Bohrlochgeophysikalische Messung der Grundwasserbewegung bei minimaler Störung des natürlichen Strömungsfeldes

The quantification of groundwater flow behaviour is an important issue in the fields of groundwater and environmental protection as well as in the field of construction engineering. In this context, knowledge of the parameters of the groundwater flow field is critical for the evaluation of flow patterns, for the definition of water protection areas and drainage activities, and for the assessment of risk potential. It is also fundamental for modelling and monitoring purposes. This paper presents a new single-well borehole measurement system for the investigation of groundwater flow directions and velocity. It can be used to measure velocities greater than 0.5 m/d. The measuring principle is based on the creation of a defined tracer signal within the well screen of a monitoring well and observation of the time-dependent change of the tracer-induced conductivity and temperature anomalies in the near and far field. To measure these two parameters, geoelectrical arrays and temperature sensors are used. A new technique was developed that creates a homogeneous tracer distribution in the annulus between the probe and casing, with only minimal disturbance of the natural flow field. The tracer density is adapted to the groundwater and thus avoids density driven convective processes