Inferring Ground Water Flow in Fractured Rock from Dissolved Radon

Ground water radon concentrations have been measured in nested piezometers and an open borehole in fractured, metasedimentary aquifers in the Clare Valley, South Australia. The vertical radon concentration profile within the undisturbed, open borehole appears to indicate the locations of hydraulically active fractures. If radon concentrations within the aquifer are uniform, then the highest radon concentration within the borehole will indicate the location of the highest flow rate into the bore. In relatively short screened piezometers, radon concentrations have been measured both before and after purging. The ratio of radon concentration before to after purging normalizes for variations in aquifer mineralogy, and can be used to quantify the ground water flow rate.

[1]  R. Wanty,et al.  Controls on 222rn variations in a fractured crystalline rock aquifer evaluated using aquifer tests and geophysical logging , 1996 .

[2]  P. Mulholland,et al.  Use of radon-222 and calcium as tracers in a three-end-member mixing model for streamflow generation on the West Fork of Walker Branch Watershed , 1993 .

[3]  D. Hammond,et al.  222Rn concentrations in deep formation waters and the geohydrology of the Cajon Pass Borehole , 1988 .

[4]  R. Ritzi,et al.  The Correlation Between Bedrock Uranium and Dissolved Radon in Ground Water of a Fractured Carbonate Aquifer in Southwestern Ohio , 1995 .

[5]  J. Logan,et al.  Boundary Conditions for Convergent Radial Tracer Tests and Effect of Well Bore Mixing Volume , 1996 .

[6]  Dietmar Klotz,et al.  Point dilution methods of investigating ground water flow by means of radioisotopes , 1968 .

[7]  P. Nelson,et al.  Transport of radon in flowing boreholes at Stripa, Sweden , 1983 .

[8]  E. P. Lawrence,et al.  Geohydrologic, geochemical, and geologic controls on the occurrence of radon in ground water near Conifer, Colorado, USA , 1991 .

[9]  K. Ellins,et al.  Using 222Rn to examine groundwater/surface discharge interaction in the Rio Grande de Manati, Puerto Rico , 1990 .

[10]  R. Morin,et al.  Fractured‐Aquifer Hydrogeology from Geophysical Logs; The Passaic Formation, New Jersey , 1997 .

[11]  A. Jessop,et al.  The effect of a fluid-filled fracture on the temperature profile in a borehole , 1981 .