022973   Hatwar H R;Rao Y V R;Bhowmik S K R;Joardar D; Agnihotri G (India Meteorological Dep, , New Delhi-110 003, Email: hrhatwar@yahoo.com) : An impact of ARMEX data on limited area model analysis and forecast system of India Meteorological Department. Mausam 2005, 56(1), 131-8.

During the Arabian Sea Monsoon Experiment (ARMEX) period India Meteorological Department (IMD) forecast products along with Other products are utilised for day-to-day monitoring and providing the guidance to the field scientists engaged in the collection of meteorological and oceanographic data. In the present study, the operational analysis and forecast products of limited area forecast system for some of the major synoptic systems, that occurred during the ARMEX period was investigated. Further, using the additional data available from ARMEX Phase-II namely SYNQP, upper air and also satellite data, the impact of these data in the IMD's operational limited area forecast system during the onset phase of monsoon 2003 has been investigated. Verification of analysis and forecast fields with this additional data has shown substantial improvement in the analysis and model predicted rainfall.

8 illus, 2 ref

022972   Hatwar H R;Jenamani R K;Kalsi S R;Subramanian S K (NO, India Meteorological Dep, New Delhi-110 003, Email: hrhatwar@yahoo.com) : Synoptic weather conditions during ARMEX. Mausam 2005, 56(1), 7-18.

The paper briefly describes the salient synoptic weather conditions that prevailed over Indian subcontinent during the two phases of ARMEX programme along with some documentation of some unique observed features e.g. rainfall, wind and cloud pattern, etc. in intraseasonal time scale with the hope that these inputs will be helpful to other researchers working on ARMEX data for further diagnostic or prognostic studies. There were five intense observation periods (IOP) during ARMEX phase-I (15 June - 16 August 2002) when some parts of West Coast of India received heavy rainfall. Important synoptic systems that prevailed during different IOPs are described. In the ARMEX phase-II (15 March - 10 April 2003 and 15 May - 15 June 2003) there was only one IOP which coincided with the onset of monsoon over Kerala and its advance into Coastal Karnataka and Konkan-Goa. The synoptic conditions along with rainfall distribution during this period are described in the paper. A few diagnostic parameters like kinetic energy and outgoing long-wave radiation are also presented.

8 illus, 6 tables, 4 ref

022971   Hareesh Kumar P V;Madhusoodanan P;Ajai Kumar M P;Rao R A (NO, Naval Phys & Oceanographic Laboratory, Kochi-680 021) : Characteristics of Arabian Sea mini warm pool during May 2003. Mausam 2005, 56(1), 169-74.

Oceanographic surveys were carried out onboard INS Sagardhwani as a part of ARMEX in the deep and coastal regions of the eastern Arabian Sea during May 2003 to study the mini warm pool characteristics. The observational period was characterized by typical pre-monsoon conditions, as indicated by weak winds and clear skies. TMI SST data showed very good agreement with the ground truth observations (root mean square departure of <126>0.2°C). Both the satellite imagery and ground truth showed surface temperature (SST) in excess of 31° C in the eastern Arabian Sea. This mini warm pool attained its maximum dimension <126>8 days prior to the onset of summer monsoon over Kerala and the dissipated stated prior to the onset date. This information can be used as an index for the prediction of summer monsoon onset. Alternate bands of cyclonic and anti-cyclonic circulation pattern were evident both in the ground truth and satellite imagery. In the regions of SST more than 31°C, surface salinity was found to be less than 34.75 PSU and its depth extent was limited to thin surface layer resulting highly stratified layer. The low saline water present in this region was due to the northward / northwestward advection of low saline waters of equatorial Indian Ocean origin and the recirculation of Bay of Bengal water mass trapped in the central Arabian Sea during winter by the eddy type of circulation.

4 illus, 20 ref

022970   Gupta S K;Deshpande R D (Phys Res Laboratory, , Ahmedabad-380 009) : The need and potential applications of a network for monitoring of isotopes in waters of India. Curr Sci 2005, 88(1), 107-18.

Meeting the water demand of a growing population in India requires large-scale engineering modification of the natural hydrological cycle that is bound to have significant environmental consequences. Therefore, it is essential to have a detailed understanding of the natural hydrological cycle in terms of processes controlling seasonal and spatial distribution of water. Some knowledege gaps in this context are: (i) quantification of sources of water vapour during different seasons; (ii) partitioning of incoming vapour into rain and its re-partitioning as evapotranspiration, soil moisture, stream flow and groundwaterl (iii) quantification of interactions between these components; and (iv) identifying geographical and climatic factors that exercise major control over the entire hydrological cycle. With a view to address these issues comprehensively, a multi-institutional collaborative programme entitled `Isotopes in Waters of India Network' is proposed. The strategy is to monitor spatial and temporal variations of isotopic composition in (i) atmospheric vapour phase, (ii) rain, (iii) major surface water sources and (iv) groundwater. This data and knowledge of isotopic fractionation process are then proposed to be used in conjunction with conventional data of fluxes and volumes to mathematically model and predict the water-related environmental consequences of planned development projects.

2 illus, 70 ref

022969   Gupta M D;Das S;Prasanthi K;radhan P K (Natn Cent for Medium Range Weather Forecasting (NCMRWF), , New Delhi-110 003) : Validation of upper air observations taken during the ARMEX-I and its impact on the global analysis forecast system. Mausam 2005, 56(1), 139-46.

During ARMEX-I several special observations were taken over Arabian Sea region and adjoining west coast of India, which gave an opportunity to study this region more thoroughly. To handle such voluminous data. ARMEX data center has been established at National Centre for Medium Range Weather Forecasting (NCMRWF), in collaboration with India Meteorological Department (IMD) and Indian Institute Technology (IIT), Delhi. One of the tasks of this center is to produce reanalysis for ARMEX period, utilizing these observations. It is essential to assimilate every observation from all available sources, especially over the data sparse oceanic regions for accurate determination of the three-dimensional structure of the atmospheric circulation. Before assimilating these data in global data assimilation system of NCMRWF, an attempt has been made to validate some of these data against observational facts from other sources. Upper-air observations (Digicora) from Dabolim, Goa have been compared with RS/RW observation of IMD, at Panjim, Goa. Though the trend in variations of all the meteorological parameters of these two stations is similar but there is a large difference in their absolute values. Reanalysis generated using the specially collected upper-air observations have been compared with the operational analysis of NCMRWF. The impact of these special observations on analysis and forecast system is found to be confined over the Arabian Sea region only in the lower troposghere. However, in the upper troposphere and stratosphere the impact is seen also over the equatorial Indian Ocean region.

7 illus, 1 table, 5 ref

022968   Gupta a;Das P (Dep of Zool and Fish, Punjab Agric Univ, Ludhiana-141 004, Email: akhilgupta47@rediffmail.com) : Some limnological features of Ranjit Sagar reservoir, Jammu and Kashmir. Geobios 2005, 32(2-3), 189-93.

Basic data on the important morphometric features of the Ranjit Sagar reservoir which is the country's highest rock and earth-filled Dam in Kathua District, are presented. It is classified as a medium-sized reservoir, spread over 87 sq. km and is free from any coastal influence. The productivity is considerably influenced by physico-chemical factors. From the values of physico-chemical parameters of water and soil, biotic community and natural diversity in the fish species, a good potential of food fishes can be expected.

1 illus, 2 tables, 11 ref

022967   Gopalakrishna G S;Kantharaj T;Balasubramanian A (Dep of Stud in Geol, Univ of Mysore, Mysore) : Morphometric analysis of Yagachi and Hemavathi river basins around Alur taluk, Hassan district, Karnataka, India. J appl Hydrol 2004, 17(1), 9-17.

Hemavathi and Yagachi rivers are tributaries to river Cauvery. The major rock types around Alur are granitic-gneisses and schists with invasion of younger basic dykes. The drainage system is dendritic to sub-dendritic and the geomorphology of the area controls the geometric configuration of the aquifer media. Major structural features observed in the area are Hemavathi-Thirthahalli mega lineament. The other lineaments are parallel to mega lineament and these are controlled the streams and their flow directions. Hemavathi and Yagachi are found to be perennial, where as the remaining streams are seasonal.

9 illus, 10 ref

022966   Gnanaseelan C;Thompson B;Chowdary J S; Chowdary J S;Salvekar P S (NO, Indian Inst of Trop Meteorology, Pune-411 008, Email: seelan@tropmet.res.in) : Evolution and collapse of Arabian Sea warm pool during two contrasting monsoons 2002 and 2003. Mausam 2005, 56(1), 187-200.

During the month of April - May, the Sea Surface Temperature (SST) over the South East Arabian Sea (SEAS) attains a maximum over 30°C or more (warmest in the world ocean), called the Arabian Sea warm pool. The warming continues throughout the pre-monsoon period and collapses with the onset of southwest monsoon. The warm pool location is very important in the sense that over this part of the Arabian Sea, the monsoon onset vortex normally forms. One of the objectives of the Arabian Sea Monsoon Experiment (ARMEX) is to understand the mechanism responsible for the evolution and collapse of warm pool. The contrasting monsoon years (2002 and 2003) and the coincidental ARMEX observations during these years give a unique opportunity to understand how the ocean during this period responded to the local and remote forcing. A three-dimensional ocean model of the North Indian Ocean (NIO) is used to simulate temperature over the Arabian Sea warm pool region and detailed analysis is performed especially during the evolution and collapse of the warm pool. The model could successfully simulate the observed inter-annual differences using Quikscat wind fields.

10 illus, 11 ref

022965   Gadgil S;Rajeevan M;Nanjundiah R (Cent for Atmospheric and Oceanic Sci, Indian Inst of Sci, Bangalore-560 012) : Monsoon prediction - why yet another failure. Curr Sci 2005, 88(9), 1389-1400.

The country experienced a deficit of 13% in the summer monsoon of 2004. As in 2002, this deficit was not predicted either by the operational empirical models at India Meteorological Department (IMD) or by the dynamical models at national and international centres. The analysis of the predictions generated by the operational models at IMD from 1932 onwards suggests that the forecast skill has not improved over the seven decades despite continued changes in the operational models. Clearly, new approaches need to be explored with empirical models. The simulation of year-to-year variation of the monsoon is still a challenging problem for models of the atmosphere as well as the coupled ocean-atmosphere system. The dynamical models to generate is expected and better prediction only after this problem is successfully addressed.

13 illus, 1 table, 34 ref

022964   Dimri A P;Mohanty U C;Rathore L S (Res and Dev Cent Snow and Aavalanche Study Establishment, , Him Parisar, Sector 37A, Chandigarh-160 023, Email: apdimri@hotmail.com) : Minimum temperature forecast at Manali, India. Curr Sci 2005, 88(6), 927-4.

Northern India is comprised of complex Himalayan mountain ranges having different altitude and orientation. Knowledge of minimum temperature in this region during winter months is very useful for assessing human comfort and natural hazards. In the present study, Perfect Prognostic Method (PPM) is used for forecasting minimum surface temperature at one of the stations, Manali, in Pir Panjal range of Himalayas. Firstly, a statistical dynamical model is developed for assessing next day's temperature category, i.e. ≤ 0°C or <62> 0°C. Once the category is known, then temperature forecast model is developed for that category. Statistical dynamical models are developed for winter season, December, January, February and March (DJFM), using multivariate regression analysis. Model is developed with data of DJFM for 12 years (1984-96) and tested with data of DJFM for 12 years (1984-96) and tested with data of DJFM for the year 1996-97. Analysis data from National Center for Environmental Prediction (NCCP), US station surface and upper air data of three stations of India Meteorological Department (IMD), India and surfacedata at Manali are used. Four experiments are carried out with four different sets of predictors to evaluate perfor mance of the models with independent data sets. They are: (i) NCEP reanalysis data, (ii) operational analyses from the National Center for Medium Range Weather Forecasting (NCMRWF) in India,

4 illus, 8 tables, 13 ref

022963   Das S (Natn Cent for Medium Range Weather Forecasting, , A-50, Sector 62, Noida-201 307, Email: somesh@ncmrwf.gov.in) : Mountain weather forecasting using MM5 modelling system. Curr Sci 2005, 88(6), 899-905.

The importance of the Himalayan barrier on the weather and climate, ecology, hydrology, agriculture and environment of the developing nations around the mountain range is well known. The Himalayan region is frequently affected by eastward moving weather systems known as western distrubances. These weather systems give wide-spread rainfall and, at times, very heavy snowfall associated with squall speed winds, hail and severe cold waves. The heavy snowfall and the gale speed winds can cause snow avalanches and landslides. The windstorms, hailstorms, thunderbolts and droughts are among other common meteorological hazards in the monuntain region. Among all the natural cycles, hydrological cycle is the most sensitive cycle, which is directly influenced by the atmospheric weather systems and general circulation. High resolution mesoscale (MM5) model has been studied for making accurate mountain weather forecasts over the Indian region. The model is run at triple mested domains at 90, 30 and 10 km resolutions. For mountain weather forecasting, four nested inner domains at 10 km resolutions are placed over the Northwest Himalayas, Central Himalayas, Northeast Himalayas and the Western ghat mountains. Several cases of heavy rainfall events associated with western disturbances, thunderstorms and severe weather have been studied. Preliminary results indicate that the model has a good capability of making severe weather forcasts up to 72 hours.

8 illus, 2 tables, 10 ref

022962   Chowdary J S;Gnanaseelan C;Thompson B;Sinha S K;Salvekar P S (NO, Indian Inst of Trop Meteorology, Pune-411 008) : Response of arabian sea to the local forcing during 2003 pre-monsoon warming phase. Mausam 2005, 56(1), 175-86.

Prior to the onset of south west monsoon the warmest part of the ocean (SST <62>30.5°C) has been observed in the South Eastern Arabian Sea (SEAS). Arabian Sea Monsoon Experiment (ARMEX) provided an excellent opportunity to understand the processes that are associated with the formation of warm pool over SEAS during March and April 2003 and its collapse in June. It is observed that SST over SEAS exceeds 29.5°C, in the weekly SST analysis from ARMEX and Tropical Rainfall Measuring Mission (TRMM) Micro wave Imager (TMI) observations in the last week of March itself. Along with ARMEX and TMI data, Quikscat near surface winds have been used in the study to examine the role of wind driven transport in this region and it was found that at southern boundary (8° N) of the Arabian Sea the transport was southward during southwest monsoon period and northward in the winter monsoon period. In March and April the weak transports and the increase in the isolation over the SEAS are supporting the growing phase of warm pool. The vertical velocity at the bottom of Ekman layer gradually increasing from last week of May 2003 and attains higher value after onset of monsoon, which helps to bring up the cold water and cool the surface. The cooling also is caused by the offshore advection of cold water from Somali coast and high salinity transport from northern Arabian Sea.

9 illus, 13 ref

022961   Chinthalu G R;Nagar S G;Seetaramayya P (NO, Indian Inst of Trop Meteorology, Pune-411 008, Email: chintalu@tropmet.res.in) : Air-sea interaction properties in the eastern Arabian sea during active phase of off-shore trough (IOP 7-9 August ARMEX-2002). Mausam 2005, 56(1), 65-75.

During southwest monsoon season, the off-shore troughs along the west coast (WC) of India occupy shallow zones of convergence. These troughs frequently develop and decay off the WC extending from North Kerala to South Gujarat. They are typical in size, horizontal extent being of the order of 100 km and are discernible from just above the boundary level to about 900 hPa. They produce heavy rainfall over the coastal stations during active phase of the monsoon and vice-versa in weak phase. In the present study the transfer of surface fluxes across the air-sea interface over eastern Arabian Sea following an intense off-shore trough is examined. This trough has developed off the WC during 7-9 August 2002. The results are discussed in relation to synoptic movement of this off-shore trough on the sea level chart.

5 illus, 3 tables, 14 ref

022960   Chaturvedi S S (Cent for Environmental Stud, North-Eastern Hill Univ, Shillong-793 022) : Monthly variation in plant biomass, net primary productivity and turnover of gangetic wasteland of Varanasi. Geobios 2005, 32(2-3), 125-8.

A study was carried out to estimata monthly variation in plant biomass, net primary productivity and turnover at two wasteland sites on the bank of river Ganga at Varanasi. The maximum total above and belowground plant biomass were found during March and April at sites-I and II, respectively. The annual net aboveground production was 164.74 gm^-2 year¹ at site and 157.77 at site-ll. Similarly, the total belowground net production ranged between 60.52 and 63.35 gm^-2 year¹ at sites-l and II, respectively. The maximum value of monthly litter biomass of total community was 9.45 and 7.32 gm^-2 at sites-I and II, respectively in May. The maximum annual turnover rates of total plant biomass and litter production were found at site-II.

3 illus, 2 tables, 13 ref

022959   Bhat G S;Rao P L;Sangolli V G;Bhat G P; Chandelkar A B;Rao H;Kadav V B (NO, Indian Inst of Sci, Bangalore, Email: bhat@caos.iisc.ernet.in) : Diurnal and intraseasonal variations observed on the West Coast of India. Mausam 2005, 56(1), 97-106.

As part of the Arabian Sea Monsoon Experiment (ARMEX), several automatic weather stations (AWSs) were installed on the west coast of India, and some among them have been recording weather data for more than one year. Here temporal variations observed at three coastal stations, namely Honnavar, Kanvar and Vijaydurg during July 2002 to December 2003 are presented. The seasonal variations in air temperature, humidity, wind speed, etc., are along the expected lines. A strong diurnal variation in rainfall pattern is observed, but the dependence on local time is different at Honnavar and Vijaydurg which are not more than 250 kilometres apart. It is shown that the surface pressure exhibit strong variations on different time scales throughout the year, and the dominant time scales shift with the seasons.

11 illus, 1 table, 5 ref

022958   Bhat G S (Cent for Atmospheric and Oceanic Sci, Indian Inst of Sci, Bangalore, Email: bhat@caos.iisc.ernet.in) : Convection inhibition energy of the inversion and the suppressed rainfall over the Arabian sea during July 2002. Mausam 2005, 56(1), 89-96.

All India rainfall was an unprecedented 49% below normal in the peak monsoon month of July in the year 2002. Surface and upper air conditions that prevailed over the Arabian Sea 100-200 km off the west coast of India during July 2002 are described here using the data collected from ORV Sagar Kanya. The total amount of rainfall measured on the ship away from the coast was less than 30 mm in July. The surface conditions were conducive for the development of deep convection in the study area. Radiosonde profiles reveal a complex thermal structure in the vertical and on a majority of the days two prominent inversions were present, one near 800 hPa and the other near 500 hPa. The characteristics of the lower inversion, including the energy barrier that it created for the development of deep clouds is presented. It is shown that on most days during July first half, the convection inhibition energy in the lower inversion layer was much more than that an air parcel ascending moist adiabatically could overcome and the vertical growth of clouds was stunted. The second half of July is intriguing and more than one factor seems to have contributed to suppressed rainfall.

8 illus, 13 ref

022957   Bhasskar P V;Bhosle N B (Chem Oceanography Div, Natn Inst of Oceanography, Diona Paula, Goa-403 004) : Microbial extracellular polymeric substances in marine biogeochemical processes. Curr Sci 2005, 88(1), 45-53.

Microbial extracellular polymeric substances (EPS) are widely distributed in marine environments and are found in free dissolved form, colloids. discreet particles like TSP and/or associated wit particulate matter, including cell aggregates, detritus, biofilms, microbial mats, etc. The chemical composition of EPS is influenced by various factors, including nutrtients, temperature, pH, physiology and age of the culture. Microbial EPS perform various functions, and are involved in diverse marine processes. The unique gelling properties of microbial EPS are considered important in the transport and transformation of organic matter, complexation of dissolved metals and bioeochemical cycling of elements. EPS are rich in organic carbon and therefore are an important source of carbon for different organisms in the food chain. The production of dissolved EPS during the bacterial growth, production of particulate organic carbon from the dissolved EPS and enzymatic breakdown and conversion of particulate EPS into dissolved organic matter within the microbial loop, form an important alternate route of organic carbon cycling in the marine trophic web. In this article, recent findings on EPS and their significance in biogeochemical processes are discussed with respect to their role in marine microbial ecology, marine food-web and other areas of uture research.

4 illus, 104 ref

022956   Basu S;Murty S V S;Anil Kumar (Planetary and Geosciences Div Phys Res Laboratory, , Navrangpura, Ahmedabad-380 009) : U, Th- <. Curr Sci 2005, 88(3), 445-8.

Nucleogenic ²¹Ne produced through (α,n) reaction on ¹⁸O in U, th-rich minerals can be used as a dating tool. Demonstrates the application of this method to apatite in carbonatite from Hogenakal, sourth India. Sm-Nd whole rock-mineral ispochron of the same hand sample has yielded an age of 2400 Ma and Rb-Sr mica-whole rock isochron method has yielded a reset age of 1900 Ma. Using nucleogenic ²¹Me authors derive a gas retention age of 845±127 Ma for the apatite from this carbonatite. This age is considerably younger than the reset Rb-Sr mica (Blocking temperature: 350°C) age, but is in good agreement with the younger 770 Ma carbonatite-syenite-alkali granite emplacement event in the region. This system therefore has the potential to identify low-temperature thermal events and to estimate cooling histories of large igneous complexes.

2 illus, 1 table, 21 ref

022955   Banerjee P (NO, Wadia Inst of Himalayan Geol, 33 GMS Road, Dehra Dun-248 001, Email: parameshb@wihg.res.in) : Inter-seismic geodetic motion and far-field coseismic surface displacements caused by the 26 December 2004 sumatra earthquake observed from GPS data. Curr Sci 2005, 88(9), 1491-6.

The 26 December 2004 great Sumatra megathurst earthquake occurred at the interface of the subsiding Indian plate with the over-riding Andaman microplate. Analysis of the regional GPS data covering both Indian plate and Sunda-South China plate indicates that convergence mechanism changes from nearly arc-normal thursting in the south, to arc-paralled dextral strike-slip faulting in the north. The main event originated in the southern segment, and rupture propagated unilaterally towards north covering almost 1400 km of length. Analysis of the coseismic GPS data from the surrounding regional Permanent GPS stations shows that the earthquake affected at least 4000 km range area surrounding the source zone. Co-seismic static offsets ranging from 138 mm to 2 mm, with directions conforming to the focal mechanism solutions, were detected. The South Indian shield shifted towards east by 10-16 mm. Interstation distance between Singapore and Bangalore decreased by ~ 30 mm, and relative to Dehra Dun, Bangalore shifted towards east by ~ 16 mm. The maximum offset was observed at the nearest GPS station at Sumatra (SAMP), which shifted towards west by ~138 mm. Far-field co-seismic static offsets provide and independent source of data to model the kinematics of large earthquakes.

5 illus, 15 ref

022954   Bajpai R K;Narayan P K (Back End Technol Dev Div, Bhabha Atom Res Cent, Mumbai-400 085, Email: rkumar@apsara.barc.ernet.in) : Natural analogue study of resubelpara group of thermal springs at Garo hills, Meghalaya for demonstration of safe geological disposal of nuclear waste. Curr Sci 2005, 88(6), 986-9.

Garoup of thermal springs (with temperatures up to 50°C) occurring around Resubelpara locality near Sarangkhol, East Garo hills district, Meghalaya has been studied to elucidate the geological analogy of various geochemical, thermal and geological features around them with those expectd around disposed nuclear waste over packs in granitic rocks in the depth range of 400-500 m in a geological repositiory. Discrete uraninite occurring in granites and high radon content have been considered to be analogous with a part of radioactive waste. High mobility of uranium is noticed under combinations of favourable groundwater chemistry (high concentration of carbonates and phosphates) and potential geological pathways. It is found that hot groundwater in granites is capable of transporting uranium into the biosphere when provided with suitable structural conduits like deep-seated faults, While in the areas of granites devoid of potential pathways, no significant transport of uranium is observed, the study demonstrates the capability of good host rock coupled with suitable geological set-up in providing long-term safe disposal of nuclear wastes. This is also an attempt to use natural analogue in India to demonstrate safety of nuclear waste disposal.

2 illus, 1 table, 9 ref

022953   Bagavath Singh A;Venkatesan R;Srinivas C V; Somayaji K M (Radiological Saf Div, Indira Gandhi Cent for Atom Res, Kalpakkam) : Atmospheric boundary layer observations on the East coast at Kalpakkam using doppler mini-sodar during different season. Mausam 2005, 56(1), 233-42.

A phased array Doppler Mini-Sodar has been installed at Anupuram near Kalpakkam nuclear site during the Coastal Atmospheric Boundry Layer Experiment (CABLE) carried out on the east coast of India. Mini Sodar was used to measure the wind profile and investigate the coastal boundary layer development due to land-sea breeze circulation for the study of coastal dispersion of pollutants. The atmospheric boundary layer its variability during SW (August 13 14 : ARMEX I and September 3, 7, 11, 14) and pre-monsoon period (April 27, 28 : ARMX II). has been studied. Large wind direction change and high vertical velocity variance were observed during the onset of sea breeze. The Thermal Internal Boundary Layer (TIBL) height has been found to increase progressively with summer - 170m, SW monsoon - 210 m and NE monsoon - 325 m whereas the Nocturnal, Boundar Layer height decrease progressively during the corresponding period: summer - 370 m, SW monsoon - 340 m and NE monsoon - 210 m.

11 illus, 15 ref

022952   Babu M N;Sankara Pitchaiah P (Atom Energy Dep, Atom Miner Directorate for Explor and Res, Shillong-793 001) : Chemical nature of Brahmanapalle-vemula mine water, Cuddapah district, Andhra Pradesh-multivariate statistical approach. J appl Hydrol 2004, 17(1), 79-85.

Forty two groundwater samples were collected from Brahmanapalle - Vemula area to study the hydro-chemical characteristics using multivariate techniques. The positive factor loadings are found loaded on Mg, K, NO₃ Cl, HCO₃ F and negative on pH. Strong positive correlation is observed between TDS and Cl. Using twelve variables 77.5% of the total variance was accounted. The communalities range between 0.8 and 0.9. Factor 1 represents strong loadings on EC, Mg, K, NO₃, and Cl explains 29.71% of the total variance. Strong loadings on K and NO₃ indicate fertilizer pollution and on Cl indicate high salinity. Distribution of high positive scores (<62>+l) in the extreme eastern end support high rock-water interaction. Factor 2 explains 19.55% of the total variance and represented by negative loadings on pH and positive on HCO₃, and F. Negative loading on pH suggests the transformation of CO₃, into HCO₃. Factor 3 represents by high loadings on Na and SO₄. Loading on Ca in Factor 4 is due to replacement by Mg and Na.

3 illus, 4 tables, 13 ref

022951   Agarwal V K;Agarwal N;Raj Kumar (Ocean Sci Div Meteorology and Oceanography Grp Space Applic Centre(ISR, , Ahmedabad-380 015) : Simulations of the 26 December 2004 Indian ocean tsunami using a multi-purpose ocean disaster simulation and prediction model. Curr Sci 2005, 88(3), 439-44.

Under advanced ocean state forescast activity at MOG/SAC, a comprehensive multi-model ensemble called TOAST comprising an ocean general circulation model, a coastal surge and tide prediction model coupled with a suitable cyclone prediction model is being tested. The model is designed specifically to simulate and predict ocean disasters like storm surge, etc. The model has flexible grids structure and apart from calculation of the surge height, it also provides the area of intense inundation in the coastal region. The ocean general circulation component of TOAST has a very clear separation of the barotropic and baroclinic modes of energy prpagation. Due to this separation, it is possible to configure the model to retain very fast gravity waves, which are generally filtered away in studies connected with OGCM, and hence indicating a possibility to simulate tsunami. The 26 December 2004 Indian Ocean tsunami has been used as the case study to see the whole life cycle from generation to runaway using this model. The earthquake data has been converted into the modelrequired parameters using an elastic plate movement model employed for most of the earthquake studies. Assumed the quake intensity at Richter scale 9.0 occurring at 0056 UTC and compared the simulation with Jason altimeter pass in the central Bay of Bengal at 0256 UTC.

8 illus, 8 ref

021783   Saigeetha A J;Banyal R K (Gandhigram Rural Inst, , Tamil Nadu, Email: saigeetha_j@rediffmail.com) : Alfred wegener - from continental drift to plate tectonics. Resonance 2005, 10(6), 43-59.

What is the nature of the force or mechanism that moves massive continents thousands of miles across? What causes violent earthquakes to displace huge landmasses abruptly? How could great mountain ranges like Himalayas and Alps rise to such incredible heights? What makes earth's interior so restless? Answers to some of these questions may lie in understanding the Earth's interior itself

11 illus

021782   Aggarwal R;Sondhi S K;Kaushal M P (Soil and Water Engineering Dep, Punjab Agricultural Univ, Ludhiana) : Groundwater management in south-west Punjab. J Res 2004, 41(1), 119-29.

The simulation optimization model has been developed by using embedding technique for optinal and sustainable ground water management for South-west Punjab. Objective function of the model was to maximize pumpage over the whole tract; subject to constraints on governing groundwater flow, groundwater potential depending upon groundwater quality and irrigation requirements, canal water availability and hydraulic heads. The study reveals that it is possible to arrest the rising trend of water table in South-west Punjab by meeting 90 per cent ET demand through seasonal and inter-seasonal redistribution of canal water relases and enhancing the groundwater pumpage by 75 per cent during kharif and 135 per cent during rabi from existing level.

2 illus, 2 tables, 7 ref

020747   Valsangkar A B (National Institute of Oceanography, , Dona Paula, Goa-403 004) : Clay as indicator of sediment plume movement in deep-sea environment. Curr Sci 2004, 87(12), 1747-51.

Future polymetallic nodules mining in the Central Indian Basin (CIB) will disturb not only the deep-sea sediments but also the benthic environment. Generation of voluminous sediment plume due to mining activity is unavoidable, even if the miner would screen the nodules just above the sea floor. The released sediments on the sea floor would migrate in the direction of the bottom water currents and affect the benthic community. It would be more hazardous when the sediment are discharged at the sea surface, as they would affect the entire water column, including light transmission, photosynthesis and productivity. The sediment plume generated by any mining system would cause long-term effects in the deep-sea environment. In order to predict the potential impact on benthic environment, it is necessary to estimate the quantity of plume to be generated, direction in which the plume would move, and how much distance the plume would travel. For this, the surface sediments in the CIB (5230 m depth) were artificially disturbed and resuspended 5 m above the seabed in 1997 during the Indian Deep-Sea Experiment. Initial studies have shown that the clay content during monitoring-1 phase significantly increased compared to post-disturbance, by 15 and 24% in the disturbed zone (DZ); 3 and 20% at the ends of the DZ; 9 and 18% north of the DZ, and 10 and 17% south of the DZ. Here, it is shown that the clay particles can be successfully used as an indicator of the plume direction as well as to estimate the distance travelled by the plume.

8 illus, 16 ref

020746   Tiwari M;Pant C C (Wadia Institute of Himalayan Geology, , 33 General Mahadev Singh Road, Dehradun-248 001) : Organic walled microfossils from the neoproterozoic black phosphatic stringers in the gangolihat dolomite, lesser Himalaya, India. Curr Sci 2004, 87(12), 1733-8.

A well-preserved microbiotic assemblage is recorded from the Jhiroli magnesite, eastern Kumanun Lesser Himalaya. The assemblage contains cyanobacterial filaments, coccoids and acritarchs identified mainly as Siphonophycus robustum, S. typicum, S. capitaneum, Gunflintia minuta, Oscillatoriopsis obtusa, Chlorogloeaopsis contexta, Sphaerophycus parvum, Leiosphaeridia crassa, Trachyhystrichosphaera vidalii, Trachyhystrichosphaera sp., Micrhystridium pallidum and Cymatiosphaera minuta. Presence of acanthomorphic acritarchs such as Trachyhystrichosphaera, Cymatiosphaera and Micrhystridium is important in assigning the age of the Gangolihat Dolomite. On the whole the microbiotic assemblage suggests Vendian or younger age for the Gangolihat Dolomite.

3 illus, 1 table, 50 ref

020745   Sarma A;Das P K (Geology Dep, G.C. College, Silchar-788 044) : Study of fossils from the tertiary carbonate sediments of shella formation (Jaintia group) exposed around Snapur- Lumpsnong area, Meghalaya. Asian J Microbiol Biotechnol envir Sci 2004, 6(4), 717-22.

The Tertiary carbonate sediments of the Shella Formation were studied from the palaeontological point of view. The upper part of these sediments bears a good foraminiferal fossil assemblage.This assemblage indicates that the sediments have shelf affinity. The presence of Discocyclina and Miscellanea foraminifers indicates the tidal zone of sheld area of Palaeocence age. The middle part contins Nummulites and Alvelina which are the charactristic genera of shelf region of the Eocene sea. the upper part is characterised by the fossils like Nummulties, Alveolina, Discocyclina, Testularia, Quinoqueloculina etc, which indicate the Middle Ecocene age.

2 illus, 8 ref

020744   Ramkumar M;Stuben D;Berner Z;Schneider J (Institute fur Mineralogic and Geochemie, Universitat Karlsrube, Germany) : Geochemical and isotopic anomalies proceding K/T boundary in the cauvery basin, South India: Implications for end cretaceous events. Curr Sci 2004, 87(12), 1738-47.

The Upper Cretaceous-Lower Tertiary deposits of the Cauvery basin show prominent geochemical and isotopic anomalies preceding the K/T boundary. Analyses of stratigraphic variations of whole-rock elemental concentrations and stable isotopic compositions in the light of sedimentation history, petrography and mineralogy of the rocks reveal that these anomalies may be due to increased detrital influx caused by sea-level and climatic changes, Deccan volcanism and release of volatile gases from buried hydrocarbons, presumably gas hydrates. Comparison of these interpretations with that of K/T sites located in Guatemala, New Mexico and Israel revealed that these interpretations are in conformity with records on gradually increasing environmental stress during Upper Cretaceous that culminated with two major catastrophic events such as bolide impact and Deccan Trap volcanism. Communication provides additional support to the growing acknowledgement of the theory that higher faunal turnover across the K/T boundary the world over might have been the result of gradual environmental deterioration rather than a sudden impact in the global scale.

3 illus, 77 ref

020743   Bansal B K;Gupta G D (NO, Seismology Div, Sci and Technol Dep, New Mehrauli Road, New Delhi-110016, Email: bansalbk@alpha.nic.in) : Geoscientific studies in and around Delhi. Curr Sci 2004, 87(12), 1646-8.

2 illus

020742   BalaselvaKumar S;Kumaraswamy K;Srileka S; Jawahar Raj N (Research Scholar, Geography Dep, Bharathidasan Univ, Tiruchirappalli-620 024) : Application of remote sensing data for land use/land cover mapping a case study of Arjuna river basin, Tamil Nadu. Biosci Biotechnol Res Asia 2003, 1(1), 43-8.

Attempt has been made to mapping the land use and land cover categories of Arjuna River basin using the Remote Sensing techniques. The study area, which is located in the southern part of Tamil Nadu. The basin covers an area of about 1687 sqkm. The basin has been subjected to different kinds of environmental degradation by both man and nature. The analysis will help for better land management for sustainable development. The analysis is based on primary, secondary and ground data. The primary remote sensing data are included IRS (LISS I, II). The interpretation key of the NRSA (1985) has been used for this purpose. The advantage of the remote sensing data over the conventional statistical data is due to its more reliability, accuracy, time saving and cost effective. The land use/land cover pattern indicates as follow, built land, agricultural land, forest, waste lands and water bodies. These classification of land use were mapped using the GIS software (Arc Info/Arc View).

2 illus, 2 tables, 10 ref

019727   Ram Singh (Agricultural Meteorology Dep, CCS Haryana Agricultural Univ, Hisar-125 004) : A climatological study on minimum temperature at Hisar. J Agrometeorol 2003, 5(1), 124-8.

^ssc5 tables, 7 ref

019726   Ram Babu;Dhyani B L;Nirmal Kumar;Tamradhwaj (Central Soil & Water Conservation Research & Training Institute, , 218, Kaulagarh Road, Dehradun-248 195) : Rainfall intensity-duration-return period equations and nomographs for Andhra Pradesh. J Agrometeorol 2003, 5(1), 35-45.

Rainfall intensity-duration-return period (IDRP) equations and nomographs were developed earlier in 1979 for two stations in Andhra Pradesh (Hydrabad and Vishakhapatnam) due to non-availability of recording rainfall data of more stations. In the study the IDRP equations and the nomographs for 22 stations of the state have been developed based on long period data obtained from the IMD, Pune. The results are discussed in relation to the general equation and nomograph for the Andhra Pradesh state.

6 illus, 2 tables, 13 ref

019725   Babar MD;Kaplay R D (Geology Dep, Dnyanopasak College, Parbhani-431 401) : Influence of canal irrigation on groundwater fluctuation and soil properties in Jayakwadi command of Maharashtra. Agropedology 2004, 14(2), 82-6.

Groundwater quality and fluctuation were studied as influenced by canal irrigation in the part of Jayakwadi command of Maharashtra. Periodical observations made on fluctuation of ground water table in irrigated and adjacent unirrigated areas of Ambad Tehsil during 1994-95, indicate rise in water table level up to 1.76 m. Groundwater is saline in irrigated area with pH 8.1 to 9.4 and electrical conductivity 1.85 to 1.99 dS??. Groundwater shows increasing trend in sodicity on the basis of SAR ranging from 3.16 to 4.61 in irrigated area as compared to unirrigated area having SAR of 0.82 to 2.12. Soils were rated as saline on the basis of their properties. The pH, EC and CaCO₃ of salt affected soil were higher in irrigated soils than normal unirrigated soils.

3 tables, 7 ref

018605   Subrahmanyam A V;Desapati T;Anil Kumar V; Deshmukh R D;Viswanathan G (Atomic Mineral, Directorate for Exploration and Research, , AMD Complex, Begumpet, Hyderabad-500 016) : Occurrence of xenotime in the Narasapur beach placers, West Godavari District, AP. Curr Sci 2004, 87(10), 1458-61.

Xenotime has been identified in the beach placers of India from Narasapur, West Godavari District, Andhra Pradesh. It occurs in 63 and 73 μm size mode, strewn in rear and inter dunes and distributed vertically down to investigated depth of 10-12 m. The average heavy mineral content in this coast is 14.7% within which the xenotime grade varies from 0.09 to 1.32 % (average 0.61 %). Though many possible source rocks' exist within, the Eastern Ghat Mobile Belt (EGMB), the bipyramidal shape and fine size of xenotime indicates high temperature of formation leading to the surmise that granite and granite pegmatites in the EGMB are the source.

4 illus, 15 ref

018604   Prince P R (NO, School of Technology and Applied Sciences, Mahatma Gandhi University,, Pathanamthitta, Kerala-689 645) : Thermodynamics of near earth plasma sheet and specific entropy parameter during substorm - A case study. Indian J Radio Space Phys 2004, 33(5), 294-300.

Heat transactions in the near earth plasma sheet at ISEE-2 site during the full course of a single substorm,is analysed. The seleeted substorm was shown to exhibit an adiabatic growth phase with non-adiabatic expansion and recovery phases. During growth phase, the sheet acts as a mere passage for the flow of energy from solar wind into the earth's atmosphere, supporting the driven model of substorms. The substorm analysed, in general, was a non-adiabatic event. The polytropic index η has proved to be unsuccessful in predicting the thermodynamic state of plasma sheet during substorm. Specific entropy parameter is suggested as a better tool for such predictions.

7 illus, 30 ref

018603   Prasad S K;Towhata I;Chandradhara G P; Nanjundaswamy P (Civil engineering Dep, S J Colloege of Engineering, Mysore-570 006) : Shaking table tests in earthquake geotechnical engineering. Curr Sci 2004, 87(10), 1398-404.

Research in earthquake geotechnical engineering has shown considerable development in the recent past. Focus has been placed on developments of model testing in earthquake geotechnical engineering. Two aspects of model-testing are given importance, namely manual shaking table and laminar box. Design, development, calibration and performance of these equipments are described. Model testing is the essential requirement of earthquake geotechnical engineering that helps in understanding the behaviour of geotechnical facilities and their performance during earthquake. Manual shaking table developed very economically can be used as an alternative to a more sophisticated shaking table. Laminar box is a sophisticated container which can enhance the accuracy in assessing the ground behaviour. Some of the important calibration techniques necessary are also discussed.

7 illus, 7 ref

018602   Odekunle T O (Geography Dep, Obafemi Awolowo Univ, IIe-Ife, Osun State, Nigeria, Email: gaderoun@oauife.edu.ng ) : Determining rainfall onset and retreat dates in Nigeria. J hum Ecol 2004, 16(4), 239-47.

The study assessed the relative efficiency of the use of rainfall amount and rainy days in the determination of rainfall onset and retreat dates in Nigeria between 1961 and 2000. Daily rainfall data were sourced from the archives of the Nigerian Meteorological Services, Oshodi Lagos. The specific locations where data were collected include: Ibadan, Ilorin, Kaduna and Kano. The method of percentage cumulative mean rainfall values was employed in the determination of the rainfall onset and retreat dates.The results obtained clearly showed that both the use of rainfall amount and rainy days are equally effective in the determination of the mean rainfall onset and retreat dates in Nigeria. With regards to the rainfall onset and retreat dates of the individual years however, the method based on the rainy days is more efficient than that based on the rainfall amount, as the formal yielded a much more realistic dates than the latter. It is thus recommended that studies investigating rainfall onset and retreat dates series of the individual years should be based on rainy days rather than rainfall amount.

9 illus, 8 tables, 19 ref

018601   Mishra R K;Agrawal Mishra R (Computer and IT Section, Tropical Forest Research Institute, Jabalpur-482 001, Email: rkm_30@yahoo.com) : Unusual behaviour caused by interplanetary turbulences in cosmic ray intensity. Indian J Radio Space Phys 2004, 33(5), 285-93.

The unusually high/low amplitude anisotropic wave train events (HAEs/LAEs) in cosmic ray intensity using the ground based Deep River neutron monitor data have been studied during the period 1991-94. It has been observed that the phase of diurnal anisotropy for majority of HAE/LAE cases remains in the same co-rotational direction. The phase of diurnal anisotropy has shifted to later hours for some of the HAE cases, whereas it shifts towards earlier hours for some of the LAE cases. Further, for majority of HAE/LAE cases the amplitude of semi-diurnal anisotropy remains statistically the same; whereas, the phase of semi-diurnal anisotropy for all HAE/LAE cases has shifted to later hours. Furthermore, for tri-diurnal anisotropy the phase shifts towards later hours for both type of events; while, amplitude remains statistically the same. The interplanetary magnetic field (IMF) and solar wind plasma (SWP) parameters during these events are also investigated. The possible sources causing these types of unusual events have been proposed.

16 illus, 2 tables, 27 ref

018600   Karegoudar A V;Satishkumar U;Kumathe S S (Water Conservation Engng Dep, Coll of Agric Engng, Raichur-584 101) : Hydrograph time parameters for flat land watershed of lower Krishna river basin. Karnataka J agric Sci 2005, 18(1), 67-70.

The selected Singanodi sub watershed (Ag2m) in Raichur taluk has been identified as a Shigh prority watershed among 187 sub-watershed in the sub catchment by the All India soil and land use survey. The priority tag assigned to the sub watershed indicates the degree of severity of the erosion hazard and subsequent transportation and deposition of a high sediment load into the Krishna river system. Among the thirteen empirical relationships tested for their efficacy in estimation time of concentration equation derived by Johnostone and Cross (1949) and estimating time to peak equation derived by Nash (1959) and Linsley et al. (1958) were found viable and can be applied for other hydrological similar ungauged watersheds.

4 tables, 11 ref

018599   Gupta S;Porwal M C;Roy P S (NO, , 6, Babu Ganj, Darshani Gate, Dehardun-248 001, Email: stutee_gupta@hotmail.com ) : Human modification of the tropical rain forest of Nicobar Islands: indicators form land use land cover mapping. J hum Ecol 2004, 16(3), 163-71.

Tropical forests are pre-disposed to human induced modification throughout the world. It has serious implications at local, regional and the global levels. Repercussions are more severe in the island ecosystems since they are ecologically vulnerable and fragile. Linkages between socio-economic drivers and the consequent modification of the landscape in terms of forest loss in the Nicobar group of islands based on indicators derived from land use land cover mapping of the satellite remote sensing data have been investigated. Although these islands have more than 80% of the area under forests but the situation varies in each of the twelve inhabited island of the group and they are under the varying degree of human pressure. Most active driver is the coconut plantation in addition to time-to-time clearing made in the past. There is a need to investigate the on-going modification of the land cover in these islands and satellite remote sensing forms a useful tool for such studies.

3 illus, 4 tables, 28 ref

018598   Govinda Raju L;Ramana G V;Hanumantha Rao C; Sitharam T G (Civil Engineering Dep, Indian Institute of Science, Bangalore-560 012, Email: lgr@civil.iisc.ernet.in) : Site-specific ground response analysis. Curr Sci 2004, 87(10), 1354-62.

The local soil conditions have a profound influence on ground response during earthquakes. The recent destructive earthquakes have again demonstrated that the topography, nature of the bedrock and nature and geometry of the depositional soils are the primary factors that influence local modifications to the underlying motion. Highlights the engineering importance of site-specific ground response analysis and difficulties faced in conducting a complete ground response analysis. Steps to be followed in conducting a meaningful site amplification study are explained. Difficulties/uncertainties in choosing an input ground motion are discussed and the various methods currently available for site amplification study are summarized. A case study on ground response analysis of a site in Ahmedabad city during the Bhuj earthquake is presented. The study shows that the varying degree of damage to multistorey buildings in the close proximity of Sabarmati river area in Ahmedabad was essentially due to amplification of the ground. Amplification was attributed to the fact that the natural frequencies of the building and frequency content of the ground motion recorded on the ground floor of the Regional Passport Staff Quarters building are in close proximity.

16 illus, 9 ref

018597   Gopal Madabhushi S P (Engineering Dep, Cambridge Univ, Cambridge CB2 1PZ, UK) : Modelling of earthquake damage using geotechnical centrifuges. Curr Sci 2004, 87(10), 1405-16.

Earthquakes can cause tremendous loss of human life and can result in severe damage to a wide variety of civil engineering structures. The behaviour of foundation systems and soil strata subjected to earthquake loading bis complex. Dynamic centrifuge modelling is a powerful tool that offers a possibility of understanding the true behaviour of foundation systems under earthquake loading. The principles of dynamic centrifuge modelling are elucidated. Implementing dynamic centrifuge modelling needs specialized equipment and instrumentation and the details of such equipment are presented. The application of dynamic centrifuge modelling to investigate the seismic behaviour of embankments on liquefiable foundation and pile foundation subjected to liquefaction-induced lateral spreading are presented. Results from these two applications reveal the usefulness of dynamic centrifuge modelling in understanding the true failure mechanisms. Such an understanding can have direct bearing on both advancement of knowledge as well as on geo-technical practice used in the design of future structures or in retrofit attempts on existing structures.

17 illus, 2 tables, 29 ref

018596   Dugam S S;Kakade S B (NO, Indian Institute of Tropical Meteorology, Pune-411 008, Email: dugam@tropmet.res.in) : Antarctica sea-ice and monsoon variability. Indian J Radio Space Phys 2004, 33(5), 306-9.

Statistically evaluation of the relationship between satellite derived Antarctic sea ice extent and Indian summer monsoon variability over the various homogeneous regions of India have been made. Analysis is carried out for 22 years (1979-2000). From the analysis it is observed that preceding winter (December-January-February) sea-ice anomaly has an inverse association with the performance of the following monsoon. It is observed that deficient monsoon years are preceded by more than normal sea-ice extent, and in excess or normal monsoon years the sea ice extent is less than the normal. The relationship is statistically significant at 1% level. From the study it is found that southern peninsular India does not show a significant relationship.

2 illus, 24 ref

018595   Deb S K (Civil Engineering Dep, Indian Institute of Technology Guwahati, Guwahati-781 039, Email: skdeb@iitg.ernet.in) : Seismic base isolation - an overview. Curr Sci 2004, 87(10), 1426-30.

3D nonlinear analysis procedure of base isolated building is discussed. Important issues related to design of base isolated building are presented. Shear test for obtaining force-displacement hysteresis loop of isolation bearings is outlined. Other important issues, e.g. (i) effects of soft soil on performance of base isolated building, (ii) effects of near fault motion, and (iii) soil-base isolated building interaction, as reported in the literature have also been discussed.

5 illus, 9 ref

018594   Choudhury D;Sitharam T G;Subba Rao K S (Civil Engineering Dep, Indian Institute of Technology, Mumbai-400 076) : Seismic design of earth-retaining structures and foundations. Curr Sci 2004, 87(10), 1417-25.

Earthquake-resistant design of earth retaining structures like retaining walls, earth dams and foundations are very important problems to minimize the devastating effect of earthquake hazards. A comprehensive review for different methods to calculate seismic earth pressures and their point of applications is shown. Numerical example shows the merit of a displacement-based analysis over force-based analysis by considering a permissible displacement of the wall. Modification of IS code for seismic design of retaining wall is proposed. Merits and demerits of several design and analytical procedures for earthen dam and foundations under seismic conditions have been provided.

5 illus, 1 table, 37 ref

018593   Babu R G;Shirahatti S S (Irrigation and Drainage Engng, , Raichur-581 401) : Effect of application of groundwater model SGMP to Gangavathi command area on the watertable buildup and drainage surplus. Karnataka J agric Sci 2005, 18(1), 71-4.

The results showed that present study area needs drainage (drainage surplus was 0.3 mm/d) based on the modeling study carried out for the period from May 1985 to May 1998. The waterlogging conditions are expanding rapidly in the study area and the model predicted that waterlogging area would spread at the rate of 223.4 ha (0.32 per cent of the total area) per annum in the future if the water management practices remain the same.

2 illus, 1 table, 4 ref

017653   Vinod kumar K;Bhattacharya A (National Remote Sensing Agency, , Balanagar, Hyderabad- 500037, Email: vinodkumar_k@nrsa.gov.in) : Remote sensing of delta progradation in Mahanadi Delta, Orissa. J Geol Soc India 2004, 64(2), 227-30.

Mahanadi Delta is a complex delta formed due to the coalescence of three sub-deltas. The northern portion of the delta i.e. Brahmani-Baitarani river mouth was monitored using IRS- 1C LISS-3 satellite data. Barrier-Lagoon type of progradation was brought put by digitally enhancing the satellite data. Density slicing technique was employed to understand the sediment diffusion pattern. This was compared with the standard distribution, pattern to understand the nature of dispersal mechanism near the river mouth here.

3 illus, 4 ref

017652   Vallinayagam G (Earth Sciences Dep, Kurukshetra Univ, Kurukshetra-136 119) : Peralkaline-peraluminous A-type rhyolites, Siwana ring complex, Northwestern India: petrogenetic modelling and tectonic implications. J Geol Soc India 2004, 64(3), 336-44.

Mode of occurrence, petrography and geochemistry of the peralkaline-peraluminous A-type rhyolites of Siwana Ring Complex, western Rajasthan have been described. Based on these data, their petrogenetic modelling and tectonic implications have been constrained. The petrogenetic studies infer a low degree partial melting of a crustal source for the origin of rhyolites.

5 illus, 3 tables, 42 ref

017651   Tiwari G S;Tiwari R N;Singh K N (Petrology Div, Geological Survey of India, , Lucknow -226 024, Email: gsiluck@up.nic.in) : Vertical successions of channel bar, point bar and natural levee deposits, Ganga and Yamuna river, Allahabad, Uttar Pradesh. J Geol Soc India 2004, 64(3), 305-16.

The modern sediments of Ganga and Yamuna rivers at Allahabad, Uttar Pradesh are studied in 17 vertical sections of channel bar, point bar and natural levee deposits. Based on this study nine lithofacies, i.e. St, Sp₂, Sp₁, Sr₁, Sr₂, Sl, Sh, Fl and Fm (8-Sand and 1- Mud sub-lithofacies) have been identified. An attempt has been made to evolve a generalised lithofacies succession for channel bar, point bar and natural levee deposits. The channel bar exhibits the litholacies succession of Sp₂, Sp₁, Sr₂, Sr₁, Sh and Fl; St, Sp₂, Sp₁, Sr₁, Sh and Fl succession in point bar and Sp₂, Sp₁, Sr₁, Sh, Fl and Fm lithofacies succession in natural levee deposits. No major difference in channel bar and point bar lithofacies succession have been found. The point bars are characterised by trough cross-bedded lithofacies-St, which are formed by the migration of 3-D dunes. The Fm lithofacies is characteristics of natural levee, the muddy deposits often show desiccation cracks. Deposition of mud takes place in low energy conditions mostly during receding floods.

5 illus, 2 tables, 21 ref