Connection between electrical resistivity and the hydraulic conductivity Ima Grabowski
Connection between electrical resistivity and the hydraulic conductivity Basic data from Föhr west and east water works with about 138 drilling profiles and resistivity logs. Graph. 1: Drillsites Föhr west Graph. 2: Drillsites Föhr east
We further used the SKY TEM model from the island Föhr from 2008 The resistivities clearly show a rough north/south seperation at a depth of -20 to -30m
We further used the SKY TEM model from the island Föhr from 2008 The resistivities clearly show a rough north/south seperation at a depth of -20 to -30m Northern Marschland Shows strong low Ohmic properties: High holocene clay content? Or Salt water intrusion? South west & east Is old Morain area with basicaly fresh water aquiveres
Is there a coherency between hydraulic conductivity and resistivity? 1 2 3 4 5 Klasse T T,u/U,t U T/U,fs U,t,s,g RES 69.1863636 51.8398058 48.0433333 47.7923077 49.6385714 Kf 1E-09 0.00000001 0.0000003 0.000003 0.000005 Statistic frame work with the data set from the water works with ~ 138 drill sites and a classification Of 18 classes of the most common Soil and their Kf-values 6 U,s,g 60.9444444 0.00001 7 fs,u 219.0575 0.00003 9 fs 160.316087 0.0001 10 f-ms 202.863964 0.0002 11 ms 183.467614 0.0005 12 f-gs 278.323684 0.0003 14 m-gs 265.742667 0.0007 15 m-gs,g 256.856098 0.0007 16 gs 269.653333 0.001 17 G,s 413.95 0.0005
One example of first modus operandi, a borehole profile and log with estimated Kf-values: Kf [m/s] 5 x 10-4 3 x 10-6
The mean of each of this 18 classes was taken and plotted against the Kf-values logarithmically scaled RES GN / Kf y = 41.93Ln(x) + 585.02 R 2 = 0.4746 RES 650 600 550 500 450 400 350 300 250 200 150 100 50 0 0.00001 0.0001 0.001 0.01 0.1 1 10 Kf And we do have a correlation here
Ima`s Area Island Föhr Jenni`s area (Jennifer Klimke, 2011; Kompilation eines widerspruchsfreien geologisch geophysikalischen Modells für den Bereich der Grundwasserversalzungszone Quakenbrück in Niedersachsen. )
Comparison with Jenni`s work: Same statistic principal of classification at a study area in Niedersachsen We received a quite similar correlation of the two data sets! Imas & Jennis RES Werte Reihe1 Reihe2 450 400 350 300 Ohmm 250 200 150 100 50 0 1E-09 1E-08 1E-07 0.000001 0.00001 0.0001 0.001 0.01 0.1 1 Kf-Werte Jenni Klimke, 2011
taking an even closer look Archie: ρ Positive correlation: Resistivity and Kf AQUIFER 0,4 0,3 = ρ φ GROUNDWATER a φ m ρ Groundwater a= 1 m = 1.3 = 25Ωm [Ωm] 300 250 200 Negative correlation : Porosity and Kf 0,2 0,1 150 100 Kf
We need to distinguish between: φ φ and total eff K f [ m/ s]
We are probably dealing with φ total in our statistic because we have the the positive correlation of Kf and resistivity but the negative correlation of Kf and porosity due to the fact that the geo-electrical Measurement is influenced by the total porosity and not by the effective porosity
But the statistics delivered us a regression equation G / witch enabled us to Build an iso-line plot of the study area Föhr. y = 41.93Ln(x) + 585.02 R 2 = 0.4746 6068000 6066000 6064000-4 6062000 3462000 3464000 3466000 3468000 3470000 3472000
Conclusion: we managed to create an iso-line plot of Kf-values of our study area The more differentiated distribution of Kf-values in the subsurface could be used As input data in modelling -4
Conclusion Steps of process Borehole profiles Water works Föhr RES Petrography Kf estimated Classification 18 soil classes RES/Kf plotts Regression line & equation Transposing to x & feeding with SKY TEM data Surfer & GIS plott