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81.
Wagh Sandeep Krishnamurthy Raghavendra Wainwright Charlotte Wang Sen Dorman Clive E. Fernando Harindra J. S. Gultepe Ismail 《Boundary-Layer Meteorology》2021,181(2-3):317-344
Boundary-Layer Meteorology - Two stratus-lowering marine fog events observed on 28 September and 4 October 2018 during the Coastal Fog (C-Fog) field campaign that took place offshore of eastern... 相似文献
82.
Natural Hazards - In recent years, natural and manmade disasters such as floods, earthquakes, wildfires, and tsunamis have occurred with human losses and environmental deterioration. Henceforth, to... 相似文献
83.
Effects of a fully submerged boulder within a boulder array on the mean and turbulent flow fields: Implications to bedload transport 总被引：1，自引：0，他引：1
Athanasios N. Papanicolaou Casey M. Kramer Achilleas G. Tsakiris Thorsten Stoesser Sandeep Bomminayuni Zhuo Chen 《Acta Geophysica》2012,60(6):1502-1546
The objective of this coupled experimental and numerical study is to provide insight into the mean and turbulent flow fields within an array of fully submerged, isolated, immobile boulders. Our study showed that the velocity defect law performed well for describing the mean flow around the boulder within the array. A prerequisite, however, was to accurately estimate the spatial variability of u* around the boulder, which was achieved via the boundary characteristics method. The u* exhibited considerable spatial variability within the array and form roughness was shown to be up to 2 times larger than the skin roughness in the boulder near-wake region. Because the boulders bear a significant amount of the flow shear, the available bed shear stress for entrainment of the mobile sediment, ?? ols , near the boulders was roughly 50% lower than the ambient ?? ols . The ?? ols variability induced by the boulders could lead to a threefold overestimation of the sediment transport rate. 相似文献
84.
Understanding the spatial distribution and variability of geochemical tracers is crucial for estimating groundwater influxes into a river and can contribute to better future water management strategies. Because of the much higher radon (222Rn) activities in groundwater compared to river water, 222Rn was used as the main tracer to estimate groundwater influxes to river discharge over a 323-km distance of the Big Sioux River, eastern South Dakota, USA; these influx estimates were compared to the estimates using Cl? concentrations. In the reaches overall, groundwater influxes using the 222Rn activity approach ranged between 0.3 and 6.4 m3/m/day (mean 1.8 m3/m/day) and the cumulative groundwater influx estimated during the study period was 3,982–146,594 m3/day (mean 40,568 m3/day), accounting for 0.2–41.9% (mean 12.5%) of the total river flow rate. The mean groundwater influx derived using the 222Rn activity approach was lower than that calculated based on Cl? concentration (35.6 m3/m/day) for most of the reaches. Based on the Cl? approach, groundwater accounted for 37.3% of the total river flow rate. The difference between the method estimates may be associated with minimal differences between groundwater and river Cl? concentrations. These assessments will provide a better understanding of estimates used for the allocation of water resources to sustain agricultural productivity in the basin. However, a more detailed sampling program is necessary for accurate influx estimation, and also to understand the influence of seasonal variation on groundwater influxes into the basin. 相似文献
85.
Sandeep Maithani 《Journal of the Indian Society of Remote Sensing》2010,38(4):604-610
In the study reported in this paper an attempt has been made to develop a Cellular Automata (CA) model for simulating future
urban growth of an Indian city. In the model remote sensing data and GIS were used to provide the empirical data about urban
growth while Markov chain process was used to predict the amount of land required for future urban use based on the empirical
data. Multi-criteria evaluation (MCE) technique was used to reveal the relationships between future urban growth potential
and site attributes of a site. Finally using the CA model, land for future urban development was spatially allocated based
on the urban suitability image provided by MCE, neighbourhood information of a site and the amount of land predicted by Markov
chain process. The model results were evaluated using Kappa Coefficient and future urban growth was simulated using the calibrated
model 相似文献
86.
Surveys in Geophysics - Several natural hazards, including earthquakes, may trigger disasters and the presence of disaster drivers further lead to the massive loss of life and property, every year... 相似文献
87.
A. K. Choudhary A. K. Jain Sandeep Singh Rm. Manickavasagam K. Chandra 《Journal of the Geological Society of India》2011,77(3):227-238
This work provides unequivocal evidence of the existence of Mesoarchean granulite facies metamorphic event in the Palghat-Cauvery
Shear Zone (PCSZ) of South India. Charnockite samples from two prominent hills at Kollaimalai (KM) and Pachchaimalai (PM)
as well as from two quarries within the Bhavani Shear Zone (BSZ) have been analyzed for their Sm-Nd and Rb-Sr ages to investigate
the existence or otherwise of the Archean granulite facies events within the PCSZ. The Rb-Sr whole-rock isochron ages for
massive charnockites from both the hills appear to be contemporaneous at 2.9 Ga with the initial Sr isotopic ratios of 0.7012
and 0.7014, respectively. However, the Rb-Sr data for whole-rock samples of basic granulites from one of the quarries within
the BSZ indicate open system behavior, while the charnockites from the other quarry have insufficient spread in 87Rb/86Sr ratios and do not yield any isochron. The Sm-Nd data, on the other hand, do not distinguish between the massive charnockite
and the lowland charnockite and yield Depleted Mantle model ages in the range 2.98±0.3 Ga for all of them. The ɛT
CHUR for all of these rocks are highly positive. Both the Sr isotopic ratios and positive ɛT
CHUR values for these rocks strongly suggest a mantle source for all of them. An upper age limit of ∼3.28 Ga may be assigned to
the crustal accretion of the protolith of all these rocks on the basis of their Nd model ages. The Rb-Sr isochron ages of
2.9 Ga for the two massifs could be the age of granulite facies metamorphism. Thus, the metamorphism in the KM and PM Hills
took place within ∼100 Ma of crustal accretion of these rocks and probably was part of the same geological event of crust
formation and metamorphism. The open system behavior with respect to Rb-Sr isotopes in the basic granulite from Bhavani is
possibly due to the migration of Sr isotopes, triggered during the later shearing of these rocks. 相似文献
88.
Sandeep Vansutre K. R. Hari Neeraj Vishwakarma 《Journal of the Geological Society of India》2013,81(4):503-513
Bhopalpatnam Granulite Belt which occur along SW margin of Bastar Craton and NE shoulder of Pranhita-Godavari Rift comprise of charnockite (enderbitic variety), garnet-sillimanite-biotite gneiss, quartzo-feldspathic gneiss and corundum bearing aluminous gneiss. High La/Yb ratio, low Eu anomaly (Eu/Eu*=1.0), high LREE/HREE ratio with uniform REE pattern, high La/Sc ratio (0.53–6.43), high Th/Sc ratio (0.03–2.56), low Ni (5.52–20.95), low Cr (31.05–117.05) and uniform Zr/Hf distribution pattern indicate a Proterozoic character. Distribution pattern of K2O, Na2O and CaO in ternary diagram show quartz-monzonite-granodiorite trend for the bulk rocks indicating that the bulk rock composition is close to TTG of early Archaean, which might have supplied the sediments for the rocks of Bhopalpatnam Granulite Belt. Geochemical and mineralogical evidence indicate an argillaceous protolith for garnet — sillimanite — biotite gneiss and corundum bearing aluminous gneiss, whereas an arkosic protolith for quartzo-feldspathic gneiss. The geochemical signatures also suggest an active continental margin setting for the rocks of Bhopalpatnam Granulite Belt with prominent Nb and Ta anomaly favouring a subduction environment between Bastar Craton and East Dharwar Craton. This is in conformity with the finding of the earlier workers suggesting a clockwise P-T path based on the combined fluid inclusion and mineral phase equilibria. The LILE geochemistry of charnockite suggests a bi-phase evolution. High LREE/HREE ratio portrays a highly evolved nature of the charnockitic melt generated through partial melting of the continental crust at the final stage of the granulite facies metamorphism during collision between Bastar and East Dharwar Cratons. 相似文献
89.
Sandeep Gupta William K. Mohanty Rajesh Prakash Atindra Kumar Shukla 《Pure and Applied Geophysics》2013,170(4):607-616
To better understand the relationship between crustal heterogeneity and seismotectonics in the National Capital Region (NCR), Delhi, India, we carried out local P- and S-velocity tomography beneath the NCR. First arrival times of the first P- and S-wave from 275 crustal earthquakes recorded by the Seismic Telemetry Network in and around Delhi of the India Meteorological Department, India, are inverted to obtain crustal P-, S-velocity and V P /V S variations in the region. Our tomographic images of the upper crust reflect well the surface geological and tectonic features. The Delhi fold belt is identified as low V P, high V S and low V P/V S. The Sohna hot spring region is appearing as low V P, low V S and high V P /V S correlating with the possible presence of fluid-filled rocks. The crustal seismicity is distributed in both the high- and low-velocity zones, but most distinctly in the low V P /V S region. 相似文献
90.
For regulating urban growth, it is imperative to produce urban growth zonation maps, in which future urbanizable areas along with their urban growth potential are delineated. As, these maps provide a rational and scientific basis for taking future decisions regarding the growth of the city. The conventional approach for generating urban growth zonation maps is subjective in nature. To reduce this subjectivity, an artificial neural network (ANN) approach has been proposed for generating urban growth zonation maps. The database required for ANN-based urban growth zonation has been compiled from remote sensing data and other existing maps. GIS is used for handling of this spatial data. A comparison of the ANN- and conventional approach-derived zonation maps was also done. The study demonstrated the potential of ANN for urban growth zonation of an area, which may provide a valuable input to the urban planning authorities for regulating urban growth 相似文献