Study of substrate and physico-chemical base classification of the rivers of Nepal     

JHA Bibhuti Ranjan  WAIDBACHER Herwig  SHARMA Subodh  STRAIF Michael 《地球空间信息科学学报》2010,13(1):70-76

The rivers in Nepal are classified in terms of geographical regions but a more scientific classification such as on the ba-sis of morphology is clearly lacking. This study was done in 9 rivers namely Jhikhukhola of the Koshi system, Aandhikhola, Arungkhola, East Rapti, Karrakhola, Seti and main channel Narayani of the Gandaki system, and two independent systems within Nepal, Bagmati and Tinau. Among the morphologies, river bed or the substratum was taken as the main variable for the analysis which was categ...  相似文献   

Remote Sensing of Turbidity and Phosphate in Creeks and Coast of Mumbai: An Effect of Organic Matter     

Deepty Ranjan Satapathy  Ritesh Vijay  Swapnil R. Kamble  Rajiv A. Sohony 《Transactions in GIS》2010,14(6):811-832

Geospatial approaches to monitoring and mapping water quality over a wide range of temporal and spatial scales have the potential to save field and laboratory efforts. The present study depicts the estimation of water quality parameters, namely turbidity and phosphate, through regression analysis using the reflectance derived from remote sensing data on the west coast of Mumbai, India. The predetermined coastal water samples were collected using the global positioning system (GPS) and were measured concurrently with satellite imagery acquisition. To study the influence of wastewater, the linear correlations were established between water quality parameters and reflectance of visible bands for either set of imagery for the study area, which was divided into three zones: creek water, shore‐line water and coastal water. Turbidity and phosphate have the correlation coefficients in the range 0.75–0.94 and 0.78–0.98, respectively, for the study area. Negative correlation was observed for creek water owing to high organic content caused by the discharges of domestic wastewater from treatment facilities and non‐point sources. Based on the least square method, equations are formulated to estimate turbidity and phosphate, to map the spatial variation on the GIS platform from simulated points. The applicability of satellite imagery for water quality pattern on the coast is verified for efficient planning and management.  相似文献   

Evaluation of vertical impact factor coefficients for continuous and integral railway bridges under high-speed moving loads     

Anand M.Gharad  Ranjan S.Sonparote 《地震工程与工程振动(英文版)》2021,20(2):495-504

In the railway bridge analysis and design method,dynamic train loads are regarded as static loads enhanced by an impact factor(IF).The IF coefficients for various railway bridges have been reported as a function of span length or frequency of the bridges in Eurocode(2003).However,these IF coefficient values neglect the effects of very high speeds(>200 km/h)and soil-structure interaction(SSI).In this work,a comprehensive study to assess the impact factor coefficients of mid-span vertical displacements for continuous and integral railway bridges subjected to high-speed moving loads is reported.Three different configurations,each for the three-dimensional(3D)continuous and integral bridge,are considered.Also,single-track(1-T)and two-track(2-T)“real train”loading cases for both these bridge types are considered.Subsequently,finite element analysis of the full-scale 3D bridge models,to identify their IF values,considering the effects of SSI for three different soil conditions,is conducted.The IF values obtained from the study for both bridge types are comparable and are greater than the values recommended by Eurocode(2003).The results reveal that with a loss of soil stiffness,the IF value reduces;thus,it confirms the importance of SSI analysis.  相似文献   

Observations and Measurements of Planktonic Bioluminescence off the South Coast and Puttalam Lagoon of Sri Lanka     

Wimalasiri  Hewa Bhashithage Udeshika Gangani Manike  Jinadasa  Sinhalage Udaya Priyantha  Dissanayake  Dadigamuwage Chamari Tathsaramala  Wijesekara  Hemantha W.  Weidemann  Alan D. 《Ocean Science Journal》2020,55(2):321-340

Marine bioluminescence is a unique phenomenon and widely studied around the world. However, information on bioluminescence is scarce in the Indian ocean. This study was carried out to understand the spatial and temporal variations in planktonic bioluminescence off the south coast and the Puttalm Lagoon of Sri Lanka. Planktonic bioluminescence intensity, zooplankton samples, water samples and oceanographic data were collected from sampling sites from January to December 2016 in three month intervals. Time series data were collected at a fixed sampling station, off the south coast of Sri Lanka, in order to understand the variation of bioluminescence intensity throughout the night and with respect to monsoon winds. Bioluminescence intensity was measured using the recoverable bathyphotometer and zooplankton samples were collected using WP-2 net with a 180 μm mesh size plankton net. The results revealed that most of the bioluminescence intensity peaks in the ocean were concentrated in the mixed layer depth zone. Bioluminescence and Chlorophyll profiles indicate the presence of both heterotrophic and autotrophic planktonic bioluminescence. Fixed station analysis showed variations in planktonic bioluminescence throughout the night and with respect to monsoon winds. Twenty two surface bioluminescent zooplankton species belonging to 15 families and 4 phyla were identified during this study. Variations in planktonic bioluminescence with respect to time and sampling locations were evident. The current study yielded encouraging results that should lead to further identification of planktonic distribution near Sri Lanka and key bioluminescent zooplankton in the region.

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Incipient Charnockite Formation in Leptynite from Vizianagaram, Andhra Pradesh: Implication for Pan-African (?) Crustal Reworking in the Eastern Ghats Belt     

Niloy Ranjan Datta  P. Sengupta  Aparajita Gangopadhyay  Sushmita Sarkar 《Gondwana Research》2001,4(4):603-604

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Biosorption of Cr(III) and Cr(VI) species from aqueous solution by Cabomba caroliniana: kinetic and equilibrium study     

P. K. Dileepa Chathuranga  Namal Priyantha  Sithy S. Iqbal  M. C. Mohomed Iqbal 《Environmental Earth Sciences》2013,70(2):661-671

This study reports the potential ability of non-living biomass of Cabomba caroliniana for biosorption of Cr(III) and Cr(VI) from aqueous solutions. Effects of contact time, biosorbent dosage, pH of the medium, initial concentration of metal ion and protonation of the biosorbent on heavy metal–biosorbent interactions were studied through batch sorption experiments. Cr(III) was sorbed more rapidly than Cr(VI) and the pH of the medium significantly affected the extent of biosorption of the two metal species differently. Surface titrations showed that the surface of the biosorbent is positively charged at low pH while it is negatively charged at pH higher than 4.0. Protonation of the biosorbent increased its capacity for removal of Cr(III), while decreasing that of Cr(VI). FT-IR spectra of the biosorbent confirmed the involvement of –OH groups on the biosorbent surface in the chromium removal process. Kinetic and equilibrium data showed that the sorption process of each chromium species followed pseudo second-order kinetic model and both Langmuir and Freundlich isothermal models. A possible mechanism for the biosorption of chromium species by non-living C. caroliniana is suggested.  相似文献   

Hydrochemical characteristics of groundwater in the plains of Phalgu River in Gaya, Bihar, India   总被引：1，自引：0，他引：1  

Rajesh Kumar Ranjan  AL. Ramanathan  Purushothaman Parthasarathy  Alok Kumar 《Arabian Journal of Geosciences》2013,6(9):3257-3267

Assessment of groundwater quality is essential to ensure sustainable use of it for drinking, agricultural, and industrial purposes. The chemical quality of groundwater of Gaya region has been studied in detail in this work to delineate the potable groundwater zones. A total of 30 groundwater samples and 2 surface water samples were collected in and around Gaya district of Bihar. The major cations follow the trend: Ca²⁺?>?Mg²⁺?>?Na⁺?>?K⁺. The domination of calcium ions in the groundwater is due to weathering of rocks. The K⁺ ranged between 0.2 and 47.95 ppm, suggesting its abundance the below desired limit; but some samples were found to be above permissible limit. K⁺ weathering of potash silicate and the use of potash fertilizer could be the source. The major anions abundance followed the order HCO ₃ ^? ?>?Cl^??>?SO ₄ ^2? ?>?NO ₃ ^? ?>?PO ₄ ^3? . Dissolution of carbonates and reaction of silicates with carbonic acid accounts for the addition of HCO ₃ ^? to the groundwater and oxidation of sulphite may be the source of SO ₄ ^2? . Principal component analysis was utilized to reflect those chemical data with the greatest correlation and seven major principal components (PCs) representing >80 % of cumulative variance were able to interpret the most information contained in the data. PC1, PC2 and PC3 reflect the hydrogeochemical processes like mineral dissolution, weathering and anthropogenic sources. PC4, PC5, PC6 and PC7 show monotonic, random and independent relationships.  相似文献   

Understanding the Cyclicity of Chemical Weathering and Associated CO<Subscript>2</Subscript> Consumption in the Brahmaputra River Basin (India): The Role of Major Rivers in Climate Change Mitigation Perspective     

Pallavi?Das  Kali?Prasad?Sarma  Pawan?Kumar?Jha  Rajnish?Ranjan  Roger?Herbert  Manish?KumarEmail author 《Aquatic Geochemistry》2016,22(3):225-251

Weathering of rocks that regulate the water chemistry of the river has been used to evaluate the CO₂ consumption rate which exerts a strong influence on the global climate. The foremost objective of the present research is to estimate the chemical weathering rate (CWR) of the continental water in the entire stretch of Brahmaputra River from upstream to downstream and their associated CO₂ consumption rate. To establish the link between the rapid chemical weathering and thereby enhance CO₂ drawdown from the atmosphere, the major ion composition of the Brahmaputra River that drains the Himalaya has been obtained. Major ion chemistry of the Brahmaputra River was resolved on samples collected from nine locations in pre-monsoon, monsoon and post-monsoon seasons for two cycles: cycle I (2011–2012) and cycle II (2013–2014). The physico-chemical parameters of water samples were analysed by employing standard methods. The Brahmaputra River was characterized by alkalinity, high concentration of Ca²⁺ and HCO₃ ^? along with significant temporal variation in major ion composition. In general, it was found that water chemistry of the river was mainly controlled by rock weathering with minor contributions from atmospheric and anthropogenic sources. The effective CO₂ pressure (log\({{\text{P}}_{{\text{C}}{{\text{O}}_{\text{2}}}}}\)) for pre-monsoon, monsoon and post-monsoon has been estimated. The question of rates of chemical weathering (carbonate and silicate) was addressed by using TDS and run-off (mm year^?1). It has been found that the extent of CWR is directly dependent on the CO₂ consumption rate which may be further evaluated from the perspective of climate change mitigation The average annual CO₂ consumption rate of the Brahmaputra River due to silicate and carbonate weathering was found to be 0.52 (×10⁶ mol Km^?2 year^?1) and 0.55 (×10⁶ mol Km^?2 year^?1) for cycle I and 0.49 (×10⁶ mol Km^?2 year^?1) and 0.52 (×10⁶ mol Km^?2 year^?1) for cycle II, respectively, which were significantly higher than that of other Himalayan rivers. Estimation of CWR of the Brahmaputra River indicates that carbonate weathering largely dominates the water chemistry of the Brahmaputra River.  相似文献   

Removal of crystal violet dye from aqueous solution using yeast-treated peat as adsorbent: thermodynamics,kinetics, and equilibrium studies     

Tasneem Zehra  Namal Priyantha  Linda B. L. Lim 《Environmental Earth Sciences》2016,75(4):357

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Side-by-Side Correlation of Texas Cone Penetration and Standard Penetration Test Blowcount Values     

William D. Lawson  Earnest O. Terrell  James G. Surles  Rozbeh B. Moghaddam  Hoyoung Seo  Priyantha W. Jayawickrama 《Geotechnical and Geological Engineering》2018,36(5):2769-2787

This paper presents side-by-side comparisons of blowcount values for the Texas cone penetration (TCP) test and the standard penetration test (SPT). The comparisons yielded statistically-significant regression models for both coarse-grained soils and fine-grained soils. Consistent with expected trends and published data, the TCP–SPT relationship is nonlinear, with weak to fair correlation strength (R² = 23–44%). For TCP blowcounts (N_{60, TCP}) varying from 25 to 200 blows/30 cm (1 ft), corresponding SPT blowcounts (N_{60, SPT}) are typically 30–60% lower than N_{60, TCP} in fine-grained soils. Likewise, corresponding N_{60, SPT} blowcounts are 10–70% lower than N_{60, TCP} in coarse-grained soils, all other things being equal. Comparative data were obtained from published sources and from project-specific field research sites used for full-scale deep foundation load tests. The final dataset consisted of 225 test pairs obtained in similar soils and geomaterials, at equivalent depths, with all blowcounts normalized to 30 cm (12 in.) penetration (i.e., blows/30 cm or blows/ft) within the bounds of typical test precision, and corrected to 60% hammer efficiency. The generally weak correlations do not support conversion of N_{60, TCP} to N_{60, SPT} (or vice versa) to compute foundation capacity for final design. But, engineers can certainly get an intuitive feel about site conditions and preliminary foundation capacity by using the correlation equations to translate their knowledge of one test to the other. This study extends previous work by formally comparing and contrasting the similar yet different SPT and TCP test methods in such a way as to make the results useful to users of both tests and to the broader geotechnical engineering community.  相似文献