Subash Chandra

Date of Birth:                03-12-1975

Nationality:                   Indian

Passport:                      E8092329 issued from Hyderabad
 


 

 

Address for correspondence:

Indo-French Centre for Groundwater Research

Post Bag 724, N.G.R.I, Hyderabad-500007, INDIA

Ph/Fax: +91 40 23434711 Ext. 2644 (office), 65227436 (Res), Fax: +91 40 23434651

E-mail: schandra75@gmail.com , chandra_sngri@rediffmail.com, schandra_s75@ngri.res.in

 

Ph.D. (Submitted in Dec., 2006)

Topic: Contribution of Geophysical Properties in Estimating the Hydrogeological Parameters of an Aquifer

University/Institute: Banaras Hindu University, Varanasi

 

  • Master of science ( Technology) in Geophysics (1997-2000)������� ����������71.53%�

University/Institute: Banaras Hindu University, Varanasi

����������� Subject studied: Exploration geophysics

 

  • Bachelor of science (Hons.) in Geology (1994-1997)��� ����� ������������������������61.34%

� �����University/Institute: Banaras Hindu University, Varanasi

����������� Subject studied: Physics, Maths, Geology

 

Research Experience��

Six years working experience in the field of groundwater for �Exploration, Management and Development of Groundwater Resources in Hard Rock Areas�. The work deals with various aspects of geophysical applications in investigating the hydrogeological parameters. The near surface inhomogeneities, which is making geophysical data and its interpretation more and more ambiguous, has been taken as R&D work. Attempts are continue to develop the tools and techniques in order to meet the above objective and bring the unambiguous data and interpretation in terms of lithology/geology.� Tools and techniques used are given below:

    1. Electrical Resistivity� profiling and soundings
    2. Electrical Resistivity tomography (ERT)
    3. Self-Potential
    4. Magnetic profiling
    5. Electromagnetic
    6. Tracer
    7. Water level analysis
    8. Diff. GPS (Trimble RTK R7,)

In addition to the above work, experience has also been gained in mineral exploration particularly exploration kimberlite pipe.� Electrical resistivity tomography (ERT) has been employed to explore and delineate the geometry of the kimberlite pipe in south India.

�

 

 

Employment

Dates

Designation

Company name

Sector of activity

January 09, 2004 onward

Scientist �B�

NGRI, Hyderabad

Groundwater

October 30, 2000 to

January 08, 2002

Project Fellow

NGRI, Hyderabad

Groundwater

 

Fellowships/Awards

Dates

Name of Fellowship

Place of work

Sector of activity

November -December 2004

French

UPMC, France

Groundwater Geophysics

October 30, 2000 to

January 08, 2002

Project Fellow

NGRI, Hyderabad

Groundwater

 

Membership��������������������������������������������������������������������������������������������������������������

Name of Society

Class of member

Number

International Association of Hdrogeologists (IAH)

Member

101170

International Association of Hydrogeological Science (IAHS)

Member

8398

The Indian Science Congress Association

Life Member

L11732

 






Language Known: Hindi & English

 

Worked in Projects:

  • Long term management of groundwater in hard rock aquifers including�� augmentation and groundwater protection from geochemical contamination (on going In-House project)
  • Development of techniques and methodologies for exploration,�� assessment and management of groundwater resources in hard rock areas (Network Project)
  • High-resolution Electrical Resistivity Tomography (HERT) Studies for Identifying Subsurface Structural Features in Himalayan Foot Hill Region
  • High-resolution Electrical Resistivity Tomography (HERT) Survey over the Annumpalle kimberlite pipe
  • Electrical Resistivity Tomography and Magnetic Resonance Sounding Studies for Characterising the Weathered-Fractured Aquifer in A.P., India
  • Geohydrological investigations at water spurting sites in Rangareddy, Nalagonda and Mahaboobnagar districts of Andhra Pradesh
  • Evolution of Cost Effective and Sustainable Management Schemes of Water Resources in Bairasagara Watershed, Kolar District, Karnataka
  • Assessment and Management of Groundwater Resources in Naguleru sub-basin, Dachepally Mandal, Guntur District, A.P

 

 

PUBLICATIONS

 

Patent (s):

  • Chandra S., and Ahmed S., 2007. Natural Recharge estimation from surface geoelectrical measurements, filed for USA/PCT, Ref. no. 0025NF2007

 

Books/Chapters

Krishnamurthy NS., Chandra S., and Kumar D., 2007. Geophysical Characterization of hard rock aquifer. A chapter in book �Groundwater Dynamics in Hard Rock Aquifers�Capital publishing company

 

Paper Published

Krishnamurthy, N.S., Chandra, S., Dutta, S., Kumar, D., Ahmed, S., Verma, S.K., (2006). Efficacy of Electrical Resistivity Tomography (ERT) Technique in Delineating Structural Features and Formations in Different Geological Terrains, Surv Geophys (under review)

Chandra, S., Ahmed, S., Ram A., (2006), Geoelectrical properties in estimating hydraulic conductivity and transmissivity: A theoretical development with field application in hard rock terrain, communicated to �J. Hydrol� (revised submitted).

Chandra, S., Atal S., Reddy D. V., Nagabhushnam P., Murthy N.S.K., Subrahmanyam K., Rangarajan R., Ahmed S. and Dimri V. P. (2006) Explication of Water Sprouting Phenomenon Observed in Parts of Andhra Pradesh, Jr. of Geol. Soc. of India, v.68, pp. 157-159.

Chandra, S., Atal S., Murthy N.S.K., Subrahmanyam K., Rangarajan R., Reddy D. V., Nagbhushanam P., Murthy J.V.S., Ahmed S. and Dimri V. P., (2006) Oozing of Water in Parts of Andhra Pradesh, India, Curr Sci India. V. 90:� 1555-1560

Chandra, S, Rao, VA, Krishnamurthy NS, Dutta S, and Shakeel A. (2006) Integrated Studies for Characterization of Lineaments to Locate Groundwater Potential Zones in Hard Rock Region of Karnataka, India, Hydrogeol J, v.14, p. 767-776

Chand R., Chandra, S.,� Rao V. A. & Jain S. C., (2004); Estimation of Natural Recharge and its Dependency on Sub-surface Geoelectric Parameters,� J. Hydrol v. 299: 67�83

Chandra, S., Ananda Rao V, and Singh, V. S., (2004): A Combined approach of Schlumberger and axial Pole-dipole Configurations for Groundwater Exploration in Hard Rock Areas. Cur Sci India vol. 86 no. 10, pp 1437 to 1443.

 

Research Papers In Non-Sci Journals/Seminars/Symposiums:�� 24

 

Technical Reports: ������ 7
 

Ph.D. Abstract

Groundwater management becomes imperative for maintaining the sustainability of the resources, which is under stress due to large scale pumping to meet the water requirement by continuous increasing population as well as mismanagement. However, its management requires various hydrogeological parameters such as hydraulic conductivity, transmissivity, recharge, aquifer geometry, etc., which is estimated by existing classical methodologies that are either costly, time consuming, or require analysis of large volume of hydrological data accumulated over a considerable time span. This is generally inadequate or lacking or unreliable in many areas. The geophysical methods could be used as an alternative approach to estimate the hydrogeological parameters reliably, with comparatively faster measurement and cost-effectiveness. This thesis, therefore, deals with various aspects of geophysical contributions for estimating the hydrogeological parameters of an aquifer in hard rock terrain.

����������� Hydrogeological, geomorphological, geophysical studies have been carried out at different watersheds (i.e. Bairasagara watershed in Karnataka state, and Maheshswaram, Wailapalli watersheds and Kakerveni sub-watershed in Andhra Pradesh state) in granitic hard rock terrain for generating the complete database as well as to understand geophysical properties of the subsurface in order to characterize this for groundwater dynamics. Aquifer characteristics, significance of weathering fracturing, groundwater recharge processes, hydraulic conductivity, transmissivity and its variation in hard rock terrain have been studied to understand groundwater dynamics. Groundwater accumulation is found varyingly distributed due to its occurrences in secondary porosity, which is highly variable in hard rock terrain because of its differential weathering and fracturing. Synthetic simulation using electrical resistivity tomography (ERT) method of lineaments such as quartz vein, dolerite dyke, and buried channel in granite has been carried out to understand the response to the electrical method from weathered-fractured layers, which constitute the groundwater prospecting zone. This has well corroborated with the field results and lithologs. A large amount of work has been carried out to delineate the hydrogeological parameters from geoelectrical or geophysical investigations. Usually deeper basement zone consists of thick soil, weathered and weathered-fractured layers. Moreover, soil is found of sandy nature in such zones. With the present scenario of groundwater over-exploitation, multi geophysical parameters such as resistivity of soil, weathered, and weathered-fractured layers along with its thickness, as well as its aerial distribution are required to explore the groundwater potential zones. High degree of weathering/fracturing, its thickness along with higher soil resistivity qualify potential zone for groundwater occurrences.�

The findings of the present work have helped in evolving the new methodologies to estimate the different hydrogeological parameters in hard rock aquifers. A new approach of vertical electrical sounding method consists of combined axial pole-dipole and Schlumberger (CAPS) configurations has been introduced to identify the lateral near surface inhomogeneities (NSI), which normally occur in the hard rock and misleads the VES resistivity sounding interpretation. Mathematical calculation has yielded the same depth of investigation for axial pole-dipole and Schlumberger configurations for CAPS arrangement that has been confirmed by physical resistivity modeling carried out in a tank filled with water as well as the field experiment. Near surface inhomogeneity effect has also been studied� by� introducing� a high resistive wooden plate in the tank and followed by the field experiment. This approach is comparatively faster and simple to carry out than the other existing methodologies for identification of NSI effects.


Another new and robust mathematical tool has been developed using electrical method for estimating natural recharge reliably in hard rock terrain. This requires three input parameters i.e. soil resistivity (rs), depth to basement (d) and annual rainfall (P) in MKS unit. This has the great advantage over the existing classical tracer technique of natural recharge estimation by facilitating the capability of estimation for any number of years in backward or forward way with corresponding known rainfall provided soil resistivity and depth to basement are once known. This also helps in studying the variation of recharge pattern with time and space. Recharge model curves have been generated for different lithological conditions such as (i) natural recharge with varying soil resistivity for different depth to basement keeping rainfall constant, (ii) with varying depth to basement for different soil resistivity keeping rainfall constant, and (iii) with varying rainfall for different soil resistivity, where the depth to basement is constant.

The third evolution deals with the development of mathematical tool for estimating the hydraulic conductivity (K) and transmissivity (T) of aquifer in hard rock terrains using geoelectrical properties such as aquifer resistivity (r) and longitudinal conductance (C) with field applications. A clear analogy exists between Ohm�s law of current flow and Darcy�s law of water flow, which has helped in establishing relationship between K and r, and between T and C.� A negative correlation is achieved between K and r in hard rocks. Transmissivity (T) has been found directly proportional to the C. The relationship has been calibrated, validated and tested with the published data as well as field data generated in granitic hard rock terrain in and around Hyderabad, India. The close similarity of transmissivity (from geoelectrical method) map with the groundwater productivity (from well measurement) map has confirmed the reliability of the technique.

Integrated studies consists of geomorphological, ERT, SP and magnetic methods have been carried out to characterize the lineament for locating the groundwater potential zones in hard rock terrain. These studies have revealed that the lineaments marked on the geomorphological map may or may not be potential to the groundwater resources and need to be studied for surface investigation using integrated approach for its groundwater potentialities. Such studies consists of ERT, IP, mise-�-la-masse, water level, water quality and isotope analysis along with geomorphological and geological have been carried out to explore the possible cause behind the water oozing phenomenon, which coincidently occurred after the major Sumatra earthquake of 9.3 magnitude on 26th� December 2004 and followed by tsunami in the Indian ocean. Studies have shown that the phenomenon of continuous water oozing for months is natural and localized that need not be taken as precursor to the major tectonic event.

The entire study demonstrates various applications of geophysical investigations in delineating and characterizing different hydrogeological and hydrological properties of the aquifer system particularly in hard rock terrain that contains inherent heterogeneity and extraordinary variability. The hydrogeological parameters thus deduced are crucial in management of groundwater resources and applications of the developed methodologies to a variety of aquifers in hard rock have confirmed the validation and ensured versatility.

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