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RESISTIVITY

Vinit C. Erram, Gautam Gupta and Saumen maiti

 

Introduction:-

The problem of water scarcity is very acute in Maharashtra. Observations indicate that wells in the basaltic aquifers with poor potential have gone dry due to over-exploitation. On the contrary, the wells located on dykes are found to be yielding sufficient groundwater. However, there is hardly any information available on the role of dykes in the hydrogeological set up as well as their role in the occurrence and movement of groundwater. The present studies aims at understanding the feasibility of applying resistivity and ground magnetic methods for detecting the carrier and barrier stretches of dykes and identify their role in hydrogeological framework of Maharashtra.

Water resources in coastal regions of Maharashtra and Goa assume a special significance because of rapid strides in developmental activities thereby depleting the available ground water. The ingress of saline water through inland drains due to tidal influence makes the potable water unfit for consumption. Geoelectrical studies in such areas will be helpful in locating fresh groundwater pockets to meet the water demands of society.

This group is actively involved in identifying potential groundwater zones in the hard rock terrains of Deccan Volcanic Province using electrical resistivity technique. This is also complemented by the bore hole, dug hole lithology and ground magnetic data. The instrument used is SSR-MP-AT Resistivity meter.

 

 

Scientific achievements:

Potential groundwater zones in parts of Dhule District, Maharashtra: A joint interpretation based on Resistivity and Magnetic data, J. Ind. Geol. Congress, 2(1), 37-45, 2010.

Vinit C. Erram, Gautam Gupta, J.B. Pawar, Suyash Kumar and N.J. Pawar

The structural discontinuities that exist in the hard terrain of Dhule in Maharashtra could be potential zones for ground water occurrences. Attempts are made to delineate the carrier and barrier stretches within the dykes, the depth to which these dykes holds potential to amass ground water and subsequent transmission. An integrated study using vertical resistivity sounding (VES) and ground magnetic data has been carried out in this region to understand the aquifer system and the movement of ground water flow in the Panjhara watershed. The longitudinal resistivity profiles along with the magnetic anomaly maps show a broad match with the magnetic high and lows thus indicating the presence of carrier and barrier stretches along the dykes D1 and D9.

Work in progress:

A. Resistivity soundings were conducted from Guhagar to Patan, Maharashtra during December 2008 and March 2009. A total of 50 VES soundings were taken during the surveys. The aim of this study is to delineate the potential groundwater bearing zones and to understand the shallow surface tectonic in these regions. Magnetic total field data at 110 points were also collected over the Guhagar-Chiplun-Koyna-Patan regions of Maharashtra with a view to construct a composite magnetic anomaly map of this region.

B. Pre monsoon VES data and close grid magnetic data were acquired over the lineaments of west coast region from Devrukh to Ganapatipule during April 2009 in order to observe the influence of lineaments on ground water flow in hard rock terrain. The post monsoon studies will be conducted over these profiles during November 2009.

C. A total of five resistivity soundings were carried out over three geothermal springs and its vicinity in west coast of Maharashtra along with very closed grid (2 metres) magnetic studies. It is envisaged that these studies will elucidate the geothermal resources and structural settings of the area.

D. During the Total solar eclipse of July 22, 2009, a network of three stations (Warna, Solapur and Killari) was surveyed with resistivity soundings for a period of five days. These studies may throw light on crustal movements in seismogenic regions (if any) and the nature of the water table before, during and after the eclipse

E. VES studies and close grid magnetic data has been acquired over the lineaments of west coast region from Sakharpa to Ratnagiri to identify the occurrence and movement of groundwater and to correlate the electrical resistivity with lineament and fracture pattern.

Some Field Photographs:

 
 
 

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