027836   HARI K R, SWARNKAR V, PRASANTH M P M (Pt. Ravishankar Shukla Univ, Raipur- 492 010, Email: krharigeology@gmail.com) : Significance of assimilation and fractional crystallization (AFC) process in the generation of basaltic lava flows from Chhotaudepur area, Deccan large Igneous province, NW India. J Earth Syst Sci 2018, 127(6), 85.

Basaltic and basaltic andesitic flows have been identified from the Chhotaudepur area in the Deccan Large Igneous Province. The SiO₂ content of these flows varies from 46.7 to 53.7 wt %. None of the samples have primary magma signatures as they exhibit low Mg # (0.42–0.68), Ni (4.8–33.4 ppm) and Cr (33.08–143.06 ppm). Highly variable concentrations of the LILE [Rb (2–74 ppm), Ba (52–351 ppm), Cs (0.1–1 ppm) and Sr (273–745 ppm)] and relatively enriched LREE are also noticed. The coherent chondrite normalized REE diagram and primitive mantle normalized multi-element diagram suggests a consanguinity among the flows. Low (Nb/Th)_PM (0.30–1.09), high (Th/Yb)_PM (3.09–16.58) ratios and marked variations in Rb concentration (2.4–74.11 ppm) with variable La/Yb (5.5–23.7) ratios suggests that magmas in the Chhotaudepur region were assimilated by the crustal components. The elevated Th/Ta and La/Yb relation further indicate concurrent assimilation and fractional crystallization process was involved in the genesis of the flows. Assimilation and fractional crystallization modelling of the flows was carried out with 20 % olivine, 25 % clinopyroxene, 45 % plagioclase and 10 % titano-magnetite as fractionating minerals and upper continental crust as the assimilant. The results reveal that all the flows were modified by AFC process.

9 illus, 2 tables, 80 ref

027843   LEE K T, HUANG P-C (National Taiwan Ocean Univ, Keelung, Taiwan, Email: pinchunhuang@gmail.com) : Assessment of flood mitigation through riparian detention in response to a changing climate - A case study. J Earth Syst Sci 2018, 127(6), 83.

Considering that urban areas may suffer more substantial losses than riparian farmlands during floods, diverting floodwater into riparian areas for temporal detention is expected to mitigate flood damage in downstream urban areas. In this study, an assessment has been conducted to evaluate the effect of flood mitigation through riparian detention in response to a changing climate in the Tou-Chien River basin of Taiwan. An integrated 1D–2D flow model was used to simulate the movement of flood wave in the main stream and the overbank flow inundating into the nearby lowlands. Based on the numerical simulation results, the flooding extents in the basin corresponding to different return periods of flood using existing flood prevention infrastructures were investigated. A detention strategy by lowering the levee along the riparian farmlands was proposed to avoid severe flooding in the densely populated urban areas of the basin. Research findings showed that the proposed detention measure can completely protect the downstream areas from overbank flooding when a flood having 20-yr period occurs, and can effectively alleviate the downstream flooding area from 27.4 to 7.6 km² for a flood possessing 200-yr period.

13 illus, 2 tables, 23 ref

027860   SENGUPTA S, KRISHNA A P, ROY I (Birla Institute of Technology, Ranchi- 835 215, Email: someshsengupta@hotmail.com) : Slope failure susceptibility zonation using integrated remote sensing and GIS techniques: A case study over Jhingurdah open pit coal mine, Singrauli coalfield, India. J Earth Syst Sci 2018, 127(6), 82.

The susceptibility of slopes in open pit coal mines to various modes of failure (i.e., plane, wedge, circular and toppling failure) could be envisaged by virtue of processing and analysis of pertinent satellite data. The aim of the present study was to integrate thematic maps generated using remote sensing image processing techniques, in order to finally produce slope failure hazard zonation maps in and around Singrauli coalfield, India. The various failure-inducing factors, variables and parameters can be extracted from different satellite data and imageries. The data acquired by different sensors such as TM, ETM+, etc., of LANDSAT series and CARTOSAT of ISRO Bhuvan was used in this study. All these data were subsequently used to create different thematic maps such as slope map, lithological map, land use/land cover map, principal component analysis map, digital elevation model (DEM), etc. An advanced analysis for extraction of lineament attributes was also undertaken.

16 illus, 4 tables, 24 ref

027842   KUSRE B C, GHOSH P, NATH K (Irrigation and Drainage Engineering Dep, Central Agricultural Univ, Sikkim- 737 135, Email: kusrebharat@gmail.com) : Prioritization of soil conservation measures using erodibility indices as criteria in Sikkim (India). J Earth Syst Sci 2018, 127(6), 81.

Erodibility indices are important parameter that can be used to describe the intensity of the soil erosion problems causing environmental concerns. These indices are convenient to estimate the susceptibility to erosion where physical measurement is very difficult. Sikkim is one such state in India where measuring erosion is a tedious process due to its difficult and inaccessible terrain conditions. In the present study, spatial variation of susceptibility of erosion in East district of Sikkim was estimated by using indices such as clay ratio, dispersion ratio, mod clay ratio and critical level of soil organic matter. The result indicates soils in East district are mostly dominated by sand particles (40.5–81.06 %) in majority of soil samples. The dispersion ratio values in most of the soils were >15 % indicating very high vulnerability to erosion. The values of clay ratio (3.44–9), modified clay ratio (mean value of 6.9) and critical level of soil organic matter content (<5 %) indicated high susceptibility to erosion. The trends of indices were generated by IDW interpolation method to understand the spatial variation of the susceptibility to erosion. The interpolated maps were overlaid on subwatershed maps to prioritize the subwatershed for planning treatment measures.

7 illus, 3 tables, 27 ref

027849   MUKHERJEE S (Earth Sciences Dep, Indian Institute of Technology Bombay, Mumbai-400 076, Email: soumyajitm@gmail.com) : Moment of inertia for rock blocks subject to bookshelf faulting with geologically plausible density distributions. J Earth Syst Sci 2018, 127(6), 80.

Moment of Inertia (MOI) for rock blocks that glided smoothly into book-shelf dispositions are deduced considering realistic linear and exponential 3D variations in density along specific axes/directions. Knowing (empirical) algebraic relations of density with depth, which could also be anything other than the exponential and linear variations considered in this work, geoscientists can deduce the MOI by following the same process. MOI for a homogeneous parallelepiped block along any direction is proportional to the length of the block in that direction. However, this simple relation does not hold true for rock blocks with variable densities. Nevertheless, as the block length increases, the MOI along that direction would also increase.

2 illus, 57 ref

027861   SHARANNYA T M, MUDBHATKAL A, MAHESHA A (Applied Mechanics and Hydraulics Dep, National Institute of Technology, Mangalore -575 025, Email: sharannyatm@gmail.com) : Assessing climate change impacts on river hydrology - A case study in the Western Ghats of India. J Earth Syst Sci 2018, 127(6), 78.

The objective of this study is to evaluate the hydrological impacts of climate change on rainfall, temperature and streamflow in a west flowing river originating in the Western Ghats of India. The longterm trend analysis for 110 yr of meteorological variables (rainfall and temperature) was carried out using the modified Mann–Kendall trend test and the magnitude of the trend was quantified using the Sen’s slope estimator. The Regional Climate Model (RCM), Coordinated Regional climate Downscaling Experiment (CORDEX) simulated daily weather data of baseline (1951–2005) and future RCP 4.5 scenarios (2006– 2060) were used to run the hydrological model, Soil and Water Assessment Tool (SWAT), in order to evaluate the effect of climate change on rainfall, temperature and streamflow. Significant changes were observed with regard to rainfall, which have shown decreasing trend at the rate of 2.63 mm per year for the historical and 8.85 mm per year for RCP 4.5 future scenarios. The average temperature was found to be increasing at 0.10$°$ C per decade for both historical and future scenarios. The impact of climate change on the annual streamflow yielded a decreasing trend at the rate of 1.2 Mm³ per year and 2.56 Mm³, respectively for the past and future scenarios. The present work also investigates the capability of SWAT to simulate the groundwater flow. The simulated results are compared with the recession limb of the hydrograph and were found to be reasonably accurate.

10 illus, 4 tables, 14 ref

027871   YIN S, LV D, WU Z, DING W (Xi’an Shiyou Univ, Xi’an- 710 065, Email: speedysys@163.com) : Assemblage of strike-slip faults and tectonic extension and compression analysis: A case study of a lower Permian commercial coal reservoir in China. J Earth Syst Sci 2018, 127(6), 77.

The Qinshui Basin was an active residual basin in the Mesozoic and Cenozoic periods and is located inside the North China Plate. The Upper Paleozoic strata in the basin have been strongly deformed and have developed a large number of strike-slip faults. The Qinshui Basin has been influenced by compressive stress from the northeast direction since the Himalayan period, and the faults have a dextral strike-slip property. Under the action of such a stress field, the right-slip, right-order faults indicate an extension region, and the right-slip, left-order faults indicate a compression region. Based on this principle, the extension and the compression areas were divided. From northwest to southeast direction in the study area, two types of regions have interactive distribution characteristics. For the Fanzhuang block in the eastern part of the study area, the fault distribution has an ‘S-type’ trend from north to south, and the middle extension region is the ‘elbow’ or the ‘hinge zone’ of the ‘S-type’ area, which can also be called the ‘stress transition zone’. The tectonic stress field of the stress transition zone is complex, and tensile fractures are usually extremely developed with extension tectonics. Gas wells with higher capacity are mainly distributed in the extension zone, while the capacity of the gas wells in the compression area is usually lower. The study showed that the distribution of the gas well capacity is consistent with the tectonic extension and compression analysis, indicating that the tectonic analysis method in this study is reliable. The Upper Paleozoic coal measure strata in the Qinshui Basin represent a whole gas-bearing and stress-bearing system, the tectonic analysis method in this study is also applicable to other types of tight reservoirs for this set of depositional systems.

13 illus, 1 table, 40 ref

027841   KUMAR P, DIMRI A P (Jawaharlal Nehru Univ, New Delhi- 110 067, Email: apdimri@hotmail.com) : Energetics of Indian winter monsoon. J Earth Syst Sci 2018, 127(5), 73.

The Indian subcontinent is characterized by complex topography and heterogeneous land use-land cover. The Himalayas and the Tibetan Plateau are spread across the northern part of the continent. Due to its highly variable topography, understanding of the prevailing synoptic weather systems is complex over the region. The present study analyzes the energetics of Indian winter monsoon (IWM) over the Indian subcontinent using outputs of mesoscale model (MM5) forced with National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR), US, initial and boundary conditions. MM5 modeling framework, designed to simulate or predict mesoscale atmospheric circulations, is having a limited-area, non-hydrostatic and terrain following 12 sigma levels. The IWM energetics is studied using MM5 model outputs. Prior to this model’s validity and deviation from the corresponding observations (NCEP/NCAR) is assessed. The model’s overestimation/underestimation of wind, temperature and specific humidity at upper troposphere proves that the model has difficulty in picking up corresponding fields at all the model grid points because of terrain complexity over the Himalayas and Tibetan Plateau. Hence, the model fields deviate from the corresponding observations. However, model results match well with the winter global energy budget calculated using reanalysis dataset by Peixoto and Oort (1992). It suggests MM5 model’s fitness in simulating large scale synoptic weather systems. And, thus the model outputs are used for calculation of energetics associated with IWM. It is observed that beyond 15 N lower as well as upper level convergence of diabatic heating, which represents continental cooling and sinking of heat from atmosphere to land mass (i.e., surface is cooler than surrounding atmosphere) dominates. The diabatic heating divergence (cooling of continents) is found over ocean/sea and whole of the China region, Tibetan and central Himalayas (because of excess condensation than evaporation). The adiabatic generation of kinetic energy depends on the cross isobaric flow (north to south in winter, i.e., the present study shows strong circulation during IWM). It is found that wind divergence of model concludes lower level convergence over study region (i.e., strong winter circulation in the model fields).

17 illus, 41 ref

027855   POSHTKOOHI M, AHMAD T, CHOUDHARY A K (Geology Dep, Delhi Univ, New Delhi-110 021, Email: m_poshtkoohi@yahoo.com) : Geochemistry and petrogenesis of Biabanak-Bafq mafic magmatism: Implication for the evolution of central Iranian terrane. J Earth Syst Sci 2018, 127(5), 72.

Precambrian magmatism in the Biabanak-Bafq district represents an extensive sequence of mafic magmatic rocks. Major, trace and rare earth elements reveal that the low-Ti basement mafic rocks are magnesium tholeiite and low-Ti cover a mafic rock belongs to Fe-tholeiite, whereas, the high-Ti alkaline mafic rocks, as well as dolerites, show much more Fe–Ti enrichment. Primitive mantle normalized trace element patterns show a relative enrichment of LREE and LILE and depletion of HFSE, but have an equally distinct continental signature reflected by marked negative Nb, Sr, P, and Ti anomalies. The composition of the intrusive rocks is consistent with fractional crystallization of olivine ± clinopyroxene ± plagioclase, whereas variations in the Sr and Nd isotope compositions suggest heterogeneous sources and crustal contamination. Low-Ti group samples contain a crustal signature in the form of high La/Yb, Zr/Nb, and negative εNd values. In contrast, high-Ti mafic magmatic rocks display an increase in La/Yb with a decrease in Proterozoic alkaline rocks recognized across the central Iran. The presence of diverse mafic magmatic rocks probably reflects heterogeneous nature of sub-continental lithospheric mantle (SCLM) source. The mafic magmatism largely represents magmatic arc or rift tectonic setting. It is suggested that the SCLM sources were enriched by subduction processes and asthenospheric upwelling.

12 illus, 2 tables, 102 ref

027872   ZHU X, SHAO M (Institute of Geographic Sciences and Natural Resources Research, Beijing- 100 101, Email: shaoma@igsnrr.ac.cn) : Distribution, stock, and influencing factors of soil organic carbon in an alpine meadow in the hinterland of the Qinghai-Tibetan Plateau. J Earth Syst Sci 2018, 127(5), 71.

Understanding the spatial distribution, stocks, and influencing factors of soil organic carbon (SOC) is important for understanding the current situation of SOC in alpine meadow ecosystems on the Qinghai– Tibetan Plateau (QTP). We sampled 23 soil profiles to a depth of 50 cm in a 33.5 hm² plot in a typical meadow on the central QTP. The distribution, stock and influencing factors of SOC was then analyzed. The mean density of soil carbon content (SOCD) was 2.28 kg m⁻² with a range of 5.99 kg m⁻². SOCD in the 0–10 cm layer was 3.94 kg m⁻² and decreased quadratically with depth. The total stock of SOC to a depth of 50 cm was ca. 2950 t, the 0–10 and 0–30 cm layers accounting for 38 and 80 %, respectively. SOCD varied moderately spatially and was distributed more homogeneously in the 0–10 and 40–50 cm layers but was more variable in the middle three layers. SOCD was significantly correlated positively with soil-water content, total porosity, and silt content and negatively with soil pH, bulk density, stone content and sand content. This study provides an important contribution to understanding the role of alpine meadows in the global carbon cycle. It also provides field data for model simulation and the management of alpine meadow ecosystems.

4 illus, 5 tables, 44 ref

027839   JOSHI A U, LIMAYE M A (Geology Dep, The Maharaja Sayajirao Univ of Baroda, Vadodara- 390 002, Email: limaye.manoj-geology@msubaroda.ac.in) : Rootless calc-silicate folds in granite: An implication towards syn- to post-plutonic emplacement. J Earth Syst Sci 2018, 127(5), 67.

Deformation of the Champaner Group of rocks that form a part of Southern Aravalli Mountain Belt, western India, occurred during the Grenville orogeny (ca. 1400–935 Ma). Two phases of deformation are recorded: D₁, persistent throughout the group and characterised by westerly plunging tight isoclinal folds and D₂, a localized phase of deformation associated with shortening of the earlier folds from the eastern margin. Both the phases of deformation are in association with the syn-tectonically emplaced Godhra granite. The present work records rootless calc-silicate folds in granite belonging to the older formation, located at the eastern fringe of the Champaner Group. Field evidences suggest superimposition of Type 2 interference pattern trending NE–SW over rootless Type 0 of varying trends from NW–SE to N–S. The superposed pattern obtained from the field study differs in terms of structural trends with the neighbouring Precambrian stratigraphic units. These stratigraphic units include the Champaner Group to which the study area belongs, the Kadana Formation of the Lunavada Group and Pre-Chamapaner Gneissic Complex. Rootless character of folds found within the study area imply syn-post plutonic emplacement of Godhra granite.

3 illus, 2 tables, 29 ref

027853   PANDEY A, SINGH I, MISHRA R L, RAO P S, SRIVASTAVA H B, JAYANGONDAPERUMAL R (Wadia Institute of Himalayan, Dehradun- 248 001, Email: ramperu.jayan@gmail.com) : Active tectonics in the Assam seismic gap between the meizoseismal zone of AD 1934 and 1950 earthquakes along eastern Himalayan front, India. J Earth Syst Sci 2018, 127(5), 66.

The Assam Seismic Gap has witnessed a long seismic quiescence since the Mw$~$8.4 great Assam earthquake of AD 1950. Owing to its improper connectivity over the last decades, this segment of the Himalaya has long remained inadequately explored by geoscientists. Recent geodetic measurements in the eastern Himalaya using GPS document a discrepancy between the geologic and geodetic convergence rates. West to east increase in convergence rate added with shorter time span earthquakes like the 1697 Sadiya, 1714 (Mw$~$8) Bhutan and 1950 (Mw$~$8.4) Tibet–Assam, makes this discrepancy more composite and crucial in terms of seismic hazard assessment. To understand the scenario of palaeoearthquake surface rupturing and deformation of youngest landforms between the meizoseismal areas of Mw$~$8.1 1934 and 1950 earthquakes, the area between the Manas and Dhanshiri Rivers along the Himalayan Frontal Thrust (HFT) was traversed. The general deformation pattern reflects north-dipping thrust faults. However, back facing scarps were also observed in conjugation to the discontinuous scarps along the frontal thrust. Preliminary mapping along with the published literature suggests that, in the eastern Himalayan front the deformation is taking place largely by the thrust sheet translation without producing a prominent fault-related folds, unlike that of the central and western Himalayas.

14 illus, 60 ref

027838   JAISWAL S, BHATTACHARYA B (Earth Sciences Dep, Indian Institute of Technology, Roorkee- 247 667, Email: bb.geol.dgc@gmail.com) : Characterization of middle Eocene tide-influenced delta: A study from core samples of Hazad member, Ankleshwar formation, South Cambay Basin, India. J Earth Syst Sci 2018, 127(5), 65.

The Hazad Member (Middle Eocene) of the Ankleswar Formation in Cambay Basin, India, is traditionally reported as deltaic system. Present work documents three major facies associations, namely, (i) sandstone-rich upper delta plain (FA-1) deposits, (ii) sandstone-mudstone heterolithic lower delta plain–delta front (FA-2) deposits, and (iii) shale-dominated prodelta (FA-3) deposits, in an overall coarsening-up to fining-up succession. Tidalites are well preserved in FA-2 and are represented by laterally accreted tidal bundles, tidal beddings and vertically accreted tidal rhythmites, described from drill core samples in this communication. Laterally accreted tidal bundles with reactivation surfaces in sanddominated heterolithic units indicate time-velocity asymmetry in subtidal condition. Tidal beddings and tidal rhythmites in mud-dominated heterolithic units, associated with asymmetric/symmetric ripple forms and desiccation cracks, indicate periodic subaerial emergence in intertidal flat depositional setting. Systematic analysis of the architecture of the tidalites in different parts of the basin signifies rapid shift in sedimentation from subtidal to intertidal flat within the lower delta plain. Transitions from prodeltaic to tidally (subtidal-intertidal) affected delta front to lower delta plain and fluvial-dominated upper delta plain depositional systems attest to high frequency transgressive-regressive cycles in response to changing accommodation, as a result of sea level fluctuations and basinal tectonisms in the Cambay Basin.

9 illus, 2 tables, 42 ref

027830   BHAT N A, JEELANI G (Earth Sciences Dep, Kashmir Univ, Srinagar-190 006, Email: mnadeem83@gmail.com) : Quantification of groundwater-surface water interactions using environmental isotopes: A case study of Bringi Watershed, Kashmir Himalayas, India. J Earth Syst Sci 2018, 127(5), 63.

Environmental isotopes including δ¹⁸O, δ²H and ³H of precipitation, streams and springs were determined in the mountainous Bringi catchment of Kashmir Himalaya, dominated by carbonate lithology. The isotopic signature of winter precipitation is reflected in stream and spring water in late spring and is, therefore, representative of snow melting. The spring waters in September bear the enriched isotopic signatures of summer rainfall. The strong correlation (r² = 0.97) between the isotopic composition of streams and springs indicates the streams and springs either share similar catchments or the springs are recharged by the streams. Chloride mass balance and isotopic mass balance studies suggest that the surface recharge component averages 337.35 m³/s, which is about 75 % of total stream discharge during the high flow period. Similarly, the contribution of surface water to groundwater recharge during the low flow period averages 7.5 m³/s, which is about 18.6 % of total stream flow. Furthermore, the mean residence time of the springs calculated from the tritium decay equation is very short (<1 year). The residence time is longer for Kongamnag and short for Achabalnag, which is further supported by dye testing.

4 illus, 2 tables, 62 ref

027859   SASTRY R G, CHAHAR S, VILADKAR M N (Earth Sciences Dep, Indian Institute of Technology, Roorkee, Email: rgss1fes@iitr.ac.in) : Statistical analysis of geo-electric imaging and geotechnical test results- A case study. J Earth Syst Sci 2018, 127(5), 62.

For conjunctive use of geoelectric imaging and geotechnical site investigations in geotechnical characterization of major civil engineering construction sites, an objective assessment of influencing factors is important. Here, we present multiple regression analyses of both geoelectric (Electrical Resistivity Tomography, ERT; Induced Polarization Imaging, IPI) and geotechnical site investigations (Standard Penetration Test, SPT) for two profiles at a construction site for CGEWHO Complex in Greater Noida region, Delhi to assess the role of influencing formation factors like sand, fines and water content. Achieved results show that SPT ‘N’ and IPI are well predicted by a linear multiple regression. On an average, the nonlinear regression has improved predicted SPT ‘N’, resistivity and chargeability by 28.55 %, 22.45 % and 9.58 %, respectively. The influence of sand and fines content is more than that of water content in the prediction of chargeability and SPT ‘N’. RMS error is less in prediction of IPI chargeability (average error of 1.96 ) in comparison to SPT ‘N’ value (average error of 11.35 %). As factors affecting chargeability (IPI) and SPT ‘N’ are similar, non-invasive IPI can be used along with few geotechnical site investigations for detailed geotechnical site investigations.

8 illus, 8 tables, 40 ref

027851   OJHA A K, SRIVASTAVA D C (Earth Sciences Dep, Indian Institute of Technology, Roorkee- 247 667, Email: ojhaarun323@gmail.com) : Effect of grain packing tightness on strain estimation from the fry method. J Earth Syst Sci 2018, 127(5), 61.

How tightly should a sample be packed for strain estimation by the Fry method? We address this issue using synthetic simulations of 900 images such that each image contains 200 randomly distributed grains, but differs from other images with respect to the packing tightness and the degree of sorting. Each image is coaxially distorted by various known strain ratios and the strain estimates from distorted images are obtained by the Fry method. The statistical errors in the strain estimates are found to grow larger with the decrease in the packing tightness irrespective of the level of distortion. We demonstrate that a progressive decrease in the packing tightness results in an increasingly clustered nature of grain center distribution and hence the larger errors. These results, obtained from the synthetic images, are corroborated by two natural examples of sandstone, one loosely packed and the other tightly packed. Based on the results of tests on synthetic and natural examples, we recommend that the Fry method should be used only on those samples that have >30 % packing density.

10 illus, 40 ref

026386   KHAN S, SINGH A, BHADAURIA S S, YADAV S S, SHARMA A (RVSKVV, Gwalior, Madhya Pradesh, Email: akhileshsingh01@gmail.com) : Soil loss estimation of a watershed of central India with integration of geospatial techniques and universal soil loss equation. Int J Agric Environ Biotechnol 2018, 11(4), 703-11.

Soil erosion is a crucial problem and a critical environmental hazard in agricultural land, river catchments and reservoirs. Its assessment by various methods such as universal soil loss equation (USLE) is widely carried out by estimating the factors of the equation in a GIS environment. The Non-River catchment in Madhya Pradesh, India comprising of 836 sq. km area was studied for soil erosion and sediment losses in entirety as well as for its 33 sub catchments. The study revealed that a vertical fall of 230 meter with a sudden drop within 10 km generates a high erosion potential by runoff water in micro catchments numbered 1,2, 3, 7, 21 and 29. The erosivity (R) parameter of catchment suggested of medium precipitation but high kinetic energy in western and southern part of the catchment. The topographic factor (LS) in western part of the catchments is higher which covers the sub catchments referred above. The forest land, fallow land and ravine lands comprising of 43.79 % of the total catchment area are having sparsevegetation and steep slopes, and are more prone to the soil erosion. In the Non River catchment no conservation practices are followed. The total annual rate of soil erosion in the catchment, as obtained by multiplying USLE factors, ranged variably under different land uses. The erosion from the steep and sparsely vegetated sub catchments under forest and fallows is highest in the range of 5.90-10.25 t/ha/yr. However, the agricultural land comprising of 50 % of the catchment area is under the ‘slight’ class of the erosion ranging from 0.05 to 2.57 t/ha/yr.

12 illus, 4 tables, 22 ref

026385   SINGLA S K, PATEL N, PAL S, HUSSAIN M (Shri Venkateshwara Univ, Uttar Pradesh) : Evaluation of the developed strategy at field level to enhance crop water productivity in Sirsa District. Int J Mgmt Soc Sci 2018, 6(5), 1-13.

The study was carried out in Sirsa, the north western district of Haryana State. The soil texture in the belt along Ghaggar River varies from silt loam to silty clay loam. About 90 % of the net area sown is irrigated against the State average of about 81 % and national average of about 40 %. Of the total net area irrigated in the district, about 80 % receives supply from the canal irrigation system. The conclusion shows the probability of getting average annual rainfall (300- 350 mm) is at 50 % chance. Probability (P) and Recurrence Interval (RI) of annual one-day maximum runoff series based on 15 years of data (N). The average relative water supply RWS (ratio of water supply and water demand over a period of time) was observed to be 0.72 in summer and 0.65 in winter at the head reach and 0.58 in summer and 0.50 in winter at the tail reach of watercourses. At present, wheat in the Rabi season and cotton or rice in the Kharif season are the main crops.The amount of inflow and outflows components and balancing of irrigation components based on the monthly deficiency and storage of water. The depth of water application to field is 0.1016 m., and tube well discharge is 135.46 m³/hr. There are a large numbers of tanks and ponds in the district which act as water conservation structures and ground water recharge structures in the district.

9 illus, 8 tables, 18 ref

026384   GUO X, NI H, LI M, ZHANG L, WANG Y, DING L (China Univ of Petroleum, Qingdao- 266 580, China, Email: nihj@upc.edu.cn) : Experimental study on the influence of supercritical carbon dioxide soaking pressure on the mechanical properties of shale. Indian Geotech J 2018, 48(2), 384-91.

Mechanical properties of shale rock is the basic issue of the drilling and development of shale oil and gas reservoir, and it is also one important issue of developing shale oil and gas reservoir fundamental theoretical research using supercritical carbon dioxide (SC-CO₂). Experimental researching on basic aspects of shale mechanical properties after soaking in SC-CO₂ can reveal the impact on the high efficiency of rock breaking, well-bore stability and fracturing. For this reason, soaking tests of shale under different carbon dioxide pressures have been done. Results showed in this paper that shale expands lightly at the beginning of soaking in SC-CO₂ but shrinks afterwards and tends to be smooth at last. With the increasing of soaking pressure, the uniaxial compressive strength of shale decreases while the Elastic Modulus (Young’s modulus) and Poisson’s ratio increases; the mechanical properties of shale changes rapidly when the pressure of CO₂ reaches the supercritical state. As the pressure keeps increasing, the change of mechanical properties of shale core is relatively slow and within a narrow range. In addition, the effect of CO₂ on the mechanical properties is not related to the soaking pressure. In fact, CO₂ affection on shale properties has not obviously changed when increasing the pressure after reaching supercritical state.

10 illus, 2 tables, 16 ref

026383   KARANDIKAR D V (D.V. Karandikar & Associates Consulting Engineers, Mumbai - 400 057, Email: dilipvk2002@yahoo.com) : Challenges to quality control in bored cast-in-situ piling in growing urban environment. Indian Geotech J 2018, 48(2), 360-76.

Extensive bored cast-in-situ piling work is being carried out in growing metropolitan and other large cities for foundations of multi-storeyed office and residential buildings, flyovers and for retaining deep excavations for basements. The roads are small, traffic is heavy, there are restrictions on timings for movement of construction machinery and with all these limitations, the owners/clients require speedy construction of piled foundations to come ‘above ground’ for superstructure construction. Geotechnical consultants and piling contractors face tremendous challenges in urban environment in ensuring quality in piling work. The challenges relate to all aspects of piling work such as pile-bore retention during boring, pile tip zone cleaning, deciding socket lengths in deep weathered rocks, meeting the pile termination criteria, concreting without interruptions etc. In case of shoring piles for basement excavations, installation of anchors adds to a further challenge since they would penetrate in adjoining plot. Micropiles are also being extensively used without regard to their inherent limitations in installation and load carrying capacity. These aspects are discussed in the presented paper.

22 illus, 7 tables, 7 ref

026382   JANA A, DEY A (Civil Engineering Dep, Indian Institute of Technology, Assam- 781 039, Email: arindamdeyiitg16@gmail.com) : Combined functioning of geotextile as barrier and drainage material in unsaturated earth retaining structures. Indian Geotech J 2018, 48(2), 342-59.

This article presents an insight into the effective functioning of geotextile as a barrier and drainage material when used in earth retaining structures under unsaturated conditions. A numerical model of the infiltration test on a one-dimensional soil column has been simulated and a finite element transient seepage analysis is conducted to determine the progression of saturated wetting front through the clay–geotextile interfaces. The barrier mechanism of a geotextile layer was highlighted in terms of the water accumulation over the soil–geotextile interface, and retardation of wetting front migration beneath the geotextile layer. It was observed that the barrier breakthrough time is substantially affected by the initial volumetric water content of the surrounding soil and the hydraulic characteristics of the geotextile. Rain water infiltration analysis of a geotextile revealed that the barrier effect assures the geotextile to be functioning as horizontal drainage layer after exceeding the breakthrough suction of the geotextile. Provision of a facing drain channels the surface runoff, as well as the water emanated from the geotextile layers, to the toe drain. Such provisions resulting in an effective drainage system substantially lowers the lateral thrust and improves the stability of the soil wall, which inadvertently enhances the sustainability of the reinforced soil walls with marginal soil backfills.

19 illus, 3 tables, 41 ref

026381   ROY S, RAJESH S (Civil Engineering Dep, Indian Institute of Technology, Kanpur, Email: hsrajesh@iitk.ac.in) : Influence of confining pressure on water retention characteristics of compacted soil. Indian Geotech J 2018, 48(2), 327-41.

Sustainability of earth structures is one of the major concerns in the field of geotechnical engineering. Recurring evaluation and maintenance related to earth structures can often lead to faulty decisions due to errors in analysis. A prominent such concern is related to compacted soils in earth structures which are unsaturated in nature and subjected to stress variations in field. Under the effect of stress state, the key parameters to assess the strength and deformation behavior of unsaturated soils might undergo various changes. In general, key parameters are obtained from soil water characteristic curve (SWCC). In the present study, an effort has been made to understand the influence of confining pressure on the SWCC of compacted soil through experimental and analytical studies. The SWCC of compacted soil at zero net confinement was obtained using tensiometers (HYPROP) and dew point potentiometer (WP4C) while for various net confining pressures, modified triaxial apparatus (using axis translation technique) is used. The measured soil suction-water content data was fitted with five most widely used SWCC models available in literature. The key parameters of SWCC fitted with least square regression technique was compared for all the five models to assess the effectiveness of the models in predicting the SWCC correctly over the entire suction range. Results indicate that there is a disparity in the obtained key parameters from various SWCC models. The influence of stress state on the SWCC obtained experimentally is compared with the analytical solution accounting the influence of stress state.

11 illus, 7 tables, 36 ref

026380   BHATTACHERJEE D, VISWANADHAM B V S (Civil Engineering Dep, Indian Institute of Technology Bombay, Mumbai- 400 076, Email: dipankanabhattacherjee@iitb.ac.in) : Effect of geocomposite layers on slope stability under rainfall condition. Indian Geotech J 2018, 48(2), 316-26.

Slope instability and associated loss of matric suction under rainfall condition is a serious global issue, and deserves special attention. The objective of the present paper is to investigate the effect of inclusion of a special variety of geosynthetic material, referred to as geocomposite (or dual-function hybrid geosynthetic) within slopes subjected to rainfall. In this regard, centrifuge based physical modelling was performed on a model silty-sand slope having 7.2 m height (prototype scale) and 2V:1H inclination at 30 gravities using the 4.5 m radius centrifuge facility available at IIT Bombay, India. A rainfall simulating assembly was designed and developed for the above study, capable of producing fine mist at a uniform rate during in-flight testing using specially designed pneumatic nozzles (intensity range: 2 mm/h to as high as 80 mm/h). The surface settlements, displacement profile, strain experienced by reinforcement layers, and pore water pressure profiles developed during rainfall were investigated in the unreinforced and reinforced slope models. It was observed that, the unreinforced slope model experienced excessive settlement and increasing phreatic levels with rainfall, leading to catastrophic failure. On the contrary, the geocomposite reinforced slope was stable under rainfall condition, and experienced negligible deformation with progress of rainfall, the maximum peak strain value being as low as 8.01 %. Further, the inclusion of geocomposite layers provided preferential drainage channels within the slope, and resulted in reduction of pore water pressure values by almost 47 %, thereby indicating the importance of coupling the functions of reinforcement and drainage simultaneously within low-permeability slopes subjected to rainfall. The above finding facilitates the use of locally available low-permeable soils in construction of reinforced soil walls/slopes, thereby economizing the project. Further, use of marginal soils in combination with geocomposites (or hybrid geosynthetics) can prevent the unsustainable mining of natural sand deposits for construction purposes, while catering to the problem of scarcity of good quality permeable granular materials in recent times.

8 illus, 4 tables, 24 ref

026379   KUMAR M, SANTRA P, SINGH S K, RAINA P, KAR A, RAM B, MOHARANA P C (ICAR-Central Arid Zone Research Institute, Rajasthan- 342 003, Email: maheshcazri@gmail.com) : Identifying sensitive soil properties as a function of land use change in Thar desert of India. Agric Res 2018, 7(2), 187-99.

Soil plays a critical role in earth’s biosphere by supporting the production of food, fodder and fiber. However, rapid land use changes in recent times in different parts of the world led to increasing concern on soil health. It has been realized that changes in land use systems significantly affect soil properties. Therefore, we studied the impact of land use systems on soil physicochemical properties in the Thar Desert of India. Surface soil samples (0–30 cm) from four land use systems: (1) sand dunes, (2) grazing lands, (3) rainfed croplands and (4) irrigated croplands have been collected and analyzed in laboratory to determine soil pH, electrical conductivity (EC), CaCO₃ content, organic carbon content, available P content, available K content and micronutrients (Zn, Fe, Mn, and Cu) content. We observed higher clay, organic carbon and nutrient contents and lower bulk density values in irrigated croplands than in other land use systems. Soil pH and EC were higher in irrigated croplands than in the other land use systems. Principal component analysis of soil physicochemical properties revealed two major soil factors, the clay–carbon factor and salinity factor, which were able to significantly differentiate the land use systems. For irrigated croplands, the clay–carbon factor was found to be higher than the rest of the land uses; however, the salinity factor was the lowest. Higher values of these two factors will lead to a favorable soil physicochemical environment for plant growth or better soil health. These two factors may further be used for assessing the impact of land use systems on soil quality in other regions.

8 illus, 4 tables, 33 ref

026378   YANG X, MAO X, SHAO X, HAN F, CHANG T, QIN H, LI M (Hohai Univ, Nanjing 210098, China, Email: mxy880731@163.com) : Enhanced techniques of soil washing for the remediation of heavy metal-contaminated soils. Agric Res 2018, 7(2), 99-104.

Soil washing has been developed as one of the ex situ traditional remediation methods for heavy metal polluted soils. It has been found to be effective in metal extraction. However, due to the distribution and speciation in soils, most metal(loid)s are present in less mobile forms which limit the washing efficiency. Therefore, methods are studied to enhance the washing performance by increasing the metals solubility and availability. This paper introduces some currently used methods and technologies, including the optimization of washing variables, lowering soil pH, application of assisted amendments and integration of electro-kinetic remediation and ultrasonication to enhance the removal of metals. In addition, it also suggests some further studies.

4 tables, 44 ref

026375   UNIYAL D P, ASWAL J S, CHANDER V, DOBHAL R, SRIVASTAVA N G, BARI S K (Uttarakhand State Council for Science and Technology (UCOST), Dehradun, Uttarakhand, Email: dpuniyal.ucost@gmail.com) : Drinking water quality assessment in schools of Garhwal region Uttarakhand, India. J Env Bio-Sci 2018, 32(1), 153-60.

The Himalayan state Uttarakhand comprises of two major divisions, Garhwal and Kumaon, consisting a total of 13 districts.Thedrinking water being used in the schools of Garhwal region of Uttarakhand is obtained directly from natural sources. The presentstudy was conducted under the WTI Division, Department of Science and Technology, phase II funded project.The drinking water quality parameters viz., pH, Total Hardness, Iron (Fe), Chloride (Cl), Fluoride (F), Dissolved Solids (TDS), Sulphate (SO₄), Nitrate (NO₃),Cadmium (Cd), Arsenic (As), Lead (Pb), Copper (Cu), Total Coliform and Total Residual Chlorine were observed in this study. It was observed that the physico-chemical properties and metal contents were as per BSI standards and found suitable for drinking purposes. However, Total coliform of some sampling sites ranged from 6-18 MPN/100 ml. Besides this some suggestions were made for improving the water quality and hygiene, which may help may help for better health conditions.

9 illus, 2 tables, 18 ref

026374   SINGH R K, KUMARSINGH A, REWATIKANT, KUMAR R, KUMAR V, SHARMA S (Chemistry Dep, M.U, Bodh- Gaya) : Study of pollutant parameters of some coal bead methane well water. J Env Bio-Sci 2018, 32(1), 49-56.

The extraction of methane gas is facilitated by pumping of ground water from coal bead mines for regular and consistent gas production. This water is discharged into near by pumps or rivers which ultimately purculate into the ground water of the area. Water samples collected from such well have been analyzed for different pollution parameters like pH, electrical conductivity (EC), Turbidity (NTU), bi-carbonate, calcium hardness, magnesium hardness, Fluoride, chloride, sulfate, nitrate, dissolved silica, potassium, and sodium. The study reveals high bi-carbonate, chloride, fluoride, and sodium carbonate in all most all the coal bead methane (CBM) wells of the area with a low concentration of calcium, magnesium, sulfate. The water of these CBM wells is not potable and at sometime, it is also not suitable for irrigation or other beneficial purposes without careful treatment.

11 illus, 2 tables, 21 ref

026377   INFANTE R (Caribbean Univ, PR 00731) : Temperature and precipitation trends in the United States Island State and Territories (1901- 2015). Asian J Sci Technol 2018, 9(05), 8165-75.

The temperature and precipitation trends from 1901 to 2015 for the United States island state and territories are presented. The area of study has similar climate and topographic characteristics. The data shows a slight temperature increase with time and a variable increase rate for the study area. The precipitation trend is variable for the study area and ranges from no significant changes in precipitation patterns with time to a slight decrease in precipitation with time. The precipitation ratio between rainy and dry season is also studied and discussed.

9 illus, 6 tables, 17 ref

026376   OROZU G, HALAELAW Y I, SAMUEL N, ALLADOUM M, GAYA D, ZEUHIINBA G H (Physics Dep, N’Djamena Univ, Chad) : An overview of chad rain enhancement. The open (Cloud Seeding Operation) project. Asian J Sci Technol 2018, 9(05), 8063-5.

In this paper, we try to emphasize the effect of cumulus congestus cloud seeding in Sahelian zone, using hygroscopic salts. For this purpose we first studied the climatic variability and impact on agricultural sector, livestock and water. Furthermore, we made a review of cloud seeding experiences abroad, then we studied the OPEN (Cloud Seeding Operations) project, from the point of view of its management, the performed activities and the perspectives of collaboration with other universities.

3 illus, 9 ref

025250   POURGHASEMI A, AKHBARI M (Political Geography Dep, Islamic Azad Univ, Tehran, Iran, Email: a.pourghasemi@hotmail.com) : The role of fossil fuel (oil and gas) in the world geopolitics of energy (case study of Iran 2000-2015). J Ecophysiol Occup Health 2018, 18(1-2), 18-23.

The energy plays a significant role in human life and almost it is not possible to continue the life without it. This is why energy has got a key role in our national and international policies and has shaped up patterns of rivalry, cooperation, conflict, violation, interaction, convergence, and divergence in the international arena and relations between countries and authorities. So, interestingly the sources of energy provision, energy corridors, consumer markets, energy trade, energy technology, and things like them increase in value. This study investigated energy resources in Iran and Middle East in library research method. In addition to have a unique geopolitical position, Iran is located in ellipse of energy and there is more than 70 percent of world resources of oil and 60 percent of world resources of gas in Iran. Also, Iran has located in the energy corridor of north to south and east to west and all of the ways pass through this wide country. Hence, it can pump money into the country not only by selling energy, but also with transmitting of energy and accordingly, it can evolve the country economy with a correct planning and engagement with countries.

1 illus, 5 tables, 22 ref

025240   WANG X, KE F, CAO Y, TU M (Nanjing Univ of Information Science and Technology, Jiangsu- 210 044, Email: wangxinzhi@126.com) : Combination of GPS, HY-2a and COSMIC observations to establish global ionospheric map. Indian J Geo-Mar Sci 2018, 47(5), 1000-10.

The systematic biases of the HY-2A altimetry satellite observations and COSMIC observations between ground-based GNSS observations are taken into account, and they were estimated together with the unknown coefficients of SH expansion by least squares. Meanwhile, Helmert variance component estimation method was used to determine the precise weights of each observations taking into account of the different accuracy of each observations. As an example, three types of observations in DOY 101, 2015 were used to establish a combined GIM in two-hourly snapshots. The differences of the combined GIM and GIM published by IGS were also analyzed. Compared with the RMS map of GIM published by IGS, it found that the accuracy of the combined GIM improved about 0.3TECU after adding HY-2A altimetry satellite and COSMIC observations. The accuracy improved more obvious in the ocean areas where HY-2A altimetry satellite observed.

12 illus, 28 ref

025239   ZHU J, KANG J (Shanghai Normal Univ, Shanghai- 200234, China, Email: jianchengkang@126.com]) : Analysis of temporal and spatial variation in sea temperature during typhoons based on argo data. Indian J Geo-Mar Sci 2018, 47(5), 990-9.

Two typhoons: MATSA (0509) and SAOMAI (0608) were selected and sea temperatures analysed. The results revealed that typhoons can cause water upwelling or downwelling in the vertical direction. On a temporal scale, upwelling or downwelling was most significant when the maximum wind speed was 25 m/s and 38 m/s. On a spatial scale, water temperature at 0-50 m depth largely decreased and vertical variation was small. At 50-300 m heating and cooling were observed, with larger vertical variation. The most significant changes were recorded at 150 m. The impact of the studied typhoons on the upper ocean can be divided into three components: In the first layer at 5-60 m depth, the driving force of the typhoon had a direct effect on the sea. In the second layer at 60-200 m this driving force had weakened, and by 200-300 m had weakened further, potentially at work inside waves (Rossby wave). Typhoon impact can also be divided into inner and outer layers, with the centre of the underlying sea area mainly affected by pumping, to a depth of 300 m. On either side beneath the typhoon centre a mixing effect predominated comprising two hot and cold water masses, with the most significant change observed here at 160 m depth.

8 illus, 3 tables, 23 ref

025238   THASNEEM T A, NANDAN S B, GEETHA P N (Marine Biology Dep, Cochin Univ of Science and Technology, Cochin-682 016, Email: bijoynandan@yahoo.co.in) : Water quality status of Cochin estuary, India. Indian J Geo-Mar Sci 2018, 47(5), 978-89.

In the present study the water quality of the Cochin estuary was monitored from June 2009 to May 2011. The depth of the Cochin estuary was found to be reduced. Range of water temperature showed an increasing trend. Salinity of the estuary showed oligo-mesohaline nature. TDS established a strong positive correlation significant at 1% level between river discharge and conductivity. Higher oxygen concentration during post-monsoon period was due to the higher primary production occurring in the surface layers during this period. Elevated levels of CO₂ and pH shifting to alkaline side indicate ecosystem stress. Organic pollution and nutrient enrichment in the Cochin estuary is attributed to the high BOD values (>5mg L^-1). Average concentration of ammonia-N₂ increased. The heavy rainfall and the increased surface runoff during the monsoon attributed to the high values of silicate in the surface waters during monsoon period. In the Cochin estuary the season wise, zone wise and year wise analysis of Redfield ratio showed a nitrogen limiting condition.

4 illus, 1 table, 51 ref

025237   HUO R, LI S, HAN F, WANG G (Xi'an Univ of Architecture and Technology, Xi'an-710055, China, Email: lssgg2015@163.com) : CT analysis on mesoscopic structure of sandstone under acidic environment. Indian J Geo Mar Sci 2018, 47(5), 962-71.

Present study consists the mesoscopic structure of sandstone under acidic environment through CT analysis. Simulation of indoor accelerated corrosion test and CT nondestructive identification technology were applied to CT scanning test for the micro-structure of sandstone at different corrosion stages. It is found that as the extension of soak time, the CT number of wet sandstone samples in different stages trended to increase at first then decrease, the CT number of dry samples gradually decreased with extension of the soak time. The CT number variance of dry and wet samples were decreased first and then increased as soak time. CT images of the internal structure of wet and dry sandstone samples in the corrosion process were obtained and processed. Mass loss of sandstone in different corrosion stages was calculated. The variation of samples' quality and density, which were achieved from the experiment on the one hand and from the calculation of CT number on the other, were compared, and good agreement was achieved. Penetration depth of the sulfuric acid solution at different soak periods was deduced.

7 illus, 6 tables, 14 ref

025236   LUHIA M, ZHIQUIANG Y (Chinese Academy of Sciences, Beijing -100 101, Pr China, Email: mlh@nao.cas.cn) : Possible solar modulation of mean sea level pressure in Madras of India during 1796 - 2002. Indian J Geo Mar Sci 2018, 47(5), 959-61.

With mean sea level pressure (MSLP) series in Madras of India during 1796 – 2002, the authors use wavelet technique to investigate possible connection between MSLP in Madras and solar activity. The study shows the modulation action from solar activity plays an important role in the MSLP series. There is a possible association existing in the MSLP series and solar activity on decade time scales.

3 illus, 14 ref

025235   SREEKANT G B, CHAKRABORTY S K, JAISWAR A K, ZACHARIA P U (ICAR-Central Coastal Agricultural Research Institute, Goa - 403 402, Email: gbsree@gmail.com) : An inventory on the coastal finfish and shellfish species of zuari estuary, southwest coast of India. Indian J Geo Mar Sci 2018, 47(5), 945-8.

Assessment of finfish and shellfish species were carried out for a period of three years through continuous surveys (400 gillnet fishing experiments) with a total fishing effort of 100 fishing days along the Zuari estuary. This study yielded 286 finfish and shellfish species comprising of 156 demersal fish, 68 pelagic fish, 38 molluscan and 24 crustacean species. The species observed in this study covered all the trophic levels in the food web as well as the ecologically vulnerable and less resilient species (20-25 %). Majority of the commercially important species of Zuari estuary were also collected in this study contribute to 70 % of the catch.

1 illus, 15 ref

025234   MAJUMDAR T J, BHATTACHARYYA R, KRISHNA K S (Space Applications Centre (ISRO), Ahmedabad, Email: tjmajumdar@rediffmail.com) : On lithospheric studies utilizing geoid/gravity anomalies over the Enderby basin, Antarctica. Indian J Geo Mar Sci 2018, 47(5), 937-44.

Present article is the study of various products of satellite data of the Enderby Basin, thereby correlated to known plate tectonic features, volcanic traces and continental margin features. Timing for breakup of the Indian continent from eastern Gondwanaland and evolution of the lithosphere in the Bay of Bengal are still remained as ambiguous issues. Geoid and free- air gravity data of the conjugate regions, Bay of Bengal and Enderby Basin, are coupled with ship-borne geophysical data for investigation of early evolution of the eastern Indian Ocean. The geoid and gravity data over the western Enderby Basin reveal a major Kerguelen Fracture Zone (FZ) and five N4°E FZs. Spectral analyses of free-air gravity anomaly over a part of the Enderby Basin near Conrad Rise indicate that the sources of those anomalies varies between 100-400 km The results obtained from these analyses may help in further exploration in these conjugate basins.

6 illus, 28 ref

025233   YADAV R, TIWARI V M (CSIR – National Geophysical Research Institute, Hyderabad, Email: virendra.m.tiwari@gmail.com) : Lithospheric density structure of Andaman subduction zone from joint modelling of gravity and geoid data. Indian J Geo-Mar Sci 2018, 47(5), 931-6.

The Andaman subduction zone is the result of the oblique convergence of Indian plate that dives beneath Eurasian (Sunda) plate and one of the most seismically active regions. Structure and dynamics of the subduction zone are still a matter of investigations, inspite of a several studies were carried out earlier. In the present study, we have delineated the 2D density structure of the Andaman subduction zone through the joint modelling of gravity and geoid data set derived from the satellite altimetry and interpreted it in term of dynamics of the region. The major features of the density structures are : subduction of Indian plate up to ~ 180 km depth; anomalously thicker oceanic crust below the Ninetyeast Ridge, Sewell rise and in the shelf region; comparatively thin lithosphere under the overriding plate. Further, the lowest gravity anomaly marks the interaction of subducting oceanic crust with overriding upper mantle.

4 illus, 38 ref

025270   SHRESTHA S, KANG T S, CHOI J C (Earth and Environmental Sciences Dep, Pukyong National Univ, Busan- 48513, Email: jcchoi@pknu.ac.kr) : Assessment of co-seismic landslide susceptibility using LR and ANCOVA in Barpak region, Nepal. J Earth Syst Sci 2018, 127(3), 38.

Nepal was affected by a catastrophic earthquake with Mw 7.8 on 25th April, 2015 with its epicenter in the central part of Barpak village. A number of co-seismic landslides were triggered by the main shock of the event and associated aftershocks. Due to the rugged topography and vicinity of the main shock, the village was extremely affected by co-seismic landslides. In total, 59 landslides were identified using Google Earth and were verified during the field survey in Barpak village. Furthermore, 11 conditioning factors, including Peak ground acceleration (PGA), epicenter proximity, fault proximity, geology, slope, elevation, plan curvature, profile curvature, topographic wetness index, drainage proximity and the sediment transport index were selected as independent variables for analysis. In this study, logistic regression (LR) and analysis of covariance (ANCOVA) models were used and their performance was assessed. Finally, the landslide susceptibility classes were produced and an evaluation of models was done by using receiver operating characteristic curves. The area under the curve for LR and ANCOVA showed 85.38 and 78.4 % accuracy, respectively. Based on the overall assessments, the LR model was more accurate than the ANCOVA model for co-seismic landslide prediction in the study area. The result of this study can be used to mitigate landslide-induced hazards and for land-use planning.

17 illus, 3 tables, 56 ref

025269   WANG J, GAO Y, WANG S (Institute of Geographic Sciences and Natural Resources Research, Beijing-100 101, Email: gaoyanchun igsnrr@163.com) : Assessing the response of runoff to climate change and human activities for a typical basin in the Northern Taihang Mountain, China. J Earth Syst Sci 2018, 127(3), 37.

Climate change and human activities are the two main factors on runoff change. Quantifying the contribution of climate change and human activities on runoff change is important for water resources planning and management. In this study, the variation trend and abrupt change point of hydrometeorological factors during 1960–2012 were detected by using the Mann–Kendall test and Pettitt change-point statistics. Then the runoff was simulated by SWAT model. The contribution of climate change and human activities on runoff change was calculated based on the SWAT model and the elasticity coefficient method. The results showed that in contrast to the increasing trend for annual temperature, the significant decreasing trends were detected for annual runoff and precipitation, with an abrupt change point in 1982. The simulated results of SWAT had good consistency with observed ones, and the values of R² and E_NS all exceeded 0.75. The two methods used for assessing the contribution of climate change and human activities on runoff reduction yielded consistent results. The contribution of climate change (precipitation reduction and temperature rise) was $~$37.5 %, while the contribution of human activities (the increase of economic forest and built-up land, hydrologic projects) was $~$62.5 %.

7 illus, 8 tables, 50 ref

025268   PUANGJAKTHA P, PAILOPLEE S (Geology Dep, Chulalongkorn Univ, Bangkok- 103 30, Email: Pailoplee.S@gmail.com) : Application of the region-time-length algorithm to study of earthquake precursors in the Thailand-Laos-Myanmar borders. J Earth Syst Sci 2018, 127(3), 36.

In order to examine the precursory seismic quiescence of upcoming hazardous earthquakes, the seismicity data available in the vicinity of the Thailand–Laos–Myanmar borders was analyzed using the Region– Time–Length (RTL) algorithm based statistical technique. The utilized earthquake data were obtained from the International Seismological Centre. Thereafter, the homogeneity and completeness of the catalogue were improved. After performing iterative tests with different values of the r₀ and t₀ parameters, those of r₀ = 120 km and t₀ = 2 yr yielded reasonable estimates of the anomalous RTL scores, in both temporal variation and spatial distribution, of a few years prior to five out of eight strong-to-major recognized earthquakes. Statistical evaluation of both the correlation coefficient and stochastic process for the RTL were checked and revealed that the RTL score obtained here excluded artificial or random phenomena. Therefore, the prospective earthquake sources mentioned here should be recognized and effective mitigation plans should be provided.

6 illus, 2 tables, 42 ref

025267   SANTRA P, KUMAR M, KUMAWAT R N, PAINULI D K, HATI K M, HEUVELINK G B M, BATJES N H (ICAR-Central Arid Zone Research Institute (CAZRI), Jodhpur-342 003, Email: Priyabrata.Santra@icar.gov.in) : Pedotransfer functions to estimate soil water content at field capacity and permanent wilting point in hot Arid Western India. J Earth Syst Sci 2018, 127(3), 35.

Characterization of soil water retention, e.g., water content at field capacity (FC) and permanent wilting point (PWP) over a landscape plays a key role in efficient utilization of available scarce water resources in dry land agriculture; however, direct measurement thereof for multiple locations in the field is not always feasible. Therefore, pedotransfer functions (PTFs) were developed to estimate soil water retention at FC and PWP for dryland soils of India. A soil database available for Arid Western India (N=370) was used to develop PTFs. The developed PTFs were tested in two independent datasets from arid regions of India (N=36) and an arid region of USA (N=1789). While testing these PTFs using independent data from India, root mean square error (RMSE) was found to be 2.65 and 1.08 for FC and PWP, respectively, whereas for most of the tested ‘established’ PTFs, the RMSE was >3.41 and >1.15, respectively. Performance of the developed PTFs from the independent dataset from USA was comparable with estimates derived from ‘established’ PTFs. For wide applicability of the developed PTFs, a user-friendly soil moisture calculator was developed. The PTFs developed in this study may be quite useful to farmers for scheduling irrigation water as per soil type.

6 illus, 8 tables, 49 ref

025266   SINGH S, MAURYA V P, SINGH R K, SRIVASTAVA S, TRIPATHI A, ADHIKARI P K (Applied Geophysics Dep, Indian School of Mines, Dhanbad- 826 004, Email: svismagp@gmail.com) : Audio-magnetotelluric investigation of sulfide mineralization in Proterozoic?Archean greenstone belts of Eastern Indian Craton. J Earth Syst Sci 2018, 127(3), 34.

Greenstone belts are well known for gold occurrences at different regions of the world. The Dhanjori basin in the eastern Singhbhum region shows major characteristics of a rifted greenstone belt. Initially, we conducted 14 audio-magnetotelluric (AMT) measurements for a profile of $~$20 km in the frequency range of 1 kHz to 10 Hz over this rather complex geologic environment covering Dhanjori Volcanics (DhV) and Kolhan Group (KG). Subsequently, gravity and magnetic surveys were also conducted over this AMT profile. The purpose of the survey was to identify and map conductive features and to relate them to metallogeny of the area along with the mapping of the basement of Dhanjori basin. The strike analysis showed N30$°$W strike for DhV for all the frequencies and for sites over KG domain in the frequency range of 100–10 Hz, but for KG domain, the obtained strike in 1 kHz to 100 Hz is N45$°$E. As the combination of transverse electric (TE), transverse magnetic (TM) and tipper (Tzy) can recover the electrical signature in complex geological environment, we discuss the conductivity model obtained from TE+TM+Tzy only. The inversion was carried for the regional profile with 14 sites and for 7 sites over KG domain. Conductivity model shows two well resolved conductors, one each in KG and Quartz Pebble Conglomerate Dhanjori (QPCD) domains respectively showing common linked concordant features between these regional and KG profiles. The conductors are interpreted as sulfide mineralization linked with QPCD group of rocks which may host gold. These conductors are also horizontally disposed due to the intrusive younger Mayurbhanj Granite. These intrusives correlate well with the gravity modeling as well. The thickness of the Dhanjori basin at the central is about 3.0 km, similar to that from gravity modeling. The conductivity model also indicates the presence of shallow conductors, but could not be resolved due to lack of high frequency data. However, the results from the close-by drill site indicate the presence of shallow sulfide mineralization hosting gold. The deep level conductors delineated from AMT studies are associated with gravity high and low magnetic. ICP-AES results of Dhanjori samples show significant concentration of gold $~$5.0 g/t, which is of economic consideration. Thus, it can be inferred that the conductors have evidences of sulfide mineralization which host gold.

10 illus, 1 table, 56 ref

025265   FU Q, YAN P, LI T, CUI S, PENG L (Northeast Agricultural Univ, Harbin-150 038, Email: fuqiang0629@126.com) : Effects of straw mulching on soil evaporation during the soil thawing period in a cold region in northeastern China. J Earth Syst Sci 2018, 127(3), 33.

To study the effect of straw mulching on soil water evaporation, it is necessary to measure soil water evaporation under different conditions of straw mulching during the soil thawing period. A field experiment was conducted in winter, and soil evaporation was measured using a microlysimeter on bare land (LD) and 4500 (GF4500), 9000 (GF9000) and 13500 kg/hm² (GF13500) straw mulch. The influence of different quantities of straw mulch on soil water evaporation during the thawing period was analyzed using the Mallat algorithm, statistical analysis and information cost function. The results showed that straw mulching could delay the thawing of the surface soil by 3–6 d, decrease the speed at which the surface soil thaws by 0.40–0.80 cm/d, delay the peak soil liquid water content, increase the soil liquid water content, reduce the cumulative evaporation by 2.70–7.40 mm in the thawing period, increase the range of soil evaporation by 0.04–0.10 mm in the early stage of the thawing period, and reduce the range of soil evaporation by 0.25–0.90 mm in the late stage of the thawing period. Straw mulching could reduce the range of and variation in soil evaporation and can reduce the effect of random factors on soil evaporation. When the amount of straw mulch exceeded 9000 kg/hm² , the effect of increasing the amount of straw mulch on daily soil water evaporation was small.

7 illus, 3 tables, 44 ref

025264   PILLAI S P, PANDE K, KALE V S (Earth Sciences Dep, Indian Institute of Technology, Mumbai-400 076, Email: dr.vivekale@gmail.com) : Implications of new ⁴⁰Ar/³⁹Ar age of Mallapur Intrusives on the chronology and evolution of the Kaladgi Basin, Dharwar Craton, India. J Earth Syst Sci 2018, 127(3), 32.

The Kaladgi Basin on the northern edge of the Dharwar craton has characters diverse from the other epicratonic Purana basins of Peninsular India. Sedimentological studies in the basin have established the presence of three cycles of flooding separated by an event of intra-basinal deformation accompanied by low grade incipient metamorphism. The overall structural configuration of the basin indicates its development by supracrustal extension accompanied by shearing in a trans-tensional regime during the Mesoproterozoic. This was followed by sagging that yielded Neoproterozoic sedimentation in a successor nested basin. ⁴⁰Ar/³⁹Ar dating of an intrusive mafic dyke along the axial plane of a fold has yielded a plateau age of 1154±4 Ma. This helps constraint the age of the various events during the evolution of this basin.

9 illus, 3 tables, 74 ref

025263   XAVIER A, MANOJ M G, MOHANKUMAR K (Cochin Univ of Science and Technology, Cochin-682 022, Email: mgatmos@gmail.com) : On the dynamics of an extreme rainfall event in northern India in 2013. J Earth Syst Sci 2018, 127(2), 30.

India experienced a heavy rainfall event in the year 2013 over Uttarakhand and its adjoining areas, which was exceptional as it witnessed the fastest monsoon progression. This study aims to explore the causative factors of this heavy rainfall event leading to flood and landslides which claimed huge loss of lives and property. The catastrophic event occurred from 14th to 17th June, 2013 during which the state received 375 % more rainfall than the highest rainfall recorded during a normal monsoon season. Using the high resolution precipitation data and complementary parameters, we found that the mid-latitude westerlies shifted southward from its normal position during the intense flooding event. The southward extension of subtropical jet (STJ) over the northern part of India was observed only during the event days and its intensity was found to be increasing from 14th to 16th June. The classical theory of westward tilt of mid-latitude trough with height, which acts to intensify the system through the transfer of potential energy of the mean flow, is evident from analysis of relative vorticity at multiple pressure levels. On analysing the North Atlantic Oscillation (NAO), negative values were observed during the event days. Thus, the decrease in pressure gradient resulted in decrease of the intensity of westerlies which caused the cold air to move southward. During the event, as the cold air moved south, it pushed the mid-latitude westerlies south of its normal position during summer monsoon and created a conducive atmosphere for the intensification of the system.

9 illus, 56 ref

025262   BHATTACHARYA B, BHATTACHARJEE J, BANDYOPADHYAY S, BANERJEE S, ADHIKARI K (Earth Sciences Dep, Indian Institute of Technology, Roorkee-247 667, Email: bb.geol.dgc@gmail.com) : Early Permian transgressive-regressive cycles: Sequence stratigraphic reappraisal of the coal-bearing Barakar Formation, Raniganj Basin, India. J Earth Syst Sci 2018, 127(2), 29.

The present research is an attempt to assess the Barakar Formation of the Raniganj Gondwana Basin, India, in the frame of fluvio-marine (estuarine) depositional systems using sequence stratigraphic elements. Analysis of predominant facies associations signify deposition in three sub-environments: (i) a river-dominated bay-head delta zone in the inner estuary, with transition from braided fluvial channels (FA-B1) to tide-affected meandering fluvial channels and flood plains (FA-B2) in the basal part of the succession; (ii) a mixed energy central basin zone, which consists of transitional fluvio-tidal channels (FA-B2), tidal flats, associated with tidal channels and bars (FA-B₃) in the middle-upper part of the succession; and (iii) a wave-dominated outer estuary (coastal) zone (FA-B4 with FA-B₃) in the upper part of the succession. Stacked progradational (P1, P2)–retrogradational (R1, R2) successions attest to one major base level fluctuation, leading to distinct transgressive–regressive (T–R) cycles with development of initial falling stage systems tract (FSST), followed by lowstand systems tract (LST) and successive transgressive systems tracts (TST-1 and TST-2). Shift in the depositional regime from regressive to transgressive estuarine system in the early Permian Barakar Formation is attributed to change in accommodation space caused by mutual interactions of (i) base level fluctuations in response to climatic amelioration and (ii) basinal tectonisms (exhumation/sagging) related to post-glacial isostatic adjustments in the riftogenic Gondwana basins.

8 illus, 2 tables, 22 ref

025261   RYBAK O, VOLODIN E, MOROZOVA P, NEVECHERJA A (Institute of Numerical Mathematics of RAS, Moscow-119333, Email: Oleg@Rybak.vub.be) : Incorporation of ice sheet models into an earth system model: Focus on methodology of coupling. J Earth Syst Sci 2018, 127(2), 28.

Elaboration of a modern Earth system model (ESM) requires incorporation of ice sheet dynamics. Coupling of an ice sheet model (ICM) to an AOGCM is complicated by essential differences in spatial and temporal scales of cryospheric, atmospheric and oceanic components. To overcome this difficulty, we apply two different approaches for the incorporation of ice sheets into an ESM. Coupling of the Antarctic ice sheet model (AISM) to the AOGCM is accomplished via using procedures of resampling, interpolation and assigning to the AISM grid points annually averaged meanings of air surface temperature and precipitation fields generated by the AOGCM. Surface melting, which takes place mainly on the margins of the Antarctic peninsula and on ice shelves fringing the continent, is currently ignored. AISM returns anomalies of surface topography back to the AOGCM. To couple the Greenland ice sheet model (GrISM) to the AOGCM, we use a simple buffer energy- and water-balance model (EWBM-G) to account for orographically-driven precipitation and other sub-grid AOGCM-generated quantities. The output of the EWBM-G consists of surface mass balance and air surface temperature to force the GrISM, and freshwater run-off to force thermohaline circulation in the oceanic block of the AOGCM. Because of a rather complex coupling procedure of GrIS compared to AIS, the paper mostly focuses on Greenland.

11 illus, 4 tables, 61 ref

025260   KUMAR B, LAKSHMI V (Civil Engineering Dep, Madanapalle Institute of Technology & Science, Madanapalle-517 325, Email: brijeshag1684@gmail.com) : Accessing the capability of TRMM 3B42 V7 to simulate streamflow during extreme rain events: Case study for a Himalayan River Basin. J Earth Syst Sci 2018, 127(2), 27.

The paper examines the quality of Tropical Rainfall Monitoring Mission (TRMM) 3B42 V7 precipitation product to simulate the streamflow using Soil Water Assessment Tool (SWAT) model for various rainfall intensities over the Himalayan region. The SWAT model has been set up for Gandak River Basin with 41 sub-basins and 420 HRUs. Five stream gauge locations are used to simulate the streamflow for a time span of 10 years (2000–2010). Daily streamflow for the simulation period is collected from Central Water Commission (CWC), India and Department of Hydrology and Meteorology (DHM), Nepal. The simulation results are found good in terms of Nash–Sutcliffe efficiency (NSE)>0.65, coefficient of determination (R²)>0.67 and Percentage Bias (PBIAS)124.4 mm/d). The PBIAS and RSR show that TRMM simulated streamflow is suitable for moderate to heavy rainfall intensities. However, it does not perform well for light- and extremely-heavy rainfall intensities. The finding of the present work is useful for the problems related to water resources management, irrigation planning and hazard analysis over the Himalayan regions.

5 illus, 5 tables, 60 ref

025259   BYAKATONDA J, PARIDA B P, KENABATHO P K, MOALAFHI D B (Civil Engineering Dep, Botswana Univ, Botswana, Email: byakatondaj@hotmail.com) : Analysis of rainfall and temperature time series to detect long-term climatic trends and variability over semi-arid Botswana. J Earth Syst Sci 2018, 127(2), 25.

Arid and semi-arid environments have been identified with locations prone to impacts of climate variability and change. Investigating long-term trends is one way of tracing climate change impacts. This study investigates variability through annual and seasonal meteorological time series. Possible inhomogeneities and years of intervention are analysed using four absolute homogeneity tests. Trends in the climatic variables were determined using Mann–Kendall and Sen’s Slope estimator statistics. Association of El Ni˜no Southern Oscillation (ENSO) with local climate is also investigated through multivariate analysis. Results from the study show that rainfall time series are fully homogeneous with 78.6 and 50 % of the stations for maximum and minimum temperature, respectively, showing homogeneity. Trends also indicate a general decrease of 5.8, 7.4 and 18.1 % in annual, summer and winter rainfall, respectively. Warming trends are observed in annual and winter temperature at 0.3 and 1.5 % for maximum temperature and 1.7 and 6.5 % for minimum temperature, respectively. Rainfall reported a positive correlation with Southern Oscillation Index (SOI) and at the same time negative association with Sea Surface Temperatures (SSTs). Strong relationships between SSTs and maximum temperature are observed during the El Ni˜no and La Ni˜na years. These study findings could facilitate planning and management of agricultural and water resources in Botswana.

8 illus, 6 tables, 60 ref