Geophysical Assessment of Unsaturated Hydraulic Conductivities – Examples from the CLIWAT Project Area Föhr

A geophysical approach for an assessment of hydraulic conductivities based on geophysical measurements is presented. It is based on the van Genuchten (1980) relation between the relative hydraulic conductivity and the saturation degree of the unsaturated zone. For the determination of the porosity we make use of Gassmanns equation linking the saturated and the unsaturated porosity. If we use seismic p-wave velocities instead of bulk moduli, the influence of the unknown shear wave velocity is small and can be neglected. For the determination of water content of the unsaturated zone GPR measurements are used. It is shown that the irreversible pore water of the sediment can lead to an overestimation of the water content, especially if the sediment is poorly sorted.