October, 2009

October, 2009   ||  Volume 13 No.4


Deep Structure of Himalaya

T.S.Balakrishnan1 and P.Unnikrishnan2

1 Formerly with Oil and Natural Gas Corporation Limited.
2 Oil and Natural Gas Corporation Limited, Western Offshore Basin, Priyadarshini,
Eastern Express Highway, Sion, Mumbai – 400 022.
E-mail: ts.balakrishnan@yahoo.com

The Siwaliks of Himachal Pradesh are contained between the MBF on the east and the eastern margin fault of the Marwar Craton. Similarly the NE margin fault of the Aravalli Craton limits the Lr.Tertiary of UP from the MBF of the Kumaon region. This fault proceeds eastwards from Tanakpur as the southern boundary of the Siwalik outcrops of Nepal and Bhutan until it meets the northern promontory of the Shillong mass. Thereafter it proceeds eastwards as the Jorhat fault of Upper Assam. The combined fault from west to east is the northern limit of the Precambrian shield.
A composite NS seismic section from Samastipur in Bihar across Nepal, the Himalaya and S.Tibet upto Tsangpo suture is available (Indepth). Two major deep faults are mapped in this section. The first is near the MBF and the other is at the foot of the Himalayan peaks in Nepal. The former coincides with the northern limit of the Precambrian shield and has a throw of about 30 km. at Moho level. The other fault at the foot of the Himalaya also has a throw of about 30 km. at Moho level. On comparing with the gravity anomaly picture these faults are located in the regions of very high gravity gradients. The western and eastern extensions of the latter can be considered to be corresponding extension of the deep faults.
These faults lie in the subduction zone of the Indian subcontinent below the Himalayan thrusts. It is apparent that in the precollision period they are part of the Indian shield like the Gondwana grabens. Interestingly the Himalayan Gondwanas are located between these fault zones, whether in Kashmir,Nepal or Arunachal Pradesh. The conclusion is that, precollision, the faults form the boundaries of a long Gondwana graben extending from Kashmir to Arunachal Pradesh. This graben limits the Precambrian shield in the north.


Remote sensing in ground water exploration for development of temple tourism in Vemulawada, Karimnagar District, Andhra Pradesh
V.Raghu and M.Venkata Swamy
A.P. State Remote Sensing Applications Centre (APSRAC)
2nd Floor, Directorate of Economics & Statistics (DES) Campus
Khairatabad, Hyderabad – 500 004, Andhra Pradesh
E-mail: raghuvangeepuram@rediffmail.com

Tourism is one of the important economic sectors, which is not flourishing as desired due to acute water shortage and other facilities. Proper management of water resources both on surface and underground is essential in areas important for tourism for the development of that industry. Therefore, an effort has been made to address the problem encountered by assessment, exploration and management of water resources using integrated remote sensing based techniques in a prominent pilgrim centre, Vemulawada in Karimnagar district, Andhra Pradesh. High-resolution IRS-IC merged (PAN+LISS-III) satellite data is used and hydrogeomorphological /ground water prospects map is prepared by visual interpretation techniques. Ground truth information is integrated and final map is prepared to aid in ground water exploration. The entire study area is occupied by pink and grey granites of Archaean age intersected by dolerite dykes. On either sides of Maneru River and Mula vagu, the flood plain consists of unconsolidated sediments like sand, silt and clay. Valley fill along local streams comprises of cobbles, pebbles, gravel, sand and silt of recent age. The water demand vis-à-vis water resources availability is evaluated based on hydrogeological set up and field investigations. Both long and short term solutions are given for water resources development at Vemulawada. As a part of the crisis management, (short term measures) ten bore wells are dug in a valley fill near Vemulawada based on recommendations followed by vertical electrical soundings. The wells have yielded a cumulative discharge of 1300 LPM. With the help of remote sensing technology such value additions can be made to enhance the tourism sector in India.

Selection of groundwater potential zones in and around Madhurawada Dome, Visakhapatnam District - A GIS approach

P.Jagadeeswara Rao, P.Harikrishna1 S.K.Srivastav2, P.V.V.Satyanarayana and B.Vasu Deva Rao3
College of Engineering, Andhra University, Visakhapatnam -530 003
1Rolta India Ltd. Andheri (East), MIDC, Mumbai – 400 093
2Geosciences Division, Indian Institute of Remote Sensing, Dehradun – 248 001
3Shapoorji Pallonji & Co. Ltd. Hyderabad - 500 003
E.mail : pjr_geoin@rediffmail.com

Hydrogeomorphological mapping coupled with hydrogeological investigations has been carried out to evaluate groundwater potential zones in and around Madhurawada. The study area, geologically a dome, is spread over 190 km2 in Greater Visakhapatnam Municipal Corporation (GVMC) in Visakhapatnam District, Andhra Pradesh. Thematic layers of drainage, geology, geomorphology, lineaments and well inventory have been generated by using toposheet (No.65O/5), GSI geology map, IRS-ID, LISS-III, April, 2004 digital data. Inventory of twenty four dug wells during pre-monsoon and post-monsoon periods of 2008 reveals that the water table fluctuates from 1.5 to 12 m bgl. Four rock types are observed, khondalite is the major type and others are later intrusives into the country rock. Ten hydrogeomorphic units are delineated on satellite data, out of which five are recharge zones and five are run-off zones. The five recharge zones, pediplain shallow, pediplain moderate, pediplain deep, valley fill shallow and piedmont slope have been intersected with geology in ArcGIS-9.1 environment. A buffer zone has been generated to lineament map to establish its influence on groundwater occurrence and distribution. The groundwater potential zones identified through GIS analysis have been classified in to five categories from very low to high.

Electrical Resistivity Distribution Studies for artificial recharge of groundwater in the Dhubdhubi Basin, Solapur District, Maharashtra, India
S.M.Sabale, V.R.Ghodake and A.B.Narayanpethkar
Department of Applied Geology, School of Earth Sciences, Solapur University, Solapur.
Email: vyanky_g@yahoo.co.in

Electrical resistivity distribution at different depth horizons for the Dhubdhubi Basin in Solapur District, Maharashtra has been delineated and represented by contour maps at different electrode spacing. These are correlated with local Geology for a semi quantitative interpretation to detect the potential zones of groundwater. The selection of sites and depth at which the artificial recharge is possible and the structures required are also suggested.



Studies on subsurface resistivity structures for groundwater harvesting in Dhubdhubi Basin, Solapur District, Maharashtra, India
A.B.Narayanpethkar, S.M.Sabale and V.R,Ghodake

Department of Applied Geology, School of Earth Sciences, Solapur University, Solapur.
Email: vyanky_g@yahoo.co.in

Measurements of electrical soundings in grid have been taken at 40 observation points, covering the entire Dhubdhubi basin, a sub basin of Bhima river in the Solapur District Maharashtra. The results of the sounding data revealed two-, three- and multi-layered earth sections. The resistivity distribution for a= 10 m, in the Wenner configuration, the pre monsoon water level contour map and structure contour map at the base of the first layer, interestingly correlate with each other for most part of the basin. The structure contour maps for five layers and structure profiling along three directions have been drawn and sites for groundwater development and groundwater harvesting are suggested.



Day to day variability in the critical frequency of F2 layer over the anomaly crest region, Ahmedabad
H.Chandra, Som Sharma and Soe Win Aung1

Physical Research Laboratory, Ahmedabad 380 009, India
1Myanmar Economic Corporation, Myanmar
E-mail: hchandra@prl.res.in

Day to day variability in the critical frequency of F-layer (foF2) over Ahmedabad is examined. Hourly data for the months of January, March and July for the year 1969 are analysed to study the variability. Daily variations on different days of the month, normalized deviations from mean and the standard deviations at each hour are studied. The deviations are up to ± 40% during night hours and up to ± 20% during day hours. While the variability during day hours is mainly because of the variability in the electric field (electrojet strength) that gives rise to vertical drift and subsequent ionization anomaly, the variability during night hours is also contributed by the variability in thermospheric neutral winds and temperature. foF2 data at selected hours for Thumba, during the months of March and April 1967 and for Kodaikanal during months of August and October of 1972 and February, March of 1973, both located close to the dip equator also show variability of up to ± 30% at midnight and ± 15% at midday.