Determination of the Flow Direction of Geothermal Waters at Manikaran using the Borehole Tracer Technique

Borehole tracer studies were carried out to determine the direction of flow of thermal waters in Manikharn hot-springs area. Inactive potassium iodide and radioactive bromine-82 were injected in one deep geothermal well (DGW) and tritium and bromine-82 were injected in another deep geothermal well on March 31 and April 1, 1984 respectively. Several wells and springs were monitored for a few days in the field itself for bromine-82 activity and samples collected from hot springs and wells over a period of three months were analysed in the laboratory for tritium and iodide. The results show a steeply high value for tritium in the sample collected on 6.4.1984 from a well located 350 m due south of the injection well and on the opposite bank of Parvati river. No significant concentration of iodide and Br-82 nor any discernible trend in their distribution was shown by any of the samples. Results of the multiple tracer injection study favour the model advocating movement of geothermal water from North to South. The velocity of flow through fractured and jointed quartzites was calculated as about 72 m/day.