Forest cover and landuse mapping in Karbi Anglong and North Cachar Hills districts of assam using landsat MSS data     

PS Roy  KK Das  KSM Naidu 《Journal of the Indian Society of Remote Sensing》1991,19(2):113-123

Karbi Anglong and North Cachar Hills districts of Assam are endowed with rich and diverse vegetation resources. Increased human pressure due to shifting cultivation and raw material extraction for industrial purposes are heavily altering the forested landscape. The present study deals with mapping of forest types in the two districts using LANDSAT-MSS digital data. The maps thus generated provide spatial distribution of bioclimatic vegetation types. Supervised maximum likelihood classification has been performed using training sets collected during field work. The spectral behaviour of vegetation types have been studied for optimising classification scheme. The classification accuracy of classes mapped has been calculated.  相似文献   

Updating urban maps with analytically rectified Small Format Aerial Photographs     

M Nazim  R P Kala 《Journal of the Indian Society of Remote Sensing》1992,20(1):1-7

Small Format Aerial Photography (SFAP) is a new emerging art of acquiring photogrammetric data with metric and non-metric cameras. SFAP with format size normally less than 55×55 mm, possesses the potential of both compiling new maps and updating existing planimetric maps of small areas. Organisations dealing with urban and other large-scale mapping, may be benefited greatly by the use of such data. In the present study, investigations are carried out to update an urban map on scale 1∶10,000 using analytically rectified SFAP from non-metric camera. Results are encouraging and presented in this paper.  相似文献   

Coastal geomorphology and sediment distribution mapping using Landsat—TM digital data —A study in Coastal area of parts of Orissa,India     

S. K. Subramanian  K. Keshavasamy  K. Hanumantha Rao  S. K. Bhan 《Journal of the Indian Society of Remote Sensing》1988,16(3):1-6

An area of about 1100 sq.km forming a part of east coast of India was taken for digital analysis using the VAX 11/780 image analysis computer system. The data used for the analysis is Thematic mapper data of Landsat 5. By using the maximum likelihood algorithm and the existing ground truth, the area was classified geomorphologicall.. In addition a qualitative mapping of suspended sediments of coastal waters in Bay of Bengal around the estuary of Dhamra river in Orissa has been carried out. In seventeen classes, eleven correspond to geomorphic units and six belongs to different categories of sediments concentration in Coastal waters.  相似文献   

Rb−Sr age of Gaik granite,Ladakh batholith,northwest Himalaya     

J R Trivedi  K Gopalan  Kewal Kisharma  K R Gupta  V M Choubey 《Journal of Earth System Science》1982,91(1):65-73

The Gaik Granite is a part of the Ladakh batholith outcropping between Gaik and Kiari in NW Himalaya. This is a pink porphyritic granite rich in biotite and poor in hornblende. Rb-Sr analyses have been made on six whole-rock samples of the Gaik Granite. Though the samples are poorly enriched in radiogenic Sr, they define a reliable isochron corresponding to an age of 235±13 (2σ) m.y. and initial⁸⁷Sr/⁸⁶Sr ratio of 0·7081±0·0004 (2σ). Biotite, plagioclase and potash feldspar fractions separated from two of the samples have yielded a much younger mineral isochron at 30±1·5 m.y. indicating a nearly complete redistribution of Sr isotopes between mineral phases at a time much later than the primary emplacement of the granite. The present results show that at least some components of the Ladakh batholith are of Permo-Triassic age. These rocks were isotopically re-equilibrated on a mineral scale during Upper Oligocene in response to the Himalayan orogeny.  相似文献   

A rule-based system for forest land use planning     

S P S Kushwaha  G Oesten 《Journal of the Indian Society of Remote Sensing》1995,23(3):115-124

This paper reports the results of an exercise on the development and application of a rule-based software program,Combine for integration of thematic information in simplest possible way. The program was used for forest land use planning in a shifting cultivation area in north-east India. The program can integrate 28 thematic information layers with upto 256 classes in each layer using 8-bit data. Additionally the software can be used for many per pixel image processing operations like merging of digitally and visually classified images, merging of a large number of thematic classes into a few wanted ones, density slicing, image thresholding etc. conveniently.  相似文献   

Active faulting south of the Himalayan Front: Establishing a new plate boundary   总被引：1，自引：0，他引：1  

Robert S. Yeats  V.C. Thakur   《Tectonophysics》2008,453(1-4):63

New tectonic uplifts south of the Salt Range Thrust and Himalayan Front Thrust (HFT) represent an outward step of the plate boundary from the principal tectonic displacement zone into the Indo-Gangetic Plain. In Pakistan, the Lilla Anticline deforms fine-grained overbank deposits of the Jhelum River floodplain 15 km south of the Salt Range. The anticline is overpressured in Eocambrian non-marine strata. In northwest India south of Dehra Dun, the Piedmont Fault (PF) lies 15 km south of the HFT. Coalescing fans derived from the Himalaya form a piedmont (Old Piedmont Zone) 15–20 km wide east of the Yamuna River. This zone is uplifted as much as 15–20 m near the PF, and bedding is tilted 5–7° northeast. Holocene thermoluminescence-optically-stimulated luminescence dates for sediments in the Old Piedmont Zone suggest that the uplift rate might be as high as several mm/a. The Old Piedmont Zone is traced northwest 200 km and southeast another 200 km to the Nepal border. These structures, analogous to protothrusts in subduction zones, indicate that the Himalayan plate boundary is not a single structure but a series of structures across strike, including reactivated parts of the Main Boundary Thrust north of the range front, the HFT sensu stricto, and stepout structures on the Indo-Gangetic Plain. Displacement rates on all these structures must be added to determine the local India-Himalaya convergence rate.  相似文献   

Aggregation of the Arctic copepod Calanus hyperboreus over the ocean floor of the Greenland Sea     

《Deep Sea Research Part I: Oceanographic Research Papers》2006,53(2):310-320

According to combined observations from vertical plankton tows, dredging with epibenthic nets 1 m above the ocean floor, video recordings and acoustic data from a scanning sonar obtained during descent and during deployment on the ocean floor, the calanoid copepod Calanus hyperboreus was aggregated in high concentrations near the ocean floor of the Greenland Sea between 2300 and 2500 m during late July and August. Concentrations were highest very close to the ocean floor and decreased rapidly further upward. These nearly mono-specific aggregations were apparently drifting in cloud-like formations with a horizontal extension of ca. 270 m with the near-bottom currents. Maximum abundances observed were up to 2 orders of magnitude higher than in the water column. The biomass in the bottom 20 m layer was around 18% of the biomass in the rest of the water column. Stage composition, reduced metabolic rates and insensibility to mechanical stimuli indicate that these C. hyperboreus were representing the resting population. The fact that high concentrations were observed during deployments lasting >1 d and in 3 years suggests that aggregation near the ocean floor is a regular, rather than an extraordinary, pattern in the life history of C. hyperboreus in the Greenland Sea, but there is need for comparison with other seas and eventually other Calanus species.  相似文献   

Evaluation of Cartographic accuracy of IRS-1A LISS II data for upgrading linear details on the existing maps (A case study of Chandigarh area)     

S. K. Mittal  K. C. Bhagra  S. C. Gupta 《Journal of the Indian Society of Remote Sensing》1994,22(3):119-129

Considering the fest pace of development, up-to-date maps have become imperative in developmental planning. Conventional map updating techniques are expensive and time consuming. The present paper makes an attempt to tackle the problem using GIS techniques. Maps generated from IRS-1A LISS II data and Survey of India (SOI) toposheets were used as input maps in GIS. These maps were overlaid to obtain the positional errors at road junction points. The area statistics of each sector were calculated taking the SOI map as reference data. The results show that the areas calculated from LISS II data and SOI map are well comparable and the deviations are within 10%, whereas the positional accuracy (MSE) of points is within 30 m. The study demonstrates that the IRS-1A LISS II data can be used for updating of maps on scale 1:100,000 and smaller in areas where linear features are identifiable in the IRS LISS II image.  相似文献   

Estimation of Sediment Yield and Selection of Suitable Sites for Soil Conservation Measures in Ahar River Basin of Udaipur,Rajasthan using RS and GIS Techniques     

Deepesh Machiwal  S. K. Srivastava  Sadhna Jain 《Journal of the Indian Society of Remote Sensing》2010,38(4):696-707

The present study aimed at quantification of sediment yield for Ahar River basin of Udaipur district in Rajasthan, India by a regional empirical model using RS and GIS techniques. The land use/land cover (LULC) map of the study area was prepared by supervised classification using satellite imagery of IRS-P6 LISS III. Overall accuracy of the prepared LULC map was 90.78%. The major portion of the study area (49%) is covered with rangeland. Slope map for the study area was developed using digital elevation model. The slope in most of the study area (40% of the total area) ranges from 1% to 4%. In addition, drainage density map of the study area was generated on micro-watershed basis. The study area is covered by a dendritic pattern of drainage which shows that rocks in the area are homogeneous and uniformly resistant to water flow. The drainage density in the study area is 1.11 km km⁻². Annual sediment yield of the study area was quantified by Garde model. The mean annual runoff and sediment yield for the area was 37.58 million m³ and 8,760 m³/year, respectively. Finally, appropriate sites for construction of soil conservation measures are suggested using Boolean logic analysis method on combined slope and drainage maps.  相似文献   

Predicting the ecological status of rivers and streams under different climatic and socioeconomic scenarios using Bayesian Belief Networks     

《Limnologica》2020

Freshwater systems have increasingly been subjected to a multitude of human pressures and the re-establishment of their ecological integrity is currently a major worldwide challenge. Expected future climate and socioeconomic changes will most probably further exacerbate such challenges. Modelling techniques may provide useful tools to help facing these demands, but their use is still limited within ecological quality assessment of water resources due to its technical complexity.We developed a Bayesian Belief Network (BBN) framework for modelling the ecological quality of rivers and streams in two European river basins located in two distinct European climatic regions: the Odense Fjord basin (Denmark) and the Sorraia basin (Portugal). This method enabled us to integrate different data sources into a single framework to model the effect of multiple stressors on several biological indicators of river water quality and, subsequently, on their ecological status. The BBN provided a simple interactive user interface with which we simulated combined climate and socioeconomic changes scenarios to assess their impacts on river ecological status.According to the resulting BBNs the scenarios demonstrated small impacts of climate and socioeconomic changes on the biological quality elements analysed. This yield a final ecological status similar to the baseline in the Odense case, and slightly worse in Sorraia. Since the present situation already depicts a high percentage of rivers and streams with moderate or worse ecological status in both basins, this means that many of them would not fulfil the Water Framework Directive target in the future. Results also showed that macrophytes and fish indices were mainly responsible for a non-desirable overall ecological status in Odense and Sorraia, respectively. The approach followed in this study is novel, since BBN modelling is used for the first time for assessing the ecological status of rivers and streams under future scenarios, using an ensemble of biological quality elements. An important advantage of this tool is that it may easily be updated with new knowledge on the nature of relationships already established in the BBN or even by introducing new causal links. By encompassing two case studies of very different characteristics, these BBN may be more easily adapted as decision-making tools for water management of other river basins.  相似文献