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Geophysical techniques are normally employed to explore the subsurface and determine the anomalies but they are always much larger in dimension. However, a very precise measurement was needed to pin point a misaligned horizontal tunnel made at 47 m depth to intercept an old bore well and rescue a four year child fallen accidently on 9th November at Jagatpura village in Jaipur, India. Due to the greater depth and presence of iron casing, electric power, etc., no equipment could work to determine the orientation of the tunnel that has lost its direction. The dimension of the site and many other constrains didn't allow conventional geophysical methods to be used. An innovative method was then designed and successfully applied, which determined 1.92 m deviation of the tunnel end point to the east from the old bore well. The digging was redirected accordingly and the bore well was intercepted. This paper describes the theoretical background, forward simulations and the field experiment of the newly designed geophysical method. Copyright 2012 Geological Society of India

Today’s dual contamination (water–rock interaction and anthropogenic impact) in groundwater system is a common problem worldwide. Abundant amount of work has been carried out to assess groundwater quality; however, a very limited work is released towards delineation of fluoride zones by water–rock interaction (WRI) and anthropogenic causes.For this reason, groundwater contamination problem has been taken up in a rural granitic hydrogeological setting of Andhra Pradesh, India. Agricultural activity, brick kiln factory and chicken farms are common anthropogenic sources available in the study area. A total of 53 groundwater and rainwater samples for monsoon months of the year 2006 have been collected and analysed. At various stages, corrections have been applied using chloride concentration limit (CCL) of 20 mg/l and fluoride concentration limit (FCL) of 1.88 mg/l. The results have proved that the dominant fluoride released by WRI action and anthropogenic action cover 15.1 and 21.7% area of the watershed, respectively. Also, present mixed state (WRI and anthropogenic causes) of groundwater quality covers the major portion of the watershed.The results of these corrections have successfully discriminated groundwater samples based on present chemical constituents. Such studies are useful for creating awareness and planning remedial measures in contaminant watershed.