Estimation of Hydraulic Conductivity Variations within Glacial Sediments at Endelave Island by Borehole NMR Data

Geological models and hydrological data serve as fundamental inputs for hydrogeological modelling assessments. In this context, slug tests are commonly employed to acquire hydrological properties of soils. However, in studying complex hydrogeological systems, obtaining enough hydraulic conductivity measurements in multiple depth intervals pose challenges. To address this challenge on Endelave Island, we utilized Borehole Nuclear Magnetic Resonance (BNMR) geophysical methods to indirectly obtain high resolution (10s of centimeters scale) hydraulic conductivity values.

Additionally, we conducted slug test measurements to ensure consistency between the estimations and real hydrological properties of soil. The geological units encountered in the boreholes comprise a sequence of glacial sediments, including clay, till, and sand, deposited within a buried valley. BNMR data successfully differentiated between sandy geological units and till or clayey units. We also observed that BNMR data can reflect changes in sorting and grain size within these geological units, as these factors significantly influence pore size distribution. Moreover, the analysis revealed the effectiveness of the BNMR technique for predicting hydraulic conductivity in glacial sediments.