Geohydrological testing for reservoir competency at the Kopili Hydroelectric Project in north-eastern India

  • Gangopadhyay S. 
International Symposium Soil and Rock Investigation by In Situ Testing Thème 3 Hydraulical and Hydrogeological Testing, to Determine the Permeability of the Pores or Transmissivity of the Fractures


Extensive areas of the reservoir of the Kopili Hydroelectric Project of north-eastern India are occupied by karstic limestone having numerous sinkholes and solution channels. Geohydrological tests were carried out to find whether the cavernous limestone is competent enough to hold water under reservoir conditions. Tracer tests conducted by using chemicals and fluorescence dyes gave positive results in many cases to prove short distance (up to 1 km) interconnection of subsurface solution channels. Further tests by environmental tritium and artificially injected tritium-loaded heavy water into groundwater through drill holes provided important data on the nature of subsurface flow.

Water-balance tests in selected sections of the Kopili river within the reservoir area and small streams flowing through the limestone terrain of the lower valleys indicated unaccounted flow or escape of water through the subsurface water regime in limestone. Certain other tests conducted in the area include measurement of the piezometric heads, recording of the dispersal rates of water by pumping coloured water through the drill holes and temperature logging at different depths of limestone. The results obtained from all these tests were of immense help in understanding the surface condition of limestone with respect to the water-tightness of the reservoir.


Tritium Drill Hole Chloride Content Tracer Test Potassium Dichromate 

Essais hydrogeologiques realises au barrage de Kopili (Inde)


D'importantes zones du réservoir du barrage hydroélectrique de Kopili dans le N.E. de l'Inde comportent des karst. Des essais hydrogéologiques ont été réalisés pour étudier l'étanchéité du réservoir. L'usage de traceurs chimiques a mis en évidence de courtes distances d'interconnexion des chenaux souterrains. Des résultats importants ont également été obtenus grâce au tritium naturel ou aux traçages au tritium artificiel.

Complétées par des jaugeages en rivière, des mesures piézométriques, des mesures de température á différentes profondeur du calcaire, ces investigations ont été d'un grand secours pour la compréhension des conditions du sous-sol et des relations entre la présence d'un réservoir et le substratum calcaire.


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Copyright information

© International Association of Engineering Geology 1982

Authors and Affiliations

  • Gangopadhyay S. 
    • 1
  1. 1.Geological Survey of IndiaIndia

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