More than three decades back I got myself involved with basin scale studies of oil prospects in the Brahmaputra and Barak valleys of Assam. Those were jobs as a surface Geophysicist in the ONGC. Subsequently, after getting involved with the academics and being a faculty member of Applied Geology department, I could pick up a few things from the hardcore geologists. Experiencing large scale bank erosion due to the Brahmaputra River, a close proximity with geomorphology first and then a tendency to relate things with subsurface processes of different orders opened up an approach to see things from a multi-disciplinary perspective.
Side by side, got interest in political economic studies on different types of movements in Assam with special reference to water conflict, water justice and consequences of growth of neo-liberalism. During lazy hours listening to Sufi music, Blues, country songs and swimming through contemporary modern poetry brought highly refreshing experience.
Qualifications: M.Sc.Tech in Applied Geophysics IIT(ISM), Dhanbad, Ph. D.(IIT, Kanpur)
Papers /Courses taught
Associated with the following papers:
- Exploration Geophysics,
- Well logging & its applications
- Seismic Stratigraphy
- Sequence Stratigraphy
- Geophysical Signal Theory
- Seismic Data Processing & Interpretation.
Engaged with five courses so far: M.Sc. (Applied geology), M.Tech (Petroleum Geology), M.Tech (Petroleum Technology), Advanced Post graduate Diploma in Petroleum Exploration Geophysics (APGDPEG), M.Tech (Exploration Geophysics)
1. Advanced Post graduate Diploma in Petroleum Exploration Geophysics (APGDPEG)[2009-2011]
2. M.Tech (Exploration Geophysics)[2012- ]
Five and half years’ (1986-1992) work association with ONGC (presently ONGCL) as a Geophysicist (Surface). Seismic data acquisition with DFS V instrument in areas of upper Assam valley and in the Barak valley.
Twenty five (25) years of teaching (1993-2018) in the Department of Applied Geology, Dibrugarh University . Raised one year post-MSc. Advanced Post Graduate Diploma in Exploration Geophysics (APGDPEG) in 2009. Upgraded the previous course to 2 yr M.Tech (Exploration Geophysics) Programme in 2012.
Chairmanship of Departmental Management Committee (DMC) for two years (2000-2001). Coordinator, Advanced Post Graduate Diploma in Petroleum Exploration Geophysics (APGDPEG) Programme, Dibrugarh University (2009-2010). Coordinator, M.Tech (Exploration Geophysics) Programme (2112- ).
Joined Engineering Geosciences Group in the Civil Engineering Department, IIT Kanpur as a part of PhD programme to conduct research on “Basin evolution, morpho-tectonics and fluvial processes in the Brahmaputra river system, Assam”.(2005-2014)
Raised Society of Exploration Geophysicists (SPG), Dibrugarh University Students’ Chapter in 2011. Raised GEOSOL, a consultancy wing on solutions related to geological and geophysical problems in 2010. Associated with “Natun Padatik” Group as an Executive Member since 2000 to spread scientific and analytical thinking in the society. Worked as a member of the editorial board for an Assamese magazine “Seuj Chinta” (Agricultural Extension Services) , published from Jorhat (1995-1996). Worked as a member of the editorial board for a Bangla magazine “Protisrot”, devoted to socio-economic-political and cultural issues, published fro Silchar for three years (1889-1991). Also, worked as the coordinator of Academic and Education Department of Anti Riot Action Forum (ARAF), Silchar, Assam (1991-1992).
Research/Area of Interest
- Earth System Science, Philosophy of science, Basin evolution, Morphotectonics, Sequence stratigraphy based mainly on wireline log data and seismic sections, Image processing and GIS based studies.
- Political economic studies on different types of movements in Assam with special reference to water conflict, water justice and consequences of growth of neo-liberalism. Contemporary modern poetry
Our recent research findings:
1.Gas leakage from palaeogene reservoir in Assam – a geophysical puzzle
Leakage from the deeper layers of gas fields is very rare. Moreover, if gas enters into a number of shallow aquifers, the problem becomes too complex to handle. However, we could demonstrate that simple and cost effective strategies can be taken up not only to understand the problem better but cheaper supply to the poor villagers can be ensured by micro-level gas-pipe networking. ‘Controls’ on the basin and probable mode of gas spread in different horizons were examined from the available data and the new data generated by conducting different types of cheaper electrical surveys as a pilot project. Based on these a concept model was put forth to explain gas leakage from the ground.
(Reference: Lahiri et al., 2016, Current Science 111(7))
2. Application of FFT in quantitative geomorphology
We could establish that Fast Fourier transform (FFT) can be applied to identify frequency (cycles per unit length) content of bankline migration, to classify the wavelengths of different forcings and subsequently to compare the relative influence of different forcings for the trend analysis of bankline shift and width variation. This helps expand the interpretative scope of dynamics of river systems and plan mitigation strategies.
(Reference: Lahiri and Sinha, 2015, Current Science 108)
3. Morpho-tectonic evolution mechanism of Majuli-type relic river islands
We have questioned the existing episodic theory of evolution of Majuli and by integration of geophysical evidence from seismic data and the surface morphological changes theorised that the Majuli Island and other similar landforms represent structural ‘highs’. We emphasized the role of basementconfiguration and tectonic setting in the evolution of such landformsrather than a merely geomorphic process. Morphotectonic evolution of these islands has involved three stages- pre-bypass uplift, Majuli formation and abandonment. The Majuli Island in the Brahmaputra valley is presently passing through the abandonment stage and is gradually being incorporated within the flood plain of the valley.
(Reference: Lahiri and Sinha, 2014, Geomorphology 227)
4. Laws of erosion in Majuli
Assuming relative change in erosion of the Majuli Island (ME) is correlatable with changes in different geomorphic parameters like areas of channel belt (CHB), braid bar (BB), channel (CH), average width of the channel (W), right bank (RB) and left bank (LB), we have used the ‘method of least squares’ to find out the empirical equations which are highly constrained by place and time. It is observed that a set of second order parabola equations which we have argued as ‘Laws of erosion in Majuli’ can relate the percentage rate of erosion of the Majuli Island with the above mentioned six parameters. Additionally, erosion of Majuli might influence the aggradationary tendency, if any, in the neighborhood of the Majuli Island. Accordingly, we have investigated the influence of Majuli erosion (ME) on Braid bar density variation in the planform (BB) as well as on BB/CH. We find that increasing erosion of Majuli witnesses side by side a growing tendency in the braid bar formation, more so in the lower part of the island. Moreover, this also shows that the eroded material is not getting transported in the further downstream side rather the aggradationary tendency has sharply increased in the adjacent areas of the lower Majuli over the last four decades compared to the earlier period.
(Reference: Lahiri, 2013, SEAJSBR 1(1))
5. First order tectono-geomorphic zonation of the upper reach of the Brahmaputra valley
The Brahmaputra valley in upper Assam is strongly influenced by the Himalayan and Naga Patkai belt orogeny and can be broadly subdivided into three types of first-order tectonogeomorphic units, namely the centraluplift, the slopes, and the depressions. The spatial variability in morphodynamics of the Brahmaputra River is strongly linked to these units.The general trend of avulsion of the north bank tributaries of the Brahmaputra River is towards the southwest, and a definite structural control of very recent origin is inferred. The palaeochannels of the southern tributaries on the other hand are much older and suggest stability at shorter timescales. These differences in dynamics of the northern and southern tributaries are in response to different tectonic regimes of the Himalayan and Naga Patkai thrusts, respectively.
(Reference: Lahiri and Sinha, 2012, Geomorphology 169-170)
1. External Expert in the Geophysics discipline of the Selection Committee in the Interview for the posts of Research Scientists (vide appointment letter no. NESAC/RMT-RS/11.5 (III)/2016 dated November 18, 2016 issued from the office of the Director, North Eastern Space Applications Centre (NESAC) held on 29th November, 2016 in the North Eastern Space Application Centre, Government of India, Department of Space, Umiam, Meghalaya.
2. Acted as Reviewer for nine (9) International Journals during 2017-21.
(i) Geodinamica Acta (Editor-in-Chief: Erdin Bozkurt) (Routledge, Taylor & Francis Group (Journal ISSN: 0985-3111/Online ISSN: 1778-3593); Impact Factor: 1.049),
(ii) Acta Geophysica, (Editor-in-Chief: Elefitheria E. Papadimitriou) (Springer International Publishing) (Print ISSN 1895-6572/Online ISSN 1895-7455 , Impact Factor: 0.968)
(iii)Current Science (Chief Editor: S.K. Satheesh) (ISSN 0011-3891)
(Published by the Current Science Association in collaboration with the Indian Academy of Sciences) (Impact Factor: 0.843)
(iv) International Journal of Disaster Risk Reduction (Editor In Chief: David Alexander) (ISSN: 2212-4209) Elsevier (Impact Factor: 1.968)
(v) GSA Bulletin (ISSN 0016-7606) (Published by The Geological Society of America) (Impact Factor: 4.039)
(vi) Quaternary Research (Editors: Dr Derek B. Booth, University of Washington, Dr Nicholas Lancaster, Desert Research Institute and Dr Lewis A Owen, North Carolina State University) [ISSN: 0033-5894 (Print), 1096-0287 (Online)] Cambridge University Press (Impact Factor: 2.310)
(vii) Journal of Earth System Science (Editor-in-Chief: N V Chalapathi Rao) [Electronic ISSN: 0973-774X] Published by the Indian Academy of Sciences, Springer (Impact Factor: 1.423)
(viii) Hydrological Processes ( Editor-in-Chief: Professor Doerthe Tetzlaff, Humboldt Iniversity and IGB Leibnitz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany) Wiley (Impact Factor: 3.256)
(ix) Physics and Chemistry of the Earth (Editors-in-Chief: Joachim Gottsmann, Junguo Liu, Marloes Mul, Hongbo Su) [ISSN: 1474-7065] Elsevier (Impact Factor: 2.308)