Geophysical characterization of groundwater protective layers

To enable an effectice proteetion of near surface groundwater reservoirs against pollution from agriculture, industry or waste disposals the protective qualities of the unsaturated layers on top of the aquifer must be quantified. On that basis the risk of groundwater contamination can be mapped and endangered regions can be protected be governmental regulations. A mean for the protective qualities can be the percolation time from the surface to the groundwater saturated zone. While groundwater is moving through the unsaturated layer the concentration of contaminants is reduced by biological and chemical processes. These processes are time consuming, and as a rule of thumb a percolation time of at least 10 years can offer an effective proteetion of our groundwater resources.