Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

R. N. Athavale ¹, R. Rangarajan ¹, D. Muralidharan ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad, 500 007, IN

Abstract

The broad pattern, emerging from recharge measurements in various basins ranging in area from few tens to few thousands of square km indicates an annual input of about 16% (or 100 mm) of the precipitation in the Indo-Gangetic alluvial tract and about 8% (or 60 mm) ofthe precipitation in the Peninsular hard-rock areas. The Tritium recharge measurements are compared with those obtained by using hydro-meteorological and hydrogeological methods. The relation between recharge values and water level fluctuations in open wells is studied and regression plots showing dependence of recharge rate on rainfall over granitic, basaltic, sedimentary and alluvial provinces are presented. Data on temporal variation in recharge due to variation in rainfall over three hydrological cycles in a granitic watershed in the semi-arid area is presented. The utility of such studies in prediction of recharge from rainfall data is illustrated.

Keywords

Hydrogeology, Groundwater, Rainfall, Recharge, Tritium.

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R. N. Athavale ¹, R. Rangarajan ¹, S. M. Rao ²

Affiliations
1 Geohydrology Group, National Geophysical Research Institute, Hyderabad, IN
2 Isotope Division, Bhabha Atomic Research Centre, Bombay, IN

Abstract

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.

Keywords

Geothermal Waters, Tracer Technique, Manikaran, Himachal Pradesh.

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S. Chandra ¹, S. Atal ¹, N. S. Krishnamurthy ¹, k. Subrahmanyam ¹, R. Rangarajan ¹, D. V. Reddy ¹, P. Nagbhushanam ¹, J. V. S. Murthy ¹, S. Ahmed ¹, V. P. Dimri ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad - 500 007, IN

Abstract

No Abstract.

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D. Muralidharan ¹, R. Rangarajan ¹, G. K. Hodlur ¹, U. Sathyanarayana ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad - 500 007, IN

Abstract

A research study has been carrted out to evaluate the economically viable depth of desiltation in old tanks to achieve a substantial increase in percolation and storage Two tanks -an old minor irrigation tank and a newly constructed percolation tank were selected in a granite terrain and infiltration studies were carried out with different thickness of silt removal Tritium tracer studies were coupled with the infiltration studies to follow the infiltrated water and evaluate the effectiveness of silt removal in percolation The study lndicated that in the case of irrigation tank, a steady state infiltration rate of 67 mm/h has increased to 350 mm/h with the removal of 65 cm silt showing a six-fold increase in infiltration rate Infiltration rate was found to be reducing by removal of 25 vm and 50 cm silt and the analysis of soil fraction indicated presence of clay at these depths The study at percolation tank indicated that the infiltration rate of 10-20 mm/h has increased to a maximum of 310 mm/h with removal of 40 cm silt The tritium tracer migration study supported a faster movement of percolated water at desilted sites by showing a greater dilution of tracer concentration and deeper penetration The research study strongly supports a necessity of carrying out infiltration studies at different places within the tank bed area with removal of varying thickness of silt to decide the optimal level of desiltation especially in old tanks before commencing revival of tank system.

Keywords

Tanks, lnfiltration rate, Optimal desilting, Percolation efficiency, Anantapur District, Andhra Pradesh.

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D. V. Reddy ¹, R. Rangarajan ¹, Simanchal Padhy ¹, G. B. K. Shankar ¹, G. Rajender Reddy ¹

Affiliations
1 NGRI, Hyderabad, IN

Abstract

No Abstract.

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