Digital Aerial Orthobase for Cadastral Mapping     

P. Srinivas  V. Raghu Venkataraman  I. Jayalakshmi 《Journal of the Indian Society of Remote Sensing》2012,40(3):497-506

Large scale aerial photographs were acquired for one entire district of Andhra Pradesh in the southern India encompassing approx. 10,000 sq.kms. The voluminous data was processed using digital photogrammetry techniques to generate seamless digital orthoimages as a base map for cadastral mapping applications. Historically the cadastral mapping was carried out with traditional surveying methods such as ETS, theodolites not at regular intervals. With the advent of modern surveying & remote sensing techniques, generation of Digital Cadastral Database for Land Information System (LIS) is possible. The trends of cadastral mapping started with individual plan of survey of parcels with local datum and arbitrary map projections. This study essentially required an accurate and standard spatial reference for seamless cadastral mapping over the entire Area of Interest (AOI) in single datum and projection. Towards this a spatial reference in World Geodetic System (WGS 84) datum with Universal Transverse Mercator (UTM) projection was established. The terrain in the study area is moderately undulating and the relief due to manmade features was not so significant. The aerial orthobase was found suitable for delineating and measuring the individual parcels information. A good GCP configuration, triangulation accuracy and reliable and consistent Digital Elevation Model (DEM) was ensured the generation of Digital aerial orthobases with an accuracy of better than 25cm over a distance of 1000m. The orthobase was used for identification, delineation of the cadastre parcels and most importantly to validate the aerial orthobase with the field measurements.  相似文献   

Co-seismic gravity changes in the Koyna-Warna region: Implications of mass redistribution     

K. N. D. Prasad  N. Srinivas  A. E. Meshram  A. P. Singh  V. M. Tiwari 《Journal of the Geological Society of India》2017,90(6):704-710

Koyna-Warna Region (KWR) is one of the known sites for reservoir triggered seismicity. The continued triggered seismicity over the five decades is restricted to a region of about 600–700 sq. km, which provides a unique opportunity to monitor geophysical anomalies likely to be associated with seismicity of the region. Present study confers temporal gravity changes recorded by gPhone and GRACE satellite and interprets observed changes in conjunction with seismological, geodetic (cGPS) observations and groundwater level measurements. GRACE data suggest that seasonal vertical deformation due to hydrological loading is ～ 2 cm, which corroborates with continuous GPS observations. Seasonal hydrological loading of the region, which is in a phase of reservoir loading, might be influencing the critically stressed KWR leading to the seasonal seismicity of the region. The gPhone gravity data distinctly show co-seismic gravity signals for eight earthquakes of M_w > 2 and gravity anomalies show positive correlation on a logarithmic scale with earthquake released energy. To investigate the cause of gravity changes, an estimate is made for 14^th April 2012 earthquake for M_w 4.8 using fault dislocation model. The recorded gravity changes of 189 μGal by gPhone located at a distance of 28 km from the hypocentre is much more than the estimate of ～0.1 μGal calculated for M_w 4.8 Koyna earthquake. Therefore, it is inferred that co-seismic gravity signals for eight earthquakes are primarily caused due to redistribution of mass at shallow depth.  相似文献   

Isostatic response of the Laccadive Ridge from admittance analysis of gravity and bathymetry data     

A.K. Chaubey  K. Srinivas  B. Ashalatha  D. Gopala Rao 《Journal of Geodynamics》2008,46(1-2):10-20

The Laccadive Ridge (L-R), trending roughly parallel to the west coast of India, is an intriguing segment of the northernmost Chagos-Laccadive Ridge (C-L-R) system. Although crustal nature and isostatic response of the southern C-L-R is well known, there are no similar studies on the L-R. In the present study, the isostatic response of the lithosphere beneath the L-R is estimated so as to characterize its crustal nature, total crustal as well as effective elastic plate thickness and mode of compensation. Twelve gravity and bathymetry profiles across the ridge were analyzed using linear transfer function and forward model techniques. The observed admittance function within the diagnostic waveband of 250 < λ > 80 km (0.025 < k > 0.080 km⁻¹) fits well with (i) the Airy model whose average crustal thickness (T_c) and density are 17 ± 2 km and 2.7 × 10³ kg m⁻³, respectively, and (ii) the thin plate flexure model of isostasy with an effective elastic plate thickness (T_e) of 2–3 km. The estimated average crustal thickness and density are in good agreement with published seismic refraction results over the ridge. The results of the present study support an Airy model of isostasy for the L-R. The low T_e value, in view of other published results in the study area, suggests stretched and loaded continental lithosphere of the L-R during the evolution of the western continental margin of India.  相似文献   

Real-time numerical simulation of tropical cyclone Nilam with WRF: experiments with different initial conditions, 3D-Var and Ocean Mixed Layer Model     

Greeshma M. Mohan  C. V. Srinivas  C. V. Naidu  R. Baskaran  B. Venkatraman 《Natural Hazards》2015,77(2):597-624

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http://www.sciencedirect.com/science/article/pii/S1674987112000254   总被引：1，自引：0，他引：1  

Y.Srinivas  A.Stanley Raj  D.Hudson Oliver  D.Muthuraj  N.Chandrasekar 《地学前缘(英文版)》2012,3(5):729-736

The applications of intelligent techniques have increased exponentially in recent days to study most of the non-linear parameters.In particular,the behavior of earth resembles the non-linearity applications.An efficient tool is needed for the interpretation of geophysical parameters to study the subsurface of the earth.Artificial Neural Networks(ANN) perform certain tasks if the structure of the network is modified accordingly for the purpose it has been used.The three most robust networks were taken and comparatively analyzed for their performance to choose the appropriate network.The single-layer feed-forward neural network with the back propagation algorithm is chosen as one of the well-suited networks after comparing the results.Initially,certain synthetic data sets of all three-layer curves have been taken for training the network,and the network is validated by the Held datasets collected from Tuticorin Coastal Region(78°7′30″E and 8°48′45″N),Tamil Nadu.India.The interpretation has been done successfully using the corresponding learning algorithm in the present study.With proper training of back propagation networks,it tends to give the resistivity and thickness of the subsurface layer model of the field resistivity data concerning the synthetic data trained earlier in the appropriate network.The network is trained with more Vertical Electrical Sounding(VES) data,and this trained network is demonstrated by the field data.Groundwater table depth also has been modeled.  相似文献   

Seasonal variations in the sediment biogenic properties of a tropical mangrove environment,southwest coast of India     

M. Nair  J. Jacob  P. A. Nisha  G. D. Martin  K. Srinivas  P. Sheeba  C. M. Laluraj  T. Joseph  K. K. Balachandran 《Environmental Earth Sciences》2010,61(1):27-35

Temporal and spatial changes in the sediment properties of a mangrove ecosystem (Cochin, southwest coast India) are presented. The region was freshwater dominated during monsoon (June–September) and seawater dominated during other two seasons. The system remained eutrophic due to the high inputs of organic matter (OM) during most part of the year. The organic-rich sediments accumulated high amount of carbohydrates (22% of OM) and proteins (11% of OM) during non-monsoon months as compared to coastal environments. Principal component analysis showed that the biochemical properties are uniformly influenced by seasonal and spatial variations. Higher concentrations of sediment protein over carbohydrate indicate an efficient mineralization leading to the non-availability of aged OM in the system. The dominance of these labile components is generally indicative of the eutrophic condition of the system.  相似文献   

A nonlinear data‐driven model for synthetic generation of annual streamflows     

K. P. Sudheer  K. Srinivasan  T. R. Neelakantan  V. V. Srinivas 《水文研究》2008,22(12):1831-1845

A hybrid model that blends two non‐linear data‐driven models, i.e. an artificial neural network (ANN) and a moving block bootstrap (MBB), is proposed for modelling annual streamflows of rivers that exhibit complex dependence. In the proposed model, the annual streamflows are modelled initially using a radial basis function ANN model. The residuals extracted from the neural network model are resampled using the non‐parametric resampling technique MBB to obtain innovations, which are then added back to the ANN‐modelled flows to generate synthetic replicates. The model has been applied to three annual streamflow records with variable record length, selected from different geographic regions, namely Africa, USA and former USSR. The performance of the proposed ANN‐based non‐linear hybrid model has been compared with that of the linear parametric hybrid model. The results from the case studies indicate that the proposed ANN‐based hybrid model (ANNHM) is able to reproduce the skewness present in the streamflows better compared to the linear parametric‐based hybrid model (LPHM), owing to the effective capturing of the non‐linearities. Moreover, the ANNHM, being a completely data‐driven model, reproduces the features of the marginal distribution more closely than the LPHM, but offers less smoothing and no extrapolation value. It is observed that even though the preservation of the linear dependence structure by the ANNHM is inferior to the LPHM, the effective blending of the two non‐linear models helps the ANNHM to predict the drought and the storage characteristics efficiently. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Environmental applications of geophysical and geochemical methods to map groundwater quality at Tuticorin, Tamilnadu, India     

Y. Srinivas  D. Muthuraj  D. Hudson Oliver  A. Stanley Raj  N. Chandrasekar 《Environmental Earth Sciences》2013,70(5):2143-2152

Coastal aquifers can become polluted due to natural and human activities, such as intrusion of saline water, discharge of effluents in industrial areas and chemical weathering of natural geological deposits. The present study is aimed mainly at understanding the geophysical and chemical characteristics of groundwater near Tuticorin, Tamilnadu, India by studying the electrical resistivity distribution of the subsurface groundwater by applying the Schlumberger vertical electrical sounding (VES) technique followed by chemical analysis of water samples. A total of 20 VES soundings were carried out to understand the resistivity distribution of the area and 21 water samples were collected to analyze the chemical quality. The interpretation and analysis of the results have identified different hydrogeologic behaviors, a highly saline coastal aquifer and freshwater locations. The results obtained from geophysical and geochemical sampling are in good agreement with each other. The approach shows the efficacy of the combination of geophysical and geochemical methods to map groundwater contamination zones in the study area.  相似文献   

Exact Delaunay normalization of the perturbed Keplerian Hamiltonian with tesseral harmonics     

Bharat Mahajan  Srinivas R. Vadali  Kyle T. Alfriend 《Celestial Mechanics and Dynamical Astronomy》2018,130(3):25

A novel approach for the exact Delaunay normalization of the perturbed Keplerian Hamiltonian with tesseral and sectorial spherical harmonics is presented in this work. It is shown that the exact solution for the Delaunay normalization can be reduced to quadratures by the application of Deprit’s Lie-transform-based perturbation method. Two different series representations of the quadratures, one in powers of the eccentricity and the other in powers of the ratio of the Earth’s angular velocity to the satellite’s mean motion, are derived. The latter series representation produces expressions for the short-period variations that are similar to those obtained from the conventional method of relegation. Alternatively, the quadratures can be evaluated numerically, resulting in more compact expressions for the short-period variations that are valid for an elliptic orbit with an arbitrary value of the eccentricity. Using the proposed methodology for the Delaunay normalization, generalized expressions for the short-period variations of the equinoctial orbital elements, valid for an arbitrary tesseral or sectorial harmonic, are derived. The result is a compact unified artificial satellite theory for the sub-synchronous and super-synchronous orbit regimes, which is nonsingular for the resonant orbits, and is closed-form in the eccentricity as well. The accuracy of the proposed theory is validated by comparison with numerical orbit propagations.  相似文献   

Sensitivity Analysis of Atmospheric Dispersion Simulations by FLEXPART to the WRF-Simulated Meteorological Predictions in a Coastal Environment     

C. V. Srinivas  K. B. R. R. Hari Prasad  C. V. Naidu  R. Baskaran  B. Venkatraman 《Pure and Applied Geophysics》2016,173(2):675-700

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