TY - BOOK

T1 - Hydrogeophysical investigations of unsaturated flow and transport

AU - Haarder, Eline Bojsen

N1 - Mundtligt forsvar af ph.d.-afhandlingen fandt sted 23. juli 2014

PY - 2014/5/30

Y1 - 2014/5/30

N2 - The objectives of the Phd-study are to investigate unsaturated flow and transport processes using hydrogeophysical methods. Experiments were carried out at three different field sites in Denmark, which are all characterized by thick unsaturated zones that consist almost entirely of sand. Results and observations from the sites are therefore comparable and can also be extended to other areas with similar geological settings. The first field experiment was a dye tracer infiltration, which was monitored using reflection ground penetrating radar (GPR). It was found that the water had infiltrated in a highly irregular manner, and the GPR data showed that moisture content had increased well below the extent of the dye staining. Second, we carried out a point injection of water, during which we monitored the moisture content development using two- and three-dimensional cross-borehole GPR and three-dimensional cross-borehole electrical resistivity tomography (ERT). In another experiment GPR and microgravimetry measurements were used for monitoring the moisture content changes arising from a forced infiltration of water across a large area. Results from both of these experiments showed that small changes in grain size and sorting degree of the sand were responsible for initiating heterogeneous development of the injected tracer plume as well as the irregular moisture content development caused by the forced infiltration. In the final experiment, cross-borehole ERT data were used for estimation of natural recharge based on long-term monitoring of the movement of a saline tracer. Comparison of ERT data samples obtained from core drilling at the same site revealed that the position of the plume with time was well-resolved in the ERT data. Further, the final recharge estimate was in agreement with lysimeter drainage data from the same site.

AB - The objectives of the Phd-study are to investigate unsaturated flow and transport processes using hydrogeophysical methods. Experiments were carried out at three different field sites in Denmark, which are all characterized by thick unsaturated zones that consist almost entirely of sand. Results and observations from the sites are therefore comparable and can also be extended to other areas with similar geological settings. The first field experiment was a dye tracer infiltration, which was monitored using reflection ground penetrating radar (GPR). It was found that the water had infiltrated in a highly irregular manner, and the GPR data showed that moisture content had increased well below the extent of the dye staining. Second, we carried out a point injection of water, during which we monitored the moisture content development using two- and three-dimensional cross-borehole GPR and three-dimensional cross-borehole electrical resistivity tomography (ERT). In another experiment GPR and microgravimetry measurements were used for monitoring the moisture content changes arising from a forced infiltration of water across a large area. Results from both of these experiments showed that small changes in grain size and sorting degree of the sand were responsible for initiating heterogeneous development of the injected tracer plume as well as the irregular moisture content development caused by the forced infiltration. In the final experiment, cross-borehole ERT data were used for estimation of natural recharge based on long-term monitoring of the movement of a saline tracer. Comparison of ERT data samples obtained from core drilling at the same site revealed that the position of the plume with time was well-resolved in the ERT data. Further, the final recharge estimate was in agreement with lysimeter drainage data from the same site.

UR - https://soeg.kb.dk/permalink/45KBDK_KGL/fbp0ps/alma99121943122005763

M3 - Ph.D. thesis

BT - Hydrogeophysical investigations of unsaturated flow and transport

PB - Department of Geosciences and Natural Resource Management, Faculty of Science, University of Copenhagen

ER -