landa, /.: A Hydrogeophysical Model for Relations Between Electrical and Hydraulic Properties of Aquifers. Jour. Hydrology, Vol. 79. 1985. Nagyistók, F.: Az elektromos fajlagos ellenállás és a rétegvíz sótartalma közötti összefüggés. Hozzászólás Gálfi j. és Liebe P. cikkéhez. Víz. Közi. V. 64/2. 1982. Pfannkuch, H. O.: On the Correlation of Electrical Conductivity Properties of Porous Systems with Viscous Flow Transport Coefficients. 1

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t. International Symposium on the Fundamentals of Transport Phenomena in Porous Media, IAHS, Haifa. 1969. Rajkai, К.: A talajfelszín nedvességtartalmának mérése TDR-módszerrel. Hidr. Közi. V. 71/1. 1991. Robinson. D. A.-Gardner, С. M. K.-Cooper, J. D:. Measurement of relative permittivity in sandy soils using TDR, capacitance and theta probes: comparison, including the effect of bulk soil electrical conductivity. Jour. Hydrology 223. 1999. Shaw, D.J:. Bevezetés a kolloid- és felületi kémiába. Műszaki Könyvkiadó, Budapest. 1980. Ujjáludi, L.\ Formation factor vs hydraulic conductivity. Interpretation of trends and conditions of field application. Proceedings of the international conference on groundwater research, Copenhagen, Danmark. 2000. Urish, D.W.-, Electrical Resistivity - Hydraulic Conductivity Relationships in Glacial Outwash Aquifers. Water Resour. Res. Vol. 17. No. 5. 1981. * * * Estimation of the hydraulic conductivity of aquifers on the basis of electrical measurements by Dr. László UJFALUDY Cand. ofTechn. Sc. physicist In searching the relationship between the electrical and hydraulic parameters our objective was to determine whether the hydraulic conductivity К can be estimated on the basis of electrical parameters, or not. The present practice is that empirical relationships are established between the field data of the formation factor F and the hydraulic conductivity K. The validity of such relationship is, however, restricted to a given geological formation. Some empirical relationships, published earlier, are shown in Figure 1. The model of Pfannkuch offers, presumably, a better approach. It gives a physically based relationship between formation factors F

a and F

u the hydraulic conductivity of the fluid k, the surface conductance ks and the specific surface area S

p (Equation 18). The coefficient of hydraulic conductivity К can be derived from the value S

p of the specific surface, using Equation 5, while parameter ks can be estimated using the Bikerman model (Equations 10., 11 ), if certain electrical parameters are known. The validity of this model was examined through the results of earlier field measurements, published in the literature, and by using the results of a series of our own laboratory measurements. Hydraulic and electrical measurements were performed with different sand and glassbead samples. Some parameters of these tests are summarised in tables 1. and 2. Relationships K= f(F) obtained on the basis of experimental results are shown in Figure 4. Qualitative analysis of the data showed that empirical field trends (direct or inverted relationships) of the function K= f[F) are well reproduced by the model. This trend is also correlated with the sample porosity n, as it is also included in the modified version of the Pfannkuch's equation (Equation 24). Beta-potentials, derived with the assumption of £ = 81 on the basis of the measurement data of Abura and Clyde, are shown in Figure 5. The quantitative analysis, on the other hand, showed that the key parameter of the model (through the Bikerman equation) is the permittivity e of the saturated sample. Values of e deduced from laboratory measurements vary with the grain size and the fluid's conductivity