Comparative assessment of three approaches for deriving stream power plots along long profiles in the upper Hunter River catchment, New South Wales, Australia   总被引：2，自引：2，他引：0  

Vikrant Jain  Nicholas Preston  Kirstie Fryirs  Gary Brierley 《Geomorphology》2006,74(1-4):297-317

The downstream distribution of stream power is derived and analysed for 11 different streams in the upper Hunter River catchment, Australia. Stream long profiles were produced in a GIS environment using DEM data and catchment area–discharge analysis. These profiles were analysed using three approaches, namely long profile smoothing, curve fitting and a theoretical model. The methodology for deriving stream power profiles using these three approaches is discussed. The long profile smoothing method provides a good approximation of the subcatchment variability in stream power trends. The curve fitting method shows that higher-order exponential curves provide a better fit for long profile data. For the streams of the upper Hunter River catchment, second-order exponential curves fit well with significantly less error. The curve fitting method predicts a bimodal (upstream and midstream) distribution of stream power, which is a deviation from our earlier understanding of a single midstream peak. The theoretical approach provides a mathematical expression of the observed bimodal stream power distribution. The bimodal distribution emphasises the erosion potential of headwater reaches. The resultant stream power distribution provides a catchment-scale characterisation of the distribution of available energy in any given system. Using these approaches, the variability of stream power in headwater reaches is explained by discharge variability, while variability in midstream and downstream reaches is related to high variability in channel gradient.  相似文献   

The kurtosis of the cosmic shear field     

Masahiro Takada  Bhuvnesh Jain 《Monthly notices of the Royal Astronomical Society》2002,337(3):875-894

  相似文献   

Groundwater investigation of the artesian wells on the palaeochannels in parts of the Great Rann of Kachchh,Gujarat, India,using remote sensing and geophysical techniques     

Bhadra  B. K.  Gor  Naresh  Jain  Ashish K.  Meena  Hansraj  Rao  S. Srinivasa 《Hydrogeology Journal》2021,29(8):2705-2724

The Great Rann of Kachchh (GRK) in Gujarat, India, is the largest salt desert in the world, which is usually filled with seawater ingression during high tide from the Arabian Sea. As a result, the soil gets saturated with saline water that has percolated down for several meters. Groundwater exploration in Rann area is a challenging task due to the prevailing hostile environment. For this purpose, multisensor satellite data have been used to delineate the palaeochannels in search of an alternate source of drinking water. In GRK, palaeochannels represent the zone of elevated fluvial sediments with respect to the surroundings. Evolutionary history of the palaeochannels indicates upliftment of GRK area during Allah Bund faulting. For assessing the groundwater potential of the palaeochannels, high-resolution electrical resistivity tomography (HERT) surveys have been carried out with the pole-dipole method. Electrical resistivity tomograms along 710 m traverses to a depth of 250 m in Dharmsala and Gainda area show higher-resistivity zones (medium to coarse sand with brackish water) below a thick low-resistivity layer (clay with saline water). A few exploratory drillings in the area confirm the existence of the palaeochannels, which act as a confined aquifer below 100 m depth. The artesian condition of the two drilled wells at Gainda and Khardoi along the northern boundary of GRK may be attributed to hydraulic gradient along the confined layers from the Tharparkar region in Pakistan. Thus, HERT is found to be a faster and more cost-effective geophysical survey technique for study of the deep aquifer.

  相似文献   

Copper Ore Identification using Spectral Similarity Measurement from Hyperion Image,Mapping of Porphyry Copper Mineralized Zone     

Krishnendu Banerjee  Manish Kumar Jain 《Journal of the Geological Society of India》2018,91(2):239-247

This work illustrates the effectiveness of hyperspectal image spectroscopy and lab spectroscopy in identification techniques of minerals in alteration zone of ore body. The adopted procedure involves testing of Hyperion image spectra, their processing for noise, spectral matching and spectral similarity measurement with selected library spectra. Average weighted spectral similarity; visual and statistical matching techniques were used to select end-members from image spectra. Minimum noise fraction and pixel purity index technique were used to retrieve end-member spectra from hyperion image. Hyperspectral image like hyperion has the capability to deliver laboratory standard spectroscopic result. This paper illustrates the capability of hyperion image spectra in copper ore identification and mapping of chalcopyrite outcrop. A systematic approach has been made in this paper. This approach describes how image end member spectra and laboratory spectra can be co-related to fetch accurate spectral form of chalcopyrite ores. Thus, statistical and graphical comparison has been carried out between image derived end member spectra and laboratory spectra of chalcopyrite for better accuracy. The visual measurements is satisfactory, R = 0.973 for fine and 0.976 for medium grained chalcopyrite ore. Excellent statistical significance levels (90–97%) are found while comparing these spectra. There are many success stories of sub-pixel and N-dimensional feature space methods to separate the hydrothermal alteration zones from iron oxide mixed ore bodies. Thus, unmixing methods are very useful for mapping of most dominating mineral parts of a pixel from hyperspectral images which have coarse spatial resolution. Finally, mapping of mineralized zone has been achieved through sub-pixel based classifiers like spectral angle mapper (SAM), constrained energy minimization (CEM) and adaptive coherence estimator (ACE) techniques.  相似文献   

Mapping of hydrothermally altered zones in Aravalli Supergroup of rocks around Dungarpur and Udaipur,India, using Landsat-8 OLI and spectroscopy     

Nirmala Jain  Ramdayal Singh  Priyom Roy  Tapas R. Martha  K. Vinod Kumar  Prakash Chauhan 《Arabian Journal of Geosciences》2018,11(16):455

We explored the utilization of Landsat-8 Operational Land Imager (OLI) data for mapping of hydrothermal alteration zones. The region in and around the cities of Dungarpur and Udaipur of Rajasthan state in India was selected for this study. The rock types of Dungarpur and Udaipur are serpentinites, talc-carbonate, talc-schist, and quartzite of the Aravalli Supergroup. Hydrothermally altered zones and resultant hydrous minerals play an important role in the genesis of these rocks. We aimed to identify possible locations of hydrothermally altered zones in regional context around Dungarpur and Udaipur using Landsat-8 OLI data. False-color composite maps and band ratios were prepared from Landsat-8 bands. Band ratios such as band 6/band 7 (short-wave infrared 1 (SWIR1)/short wave infrared 2 (SWIR2)), band 4/band 3 (red/green), and band 5/band 6 (near infrared (NIR)/SWIR1) and visual interpretation techniques were used to identify the hydrothermally altered zones. Spectroscopic analyses of field rock samples were done to validate the hydrothermal alteration zones delineated from the analysis of Landsat-8 data. We present the combined results of Landsat-8 and field spectroradiometer analysis which brings out the hydrothermal alteration zones associated with hydrous minerals (antigorite, lizardite, montmorillonite, vermiculite, talc, and saponite). The study demonstrates the utility Landsat-8 OLI (with field spectroradiometer data) in the mapping of hydrothermally altered zones as a key in understanding geological processes.  相似文献   

Structurally-controlled melt accumulation: Himalayan migmatites and related deformation — Dhauli Ganga valley, Garhwal Himalaya     

A. K. Jain  Puneet Seth  Mrinal Shreshtha  P. K. Mukherjee  Keser Singh 《Journal of the Geological Society of India》2013,82(4):313-318

In the uppermost parts of the Higher Himalayan Crystallines (HHC) of the Great Himalaya, widespread in situ partial melting of sillimanite+K-feldspar gneiss resulted in the formation of migmatite and resultant melt accumulation near the South Tibetan Detachment System (STDS) during various deformation events along the Dhauli Ganga valley in Garhwal. The oldest migmatite phase, designated as the Me1, parallels the main foliation S_m as the stromatite layers and concordant leucogranite bands. Younger melt phases Me2, Me3 and Me5 are recorded along small-scale ductile thrusts, extensional fabric and structureless patches, respectively. It is only the Me4 melting phase that is evidenced by large-scale melt migration along cross-cutting irregular veins. These were possible conduits for migration and accumulation of melt into larger leucogranite bodies like the Malari granite (19.0± 0.5 Ma).  相似文献   

Assessment of greenhouse gas emissions from coal and natural gas thermal power plants using life cycle approach   总被引：2，自引：1，他引：1  

K. Kr. Agrawal  S. Jain  A. Kr. Jain  S. Dahiya 《International Journal of Environmental Science and Technology》2014,11(4):1157-1164

The importance of mitigation of climate change due to greenhouse gas (GHG) emissions from various developmental and infrastructure projects has generated interest at global level to reduce environmental impacts. Life cycle assessment may be used as a tool to assess GHG emissions and subsequent environmental impacts resulting from electricity generation from thermal power plants. This study uses life cycle approach for assessing GHG emissions and their impacts due to natural gas combined cycle (NGCC) and imported coal thermal power plants using the IPCC 2001 and Eco-Indicator 99(H) methods in India for the first time. The total GHG emission from the NGCC thermal power plant was 584 g CO₂ eq/kWh electricity generation, whereas in case of imported coal, it was 1,127 g CO₂ eq/kWh electricity generation. This shows that imported coal has nearly ~2 times more impacts when compared to natural gas in terms of global warming potential and human health as disability-adjusted life years from climate change due to GHG emissions such as carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O).  相似文献   

Fitting a simplified two-parameter gamma distribution function for synthetic sediment graph derivation from ungauged catchments     

P. K. Singh  M. K. Jain  S. K. Mishra 《Arabian Journal of Geosciences》2013,6(6):1835-1841

A simple procedure is proposed and demonstrated to generate synthetic sediment graphs (SSG) for ungauged catchments. The proposed procedure makes use of widely used two-parameter gamma distribution function in a simplified manner. The shape and scale parameters of the distribution are derived using simple analytical procedures given by Bhunya et al. (J Hydrol Eng 8(4):226–230, 2003) for situations where partial data is usually available as in the case with sedimentation studies. The direct sediment graphs are computed by convolution of unit sediment graph with the mobilized sediment. The suitability of the proposed procedure is tested using the temporally observed sediment graph data of seven small watersheds of Piedmont Province of the Potomac River Basin, Washington D.C., USA. The results obtained are compared with the rigorous synthetic procedure of Chen and Kuo (J Hydrol 84:35–54, 1986). The goodness-of-fit in terms of absolute relative error in peak sediment outflow rate and time-to-peak sediment outflow rate between observed and computed sediment graphs by proposed as well as Chen and Kuo method shows that the proposed procedure produces results well comparable and even better than those obtained using Chen and Kuo procedure and therefore can be successfully used for development of SSG for ungauged catchments. It is worth noting here that the proposed procedure is very simple in application as compared to the rigorous procedure of Chen and Kuo and eliminates the restriction on storm duration and incorporates the routing concept which plays an important role in sedimentation. Moreover, since the proposed procedure makes use of probability distribution function, several other suitable distributions can also be explored for derivation of synthetic sediment graphs from ungauged catchments.  相似文献   

Investigation on spectral behavior of Solar transients and their interrelationship     

Sharad C. Tripathi  Parvaiz A. Khan  A. M. Aslam  A. K. Gwal  P. K. Purohit  Rajmal Jain 《Astrophysics and Space Science》2013,347(2):227-233

We probe the spectral hardening of solar flares emission in view of associated solar proton events (SEPs) at earth and coronal mass ejection (CME) acceleration as a consequence. In this investigation we undertake 60 SEPs of the Solar Cycle 23 along with associated Solar Flares and CMEs. We employ the X-ray emission in Solar flares observed by Reuven Ramaty Higly Energy Solar Spectroscopic Imager (RHESSI) in order to estimate flare plasma parameters. Further, we employ the observations from Geo-stationary Operational Environmental Satellites (GOES) and Large Angle and Spectrometric Coronagraph (LASCO), for SEPs and CMEs parameter estimation respectively. We report a good association of soft-hard-harder (SHH) spectral behavior of Flares with occurrence of Solar Proton Events for 16 Events (observed by RHESSI associated with protons). In addition, we have found a good correlation (R=0.71) in SEPs spectral hardening and CME velocity. We conclude that the Protons as well as CMEs gets accelerated at the Flare site and travel all the way in interplanetary space and then by re-acceleration in interplanetary space CMEs produce Geomagnetic Storms in geospace. This seems to be a statistically significant mechanism of the SEPs and initial CME acceleration in addition to the standard scenario of SEP acceleration at the shock front of CMEs.  相似文献   

Latest Results Found with Ring-Diagram Analysis     

C. S. Baldner  S. Basu  R. S. Bogart  O. Burtseva  I. González Hernández  D. Haber  F. Hill  R. Howe  K. Jain  R. W. Komm  M. C. Rabello-Soares  S. Tripathy 《Solar physics》2013,287(1-2):57-69

Ring-diagram analysis is a helioseismic tool useful for studying the near-surface layers of the Sun. It has been employed to study near-surface shear, meridional circulation, flows around sunspots, and thermal structure beneath active regions. We review recent results obtained using ring-diagram analysis, state some of the more important outstanding difficulties in the technique, and point out several extensions to the technique that are just now beginning to bear fruit.  相似文献