Determination of seismic wave attenuation in Delhi,India, towards quantification of regional seismic hazard     

Banerjee  Soham  Kumar  Abhishek 《Natural Hazards》2018,92(2):1039-1064

Natural Hazards - National capital of India, Delhi is under moderate to high seismic hazard due to active regional faults such as the Mahendragarh fault, the Delhi Haridwar fault, the Sohna fault,...  相似文献   

Bridge construction and river channel morphology—A comprehensive study of flow behavior and sediment size alteration of the River Chel,India     

Mery Biswas  Puja Banerjee 《Arabian Journal of Geosciences》2018,11(16):467

Human has always modified its surroundings for better adaptation which include the building of urban landscapes, dams, and engineering constructions like bridges and other infrastructures. It has been unveiled from the study of River Chel that when the rail bridge was constructed before 1913, the natural width of the river was nevertheless maintained but the problem was initiated and after the road bridge construction in 1970s when the river width was minimized,the morphological changes started in a large scale. Such modifications have affected nature as well as human communities both positively and negatively. This paper will try to portray the evolution of channel shifting and changes of sediment size regime that the River Chel is experiencing due to the construction of bridges across the middle part of its course. So, this study is concerned about the changes in channel pathway since last 100 years and field-based hydrological parameters and sediment size analysis reveals some distinct changes in the channel planform with alteration of sediment size regime. Simulation of the hydraulic modeling in HEC-RAS specifies the probable affected area with bridges and without bridges in both upstream and downstream of the river course. Hence, the study unveils the alteration of the river hydrology and sediment size caused due to anthropogenic effects and impact of such flow analysis has been evaluated through the bridge scour calculation by CUS method. The discussion concludes that the Odlabari road bridge construction (after 1970) has modified the normal hydrological behavior of the river with a higher probability of bank erosion in downstream and floods in upstream resulting river bottleneck condition.  相似文献   

Analytic hierarchy process and information value method-based landslide susceptibility mapping and vehicle vulnerability assessment along a highway in Sikkim Himalaya     

Polash Banerjee  Mrinal Kanti Ghose  Ratika Pradhan 《Arabian Journal of Geosciences》2018,11(7):139

In hilly areas, highway projects can be a cause of landslides as well as an element of vulnerability due to landslides. Hence, landslide susceptibility mapping of highway corridors can substantially mitigate loss of life and property. For this, a Landslide Susceptibility Assessment Model (LSAM) was developed for a corridor of 27 km along NH 10 in the East Sikkim. Landslide inducing factors viz. Aspect, Distance from Fault, Distance from Road, Drainage Density, Land use and Land cover, Lithology, Plan Curvature, Rainfall, Slope, Soil Depth, and Soil Texture were considered for the study. Results show that areas in proximity to the highway and areas with steeper slope had a higher landslide susceptibility than otherwise. Spatial explicit sensitivity analysis indicated that LSAM was sensitive to distance from the highway and slope. Vehicle vulnerability assessment of base year and horizon years showed that vulnerability increased through time. LSAM is appropriate for hazard mitigation for areas with poor historical data on landslides.  相似文献   

Petrology and geochemistry of the ultramafic–mafic Mawpyut complex,Meghalaya: a Sylhet trap differentiation centre in northeastern India     

Srinanda Chaudhuri  Jyotisankar Ray  Christian Koeberl  Martin Thni  Riya Dutta  Abhishek Saha  Mousumi Banerjee 《Geological Journal》2014,49(2):111-128

The present article describes, for the first time, petrological and geochemical details of the Mawpyut differentiated complex which is related to the Sylhet trap located at Jaintia Hills district, Meghalaya, northeastern India. The Mawpyut complex occurs as an arcuate body that intrudes into the surrounding Shillong Group rocks. The complex in general contains ‘ultramafic’ and ‘mafic’ rocks, as well as minor syenitic veins that postdate the main units. The lithotypes correspond to cumulate and noncumulate units. The cumulate unit is represented by olivine clinopyroxenite, clinopyroxenite, plagioclase‐bearing ultramafic, olivine gabbronorite, mela‐gabbronorite, melagabbro, orthopyroxene gabbro, and gabbro, all with a pronounced cumulus texture. The noncumulate unit is marked by gabbro, monzonite, monzodiorite, and quartzsyenite. The use of several major and trace element variation diagrams suggests that magmatic differentiation led to the formation of cumulate and noncumulate units. In chondrite‐normalized REE diagrams the cumulate rocks show flat LREE and MREE patterns and a moderate positive Eu anomaly (in plagioclase‐bearing ultramafics) due to plagioclase cumulation. The rocks of the noncumulate unit show a strongly fractionated REE pattern and no Eu anomaly. The noncumulate mafic rocks are geochemically comparable to high‐phosphorous/high‐titanium basalts (HPT) indicative of low pressure fractional crystallization. In a primitive mantle‐normalized multielement diagram some of the cumulate rocks show pronounced negative anomalies for K and P, indicating anorogenic mafic magmatism in a within‐plate setting. The rocks of the noncumulate unit show a slight negative anomaly for Yb and a Nb–Ta trough, indicating a subduction‐related signature that perhaps is inherited from subducted sedimentary rocks incorporated during crustal contamination of the derived magma (left after crystal cumulation) with country rocks. Various trace element ratios for the cumulate mafic rocks indicate parent EMI/EMII/HIMU sources with a very limited crustal signature. The noncumulate mafic rocks (corresponding to the derived evolved magma) indicate EMI/EMII/HIMU sources with a pronounced crustal contamination. The Sr–Nd isotopic compositions of the Mawpyut samples typically plot in the continental flood basalt field, with an affinity to the EMII source. The isotopic compositions of the noncumulate rocks also clearly indicate crustal contamination. We suggest that partial melting (involving garnet in the residue) of the enriched mantle source EMI/EMII/HIMU could have derived the parental melt; this melt, in turn, underwent assimilation and fractional crystallization to produce the variety of cumulate‐noncumulate lithologies of the Mawpyut complex. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Empirical assessment of flood wave celerity–discharge relationships at local and reach scales     

Aline Meyer  Ayan Santos Fleischmann  Walter Collischonn  Rodrigo Paiva  Pedro Jardim 《水文科学杂志》2013,58(15-16):2035-2047

ABSTRACT

An accurate comprehension of celerity (flood wave speed) dynamics is a key step for understanding flood wave propagation in rivers. We present the results of empirically estimated celerity values in 12 Brazilian rivers, and analyse the behaviour of celerity–discharge relationships (CxQ). Celerity was estimated with a reach-scale (RS) method, based on the peak travel time between stations; and with a local-scale (LS) method, based on the derivative of discharge–cross-section area relationships surveyed at gauging stations. The results indicate that the magnitudes of celerity values obtained by the methods are reasonably comparable, and can rarely be considered constant, varying with river discharge. Three reaches presented differing CxQ relationships at local and reach scales, which suggests that in situ cross-sections at gauging stations should not be extrapolated as representative of the whole reach for flood routing studies, and that CxQ relationship assessments might provide relevant insights for hydrological modelling.  相似文献   

Changes in the Level of Proteins,Free Amino Acids and Protease Activities of Clarias batrachus in Response to Sodium meta‐arsenite Intoxication     

Randhir Kumar  Tarun K. Banerjee 《洁净——土壤、空气、水》2013,41(12):1196-1200

Increased hazard of arsenic toxicity at many provinces of India causing extensive contamination of their wetlands. To illustrate the consequences of the arsenic menace on the aquatic fauna, a nutritionally important freshwater catfish Clarias batrachus (Linn.) was subjected to the stress of sublethal concentration (1 mg/L; 5% of 96‐h LC₅₀ value) of sodium meta‐arsenite. The alterations induced by the arsenic salt on certain biomolecules (proteins, free amino acids (FAA), and protease activities) in five tissue components (muscle, liver, brain skin, and gills) of the fish using biochemical techniques were estimated. Significant (p < 0.01) decrease in the concentration of proteins in all the tissues (19.74–44.84% in muscles; 3.17–49.39% in liver; 10.05–36.16% in brain; 12.62–52.01% in skin and 7.34–61.69% in gills), and significant (p < 0.01) increase in FAA (6.84–269.89% in muscles; 125.89–358.03% in liver; 1.07–152.90% in brain; 29.31–401.62% in skin and 38.53–165.07% in gills), and protease activities (43.59–183.33% in muscles; 19.52–131.90% in liver; 8.85–46.72% in brain; 33.33–261.53% in skin and 25.39–50.79% in gills) of the exposed fish were observed. This increase in amino acids and enzyme activity point out toward breakdown of protein leading to their depletion.  相似文献   

Variation in U-238 and Th-232 enrichment in U-mineralized zone and geological controls on their spatial distribution,Singhbhum Shear Zone of India     

K. S. Banerjee  R. Guin  J. L. Gutierrez-Villanueva  M. E. Charro  D. Sengupta 《Environmental Earth Sciences》2012,65(7):2103-2110

The determination of the natural radioactivity has been carried out, by means of gamma-ray spectrometry, in exposed rock samples collected from various geological formations across the Singhbhum Shear Zone of India. The spatial variation in the concentration of primordial radionuclides reflects, in general, the geochemical variance among the analyzed rocks and affirms the earlier views on genesis of uranium mineralization. This study further speculates new possibilities of thorium depletion during shearing and metamorphism. All the obtained U-values were more than the worldwide average U-concentration (which is about 40 Bq/kg). Interestingly, U-concentration in mica schists from Singhbhum group of rocks and in slates and argillaceous quartzites from Iron Ore group of rocks was five to seven times higher than the global values. In contrast, the granites in study area showed comparatively lower U-concentration. The overall results suggest the control of complex metamorphism and shearing on U-distribution in the terrane. The contribution of ²³⁸U, ²³²Th and ⁴⁰K to the total radiation dose in the study area was found to be significant ranging from 110 to 310 nGy/h in comparison with the lower global, as well as Indian average values.  相似文献   

The origin and maturation of lagoonal glauconites: a case study from the Oligocene Maniyara Fort Formation,western Kutch,India     

Santanu Banerjee  Shovan Lal Chattoraj  P. K. Saraswati  Somnath Dasgupta  Urbashi Sarkar  Adam Bumby 《Geological Journal》2012,47(4):357-371

An integrated study of the sedimentology, micropalaeontology, mineralogy and geochemistry of glauconites in the Oligocene Maniyara Fort Formation (western Kutch, India), has been undertaken. Authigenic glauconites, mostly of evolved type, formed within a back‐barrier lagoonal environment. Foraminifera help constrain the biostratigraphy and along with sedimentological evidence, provide information on the depositional conditions. Glauconite in the Maniyara Fort Formation occurs either as infillings within intra‐particle pores of larger foraminifers, or as an altered form of faecal pellets. X‐ray diffraction studies reveal the less mature nature of glauconite infillings compared to the glauconite pellets. Electron microprobe investigation confirms a relative enrichment of K₂O and total Fe₂O₃ in the latter. Both varieties of glauconite formed by initial authigenic precipitation of K‐poor glauconite and subsequently matured by addition of potassium in the interlayer sites and fixation of total iron in the octahedral sites; calcium, magnesium and aluminum were released from the glauconite structure concomitantly. Alkaline conditions during the entire process of glauconite formation did not allow dissolution of foraminiferal tests. Mineralogical and chemical characteristics of the Maniyara Fort Formation glauconites are more similar to deep marine glauconites than those reported from other shallow or marginal marine settings. A low negative cerium anomaly, as well as abundant pyrite, suggests formation of glauconite in sub‐oxic micro‐environments, created by decay of organic matter associated with foraminiferal chambers and faecal pellets. Sub‐oxic condition apparently prevailed relatively longer within the Maniyara Fort Formation lagoons. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Appraisal of the prevalence of severe tropical storms over Indian Ocean by screening the features of tropical depressions     

Chaudhuri  Sutapa  Middey  Anirban  Goswami  Sayantika  Banerjee  Soumita 《Natural Hazards》2012,61(2):745-756

Natural Hazards - Tropical cyclones are one of the nature’s most violent manifestations and potentially the deadliest of all meteorological phenomena. It is a unique combination of violent...  相似文献   

Oreganum Stalks as a New Biosorbent to Remove Textile Dyes from Aqueous Solutions     

Ebru Mavioglu Ayan  Pelin Secim  Serhat Karakaya  Jale Yanik 《洁净——土壤、空气、水》2012,40(8):856-863

In the present study, Oreganum onites L. stalks in natural and chemically modified with HNO³ and H³PO⁴ used as adsorbent for removal of both acidic and basic dyes from waters. The adsorption was studied as a function of pH and contact time by batch method. All tested biosorbents were characterized by FT‐IR, scanning electron microscopy, and measuring the pH dependence of the zeta potential. The adsorption isotherms were fitted to Langmuir isotherm. The maximum adsorption capacity of dyes was 280.73 mg g^?1 for Basic Red 18, 147.06 mg g^?1 for methylene blue and 112.36 for Acid Red 111, which is comparable to that of other lignocellulosic materials. The modification process was considerably increased the biosorption capacity of lignocellulosic material, resulting in a 56–63% increase in the biosorption capacity of basic dyes and a 125% increase in the biosorption capacity of acidic dye. The present study illustrated that the most effective factors in the adsorption of basic dye were surface charge and acidic groups on lignocellulosic biosorbents, while non‐electrostatic forces as well as electrostatic forces were also effective in the adsorption of acidic dye. In conclusion, Oreganum stalks can be considered as a very prospective adsorbent for the removal of tested basic and acidic dyes.  相似文献