The exchange of groundwater-surface water has been invetigated in the western part of Denmark. Holtum AA provides the framework for all the performed investigations. Several methods are used, primarily eld based measurements ombined with numerical models to achieve insight to the governing processes of interaction between groundwater and surface water. By using heat as a tracer it has been possible to use temperature directly as calibrationtargets in a groundwater and heat transport model. Thus, it is possible to use heat investigate the change in groundwater discharge in dynamic conditions relatered to rainfall-runo events. By combining geochemical, geophysical and hydrogeological models with numerical modeling, groundwater flow paths to a stream were investigated in a wetland. By combining the dierent tracers, condence in the paramters of the numerical model could be established and geochemical patterns were interpreted. The strength of the approach using mulitiple tracers was obvious since the deduced flow paths could not have been established from a single tracer alone.
The combination of groundwater age traces (CFCs) with streamflow accretion was used to constrain a groundwater stream flow model at catcment scale. However, this was not possible since the model did not simulate observed stream flow accretion and therby simulating groundwater ages that were not comparable with calculated CFC ages. The errors are likely related to the fact that the measured streamflow accretion dis not represent steady-state conditions. However, the hypothesis could still be tested with a more robust data set of flow accretion and potentially oer an alternative tool for constraining groundwater flow model where the focus is on GW{SW exchange.
Further investigations at the catchment scale was carried out by using simple temperature devices along a stream to delineate the areas of interest in regard to GW{SW exchange. Thus, at several locations in a stream a temperature data logger was placed in the water column and right at the streambed-water interface. By looking at the correlation of streambed/stream temperature with air temperatures areas of enhanced groundwater discharge were identified.