Annual Report 1999-2000

Scientific Research

Agrometeorology

Field experiments and modelling studies on the effect of weather and climate on the crop growth, pest and disease development and yields are being undertaken under this programme. The data generated has been used to develop sub-routines for agrometeorological processes, testing and validation. Modelling the effect of weather and climate on cotton growth, yield and development of rice blast disease forecasting model are underway.

Development of an agrometeorological data bank is under progress at the Central Research Institute for Dryland Agriculture (CRIDA), Hyderabad for collection, compilation and archival of various types of crop and weather data generated under agrometeorology projects supported by Indian Council of Agricultural Research and DST. The data generated through field experiments using three varieties, six dates of planting for two years has been used to validate CERES-Rice model. It was noted that many of the results are of practical importance to the farmers. New studies were initiated to study the nitrogen flux from rice wheat system in northwest India, and methane emission from rice fields in the northeastern region. The methane flux measurements at Lucknow indicated diurnal and seasonal variability and useful to the methane budget estimates necessary for global warming and climate change studies. Experiments on methane emission from natural wet lands are under progress. These results raise the importance of other currently unknown sources of methane such as organic-rich non-flooded soils contributing to the methane budget.

Radio Acoustic Sounding System (RASS)

The Radio Acoustic Sounding System will have the ability to provide temperature profile (up to 5 km) and wind profile (up to 10-16 km) in the atmosphere. The indigenous development work is close to completion at the Society for Applied Microwave Electronics Engineering and Research (SAMEER), Mumbai with some software back up by Sri Venkateswara University, Tirupati. The prototype units of feeder network, power transmitter unit, high power duplexer and a Signal generator and Processors have been completed. Also, the UHF receiver design, inclusive of a signal simulation scheme has been completed. The technical specification tests were also completed. The system will have wide range of applications in weather forecasting.

Indian Climate Research Programme (ICRP)

Understanding the nature of climate variability and climate change is not only one of the most challenging areas of scientific endeavour, but also of great practical importance to India, whose fortunes are tied to the vagaries of the monsoon. Modelling the physical processes responsible for climate variability and predictability on seasonal, inter-annual, decadal and centennial time scales is essential. The initial conditions have greater role to play in the short range and medium range weather forecasts, whereas the slowly varying boundary conditions are crucial for monthly and seasonal mean forecasts using the AGCMs. Recognising the importance of climate research in the country the Department has initiated a new programme called Indian Climate Research Programme (ICRP) during the ninth five year plan. An implementation plan document has been prepared to identify the research priorities in understanding climate variability at different time scales and its impact on agriculture, economy etc. The programme consists of (i) analysis of observational data from ground-based, ship-based and satellite-based measurements, (ii) modelling studies with coupled ocean-atmospheric general circulation models and (iii) identification of the climate component of agricultural productivity, impact of climate on environment, global warming and climate change etc.

A major coordinated multi-institutional Ocean-atmosphere field experiment namely ‘Bay of Bengal Monsoon Experiment (BOBMEX)’, to study the air-sea interaction processes and monsoon variability has been successfully implemented. Time series atmospheric flux measurements, at two fixed points in the Bay of Bengal during different epochs of southwest monsoon conditions, were monitored for the first time from the ship platforms. This unique field experiment utilised the services of two Oceanographic Research Vessels of Department of Ocean Development and Naval Physical Oceanographic Laboratory (for 6-weeks duration). Also, Met-Ocean Buoys and coastal and Island stations meteorological network - have been successfully commissioned during 15th July to 31st August, 1999 to investigate the air-sea interaction process related to Southwest monsoon in the Bay of Bengal. About 80 scientists from various institutions and Universities participated in this national programme.

Initiated studies on development of optimised atmospheric general circulation model, impact of natural processes and anthropogenic activities on the atmospheric chemsitry, and statistical modelling of crop-weather relationships. In order to take up new research projects, a background technical paper on ‘Meteorological extremes and local climate variability’ was prepared. A brainstorming session on the above subject has been planned at Bhubaneswar. Also, a workshop on the Geosphere-Biosphere interactions in the Northeast has been planned.

Deep Continental Studies

Deep Continental Studies (DCS) Programme is a collaborative, multi-disciplinary Earth Science Research Programme aimed to develop understanding of the deep crustal configuration and related processes of the Indian Lithosphere. The programme's principal scientific components are built around a few selected geotransects or study areas. The focus of the investigation during the last few years has been mutli-disciplinary studies, along Nagaur-Jhalwar transect (NW Rajasthan Shield), Central Indian Craton , South Indian shield and NW Himalayan geotransect (HIMPROBE). After a detailed discussion in Programme Advisory and Monitoring Committee, a programme on ore forming fluids and related metallogeny was concretised. A few projects on metallogeny and ore fluids were sanctioned during this year.

New Projects:

Following new projects have been sanctioned during the year 1999:

• Genesis of Greenstone-hosted gold deposits in and around Hutti and Mallapakonda with exploration implications (IIT, Kharagpur)
  
• Geology and metamorphic history of Kambam valley and adjacent areas, Southern
• Grammlite Zone (Mysore University)
  
• Development of parallel seismic data processing algorithms (C-DAC, Pune)
  
• Evolution of Kodaikanal Cardamam Hills Chamockite Massif, S. India (CESS, Trivandrum)
  
• Study of the structure of the Ophioilites of the Indus suture zone by using gravity and magnetic data along HIMPROBE geotransect (UOR, Roorkee)
  
• Modelling of fluid migration and behaviour in subduction related metamorphism in Indus suture zone, Ladakh (WIHG, Dehradun)
  
• Metallogenic evolution of Gold Copper mineralisation in the Sakoli Group (ISM, Dhanbad)
  
• Evolution of ore fluids and gold metallogeny: Eastern Mahakoshal Greenstone belt (ISM., Dhanbad)
  
• Deep Continental and Tectonic Studies of Chhatisgarh basin by gravity and magnetic methods (BHU, Varanasi)
  

Ongoing Projects

• Integrated Geotransect (Kuppam-Palani) across the Southern Indian Shield
  

Keeping in view several fundamental aspects of lithospheric evolution of the South Indian Craton, an integrated programme has been launched. Field observations and data acquisition related to co-incident reflection-refraction, gravity, magnetic and M-T studies, deep electrical sounding studies pertaining to the region north and south of Moyar-Bhavani and Palaghat-Cauvery shear zones have been initiated. Preliminary analysis of seismic data indicates the presence of two independent structural blocks with a probable suturing extending in the E-W to ENE-WSW direction. The Bouger anomaly shows a smooth anomaly pattern with a broad low over Peniyar river. Results of preliminary analysis of the MT data brings out the typical geoelectric signatures of different known geological structures in the region.

• Geothermal Regime and radioelemental distribution in the Southern Granulite Terrain

With a view to obtain a first order heat flow distribution of the Southern Granulite Terrian (SGT), it was envisaged to drill six boreholes. Drilling of these boreholes (ranging in depth from 230 m to 500 m) at the six sites has been completed. Analysis of the data is in progress.

• Geodynamics and Exhumation of the South Indian Granulite terrain.

Geological field investigations have already been carried out in two field seasons. During the fieldwork, besides lithological mapping, extensive structural data and detailed sampling were done. Detailed petrological / mineralogical and geochemical studies of samples have been carried out. Preliminary results indicate that crustal rocks are prevalent within Palaghat -Cauvery Shear Zone. Detailed work on Fission Track dating for understanding the exhumation process is in progress.

• Geophysical interpretation along Nagaur-Jhalwar and Jaipur-Raipur transect
  

A new scheme to interpret non stationary gravity profile, based on fractals, has been developed. This scheme when applied to gravity profile along Nagaur-Jhalwar transect resulted into three stationary sub profiles with high resolution of different structural features.

• HIMPROBE (NW Himalayan Geotransect)

Considering the importance of North West Himalayas in understanding of the geodynamics of the Himalayan region, a multi-disciplinary & multi-institutional programme named HIMPROBE has been initiated. Under this project, an expedition to Tso-Morari region of Ladakh Himalayas was carried out with an extensive field work. During this field work, new localities of eclogites have been mapped. Detailed work on eclogites is in progress.

• Completed Projects

In a project entitled "Seismic Tomography of SONATA belt", the following achievements have been reported

a) Koyana Seismic Zone Experiment

The seismic segments of Koyana region have close linkages with the Western Ghat escarpment and Warna fault. Ninety percentage of seismicity is confined within the depth range of 3-10 km. The depth distribution of earthquakes delimits the seismogenic zone with its base at 10 km indicating a transition from an unstable to stable frictional sliding regime. The lack of shallow seismicity between 0 to 3 km indicates a mature fault system with well developed gauge zones, which inhibit shallow earthquake nucleation. The teleseismic tomography results reveal segmented and matured seismogenic fault systems in the Koyana region where seismicity is possibly controlled by strain build up due to competent lithology in the seismic zone with a deep crustal root.

b) Narmada-Son Lineament experiment

Teleseismic depth sounding across Narmada-Son Lineament provided the first direct evidence for existence of a deep seated Low Velocity Zone beneath it. Preliminary modelling of data suggests a 2-4% low velocity in the depth range of 100-300 km beneath the central part of array encompassing largely the Vindhyan basin in contrast with high velocity lid in the northern and southern edge. This may be interpreted as a consequence of asthenospheric upwarp beneath Vindhyan basin.

• In a project entitled "Development of Techniques to interpret gravity data for deep continental studies by ISM, It has been reported that
  • Softwares for maximum entropy method and maximum likelihood method have been completed and tested on real & simulated data.
  • The problem of positive and negative masses over rift valleys could be solved by simulating two horizontal cylinders with their centres lying on the same vertical axis.
  • The mapping of fault plane has been first simulated by considering a horizontal faulted slab with finite throw by analytical signal approach. The method of simulated annealing coupled with non-linear optimization technique has been used to derive model parameters of a faulted slab. It has been observed that the method requires observed data of high accuracy. Further, dip of fault plane exhibits large variations.

• Gravity data have been recorded along a geotransect across central Indian Suture (CIS) along Mungwani-Rajnandgaon transect. It shows a regional high to the north of the CIS coinciding with the Satpura Mobile Belt (SMB) which decreases as a gradient towards the south. A small wavelength gravity`low' superimposed over this large wavelength gravity gradient coincides with the CIS indicating a deep seated fault and a shallow low density body. The resulting crustal section shows a thick crust of the order of about 45-50 km with thicker higher density lower crust and a high density (2.81 g/cc) body in the upper crust north of CIS suggesting collision and underplating under the SMB.
  
• In a project entitled "Magnetotelluric Studies across Narmada Son Lineament and Bhandara Craton in Central India", it has bee reported that the block structure deduced from the Magnetotelluric modelling results clearly indicates that the subsurface resistivity of the crustal section shows a systematic change from southeast to northwest along the traverse. From very high resistive block in the south to a moderately resistive block followed by conductive and more conductive blocks as we go northwards indicating presumably the presence of increasingly reactivated crust towards north.

Publications

With a view to disseminate information regarding achievements of the Projects under implementation and other issues related to the DCS Programme, DCS Newsletter is being brought out. 2 issues of the DCS Newsletter have been brought out during the current year.