Appraisal of land use/land cover of mangrove forest ecosystem using support vector machine   总被引：2，自引：1，他引：1  

Sudhir Kumar Singh  Prashant K. Srivastava  Manika Gupta  Jay Krishna Thakur  Saumitra Mukherjee 《Environmental Earth Sciences》2014,71(5):2245-2255

Human activities in many parts of the world have greatly changed the natural land cover. This study has been conducted on Pichavaram forest, south east coast of India, famous for its unique mangrove bio-diversity. The main objectives of this study were focused on monitoring land cover changes particularly for the mangrove forest in the Pichavaram area using multi-temporal Landsat images captured in the 1991, 2000, and 2009. The land use/land cover (LULC) estimation was done by a unique hybrid classification approach consisting of unsupervised and support vector machine (SVM)-based supervised classification. Once the vegetation and non-vegetation classes were separated, training site-based classification technology i.e., SVM-based supervised classification technique was used. The agricultural area, forest/plantation, degraded mangrove and mangrove forest layers were separated from the vegetation layer. Mud flat, sand/beach, swamp, sea water/sea, aquaculture pond, and fallow land were separated from non-vegetation layer. Water logged areas were delineated from the area initially considered under swamp and sea water-drowned areas. In this study, the object-based post-classification comparison method was employed for detecting changes. In order to evaluate the performance, an accuracy assessment was carried out using the randomly stratified sampling method, assuring distribution in a rational pattern so that a specific number of observations were assigned to each category on the classified image. The Kappa accuracy of SVM classified image was highest (94.53 %) for the 2000 image and about 94.14 and 89.45 % for the 2009 and 1991 images, respectively. The results indicated that the increased anthropogenic activities in Pichavaram have caused an irreversible loss of forest vegetation. These findings can be used both as a strategic planning tool to address the broad-scale mangrove ecosystem conservation projects and also as a tactical guide to help managers in designing effective restoration measures.  相似文献   

Monitoring surface elevation changes in Jharia coalfield,India using synthetic aperture radar interferometry     

Mukesh Gupta  Kamini Kanta Mohanty  Devendra Kumar  Ramanuj Banerjee 《Environmental Earth Sciences》2014,71(6):2875-2883

This paper investigates surface elevation changes that occurred during 1996–2004 in the Jharia coalfield through the digital elevation model (DEM) generated using synthetic aperture radar interferometry (InSAR) using ERS-1/2 (European Remote Sensing Satellite) tandem and RADARSAT-1 data. The comparison of elevation values derived from the InSAR DEM and topographic height data shows a bias of 23.08 m with root-mean-square error of ±2.31 m (5.8 %). The accuracy of the DEM was investigated by comparing the elevation profiles with the digitized elevation contour data at four different locations. The profile comparison shows a mean bias of 22.68 m. Local topography shows changes in elevation up to ±40.00 m due to mining activities on the 8-year time period. The results of InSAR-derived heights and topographic heights were comparable and well-matched except at a few locations where topographic data were unavailable. DEM generated using InSAR due to its high spatial details is ideal for the detection and estimation of surface elevation changes in mining areas.  相似文献   

Geomorphic portrait of the Little Rann of Kutch     

Vishal Gupta  A. A. Ansari 《Arabian Journal of Geosciences》2014,7(2):527-536

Little Rann of Kutch is an integral part of the Rann of Kutch, occupying southeastern part of it. It remains a saline-inundated regime, partially seasonal and partially around the year. The study area experiences a very high ambient temperature at one point of time while it gets flooded by both the tidal water ingression and freshwater poured by the seasonal rivers during the monsoon season. And as a result, the area experiences a seasonal reversal of geomorphic processes which in turn is reflected through its distinctive and dynamic landforms. Geologically, this area was a part of oceanic floor and has immerged in the recent past. Geomorphology of the area plays a dominant role in the pattern and cause of saline water intrusion. The surface of Rann is at or slightly above sea level and possesses a monotonously plain character with some outcrop in the form of sandstone capped by basalts, resembling to island in the mid of the Rann. During 3 months of the southwest monsoon, storm tides, aided by the wind, force water from the Arabian Sea over the flat surface of the Ranns. Rainfall is fairly low, so that as the water recede and evaporate, they leave behind a crust of halite and gypsum crystals which grow in the clay and sands. This monotonously saline flat surface with annual inundation, have executed the Rann a mysterious piece of terrain. The characteristics and role of sediments in terms of erosional and depositional characteristics, their plasticity, facilitating capillary rise, their hygroscopic absorption capacity, infiltration capacity, permeability, etc. gives both short- and long-term implication to the area. Apart from the above concern, the soil has a great deal to play in terms of the vegetal and faunal cover. Considering these above characteristics, study area has been regionalized in order to have a better understanding and planning for the study area. The study area being an economic zone, also confronts with several environmental problems.  相似文献   

Towards a comprehensive approach to parameter estimation in land surface parameterization schemes     

Rafael Rosolem  Hoshin V. Gupta  W. James Shuttleworth  Luis Gustavo Gonçalves de Gonçalves  Xubin Zeng 《水文研究》2013,27(14):2075-2097

In climate models, the land–atmosphere interactions are described numerically by land surface parameterization (LSP) schemes. The continuing improvement in realism in these schemes comes at the expense of the need to specify a large number of parameters that are either directly measured or estimated. Also, an emerging problem is whether the relationships used in LSPs are universal and globally applicable. One plausible approach to evaluate this is to first minimize uncertainty in model parameters by calibration. In this paper, we conduct a comprehensive analysis of some model diagnostics using a slightly modified version of the Simple Biosphere 3 model for a variety of biomes located mainly in the Amazon. First, the degree of influence of each individual parameter in simulating surface fluxes is identified. Next, we estimate parameters using a multi‐operator genetic algorithm applied in a multi‐objective context and evaluate simulations of energy and carbon fluxes against observations. Compared with the default parameter sets, these parameter estimates improve the partitioning of energy fluxes in forest and cropland sites and provide better simulations of daytime increases in assimilation of net carbon during the dry season at forest sites. Finally, a detailed assessment of the parameter estimation problem was performed by accounting for the decomposition of the mean squared error to the total model uncertainty. Analysis of the total prediction uncertainty reveals that the parameter adjustments significantly improve reproduction of the mean and variability of the flux time series at all sites and generally remove seasonality of the errors but do not improve dynamical properties. Our results demonstrate that error decomposition provides a meaningful and intuitive way to understand differences in model performance. To make further advancements in the knowledge of these models, we encourage the LSP community to adopt similar approaches in the future. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Thermosolutal-convective instability of a composite plasma in a stellar atmosphere including the effects of finite larmor radius and Hall currents     

K. C. Sharma  Urvashi Gupta  R. C. Sharma 《Astrophysics and Space Science》1991,186(2):179-189

Thermosolutal-convective instability of a composite plasma in a stellar atmosphere is considered to include the effects, separately, due to finite Larmor radius (FLR) and Hall currents in the presence of a uniform horizontal magnetic field. The sufficient conditions for the existence of monotonic instability are derived and are found to hold good both in the presence, separately, of FLR and Hall current effects.  相似文献   

Hall effects on oscillatory MHD boundary-layer flow under variable suction     

M. U. S. Reddy  N. K. Samria  R. Prasad  H. N. Gupta 《Astrophysics and Space Science》1991,183(2):273-283

The effects of Hall current on the oscillatory hydromagnetic boundary-layer flow under variable suction, past an infinite porous flat plate in the presence of a transverse magnetic field is discussed. The expressions for velocity and skin-friction are obtained and their variations for small and large frequency of oscillations are extensively discussed.  相似文献   

String cosmology with Brans-Dicke theory     

Subenoy Chakraborty  Alakananda Gupta 《Astrophysics and Space Science》1996,239(1):65-70

In this paper string cosmology has been developed in the presence of Brans-Dicke scalar field coupled to Einstein gravity. Solutions are obtained for both geometric andp-string models and physical situations are discussed.  相似文献   

Development of a three channel photometer for UPSO, Naini Tal     

B. N. Ashoka  Kumar  V. C. Babu  S. Seetha  V. Girish  S. K. Gupta  Ram Sagar  S. Joshi  P. Narang 《Journal of Astrophysics and Astronomy》2001,22(1):131-144

The design and performance of a portable three channel photometer installed at the Uttar Pradesh State Observatory (UPSO), Naini Tal is described. The photometer is modular and the whole unit can be disassembled as individual channels such that the system can also be used as a single channel or two channel photometer. The system also has provision to monitor a guide star. The instrument was put into operation since November 1999 on the 1m Sampurnanand telescope at UPSO, Naini Tal. Since then, it is used extensively for the ‘Survey of rapidly oscillating Ap (roAp) stars in the northern sky’ from UPSO. Observational results using this new photometer in its initial phase of operation are discussed. The advantage of having continuous sky measurement is demonstrated.  相似文献   

Some Inhomogeneous Perfect Fluid Cosmological Models in the Presence of Electromagnetic Field     

Ghanshyam Singh  Preeti Mehta  Suman Gupta 《Astrophysics and Space Science》2002,281(4):677-688

Some cylindrically symmetric inhomogeneous cosmological models for perfect fluid distributions with electromagnetic field are obtained. To get a determinate solution, a supplementary condition between metric potentials is used. Various physical and geometrical properties of the models with some special cases are also discussed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Experimental studies on three potassium-rich ultramafic rocks from Damodar Valley, East India     

A. K. Gupta  B. Chattopadhyay  W. S. Fyfe  M. Powell 《Mineralogy and Petrology》2002,74(2-4):343-360

Summary An experimental study on the phase relationships of three potassium-rich ultramafic rocks from the Damodar Valley, Gondawana basins, has been performed under upper mantle P–T conditions (1.0–2.5 GPa, 700–1200 °C). The Mohanpur lamproite and Satyanarayanpur minette, both from the Raniganj basins, have been investigated with the addition of 15 wt% H₂O. No water was added in the experiments done on an olivine minette from the Jarangdih coal mine, Bokaro Basin, which originally contains 15 wt% CO₂ and 2.86 wt% H₂O. In all cases, olivine is the liquidus phase followed by phlogopite. The subsolidus assemblage for the three rocks is a phlogopite-bearing harzburgite, associated with apatite, Mg-ilmenite and carbonates for the Jarangdih rock; apatite, chromian spinel and carbonates and priderite (only between 1.0 and 1.2 GPa) in the case of the Mohanpur lamproite, and finally apatite, chromian spinel, rutile, and carbonate in the Satyanarayanpur sample. Although orthopyroxene is absent in the natural potassium-rich ultramafic rocks, its presence in the run products of the Jarangdih rock is possibly related to a reaction between olivine and a CO₂-bearing fluid phase. The presence of orthopyroxene in the run products of Mohanpur and Satyanarayanpur rocks may be due to a reaction between K-feldspar, olivine and a vapour phase to produce phlogopite and orthopyroxene. On the basis of present experimental investigation and isotopic studies made by previous investigators, it has been suggested that these K-rich rocks have crystallized from melts derived by vein-plus-wall-rock melting of a phlogopite-bearing harzburgite source rock. Received December 15, 1999; revised version accepted June 17, 2001  相似文献