DOLE G, PATIL-PILLAI S, KALE V S
045216 DOLE G, PATIL-PILLAI S, KALE V S (Environmental Science Dep, Savitribai Phule Pune Univ, Pune- 411 007) : Multi-tiered, disrupted crust of a sheet lava flow from the Diveghat Formation of Deccan Traps: Implications on emplacement mechanisms. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01418-9.
The crust is a vesicular layer that caps the compact core of sheet lava flows. We describe for the first time, a crust composed of multiple layers (each distinguished by a chilled glassy rind) from the Diveghat Formation in the western Deccan Volcanic Province. The multiple layers of crust developed over a single compact core of a single sheet lava flow, are shown to have been sequentially deformed in multiple phases. This is interpreted to have resulted from the endogenous emplacement of lava in successive pulses (rather than as a continuous stream) during the extrusion of the sheet lava flow. This model has several implications on the mechanism of emplacement of sheet flows in continental flood basalt provinces.
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CHATTOPADHYAY N, MALATHI K, TIDKE N, ATTRI S D, RAY K
045215 CHATTOPADHYAY N, MALATHI K, TIDKE N, ATTRI S D, RAY K (India Meteorological Dep, Climate Research & Services, Pune- 411 005) : Monitoring agricultural drought using combined drought index in India. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01417-w.
Long period data and information indicate that India faced number of droughts-like situation from colonial period. A number of indices have been developed nationally and internationally to monitor agricultural drought based on remote sensing; however, to predict the onset of agricultural drought and its evolution and monitoring in time and space in a more efficient way qualitatively, Combined Drought Index (CDI) has been developed using meteorological, land based and remote sensing observations. In this study, an effort has been made to monitor agricultural drought based on exploitation of new data, methodologies and metrics that would aid the experts to make best judgments of regional-scale drought conditions through CDI using geospatial technology. The present study has been carried out for three consecutive years of 2014, 2015 and 2016 in five states (Andhra Pradesh, Chhattisgarh, Haryana, Maharashtra and Telangana) in India at district level for southwest monsoon season when rainfed kharif crops are grown extensively across the above-mentioned states in India. CDI gives a synthetic and synoptic overview of the drought situations using a classification scheme derived from various individual indices as it has been developed to combine the strength of various indices.
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DHAMODHARAN S, RAWAT G, KUMAR S, BAGRI D S
045214 DHAMODHARAN S, RAWAT G, KUMAR S, BAGRI D S (Wadia Institute of Himalayan Geology, Dehradun) : Sedimentary thickness of the northern Indo-Gangetic plain inferred from magnetotelluric studies. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01422-z.
Knowledge of the sedimentary thickness and configuration of the basement structure are important to estimate the seismic hazards in active foreland basin. We present sedimentary thickness of the northern Indo-Gangetic plain estimated from impedance tensors of 12 magnetotelluric sites. Occam’s one dimensional inversion scheme was applied to invariant of the magnetotelluric tensors for the period range of 0.001–1 sec at each site. Inverted one dimensional model corroborates north-easterly dipping Indian basement and accordingly increased thickness of the sedimentary column towards north and east direction. The top sedimentary layers of varying thickness and resistivity are correlated with the known borewell logs and previous geophysical studies around the study area. Significant difference is observed in the resistivity of the Indian basement and thickness of the sedimentary column across the Delhi Hardwar Ridge. The difference in resistivity may be an indicative of variation in compactness and degree of saturation of the sedimentary cover and the nature of the Indian basement rock across the Delhi Haridwar Ridge.
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ROY C, MONDAL N, PEKETI A, FERNANDES S, MAPDER T, VOLVOIKAR S P, HALDAR P K, NANDI N, BHATTACHARYA T, MAZUMDAR A
045213 ROY C, MONDAL N, PEKETI A, FERNANDES S, MAPDER T, VOLVOIKAR S P, HALDAR P K, NANDI N, BHATTACHARYA T, MAZUMDAR A (Microbiology Dep, Bose Institute, Kolkata- 700 054) : Geomicrobial dynamics of Trans-Himalayan sulfur–borax spring system reveals mesophilic bacteria’s resilience to high heat. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01423-y.
Geomicrobiology of sulfur–boron-dominated, neutral-pH hydrothermal systems was revealed in a Trans-Himalayan spring named Lotus Pond, located at 4436 m, in Puga Valley, Ladakh (India), where water boils at 85 °C. Water sampled along Lotus Pond’s outflow (vent to an adjacent river called Rulang), representing an 85–14 °C gradient, had high microbial diversity and boron/chloride/sodium/sulfate/thiosulfate concentration; potassium/silicon/sulfide/sulfite was moderately abundant, whereas cesium/lithium small but definite. Majority of the bacterial genera identified in the 85–72 °C samples have no laboratory-growth reported at >45 °C, and some of those mesophiles were culturable. Sulfur-species concentration and isotope-ratio along the hydrothermal gradient, together with the distribution of genera having sulfur-oxidizing members, indicated chemolithotrophic activities in the 85–72 °C sites. While biodiversity increased in the vent-to-river trajectory all-day, maximum rise was invariably between the vent (85–81 °C) and the 78–72 °C site; below 72 °C, diversity increased gradually. Biodiversity of the vent-water exhibited diurnal fluxes relatable to the sub-surface-processes-driven temporal fluxes in physicochemical properties of the discharge. Snow-melts infiltrating (via tectonic faults) the ~160 °C geothermal reservoir located within the breccia, at ~450 m depth, apparently transport mesophilic microbes into the thermal waters. As these micro-organisms emanate with the vent-water, some remain alive, illustrating that natural bacterial populations are more heat-resilient than their laboratory counterparts.
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KRISHNA K S, ISMAIEL M, SRINIVAS K, SAHA D
045212 KRISHNA K S, ISMAIEL M, SRINIVAS K, SAHA D (Hyderabad Univ, Hyderabad- 500 046) : Post-breakup deformations in the Bay of Bengal: Response of crustal strata to the sediment load. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01436-7.
Passive continental margins are tectonically inactive, but a few of them including the East India Passive Margin (EIPM) show evidences for post-breakup deformations. This unusual process prompted us to investigate the post-rift deformations on EIPM and adjacent deep-water region for understanding the possible mechanisms. Seismic reflection images of the Bay of Bengal reveal a post-rift deformation with a manifestation of extensional faults in Krishna–Godavari (K–G) basin and on flanks of the 85°E Ridge. In K–G basin, one of the rift-related faults reactivated during the Early Miocene time (~16 Ma), while on flanks of the 85°E Ridge new normal faults originated at about 6.8 Ma. From detailed analysis of fault throws, it is observed that the fault in K–G basin recorded a cumulative throw of about 900 m between the basement and Early Miocene horizon (~16 Ma), later the fault was reactivated at 6.8 Ma and continued the activity progressively until 0.3 Ma before cessation. The fault system on the margin spatially extends for about 300 km between offshore extensions of the Pranahita–Godavari graben and Nagavali–Vamshadhara shear zone. The faults on 85°E Ridge, initiated at 6.8 Ma and continued until 0.8 Ma, have cumulative throws of about 60 and 110 m on western and eastern flanks of the ridge, respectively. Back-stripping analysis of the fault from the K–G basin discloses two distinct phases of subsidence history: (i) during the first phase (120–23 Ma) the basement subsided at a rate of 46–18 m/Myr due to thermal cooling of the lithosphere, (ii) during the second phase (23 Ma–Present) rapid subsidence rate (69.56 m/Myr) of basement is noticed as a consequence of deposition of copious amounts of Bengal Fan sediments. The thick sedimentary strata exerted vertical load on underlying heterogeneous crust that led to build excessive internal stress and release through weak zones (lying at intersecting planes of heterogeneous crustal blocks). The stress, thus released through fault planes has caused the deformation of crust as well as overlying sedimentary strata.
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FILDES S G, CLARK I F, SOMARATNE N M, ASHMAN G
045211 FILDES S G, CLARK I F, SOMARATNE N M, ASHMAN G (South Australia Univ, SA- 5000, Australia) : Mapping groundwater potential zones using remote sensing and geographical information systems in a fractured rock setting, Southern Flinders Ranges, South Australia. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01420-1.
In Australia, water resource management is a major socio-economic and environmental issue and an essential component of progress. This is more acute in arid and semi-arid regions of Australia. The Southern Flinders Ranges townships of Quorn and Hawker in common with much of the Flinders Ranges suffers from a lack of reliable data to help water resource managers. This paper discusses the delineation and assessment of groundwater potential zones using remote sensing and geospatial techniques in the region, using multi-criteria analyses. The study integrates many thematic layers (rainfall, lithology, lineament density, topographic wetness, slope and aspect) in a GIS environment in order to identify groundwater potential zones. Weights are assigned to class attributes within and between each thematic data layer using an Analytical Hierarchy Process based on the relative importance of each layer. The weighted thematic data layers are then combined to produce a probability of groundwater potential zone map of each study area. The groundwater potential zones were verified with available water data, and showed consistency with the interpretations.
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GUPTA A, DIMRI A P, THAYYEN R, JAIN S, JAIN S
045210 GUPTA A, DIMRI A P, THAYYEN R, JAIN S, JAIN S (Jawaharlal Nehru Univ, New Delhi) : Meteorological trends over Satluj River Basin in Indian Himalaya under climate change scenarios. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01424-x.
Temperature and precipitation distributions depend on variable topography and heterogeneous landuse/landcover in the Indian Himalayan Region (IHR). It imparts a major concern for hydrological, glaciological modelling, dam structure assessment, etc. Thus, there is an inherent requirement of robust information for climate impact studies over the topographical variable and landuse heterogenous region in the Indian Himalayan Region (IHR). In particular, the importance of bias corrections become critically important over Himalayan river basins, in which model outputs with the corresponding in-situ observations are used for improving the model distribution. These improved details in present and future, as well, are important to carry out the climate change impact studies at basin scale for hydrological, glaciological, climatological studies, etc. Thus, in the present study firstly, model fields are bias corrected with the corresponding in-situ observations. And then trends in these bias corrected data is compared with the corresponding in-situ observations. These assessment of present and future changes in temperature and precipitation over Satluj River Basin (SRB) located in the western Himalayas is illustrated. Model fields are considered from a Regional climate model (REMO) from Coordinated Regional Downscaling Experiment-South Asia (CORDEX-SA) in three Representative Concentration Pathways (RCPs), i.e., 2.6, 4.5 and 8.5 W/m2. These projections are bias corrected using distributed quantile mapping. The precipitation (temperature) bias correction is performed using the distributed quantile mapping on the gamma (normal) distribution. The standard trend statistics is applied for quantitative assessment. A good capture of bias correction in temperature and precipitation is illustrated. Efficient bias removal is depicted in cumulative distribution curve (CDF) at individual station. Trend analysis shows that highest rate of precipitation decrement at low altitude station (Kasol) with the rate of −6.362 mm/year in RCP 8.5. Over the SRB highest rate of temperature increment is seen at highest altitude station (Kaza) with the rate of 0.084°C/year in RCP 8.5. On an average, fall in precipitation and increase in temperature with >99% confidence level in RCP 8.5 is seen. In addition, intensity lowers in other lower RCPs. The study sums up with the efficacy of CORDEX-SA REMO model in capturing present and future change in temperature and precipitation over the SRB in western Himalayas using the bias correction.
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JOHNY C J, PRASAD V S
045208 JOHNY C J, PRASAD V S (National Centre for Medium Range Weather Forecasting, Noida- 201 309) : Application of hind cast in identifying extreme events over India. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01435-8.
India Meteorological Department (IMD) is operationally producing forecasts at T1534 resolution using NCMRWF GFS (NGFS) model and biases are reported in some regions. In order to identify the model biases and applying necessary correction measures to improve forecast, retrospective forecast is carried out for the 20 yrs period from 1999–2018 using operational version of NGFS model. In this study, model’s ability to predict extreme temperature and rainfall events in Indian region irrespective of model biases is investigated. It is found that model is able to predict extreme temperature events accurately with sufficiently long lead time (7 days). In case of extreme rainfall at shorter lead time (3 days), model is able to predict accurately and accuracy decreases with increase in lead time. Employing bias correction methods reduced large biases in some regions.
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RAM P, GUPTA V, DEVI M, VISHWAKARMA N
045207 RAM P, GUPTA V, DEVI M, VISHWAKARMA N (Wadia Institute of Himalayan Geology, Dehradun- 248 001, Uttarakhand) : Landslide susceptibility mapping using bivariate statistical method for the hilly township of Mussoorie and its surrounding areas, Uttarakhand Himalaya. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01428-7.
Landslide is a normal geomorphic process that becomes hazardous when interfering with any development activity. It has been noted that ~400 causalities occur in the Himalayan region every year due to this phenomenon. The frequency and magnitude of the landslides increase every year, particularly in the hilly townships. This demands the large scale landslide susceptibility, hazard, risk, and vulnerability assessment of the region to be carried out. In the present study, Mussoorie Township and its surrounding areas located in the Lesser Himalaya has been chosen for Landslide Susceptibility Mapping (LSM) that involved bivariate statistical Yule coefficient (YC) method. It calculates the binary association between landslides and its various possible causative factors like lithology, land use-landcover (LULC), slope, aspect, curvature, elevation, road-cut, drainage, and lineament. The results indicate that ~44 % of the study area falls under very high, high and moderate landslide susceptible zones and ~56 % in the low and very low landslide susceptible zones. The dominant part of the area falling under high and moderate landslide susceptible zones lies in the area covered by highly fractured Krol limestone exhibiting slope ranging between 65 ° and 77 °. The study would be useful to the planners for the land-use planning of the area.
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KANASE R D, DESHPANDE M S, KRISHNA R P M, MUKHOPADHYAY P
045206 KANASE R D, DESHPANDE M S, KRISHNA R P M, MUKHOPADHYAY P (Indian Institute of Tropical Meteorology, Pune- 411 008) : Evaluation of convective parameterization schemes in simulation of tropical cyclones by Climate Forecast System model: Version 2. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01433-w.
Recently, a high resolution atmospheric general circulation model, i.e., Global Forecast System has been operationalized for 10 days weather forecast over Indian region. However, for extreme weather systems such as cyclones, different physical processes and their interactions with atmosphere and ocean play an important role in cyclone intensity, track, etc. Keeping this in view, Coupled Forecast System model version 2 has been used to evaluate the simulation for three severe cyclones (Phailin, Viyaru and Lehar) of 2013. In the present study, along with already existing mass-flux cumulus parameterization, i.e., Simplified Arakawa–Schubert (SAS) and revised SAS (RSAS) parameterization schemes, an additional convective adjustment scheme, i.e., Betts–Miller–Janjic (BMJ) is implemented and its performance is evaluated for the Indian Ocean cyclones. The experiments are conducted with three cumulus schemes at three different resolutions (T126, T382, and T574). Both SAS and RSAS overestimate convective rain, whereas BMJ scheme produces convective rain comparable with the observation due to the fact that BMJ produces deeper convection and does not trigger the convection too often. BMJ sustains the instability and deep convection longer thereby impacting the cyclone intensity and heavy rainfall associated with it. It is also noted that BMJ is efficient in producing rain than the SAS and RSAS. From the analyses of OLR and rain rate, BMJ is found to simulate a much realistic relation of cloud and precipitation. The paper argues that compared to available SAS and RSAS, BMJ scheme realistically produces heavy precipitation associated with the tropical cyclone over Indian region in a coupled model.
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CHAKRAVARTY K, MURUGAVEL P, CHRISTY A A, SINGH V, PANDITHURAI G
045205 CHAKRAVARTY K, MURUGAVEL P, CHRISTY A A, SINGH V, PANDITHURAI G (Indian Institute of Tropical Meteorology, Pune- 411 008) : Impact of electrified and non-electrified clouds on the inter-seasonal characteristics of surface-based precipitation. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01432-x.
A multi-sensor analysis of the characteristics of electrified and non-electrified clouds along with their impact on the surface-based raindrop size distribution (DSD) during the inter-seasonal phases of Indian summer monsoon over a heavy precipitation region of Western Ghat (WG) has been highlighted in the present paper. The analysis reveals that during the pre-monsoon (monsoon) months, raindrops of larger diameter dominate the rainfall evolving from the non-electrified (electrified) clouds compared to the rainfall evolving from the electrified (non-electrified) ones. The complex relationship of the convective rainfall with highly charged electrified clouds forces the smaller drops aloft and thereby allowing the larger drops to precipitate locally during the pre-monsoon season. While for the monsoon months, as most of the rainfall originates from the deep clouds, the chances of drops to break-up/evaporate is comparatively less for the precipitation evolving from electrified clouds with charged droplets with respect to the non-electrified ones. Hence, drops of larger diameter dominate the monsoon rainfall associated with lightning. Correspondingly, the paper also highlighted a case study of the changing morphology of the vertical structure of clouds and surface precipitation with the evolution of lightning during various stages of a typical rainfall event over the orographic region of WG.
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ROY N, MUKHERJEE S, SAHU R B
045204 ROY N, MUKHERJEE S, SAHU R B (Jadavpur Univ, Kolkata- 700 032) : Influence of trapped soft/stiff soil layer in seismic site response analysis. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01442-9.
As the ground response analysis serves an integral part of site specific seismic hazard study to obtain design ground motion, a proper and accurate estimation should be of prime importance. The paper presents a study on the effect of trapped soft and stiff soil layer on equivalent linear ground response analysis implemented in computer program STRATA. For this purpose, the concept of normally stiff and inversely stiff soil profiles have been introduced. The study clearly indicates the higher impact of a trapped soft soil layer profile, i.e., inversely stiff soil profile with soft layer, in comparison with trapped stiff layer profile, i.e., inversely stiff profile with stiff layer. For low to moderate ground motions, as the depth of the trapped soft layer increases, peak amplification and peak frequency reduces, and for high intensity input ground motion, significant reduction only in the peak frequencies is observed. On the other hand, as the depth of trapped stiff soil layer increases the outcome of ground response analysis remain quite similar. Peak transfer function, peak frequency, peak spectral ratio and peak spectral acceleration are found to exhibit a COV ≤ 60 to 100 % for all combinations of IS-Soft profiles, whereas, IS-Stiff profiles exhibit a maximum COV ≤ 15 to 25 % for all the considered input ground motions. Computed normalized-root mean square error (Norm-RMSE) values also clearly indicate the higher deviations in the ground response analysis for different combinations of trapped soft soil profiles, from that of normally stiff profile, whereas, trapped stiff layer profiles show lower deviations in the Norm-RMSE values. The profiles with trapped soft layer exhibit a Norm-RMSE value ≤0.8, whereas, trapped stiff layer profiles exhibit a Norm-RMSE value ≤0.2, which clearly demonstrate the large deviations in the outcome of ground response analysis in case of trapped soft layer profiles.
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KURNAZ T F, INCE Y
045203 KURNAZ T F, INCE Y (Transportation Services Dep, Mersin Univ, Mersin- 33343, Turkey) : Evaluation of seismic hazard with probabilistic approach for Antakya Province (Turkey). J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01438-5.
Antakya province is tectonically affected by Dead Sea and East Anatolian faults and the Cyprus arc. Although there had been major and devastating earthquakes in the historical period, the fact that there is no major earthquake in the instrumental period increases the risk of seismic hazard of the region. In this study, it is aimed to perform a probabilistic seismic hazard analysis application for Antakya province, Turkey. For this purpose, the earthquakes (Mw ≥ 4) which occurred between 1900 and 2017 were used. Nine seismic source zones that could affect the Antakya province were identified and the seismic hazard parameters calculated for each zone. Peak ground acceleration (PGA) values that can occur in a possible earthquake were obtained according to a recurrence period of 475 yrs by using two different attenuation relationships and presented with iso-acceleration maps. The calculated PGA values in the study area are found as between 0.32 and 0.57 g for both attenuation relationships. The areas located on the north of Kırıkhan district have the highest risk of seismic hazard in the study area according to determined PGA values.
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AHMAD S, ANSARI Z
045202 AHMAD S, ANSARI Z (Geology Dep, Aligargh Muslim Univ, Aligarh) : Characteristics of rock–water interaction in Gangotri proglacier meltwater streams at higher altitude catchment Garhwal Himalaya, Uttarakhand, India. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01426-9.
Proglacial streams play an important role in water–rock interaction due to different climatic conditions at different altitudes. The main objective of the present study is to analyze the variation of glacier hydrochemistry and sedimentation processes at different altitudes. The results show that the bed sediments in higher altitude streams are fine sand, poorly sorted, leptokurtic in nature and dominated with high proportion of feldspar and biotite. At lower altitude, the bed sediment is coarse sand, moderately sorted and platykurtic in nature with relatively high proportion of quartz. The high concentration of biotite and feldspar in silt/lay size fraction are responsible for high proportion of magnesium in Gangotri proglacier meltwater than others. Meltwater is slightly acidic and hydrochemical facies shows Ca+2–Mg+2–HCO3− type. The concentration of Ca+2, Mg+2, Na+, and K+ decreases with altitude due to dilution produced by augmentation of freshly monsoonal recharged groundwater from meadow and forest in downstream. The cation exchange, carbonate/silicate weathering and groundwater, subglacial water sources control the hydrochemistry of proglacial streams at lower altitude.
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SRIVASTAVA A K, BANSOD M N, SINGH A, KALE V M
045201 SRIVASTAVA A K, BANSOD M N, SINGH A, KALE V M (Geology Dep, Sant Gadge Baba Amravati Univ, Amravati- 444 602) : Model showing influence of tectonics and energy condition of the fluvial environment on facies architecture: A case history of Quaternary alluvial deposits of Purna basin, central India. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01441-w.
Present work includes identification of lithofacies and reconstruction of depositional environments including controls of tectonics, and energy condition of the medium on sedimentation pattern of alluvial deposits of Purna basin, central India. The basin exhibits good development of dominantly areno-argillaceous sediments along with restricted occurrences of boulder-pebbly lithounits, covering together an area of 6,522 km2. These sediments are also characterized by preservation of various calcrete morphotypes, vertebrate remains and Youngest Toba Tuff (YTT) ash in certain stratigraphic units. The work is based on detailed field and lithological studies of 20 river-cut sections exposed along the course of Purna river, representing entire alluvial deposits in both vertical and lateral profiles. Three lithofacies associations have been identified, i.e., (1) gravelly facies association (FA-1), (2) sandy facies association (FA-2) and, (3) silty-clayey facies association (FA-3). These associations consist of total 10 lithofacies distributed as: (i) matrix supported massive gravelly (Gmm) facies, (ii) matrix supported gravelly (Gmg) facies, (iii) horizontally stratified gravelly (Gh) facies, (iv) planar stratified gravelly (Gp) facies (FA-1), (v) horizontal sandy (Sh) facies, (vi) planar cross stratified sandy (Sp) facies, (vii) low angle cross bedded sandy (Sl) facies, (viii) massive sandy (Sm) facies (FA-2), (ix) laminated sandy (Fl) facies, and (x) palaeosol (P) facies (FA-3). Various architectural elements have also been identified. Based on lateral and vertical profiling of the lithofacies architecture, it is interpreted that gravel dominated facies in the mountainous region of the basin area are deposited by medium to high energy debris flow,whereas sandy and silty-clayey facies in the plain area are because of saltation and suspension modes of deposition under medium to low energy condition of depositing medium. The tectonic and topographical controls are well reflected on the sedimentation pattern and the same has been illustrated by proposing a model. Discussions along with the model have also been made on the progressive development of bazada or, pediment zone along the northern margin of the basin marked by the foothills of Satpura mountain ranges.
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AMONKAR A, IYER S D, BABU E V S S K, MANJU S
045200 AMONKAR A, IYER S D, BABU E V S S K, MANJU S (CSIR- National Institute of Oceanography, Dona Paula- 403 004, Goa) : Extending the limit of widespread dispersed Toba volcanic glass shards and identification of new in-situ volcanic events in the Central Indian Ocean Basin. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01429-6.
We report the widespread extent of Toba volcanic glass shards in the Central Indian Ocean Basin. Investigation of four sediment cores (7 º–17 ºS) revealed several shard-rich horizons (SRH) that provide the first detailed tephrochronology for volcanic glass shards in the CIOB. A comparative study of surface sediments floored with Youngest Toba Tuff (YTT), indicate that irrespective of the rate of sedimentation, YTT in the basin is restricted to a depth of <35 cm-bsf. We utilized microtektites (0.77 Ma), associated with the Oldest Toba Tuff (OTT) glass shards, as a proxy for age calculation of the SRH. The results are comparable with well-established ages derived from paleomagnetic and δ18O methods for the Leg 21 ODP Site 758. The other significant finding of this study includes the first report of Middle Toba Tuff (equivalent to Layer C) and Layer D that are present between YTT and OTT (Layer E) and also Layers G, H, h, I, J, K, L and M. All these layers correspond with those reported for ODP Site 758. Furthermore, two SRH between layers G and H show signatures of localized in-situ phreatomagmatic origin, suggesting that CIOB is apparently more active – tectonically and volcanically than it is presumed.
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ALI A, ACHYUTHAN H
045198 ALI A, ACHYUTHAN H (Anna Univ, Chennai- 600 025) : Paleoenvironment shifts during MIS 3: Loess and loess paleosols of Kashmir Valley, India. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01440-x.
Kashmir valley receives the rainfall owing to the dominant westerly winds and experiences less impact of the southwest monsoonal rains (SWM). In this valley, loess and loess paleosols occur as a thin veneer covering the landscape. The loess paleosols form an important proxy for paleoclimate reconstruction and understanding the late Quaternary paleoenvironmental shifts. For this purpose, the loess, paleosols within the loess lithosections were lithologged and the sediment samples were subjected to various grain-size textural and geochemical analysis. The U-ratio of the sediments supported by parameters such as TOC, CaCO3 content, ratios of Zr/Rb, Rb/Sr, Ba/Sr, K/Ba, K/Rb, chemical index of alteration (CIA) and clay mineralogy indicate that the loess paleosols have undergone weak to moderate degree of pedogenesis. The U-ratio and Zr/Sr ratio also reflect variations in the wind velocity ranging from weak to moderate conditions for the loess deposition. The Ba/Sr and Rb/Sr ratios signify varied precipitation conditions, particularly with higher precipitation during the paleosol formation. The A–CN–K plot exhibits weaker to intermediate type of weathering of the loess horizons. TiO2 % vs. Al2O3 % binary plot illustarates mostly basaltic to rhyolite/granite type of rock source and the Panjal Traps is one of the major sources of the loess deposition. The lower end of the exposed Choori and Burzahama lithosections were dated by OSL method to 54 ± 2 ka at 9.5 m depth and 52 ± 2 ka at 8 m of depth, respectively. Geochemical analysis and OSL dating of the Choori and Burzahama lithosections reveal that climate during the marine isotope stage 3 (MIS 3) was dominantly warm and dry (stadial conditions) in Kashmir valley when the loess layers covered the valley and since then the loess horizons have undergone weak to intermediate, moderate type of weathering in cool and dry conditions.
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BORGOHAIN P, HUSSAIN M F, BEZBARUAH D, VANTHANGLIANA V, PHUKAN P P, GOGOI M P, BHARALI B
045196 BORGOHAIN P, HUSSAIN M F, BEZBARUAH D, VANTHANGLIANA V, PHUKAN P P, GOGOI M P, BHARALI B (Geology Dep, Pachhunga Univ Coll, Aizawl- 796 001, Mizoram) : Petrography and whole-rock geochemistry of Oligocene Barail Sandstones of Surma basin: Implications for tectono-provenance and paleoclimatic condition. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01431-y.
The Oligocene Barail Sandstones of Surma basin from parts of Champhai District of Mizoram, northeast India has been studied for their tectono-provenance setting using petrography and geochemistry. The studied sandstones are poor to moderately sorted, subarkosic to sub-litharenite and show dominance of quartz (avg. 54.46 %) followed by feldspars (avg. 7.22 %), rock fragments (avg. 4.98 %), mica (avg. 5.89 %), matrix (avg. 14.47 %) and cement (avg. 12.98 %). Dominance of polycrystalline and undulatory monocrystalline quartz indicates contribution from medium grade metamorphic sources, primarily of granite gneisses. High concentration of SiO2 with moderate to low concentration of Al2O3, Fe2O3, MgO, Na2O and K2O resembles the composition of upper continental crust. Moreover, moderate to high concentration of Th and V, depleted value of Ni along with TiO2/Zr suggests derivation of sediments from felsic sources. The ratios of Eu/Eu* (avg. 0.63) and LaN/LuN bears resemblance with the upper continental crust. Overall analyses show that the sediments were derived from the felsic terrain of neighbouring orogens probably represented by granite-gneisses and have undergone a moderate degree of weathering (avg. values of CIA: 70.20, CIW: 81.03, PIA: 77.63, WIP: 38.45, ICV: 1.06, Iw = 2) in a semi-humid to humid climatic conditions [Qp/(F + RF):Qt/(F + RF) = 0.20].
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MUKHERJEE A, BABU S S, GHOSH S
045195 MUKHERJEE A, BABU S S, GHOSH S (Geology and Geophysics Dep, Indian Institute of Technology, Kharagpur- 721 302) : Thinking about water and air to attain Sustainable Development Goals during times of COVID-19 Pandemic. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01475-0.
In 2020, we are in the doorstep of a new decade, during which the UN Sustainable Development Goals (SDG) are to be achieved, collectively as one nation and one human-hood, where availability of safe, sustainable and clean water and air forms the core of multiple goals. However, the emergence of the COVID-19 pandemic across the globe has resulted a newer challenge and paradigm for an evolving socio-scientific priorities. It is generally expected that the impacts of the pandemic would be in shorter time-scale, while the planned time and pathway for attaining the SDG are typically mandated in longer-term, hence may remain mostly unaffected. However, the stringent lockdown measures, isolated economies and financial burden to contain the pandemic emergency have resulted to slowdown of socio-economic development, which if continues for a longer period, would put a question mark on developing plans and pathways to achieve the SDGs, even in decadal-scale. Hence, in these newer times, it is important to understand the real priorities of availability of clean water and air, which are already stressed worldwide and in India, because of various natural and human-influenced triggers. This ongoing pandemic has provided an unprecedented opportunity to evaluate the impact of human development and consequent feedback of nature and human society in pre- and post-COVID scenarios on water–air–human life, which can help to re-think and re-orient the societal development priorities. It is a rare opportunity for scientists to impress the policy-makers with real-time examples on the efficacies of potential mitigation strategies for climate change, water and air pollution, and the importance of enduring investment on environmental causes and consequent benefits that can secure health and development for our future generations.
37 ref
CHINNASAMY P, SOOD A
045194 CHINNASAMY P, SOOD A (Indian Institute of Technology Bombay, Powai- 400 076, Mumbai) : Estimation of sediment load for Himalayan Rivers: Case study of Kaligandaki in Nepal. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01437-6.
Himalayan regions have increasing sediment yield due to undulating topography, slope and improper watershed management. However, due to limited observation data, and site accessibility issues, less studies have quantified sedimentation loads in the Himalayas, especially Nepal. This has hindered the investments on run-of-river hydropower projects as high and unpredicted sedimentation has increased losses in hydropower production. Therefore, there is a need to understand key physical processes driving sedimentation in these regions, with the available data. This study used the Soil and Water Assessment Tool (SWAT) to estimate the sedimentation yields in the Kaligandaki basin of Nepal, which is an important tributary that drains into the Ganges. Multi-source data from field observations, remote sensing platforms, surveys and government records were used to set up and run the SWAT model for the Kaligandaki basin from 2000 to 2009. Results for the 10-year model run indicate that 73% of the total sediment load is estimated to come from the upstream regions (also known as High Himalayan region), while only 27 % is contributed from the Middle and High Mountain regions (where land management-based interventions were deemed most feasible for future scenarios). The average sediment concentration was 1986 mg/kg (ppm), with values of 8432 and 12 mg/kg (ppm) for maximum and minimum, respectively. Such high sedimentation rates can impact river ecosystems (due to siltation), ecosystem services and hydropower generation. In addition, model results indicate the need for better high frequency observation data. Results from this study can aid in better watershed management, which is aimed at reducing sedimentation load and protecting Himalayan rivers.
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SAHU A, VISHWAKARMA N, SINGH Y, VERMA C B
045193 SAHU A, VISHWAKARMA N, SINGH Y, VERMA C B (Applied Geology Dep, National Institute of Technology, Raipur- 492 010) : Mineral chemistry of high-Al chromian spinel from ultramafic rocks of the Babina–Prithvipur transect, Bundelkhand Craton, Central India: Implication for petrogenesis and tectonic setting. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01448-3.
Bundelkhand Craton is an important Archaean cratonic nuclei of the Central Indian Shield and comprises two greenstone complexes, i.e., the Babina–Mauranipur Greenstone Belt and the Girar–Madawara Greenstone Belt. The E–W trending Babina–Mauranipur Greenstone Belt in the central part of the craton, encloses several isolated lensoid shaped ultramafic bodies which has suffered various degrees of alteration and metamorphism. As per modal mineral analysis, the ultramafic rocks of the Babina–Prithvipur section belong to harzburgite and also contain high-Al chromian spinel along with olivine, ortho-pyroxene and amphibole. Mineral chemistry reveals that the spinels are of high Al and Cr poor variety, where Al2O3 and Cr2O3 contents range from 40.06 to 54.34 wt.% and 9.05 to 14.89 wt.%, respectively. The TiO2 content is extremely low (average ≈0.07 wt.%). The Cr# value of the spinel is <0.2, whereas Mg# ranges from 0.495 to 0.633. The forsterite contents of the olivine ranges from 86.088 to 88.105 wt.%. Average CaO and NiO contents of the olivine stand 0.03 and 0.24 wt.%, respectively. Composition of the analyzed ortho-pyroxene belongs to En84.20–87.75Wo0.15–0.39 with low CaO content of 0.080 to 0.207 wt.%. As per mineral chemistry, these harzburgite rocks of the Babina–Prithvipur section belong to mantle peridotite. Melt calculation for the spinel also suggests a least differentiated magmatic product, which is also supported by the olivine spinel mantle array diagram as all the samples are plotted within the mantle array field very close to the fertile mantle source. Low TiO2 and high Al contents of spinel also reflect the MORB type peridotite characteristics for these ultramafic rocks which probably originated from least differentiated plagioclase free mantle derived harzburgite/lherzolitic magma in a rift related spreading centre. As a whole these ultramafic rocks appear to be the remnant of the early crust that existed during the Archaean time.
89 ref
MOADDAB R, JAHANGIRI V, SHAKIB H
045191 MOADDAB R, JAHANGIRI V, SHAKIB H (Tarbiat Modares Univ, Tehran, Iran) : Correlation of spectral acceleration values in Iranian ground motions. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01439-4.
Spectrum compatibility is commonly used as a tool for ground motion record selection in order to perform dynamic analysis. Conditional mean spectrum calculation, which can be used as a target spectrum, requires obtaining correlation coefficients between spectral acceleration values at multiple periods. To date, the correlation coefficients have not been evaluated exclusively from ground motions recorded in Iran. This study represents results obtained from the calculation of correlations for spectral acceleration values from Iranian ground motion data and Zagros and Alborz-central Iran seismic regions, separately. The obtained results can be used for conditional mean spectrum calculations at Iranian sites. The observed correlation coefficients for Iranian records are compared to the correlations developed from the Western United States ground motion data. It is seen that correlation coefficients obtained from the Western United States ground motion data are less than the ones calculated in the study and therefore would cause further reducing of the target spectrum of interest.
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ARYASREE S, NAIR P R, HEGDE P
045190 ARYASREE S, NAIR P R, HEGDE P (Technical Univ, Darmstadt- 642 87, Germany) : Radiative characteristics of near-surface aerosols at a tropical site: An estimation based on concurrent measurements of their physico-chemical characteristics. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01444-7.
This study is an attempt to estimate the radiative characteristics of aerosols, namely, the scattering coefficient (βsc), absorption coefficient (βab), extinction coefficient (βex), single scattering albedo (ω) and the phase function P(θ), on a seasonal basis, incorporating the concurrent measurements of aerosol mass loading, size distribution and chemical composition at the tropical coastal site, Thiruvananthapuram. The software package Optical Properties of Aerosols and Clouds (OPAC) has been made use for the estimation of the radiative parameters. This paper presents the seasonal features of aerosol chemical composition and their source characteristics also. Along with this, the association between size-resolved number density of aerosols and their chemical characteristics were also investigated through correlation analysis. The location is significantly influenced by human activities as seen from the dominance of the anthropogenic component which is highest in winter (22 %) with comparable values in pre-monsoon and post-monsoon and minimum in monsoon (13 %). The sea-salt contribution is found to peak in monsoon (~40 %) and attain a minimum in winter. The source characterization using principal component analysis along with back-trajectory analysis showed the seasonally changing mixed aerosol sources over the region. Accordingly, the radiative properties of aerosols also exhibit significant seasonal variations. βsc varied from 0.04 to 0.14 km−1 and βab between 0.01 and 0.05 km−1 over a year. The single-scattering albedo exhibited significant seasonal differences being ~0.71 for winter and ~0.89 (0.55 μm) for monsoon season, indicating the presence of more absorbing aerosols in winter.
124 ref
WU L, HU F, XIE L
045187 WU L, HU F, XIE L (South China Agricultural Univ, Guangzhou- 510 642, China) : Characteristics of extreme precipitation in South China during April–July for early rice season. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01466-1.
Extreme precipitation has significant impacts on human society and agriculture development under global climate change as well as severe effects on rice development. However, little research has been done on the characteristics of extreme precipitation in different rice growth stages. Taking the South China region as a case study, the characteristics of extreme daily precipitation in the early rice season (April–July) from 1960 to 2009 were investigated by using percentile method. Results indicated that extreme precipitation threshold increases since the tillering stage, and there is big difference between the first and the rest growth stages. Extreme precipitation is serious in the eastern part than in the western part of South China during the seeding and tillering stage, and reverse since the booting stage. Frequency of extreme precipitation increases in recent decades after the booting stage. Finally, flood risk regions form more easily in the coastal cities and the western part of South China in the 1990s and 2000s since the tillering stage.
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MO G, ZHANG Y, HUANG Y, MO C, YANG Q
045186 MO G, ZHANG Y, HUANG Y, MO C, YANG Q (Guangxi Univ of Finance and Economics, Nanning- 530 003, China) : Evaluation and hydrological impact of land-use changes in the Longtan basin. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01458-1.
Compared to climate change, land-use changes were the main driving factors to short-term hydrological variety. To evaluate land-use types variation and quantify its hydrological impact, this paper identified the temporal-spatial features and simulated the hydrological process of different land-use types over the last two decades (1990–2010) based on the soil and water assessment tool (SWAT). Meanwhile, the possible influence of land-use changes on streamflow in the next 30 years (2020–2050) was also considered. Results indicated that (1) land-use types mainly constituted of forest land, grassland and cultivated land, which had the largest decreasing rate of 17.34 km2/10a. At the same time, inter-conversion mainly conducted among the main land-use types and had a similar transfer structure for these two sub-periods (1990–2000, 2000–2010) during 1990–2010, with a more dramatic transformation in 2000–2010. (2) Simulated annual and monthly surface runoff did not vary greatly from 1990 to 2010 and presented a relatively uniform monthly distribution. At the same time, the increased vegetation coverage (forest land and grassland) can not only reduce surface runoff but also prevent peak flood with increasing and decreasing steeply. (3) Finally, hydrological variability to the future land-use change will not be intensive, which possibly related to the undeveloped regional economic and insignificant human activities. But it also needed some measures to maintain a balanced nature, such as the soil and water conservation measures and returning cultivated land to forest land and grassland.
37 ref
KUMARI R, KUMAR P, KUMAR N, SANDEEP
045185 KUMARI R, KUMAR P, KUMAR N, SANDEEP (Wadia Institute of Himalayan Geology, Dehradun) : Role of site effect for the evaluation of attenuation characteristics of P, S and coda waves in Kinnaur region, NW Himalaya. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01454-5.
The site effect and attenuation studies are carried out for Kinnaur region of northwest Himalaya, India. A total of 109 local events happened in Kinnaur region of magnitude range 1.6–4.5, are utilized for present work. The earthquake records are influenced by the site effect depending on soft sediment thickness beneath the recording sites. Therefore, in the present study, records are corrected for site effects to estimate P (Qp), S (Qs) and coda (Qc) wave quality factor. The regional frequency dependent attenuation relations, i.e., Qp(f)=(29±1)f(1.01±0.05)Qp(f)=(29±1)f(1.01±0.05), Qs(f)=(38±5)f(1.1±0.06)Qs(f)=(38±5)f(1.1±0.06) and Qc(f)=(74±11)f(1.17±0.01)Qc(f)=(74±11)f(1.17±0.01) are established for the Kinnaur region. The Kinnaur Himalaya mainly belongs to Higher Himalaya Crystalline (HHC) and Tethys Himalaya, where these two geological units are differentiated by the South Tibetan Detachment System (STDS). The resonance frequencies and attenuation characteristics are estimated for both regions, i.e., HHC and Tethys Himalaya. A comparison is made between HHC and Tethys Himalaya in the form of resonance frequencies and attenuation properties. The low value resonance frequency and high rate of attenuation towards the northern side of STDS, i.e., Tethys Himalaya support the presence of low-grade metasedimentary rocks. It suggests that Tethys Himalaya has high seismic hazard potential zone compared to HHC.
67 ref
VARGHESE S J, SURENDRAN S, AJITHKUMAR B, RAJENDRAN K, KITOH A
045184 VARGHESE S J, SURENDRAN S, AJITHKUMAR B, RAJENDRAN K, KITOH A (CSIR Fourth Paradigm Institute, Bangalore- 560 037) : Future changes in rice yield over Kerala using climate change scenario from high resolution global climate model projection. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01459-0.
The impact of climate change on agricultural yield is one amongst the major concerns the world is witnessing. Our study focusses on rice yield prediction for an agricultural research station in Kerala with the help of climate change scenario input from the Meteorological Research Institute (MRI) Global Climate Model (GCM) projection under Representative Concentration Pathway 8.5 (RCP8.5). We have used Cropping System Model (CSM) Crop Estimation through Resource and Environment Synthesis (CERES) Rice within Decision Support System for Agrotechnology Transfer (DSSAT) package for predicting the yield. Our study has the novelty of using very high-resolution climate data from a model which is highly skilful in capturing the present-day climate features and climatic trends over India (in particular, over the Western Ghats), as input for simulating the future crop yield. From this study, we find that the rice yield decreases due to rise in temperature and reduction in rainfall, thereby reducing the crops maturity time in the future. Based on our results, the adaptation measures suggested to achieve better yield under future warming conditions are: (i) to opt for alternative rice varieties which have tolerance to high temperatures and consume less water, and (ii) shifting of planting date to the most appropriate window.
68 ref
KANDREGULA R S, KOTHYARI G C, CHAUHAN G, PANCHOLI V, SWAMY K V, LAKHOTE A, MISHRA S, THAKKAR M G
045183 KANDREGULA R S, KOTHYARI G C, CHAUHAN G, PANCHOLI V, SWAMY K V, LAKHOTE A, MISHRA S, THAKKAR M G (Active Tectonics Dep, Institute of Seismological Research, Gandhinagar, Gujarat) : Evaluating the seismic hazard in the Kachchh Region, western India using the river gradient length anomaly technique. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01449-2.
In the present study, we assess seismic hazard potential and surface deformation pattern along and across the strike of major active faults in the intra-plate Kachchh Rift Basin (KRB). Towards this, we adopted river Gradient Length Anomaly (GLA) technique, which detects recent tectonic deformation along a river profile on local and regional scales. The major deviations along the river profile can be correlated with exogenic (erosion/sedimentation/anthropogenic) and endogenic (active tectonic movement) processes. We analysed 130 river profiles for GL anomalies, over an area of ~26,700 km2 in the KRB to identify possible locations that have undergone active tectonic deformation associated with the fault movement. The acquired results show that the higher magnitude negative GL anomalies (uplift) are observed proximal to the fault zones. Our estimates reveal that, around 13 % of the study area falls under high tectonically active zone, around 27 % of the area falls under moderately active zone, while 60 % of the area shows very low or negligible tectonic activity. The estimated results of the GL anomalies are compared with the existing double-difference tomograms, to understand the role of subsurface fault dynamics on the GL anomalies. Furthermore, the results of GLA are correlated with the existing results of the peak ground acceleration (PGA) values of the basin, in order to obtain the precise information regarding surface deformation and site-specific ground acceleration for accurate assessment of seismic hazard.
77 ref
SANAP S D, MOHAPATRA M, ALI M M, PRIYA P, VARAPRASAD D
045182 SANAP S D, MOHAPATRA M, ALI M M, PRIYA P, VARAPRASAD D (India Meteorological Dep, Office of the Climate Research and Services, Shivajinagar- 411 005, Pune) : On the dynamics of cyclogenesis, rapid intensification and recurvature of the very severe cyclonic storm, Ockhi. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01457-2.
A very severe cyclonic storm (VSCS), ‘Ockhi’ started its journey from southwest Bay of Bengal (BoB) over Comorin area (7.5°N–77.5°E) as a low-pressure area on 28 November, 2017. Initially it moved north-westwards across Lakshadweep Islands without hitting Tamil Nadu or Kerala coast, then moved north-eastward over the Arabian Sea and dissipated upon hitting south Gujarat coast on 06 December, 2017. Rapid intensification (RI), clockwise recurvature and a longer track were the major features of the VSCS, Ockhi. In the present study, an attempt has been made to understand the mechanism of cyclogenesis, RI and recurvature of the Ockhi using satellite and reanalysis datasets. Initially, role of easterly waves (EW) and Madden Jullian Oscillations (MJO) on the cyclogenesis of tropical cyclone Ockhi is addressed. Our analysis suggests that the EW (MJO) played a seminal (insignificant) role in preconditioning the atmosphere for the cyclogenesis of the Ockhi. Our detailed analysis using various oceanic parameters indicate that, the passage of the cyclonic storm over the regions of high thermal energy, especially warmer ocean mean temperature (OMT) at 100 m depth, was instrumental in its rapid intensification. Further, we addressed the recurving feature of the VSCS Ockhi using steering flow analysis. It is found that strong north-eastward steering winds, embedded in subtropical westerlies with deep southward extent, favoured the recurving of the Ockhi towards north-eastward by suppressing the conventional westward (north-westward) track movement.
51 ref
NAGAMANI D, SIVARAM K, RAO N P, SATYANARAYANA H V S
045181 NAGAMANI D, SIVARAM K, RAO N P, SATYANARAYANA H V S (CSIR- National Geophysical Research Institute, Hyderabad- 500 007) : Ambient noise and earthquake HVSR modelling for site characterization in southern mainland, Gujarat. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01443-8.
This study provides the assessment of site characterization and possible shallow shear-velocity structure from the study of the horizontal to vertical spectral ratio (HVSR) measurements using the ambient noise or microtremor (herein called classical HVSR), extracted Rayleigh wave from the ambient noise data (herein called standard HVSR) and earthquake (herein called earthquake HVSR) data at five stations in the Surat district of mainland Gujarat, India. These locations are the hub of many mining and industrial projects like oil and natural gas, which need to function safely within the seismic hazard and ground shaking limits. From the classical and standard HVSR datasets, estimates of the predominant resonant frequency of the soil are obtained, observed to be well matched, from which first order inversions are carried out around the predominant frequency to provide a fair estimate of thickness of the regimented layer over a hard seismic substratum up to a depth of 100 m. In the standard HVSR datasets, the Rayleigh wave ellipticity curves are extracted with time–frequency analysis using continuous wavelet transforms. This is followed by the Rayleigh wave ellipticity inversion approach to derive a first order approximate sedimentary shear velocity structure. We also compute HVSR measurements using earthquakes. The noise and earthquake HVSR curves are well-matched in terms of the predominant frequencies and range from 3.8 to 16.7 Hz and 3.2 to 16.5, respectively. The estimated VS30 values (the average shear wave velocity (VS) for the top 30 m of the soil) vary from 520 to 1350 m/s, matching well with some of the geotechnical studies conducted here. The study emphasizes the effectiveness of the single station HVSR method in determination of hitherto unknown soil structures as economical and non-invasive exploration viability and proving quite useful for critical centres of industrial establishments.
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KARIYATHAN T, PILLAI D, ELIAS E, MATHEW T A
045180 KARIYATHAN T, PILLAI D, ELIAS E, MATHEW T A (Indian Institute of Science Education and Research Bhopal, Bhopal- 462 066, Madhya Pradesh) : On deriving influences of upwind agricultural and anthropogenic emissions on greenhouse gas concentrations and air quality over Delhi in India: A stochastic Lagrangian footprint approach. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01453-6.
Delhi, the capital city of India witnesses severe degradation of air quality and rapid enhancement of trace gases during winter. Still it is unclear about the relative role of the meteorological conditions and the post-monsoon agricultural stubble burning on the occurrence of these events. To overcome this, we examine the use of applying high-resolution transport model to establish the link between atmospheric concentrations and upstream surface fluxes. This study reports the implementation of a Lagrangian approach and demonstrates its capability in deriving the upwind influences over Delhi. We simulate stochastic back trajectories over Delhi by implementing stochastic time-inverted Lagrangian transport (STILT) model, driven by the meteorological fields from the European Centre for Medium Range Weather Forecasts (ECMWF) model. During the post-monsoon, when mixing layer height is shallow, we find high near-field influence. The variations in footprint simulations with receptor heights show the effect of mixing layer dynamics on the air-parcels. By using atemporal emission fields, we find a considerable impact of meteorological conditions during November that contributes to the enhancements of trace gases. Together with strong emissions (anthropogenic and biomass burning), these enhancements can be several orders higher compared to other seasons. Through the receptor-oriented STILT implementation over India, we envision a wide range of applications spanning from air quality to climate change. An advantage of this implementation is that it allows the use of pre-calculated footprints in simulating any trace gas species and particulate matter, making it computationally less demanding than running an ensemble of full atmospheric transport model.
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DAS P K, CHANDRA S, DAS D K, MIDYA S K, PAUL A, BANDYOPADHYAY S, DADHWAL V K
045179 DAS P K, CHANDRA S, DAS D K, MIDYA S K, PAUL A, BANDYOPADHYAY S, DADHWAL V K (Regional Remote Sensing Centre-East, Kolkata) : Understanding the interactions between meteorological and soil moisture drought over Indian region. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01460-7.
The present study aims at analysing the relationship between meteorological and soil moisture droughts over different meteorological regions of India based on change-point, trends and probability analysis. The long term gridded standardized-precipitation-evapotranspiration-index (SPEI) and standardized-soil-moisture-index (SSMI) data during 1980–2015 were used to address the meteorological and soil-moisture drought, respectively. The significant changes in the time-series SPEI and SSMI data at different time-scales were estimated using Pettitt’s test. The variations in change-points among different time-scales of SSMI were much lower than SPEI, specifically in parts of NW and central India. The inter-annual variability of drought parameters, i.e., duration and magnitude, showed good agreement between meteorological and soil moisture droughts for mild drought conditions. However, under moderate drought conditions, the behaviour of meteorological and soil moisture drought was different, specifically over peninsular India. The trend analysis revealed that SSMI based drought occurrences were significantly decreasing over all the four meteorological regions, whereas in case of SPEI, significant trends were observed only over peninsular India for mild drought condition. The probability of occurrences of both meteorological and soil moisture droughts were higher over major parts of India in case of mild droughts, whereas the values were lower for moderate drought conditions.
49 ref
AKOLKAR G N, LIMAYE M A
045178 AKOLKAR G N, LIMAYE M A (Geology Dep, The Maharaja Sayajirao Univ of Baroda, Vadodara- 390 002, Gujarat) : Geochemistry of calc-silicate rocks around Lunavada region, NE Gujarat: Implications for their protolith, provenance and tectonic setting. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01463-4.
In this work, the calc-silicate rocks affiliated to the ‘Kadana Formation’, a youngest formation of the Lunavada Group have been investigated. These rocks are found to be embedded within associated rock types, viz., quartzites and metapelites in the form of isolated lensoidal bodies. Contact metamorphic textures and the typical mineral assemblage, viz., Act +Di + Cal + Qtz + Ttn ± Mc ± Pl ± Bt ± Ep ± Scp ± Chl with minor proportion of apatite, zircon and opaques can be observed in these calc-silicates. Major oxides, trace and rare earth elements were analysed to investigate the protolith type, provenance and tectonic setting of these rocks. Protolith must be calcareous sandstone with varied proportion of clay and deposited in shallow water environment as revealed by CaO, Al2O3 and FeO+MgO and Al–Zr–Ti ternary diagram, respectively. Low to moderate weathering of source rocks has been indicated by A–CN–K ternary diagram. Th/Sc vs. Zr/Sc and Th/Co vs. La/Sc plots confirm the continental source with felsic nature for these rocks and the calc-silicate samples fall within the active continental margin region of Sc–Th–Zr/10 diagram which also justify the kind of provenance for primary sediments.
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SAFARI M, HEZARKHANI A, MASHHADI S R
045177 SAFARI M, HEZARKHANI A, MASHHADI S R (Mining and Metallurgical Engineering Dep, Amirkabir Univ of Technology, Tehran, Iran) : Hydrogeochemical characteristics and water quality of Aji-Chay river, eastern catchment of Lake Urmia, Iran. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01469-y.
The Aji-Chay river is the most important river discharging into endangered Lake Urmia in NW of Iran. The present study investigates the hydrogeochemical characteristics and origin of dissolved ions in the Aji-Chay river and some of its tributaries passing through Tabriz plain which is located at the east side of Lake Urmia. For this purpose, 317 water samples were collected during 9 years (2005–2014) from four stations and clustered to nine groups using K-means algorithm. Major cations and anions were considered to distinguish the hydrogeochemical evolution of water. The Piper, Langelier–Ludwig and Stiff diagrams classified water samples into predominant Na–Cl endmember and Ca–HCO3 only in the upstream zone. With respect to Gibbs diagrams, mineral saturation indices and geology of the area, water chemistry of the Aji-Chay river reflects that water–rock chemical interactions including dissolution/precipitation of carbonate and sulfate minerals known as dedolomitization and dissolution of evaporitic salts along the flow path are the dominant factors controlling the water chemistry; furthermore, evaporation, silicate weathering, and ion exchange reactions change the chemistry of water to some extent. Overall, water quality is evaluated as poor. Furthermore, intense halite dissolution increases Na concentration in water which in turn reduces its suitability for irrigation purposes.
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KHOSHCHEHREH M, GHOMESHI M, SHAHBAZI A
045175 KHOSHCHEHREH M, GHOMESHI M, SHAHBAZI A (Water and Hydraulic Structures Dep, Shahid Chamran Univ of Ahvaz, Ahvaz, Iran) : Hydrological evaluation of global gridded precipitation datasets in a heterogeneous and data-scarce basin in Iran. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01462-5.
Accurate estimation of the precipitation characteristics, including the value, temporal pattern, and spatial distribution, plays a significant role in the input uncertainty reduction for rainfall-runoff models. In many basins, the improper spatial distribution of rain gauge stations or their limited historical recorded data causes many challenges, especially in heterogeneous catchments which due to the impact of the drastic geographical alterations on the rainfall distribution pattern, the cover of the ground stations cannot estimate the actual precipitation rate. This challenge can be potentially solved by adopting rainfall products as alternative or complementary data sources. In this research, three rainfall products (PERSIANN-CCS, CMORPH and ERA-Interim), were compared against rain gauge stations for calibration of a daily conceptual lumped rainfall-runoff model (CRFM) in a data-scarce and heterogeneous basin located in southwestern Iran. The results indicated that ERA-Interim has the best performance among other datasets. Better performance of this dataset compared to the in-situ data also suggests a better estimation of the basin average as well as the temporal pattern of precipitation. The KGE value was obtained as 0.8 and 0.74, respectively, for a rainfall-runoff model that utilized the ERA-Interim as input in the calibration and validation periods. The results showed that the performance of satellite-based data of CMORPH and PERSIANN-CCS is not acceptable in simulating the daily flow. Also, the seasonal assessment showed that ERA-Interim has a better performance compared to other datasets, during fall and winter. However, in the spring, the performance of all datasets significantly reduces, and the range of BIAS variation increases. Generally, all datasets were shown to perform better in simulating the flow in terms of the transition from dry to wet periods, rather than wet to dry periods.
2 tables, 64 ref
GUGULOTHU S, DHAKATE R, SREEDHAR K, RAMESH A, SAXENA P R
045174 GUGULOTHU S, DHAKATE R, SREEDHAR K, RAMESH A, SAXENA P R (CSIR- National Geophysical Research Institute, Hyderabad- 500 007) : Geophysical and hydrochemical studies for sustainable development of groundwater resources in northwestern part of Telangana State, India. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01452-7.
Studies have been carried out to assess groundwater potential using geophysical analysis and water quality indices in parts of Nyalkal and Zaheerabad Mandal, Medak District, Telangana State. As a part of the study, 50 groundwater samples were collected and 103 Vertical Electrical Soundings (VES) had been carried out. The water quality was assessed with respect to various major ion chemistry and trace elements. It is found that major ions and trace elements are within the permissible limits, except Al, Pb, and Zn metals, which slightly exceeded beyond permissible limits. However, the results of VES reveal that in some parts of the study area, the resistivity range for topsoil (26.61–930 Ωm), lateritic zone (453–738 Ωm), clayey/sandy clay layer (4.71–94.2 Ωm), weathered/fractured bedrock (60.5–928 Ωm) and weathered/vesicular/massive basalt (8.05–676 Ωm) are found with the formation of thick overburden and fractured basement. It is also found that the groundwater prospects are moderate to high depending on the extent of the weathering zone.
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EL-RAYES A, OMRAN A, GERIESH M, HOCHSCHILD V
045173 EL-RAYES A, OMRAN A, GERIESH M, HOCHSCHILD V (Geology Dep, Suez Canal Univ, Ismailia- 415 22, Egypt) : Estimation of hydraulic conductivity in fractured crystalline aquifers using remote sensing and field data analyses: An example from Wadi Nasab area, South Sinai, Egypt. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01470-5.
Fractured crystalline aquifer is considered as the main source of water supply in most of the arid and semi-arid regions. Fractures play an essential role as pathways through which groundwater flows from high catchments to supply the productive wells in lowlands. The hydraulic conductivity measurements for highly fractured crystalline aquifers are a must for optimal management of groundwater extraction from these aquifers. The current work aims at estimating the hydraulic conductivity of the crystalline aquifer by using an unconventional approach based entirely on the processing of remotely-sensed lineament data and field observations. Extracted lineaments at four sites near the productive wells along Wadi Nasab area (WNA) were traced from Landsat (ETM+7) and other ancillary geological data by using image processing and GIS tools. Hence, four discrete fracture networks (DFN) were designed and practiced for the selected test sites to model the groundwater flow through the fracture system in order to estimate the hydraulic conductivity of the investigated crystalline aquifer. The achieved results indicated that the hydraulic conductivity of fractured basement aquifer of WNA varied between 2.3 × 10−7 and 6.1 × 10−7 m/s. The estimated hydraulic conductivity values are close to the values of previous field infiltration tests in the nearby area at Sinai. The previously estimated infiltration rates (expressing the vertical hydraulic conductivity) on the fractured crystalline outcrops ranged between 2.6 × 10−6 and 6.5 × 10−7 m/s, which are concordant with achieved results. Moreover, the achieved values match the previously published values of hydraulic conductivity for similar crystalline aquifers around the world, reflecting the high validity of the used unconventional, low-cost approach to estimate the hydraulic conductivity of fractured crystalline aquifers. The designed approach can be potentially practiced on similar basins in Sinai peninsula and other comparable basins having similar geological and climatic environments around the world.
119 ref
KUMARI B, PANDEY A C
045172 KUMARI B, PANDEY A C (Central Univ of Jharkhand, Ranchi, Jharkhand) : Geo-informatics based multi-criteria decision analysis (MCDA) through analytic hierarchy process (AHP) for forest fire risk mapping in Palamau Tiger Reserve, Jharkhand state, India. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01461-6.
Forest fires constitute a foremost environmental calamity that distresses the sustainability of the forest. The main source of degradation of Jharkhand forests are forest fires conquered by forest species of Sal and Bamboo. Palamau Tiger Reserve in Jharkhand state, India, is becoming more susceptible to forest fire due to anthropogenic disturbance coupled with speedy upsurge in population. In this study, forest fire risk in PTR was evaluated based on various fire inducing factors, viz., forest fuel, settlements, roads, bare soil index, elevation slope and aspect. Geoinformatics based multi-criteria decision analysis (MCDA) through method of AHP (analytic hierarchy process) used to extract forest fire risk map in five classes: Very low risk, low risk, moderate risk, high risk and very high risk. The results obtained showed that about 180 km2 (14.85 %) falls under very low fire risk zone, 234 km2 (19.30 %) falls in low fire risk zone, 269.73 km2 (22.16 %) falls under moderate fire risk zone, 299.36 km2 (24.59 %) falls under high fire risk zone and 232.56 km2 (19.10%) falls in very high fire risk zone. Forest fire risk map was validated from historical fire incidents observed through field data, MODIS and SNPP-VIIRS satellite products. The results showed that the geoinformatics based forest fire risk zones delineated through MCDA-AHP method are in good agreement with historical forest fire occurrences, henceforth may be utilised for fire planning for mitigation in forest areas.
41 ref
KEESARI T, ROY A, PANT D, SINHA U K, KUMAR P V N, RAO L V
045171 KEESARI T, ROY A, PANT D, SINHA U K, KUMAR P V N, RAO L V (Isotope and Radiation Application Div, Bhabha Atomic Research Centre, Trombay, Mumbai) : Major ion, trace metal and environmental isotope characterization of groundwater in selected parts of Uddanam coastal region, Andhra Pradesh, India. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01467-0.
This paper elaborates the hydrochemical and environmental isotope (δ2H and δ18O) inferences obtained from Uddanam region, Andhra Pradesh, India. Groundwater samples collected during pre-monsoon (June 2019) showed that the quality is fresh (EC < 1539 µS/cm) and contaminants like fluoride (<1.6 mg/L) and nitrate (<49 mg/L) are present within permissible limits. The composite water quality indices for drinking (DWQI: 14.1–92.5) and irrigation (IWQI: 2.8–20.2) are found to be satisfactory. The major water types are found to be Ca–Na–HCO3, Na–Ca–HCO3, Na–Mg–HCO3–Cl, Ca–Mg–HCO3–Cl and Na–HCO3. Three geochemical pathways are found signifying evaporite dissolution, contribution of silicate mineral weathering and base-exchange process, which is supported by estimated chloro-alkaline indices (CAI-1: −4.3 to −0.2, CAI-2: −1.03 to −0.08). Trace metal data clearly suggest that groundwater is free from any metal pollution. Dissolved silica (SiO2) levels range from 34 to 131 mg/L and do not show any particular spatial trend. Isotope data infer that groundwater is recharged by rainwater after undergoing evaporation (δ18O: −6.0‰), which matches with that of the combined isotope signature (δ18O: −5.5‰) of SW and NE monsoon rainfall. δ18O–TDS correlations and hydrochemical facies evolution (HFE) diagram do not infer any seawater intrusion into these coastal aquifers.
55 ref
SINGH A T, SHARMA P, SHARMA C, LALURAJ C M, PATEL L, PRATAP B, OULKAR S, THAMBAN M
045170 SINGH A T, SHARMA P, SHARMA C, LALURAJ C M, PATEL L, PRATAP B, OULKAR S, THAMBAN M (Ministry of Earth Sciences, Goa- 403 804) : Water discharge and suspended sediment dynamics in the Chandra River, Western Himalaya. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01455-4.
Glacier systems are important components of the hydrological cycle and a major source of meltwater and sediment flux that controls the river ecology, water quality, and hydropower generation in the Indian Himalayan Region (IHR). Thus, understanding short- and long-term changes in water and suspended sediment (SS) dynamics is crucial in highly sensitive pro-glacial Himalayan Rivers. In the present study, the Chandra River basin in Western Himalaya was chosen to study river discharge, SS transport dynamics, physical erosion rate, and their governing factors for the 2017 melting season (May–September). The daily mean water discharge and SS concentration in the Chandra River was 260.7 m3s−1 and 775.5 mgL−1 with maximum discharge and SS flux in the month of July. The air temperature showed significant relationship with the river discharge (R2 = 0.67; n = 156; p < 0.001), which in turn controlled the SS export in the basin (R2 = 0.86; n = 130; p < 0.001). An anticlockwise sediment-discharge hysteresis during peak flow conditions suggest exhausted sediments or large distance of sediment transport (>100 km) from the upper glacierized region to the end of the basin. Statistical analysis of SS particle size showed poorly sorted immature grains with a dominance of silt particles (85%), followed by sand (8.5%) and clay (6.5%). The SS estimates revealed a total suspended sediment yield of 1285 tons km−2 yr−1 and physical erosion rate of 0.47 mm yr−1. Considering the socio-economic importance of the Himalayan region, the present study will help to evaluate the water and sediment budget of the Chandra River, Western Himalaya and to establish their relationship to the meteorological conditions in the basin.
43 ref
JACOB J, PITCHIKA V K, DUBEY K M, MISHRA A, KUMAR P, KUMAR S, MAHALE V P, CHAUBEY A K
045169 JACOB J, PITCHIKA V K, DUBEY K M, MISHRA A, KUMAR P, KUMAR S, MAHALE V P, CHAUBEY A K (CSIR- National Institute of Oceanography, Maharashtra- 400 053, Mumbai) : Tectonic appraisal of the Mid-Thane Creek of Mumbai, India: An integrated geophysical approach. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01464-3.
Integrated geophysical surveys, comprising marine magnetic, high resolution shallow seismic and single-beam bathymetry were conducted to assess subsurface tectonics of the Mid-Thane Creek (MTC) of Mumbai. The bathymetry in the intertidal zone of MTC varies drastically due to periodic dredging, with maximum depth up to 6.4 m and a minimum of ~−1.6 m. High resolution shallow seismic sections up to the depth of ~35 m from the sea-floor are generated to analyze the neotectonic activity of the creek. Imprints of deep-seated lineaments are recognized from magnetic anomaly map of the MTC. To delimit lateral extent of the lineaments/faults, results of several derivative methods including tilt derivative and standard Euler deconvolution are merged with the selected crest value of the horizontal derivative. To estimate depth to the source, Euler deconvolution, tilt derivative, analytic signal, and source parameter imaging method have been used. However, the depth estimation for the lineaments/faults is highly discrepant for this region, because of the complex tectonics associated with the periodic emplacements of Deccan flood basalt. To confine the top and bottom boundary of this highly magnetized basaltic layer, we have carried out spectral analysis considering 18 windows of 2000 × 2000 m with an overlap of 500 m. The average depth to the top and bottom of the source body estimated using spectral analysis is consistent with the depth estimated from the derivative filters. This confirms that the lineaments identified by the derivative filters may embed in the basaltic layer of MTC. The most prominent lineament interpreted from the seismic and magnetic data, in the central region of MTC is inferred as the marine analogue of Alibagh–Uran Fault passing through the mainland of Alibagh and Uran close to Mumbai city.
72 ref
KANG X B, XU M, LI K, LIU X
045168 KANG X B, XU M, LI K, LIU X (Chengdu Univ of Technology, Chengdu- 610 059, People’s Republic of China) : Exploration and utilisation of groundwater resources in extreme arid regions of the Tibetan Plateau: A case study on Ali area, China. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01472-3.
Identifying a good site for groundwater exploitation in arid areas with scarce hydrogeological data is a challenging task. In this study, west of the Tibet Autonomous Region located at the peak of the world ridge that belongs to the extreme water-scarce poverty zone is used as the study area. This study is the first to determine the formation and controlling factors affecting the groundwater resources in Ali area via comprehensive geophysical and geochemical prospecting. The meteorological and hydrological characteristics of the study area are analysed, and the source and characteristics of water vapour in the study area are determined. Although the Indian peninsula and the Arabian Sea water vapour transmission paths exist, only small amounts of water vapour enter the area because of the distance limit and alpine barrier, which is the main reason for the drought in the study area. An overall conclusion of the hydrogeological condition and groundwater resources in Ali area is drawn on the basis of geophysical surveying, hydrogeological drilling, and water chemical analysis. The distribution of water resources in the Quaternary Aquifer, which is controlled by water vapour transport, aquifer-forming deposits, river distribution, and temperature, is not well-proportioned. The aquifer potentiality reduces from the southern to the northern direction in sequence. Thus, the great mass of midlands and the northern region belong to drought zones. Groundwater salinity, which is affected by drought, is higher than surface water salinity and obviously increases in constituent concentrations. The findings promote the understanding and utilisation of water resources in the study area.
50 ref
CHOUDHURY D, GUPTA A, RANI S I, GEORGE J P
045167 CHOUDHURY D, GUPTA A, RANI S I, GEORGE J P (Ministry of Earth Sciences, Noida- 201 309) : Impact of SAPHIR radiances on the simulation of tropical cyclones over the Bay of Bengal using NCMRWF hybrid-4DVAR assimilation and forecast system. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01473-2.
Observing System Experiments (OSEs) were conducted to analyze the impact of assimilation of Megha-Tropique’s (MT) Sounder for Probing Vertical Profiles of Humidity (SAPHIR) radiances on the simulation of tracks and intensity of three tropical cyclones (Kyant, Vardah, and Maarutha) formed over the Bay of Bengal during 2016–2017 North Indian Ocean cyclone period. National Centre for Medium Range Weather Forecast (NCMRWF) Unified Model (NCUM) Hybrid-4DVAR assimilation and forecast system was used for the OSEs. Assimilation of SAPHIR radiances produced an improvement of 9 % and 12 %, respectively, in the cyclones’ central sea level pressure (CSLP) and the maximum sustained wind (MSW), while an improvement of 38 % was seen in the cyclone tracks within the forecast lead time of 120 hrs. Initial assessment shows that the improvement in the cyclone intensity is due to the assimilation of the unique surface peaking channel of SAPHIR (channel-6), whereas the improvement in the cyclone track is due to the assimilation remaining five channels of SAPHIR. Thus, the assimilation of SAPHIR radiances in the NCUM system showed improvement in both intensity and track of the cyclones over the Bay of Bengal; however, more cyclone cases over different ocean basins have to be analyzed to make a robust conclusion. This study specifies the importance of similar microwave humidity instruments in the same frequency range for the detailed exploration of cyclone track and structure.
33 ref
CHAUHAN H, TRIPATHI A, PANDIT D, RAO N V C, AHMAD T
045166 CHAUHAN H, TRIPATHI A, PANDIT D, RAO N V C, AHMAD T (Geology Dep, Banaras Hindu Univ, Varanasi- 221 005) : A new analytical protocol for high precision U–Th–Pb chemical dating of xenotime from the TTG gneisses of the Bundelkhand Craton, central India, using CAMECA SXFive Electron Probe Micro Analyzer. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01482-1.
Xenotime is a significant accessory mineral which is being extensively used for precise U–Th–Pb geochronology by Electron Microprobe Analysis (EPMA). This paper presents a protocol for high analytical precision (<3% uncertainties on the measured ages) developed for the accurate estimation of U–Th and Pb content in xenotime using SXFive EPMA at the Department of Geology, Banaras Hindu University, by deploying five spectrometers attached with TAP, LIF, LPET, LTAP and PET crystals. The protocol is applied to the xenotime grains of tonalite-trondhjemite-granodiorite-gneiss (TTG) rocks from the geochronologically well-constrained terrain of the Bundelkhand Craton, central India. The obtained xenotime age 2929±23 Ma of TTGs is in agreement with the earlier published Neoarchaen 2697±3 Ma Pb–Pb zircon ages from the same area which validates the authenticity of the analytical method developed at the BHU-EPMA facility.
43 ref
BHATTACHARYA A R, VERMA A K
045163 BHATTACHARYA A R, VERMA A K (Lucknow Univ, Lucknow- 226 007) : Grain-shape controlled strain in quartz grains in high ductile flow regime: Observations from the Main Central Thrust Zone of the Kumaun Himalaya, India. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01479-w.
In ductile shear zones, the strain shown by the rocks depends much on the composition and shape of the mineral constituents. Under simple shear, quartz grains commonly reorient themselves in the direction of tectonic transport or flow. In ductile shear zones, quartz grains are elliptically stretched in the direction of mylonitic foliation to accommodate the imposed ductile strain. Our observations on the rocks of a crustal scale shear zone, the Main Central Thrust (MCT) of the Himalaya, however, reveal that at several places of the shear zone the quartz grains are polygonal and show planar boundaries. The fabric of rocks at such places is not compatible with that of the prevailing fabric of rocks, and can be described as strain insensitive fabric. Following the Panozzo (J. Struct. Geol. 6:215–221, 1984) method, we have estimated strain from quartz grains that show planar boundaries. Our results show that in the MCT zone, the areas of high ductile strain, as existing near the trace of the MCT, the amount of strain shown by such grains of quartz is low, while in areas of low strain, as existing in areas away from the MCT, the amount of strain is relatively higher. As such, the method holds importance in those cases where grain shapes (i.e., planar boundaries) put constraint on estimation of strain because the conventional methods of strain estimation require elliptical shape of objects. This is possibly the first application of the Panozzo method on deformed rocks from India.
15 ref
NARAYANA A C, NAIDU P D, BHAVANI P G, AHMAD M
045162 NARAYANA A C, NAIDU P D, BHAVANI P G, AHMAD M (Hyderabad Univ, Hyderabad- 500 046) : A coherent response of Southern Indian Ocean to the Antarctic climate: Implications to the lead, lags of atmospheric CO2 during deglaciation. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01484-z.
A record of δ18Oc from the Indian sector of Southern Ocean and atmospheric CO2, and δ18O of European Project for Ice Coring in Antarctica (EPICA) and Greenland Ice Sheet Project 2 (GISP2) reveals that a coherent response between δ18O record of Antarctic ice core and the δ18Oc record from Southern Indian Ocean during the deglaciation with initial warming starting around 18 kyr BP which is in agreement with the raise of atmospheric CO2 during same time. A distinct asynchrony between the records of δ18Oc from the Southern Indian Ocean and δ18O of GISP2 during the last deglaciation is noticed. We report that Southern Ocean degassing played an important role in raising atmospheric CO2 through Atlantic Meridional Overturning Circulation (AMOC), which has an implication in triggering abrupt climate events through coupling of ocean and atmospheric processes.
38 ref
CHANU C S, MUNAGAPATI H, TIWARI V M, KUMAR A, ELANGO L
045161 CHANU C S, MUNAGAPATI H, TIWARI V M, KUMAR A, ELANGO L (CSIR- National Geophysical Research Institute, Hyderabad) : Use of GRACE time-series data for estimating groundwater storage at small scale. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01465-2.
This study integrates the time series of satellite data, i.e. (terrestrial water storage (TWS) extracted from Gravity Recovery and Climate Experiment (GRACE), soil moisture (SM) from Global Land Data Assimilation System (GLDAS), rainfall from Tropical Rainfall Measuring Mission (TRMM)) with in-situ data, i.e. (groundwater (GW) observatory well data and surface water (SW) as reservoir level from Tamil Nadu Public Work Department (TN PWD)) to estimate the water storage of the study area for the period from 2002 March to 2016 December. The study area encompasses three districts of Tamil Nadu State – Chennai, Kancheepuram and Tiruvallur. It was previously observed that the groundwater level in this study area is decreasing at an alarming rate. Trends and residuals of the times series of all the previously stated components were analyzed. Negative trends were observed in the case of ΔSW, ΔSM, ΔGW, ΔTWS-GRACE, but rainfall shows a slight positive trend. Rainfall, being the input for water storage, a marginal increase in rainfall cannot affect the variability of ΔSM, ΔSW, ΔGW and ΔTWS-GRACE. ΔTWS decreases approximately 0.12 cm yr−1 averaged water level equal to a total volume −7.5 km3. The result of this study shows a decrease in the total storage of groundwater in the study area during the study period from 2002 March to 2016 December. Seawater intrusion due to an increase in sea surface height also shows an impact on ΔTWS derived from grace, in the form of anomalously elevated ΔTWS. A good agreement between ∆TWS-GRACE and ∆TWS-in-situ is found except where sea-water intrusion occurs.
45 ref
SARKAR A, BHATTACHARJEE D, CHATTOPADHYAY A
045160 SARKAR A, BHATTACHARJEE D, CHATTOPADHYAY A (Geology Dep, Delhi Univ, Delhi) : Size distribution of survivor clasts in pseudotachylyte and cataclasite: Implications for crushing and melting processes in seismic fault zones. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01480-3.
Quartz/feldspar fragment (‘clast’) sizes were measured in thin sections of three types of fault zone rocks, e.g., melting-dominated pseudotachylyte (M-Pt), crushing-dominated pseudotachylyte (C-Pt) and cataclasite (Ct), from two well-studied Precambrian shear/fault zones in the Indian craton (e.g., the Gavilgarh–Tan Shear zone in central India and the Sarwar–Junia Fault zone in western India). Logarithmic plots of clast area vs. cumulative frequency in the pseudotachylytes demonstrate a fractal clast-size distribution (c.s.d.) for the intermediate size range, whereas the finer and coarser clast size fractions clearly deviate from the fractal trend. Under-representation of the finer size clasts in the pseudotachylyte samples may be attributed to their preferential melting and removal from the clast population. The relative paucity of coarse clasts, on the other hand, is possibly due to a sampling bias against coarse clasts. The c.s.d of the cataclastic rock shows a multi-fractal character with two different slopes (i.e., lower D-value for finer clast sizes) and absence of the left-hand (finer size) fall off. This suggests less efficient crushing in the finer clast size fraction. The proportion of clasts, compared to the matrix, is very small in M-Pt, increases in C-Pt and is highest in Ct, suggesting that melting of rock/mineral fragments is a dominant process in forming M-Pt, whereas it is less significant in C-Pt, and is absent in Ct, which corroborates the microscopic observations.
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DAS R, GOGOI B , JAISWAL M K
042844 DAS R, GOGOI B , JAISWAL M K (Geography Dep, Cotton Coll, Guwahati - 781 001, Assam, Email: dratul.das@gmail.com) : Soil loss assessment in sadiya region, Assam, India using remote sensing and GIS. Indian J Sci Technol 2020, 13(23), 2319–27.
This study focuses on identifying areas of intense soil erosion in Sadiya, a subdivision of Tinsukia district of Assam in India to facilitate appropriate implementation of soil management and conservation schemes in an administrative unit. A comprehensive methodology of Remote Sensing (RS) and Geographical Information System (GIS) is implemented with an empirical model called the Revised Universal Soil Loss Equation (RUSLE). RUSLE is the best model to assess soil loss creating different raster layers in GIS. This study estimates about 443865 tons of soil loss occurs in Sadiya region annually. The maximum rate of soil loss recorded in Sadiya region is 888.26 t ha−1 year−1 the average soil loss estimated for the region is 5.45 t ha−1 year−1 . In addition, a final soil loss map is also created to show the zones of varied soil erosion rates/intensities. The use of RS and GIS in soil loss estimation gives highly accurate result and can be used for extensive area with low cost. The study reveals that soil loss is a serious issue in the region where agriculture is the main economic activity. The outcome of the study may be used directly to address the hazard through management practices.
7 illus, 4 tables, 13 ref
SINGH O, PANWAR S
044791 SINGH O, PANWAR S (Zoology Dep, Sahu Jain Coll, Najibabad- 246 763, Email: drovsgill@gmail.com) : Infestation of nematode parasite filochona teleostei in relation to size, weight and age of snow trout Schizothorax richardsonii (gray). J Mountain Res 2020, 15, 35-45.
Parasitological investigation was conducted to assess the effects of various biotic factors viz. length, weight and age of host on the infection patterns of Filochona teleostei (Singh & Malik, 1992) in snow trout Schizothorax richardsonii (HAM.) from hill streams of Garhwal Himalayas. The statistical analysis was carried out to calculate infection incidence, mean worm burden, regression values and their significance. About 20 % fishes (18 % male and 22 % female) were found infected with nematode parasites. Infection patterns of Filochona teleostei revealed a negative correlation (r= - 0.347 to - 0.734) with length, (r= - 0.499 to - 0.671) with weight and (r= - 0.576) with age of host fish. The age immunity and stronger host resistance developed by the larger fishes are the possible reasons for the decrease in infection in larger and older fishes.
5 illus, 3 tables, 39 ref