Helium survey for delineating areas of karst-suffosion processes caused by high-rate groundwater withdrawal

In urban area, groundwater is subjected to many different stresses. One of these, high-rate groundwater withdrawal, contributes to the formation of hydrodynamic, hydrogeochemical, and thermal anomalies within the developed aquifer and to the intensification of karstification and suffosion. (Suffosion refers to undermining through removal of sediment by mechanical and corrosive action of ground-water.) Many different investigative methods or combinations of methods are used to delineate karst zones. Many of these known techniques are labor-consuming, expensive, and inefficient, and are not applicable in urban areas. Under these conditions, a helium survey method may be effectively applied as a viable option to the frequently used techniques. An example of this method for delineation of karst zones in Carboniferous carbonate rocks in an urban area is discussed and the helium survey data are compared with hydrogeochemical, thermodynamic, and tritium survey data.