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Seasonal variations of phytoplankton diversity in the Coleroon coastal waters, southeast coast of India 总被引：1，自引：0，他引：1
The results of an investigation carried out during June 2005 to May 2007 on physico-chemical parameters,species composition and community structure of phytoplankton including Chlorophyll a(Chl-a) at the Coleroon coastal waters(Southeast coast of India) are reported.Air and surface water temperatures(°C) varied from 25.1 to 30.1 and from 24.5 to 28.5 respectively.Salinity values varied from 6 to 28.5 and the pH ranged between 7.0 and 8.3.Variation in dissolved oxygen content was from 3.1 to 7.5 mg/dm-3 while the light extinction coefficient values(LEC) ranged between 3.1 and 10.1 cm.The ranges of inorganic nutrients(μmol/dm-3) viz.,nitrate,nitrite,phosphate and silicate were 10.1-23.4,1.2-8.9,0.2-3.1 and 55-125,respectively.The ranges of Chlorophyll a(μg/dm-3) values was 2.0-7.5.Presently,124 phytoplankton species representing different classes viz:Bacillariophyceae(77),Dinophyceae(19),Cyanophyceae(15),Chlorophyceae(10) and Chrysophyceae(3) were recorded.The phytoplankton cell abundance varied from 0.290 to 111.662 cells/cm-3,with peak diversity(3.38 bits/ind.) during summer season.The maximum abundance was found during summer season coinciding with the stable hydrographical conditions.The seasonal distribution and abundance of phytoplankton are discussed in relation to hydrographical parameters.Canonical Correspondence Analysis(CCA) was applied in this paper for discriminating environmental factors having effect on phytoplankton community at species level.Coleroon coastal water is subjected to long term fluctuations in physico-chemical parameters depending upon the seasonal tidal amplitude and freshwater influx resulting in a continuous exchange of organic,inorganic,plant and animal matters. 相似文献
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The results of an investigation carried out during June 2005 to May 2007 on bloom-forming phytoplankton species composition and abundance in the Parangipettai and Coleroon coastal waters(Southeast coast of India) are reported.Air and surface water temperatures(℃) varied from 25.1 to 30.1 and 24.5 to 28.5,respectively,in the former waters and from 25.5 to 31.2 and 25.0 to 29.3 in the latter waters.The respective salinities varied from 6.0 to 28.5 and 5.0 to 33.1 and the respective pH ranged between 7.0 and 8.3 and 7.2 and 8.3.Correspondingly,the dissolved oxygen content varied from 3.1 to 7.5 and 3.1 to 7.9 mgL-1 while the light extinction coefficient(LEC) values ranged between 3.1 and 10.1 and 1.8 and 11.0.The content ranges of inorganic nutrients,i.e.,nitrate,nitrite,phosphate and silicate(μmolL-1),in the Parangipettai and Coleroon coastal waters were:6.5-27.0;1.0-8.9;0.1-3.0 and 15.0-140 and 10.1-23.4;1.2-8.9;0.2-3.1 and 55-125 respectively.The chlorophyll a contents in both waters ranged from 2.0-7.5 μgL-1.Presently,124 phytoplankton species representing different classes were recorded in the Coleroon coast,viz,Bacillariophyceae(77);Dinophyceae(19);Cyanophyceae(15);Chlorophyceae(10) and Chrysophyceae(3),whereas 117 phytoplankton species were recorded in the Parangipettai coast,viz,Bacillariophyceae(66);Dinophyceae(22);Cyanophyceae(19);Chlorophyceae(7) and Chrysophyceae(3).The phytoplankton cell abundance in the Parangipettai and Coleroon coastal waters varied from 290 to 111662 and 140 to 132 757 cells L-1,respectively,with peak diversity(3.38 and 3.52 bits ind-1.) recorded in summer.The maximum abundance occurred in summer coinciding with the stable hydrographical conditions.The seasonal distribution and abundance of phytoplankton are discussed in relation to hydrographical parameters.Totally 31 and 24 species of phytoplankton were found to be bloom-forming in the Parangipettai and Coleroon coastal waters,respectively.Presently Trichodesmium bloom was also observed,which appeared at the 10 fathom level of the coastal water and quickly spread to the marine zone of the Vellar estuary and near the mouth region of the mangrove waters.The Parangipettai and Coleroon coastal waters are subject to long term fluctuations in physico-chemical conditions depending upon the seasonal tidal range and freshwater influx,resulting in a continuous exchange of organic,inorganic,plant and animal matters. 相似文献
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In this paper, remote sensing, geographic information systems (GIS) and fieldwork techniques were combined to study the groundwater conditions in Vaigai basin, Tamilnadu. Several digital image processing techniques, including standard color composites, intensity–hue–saturation transformation and decorrelation stretch were applied to map rock types. Remote sensing data were interpreted to produce lithological and lineament maps such as geology, geomorphology, soil hydrological group, land use/land cover and drainage map were prepared and analyzed using GIS Arc Map GIS Raster Calculator module as geomorphology?×?12?+?drainage?×?9?+?lineament?×?5?+?geology?×?8?+?land use?×?2?+?relief?×?4. The final cumulative map generated by applying the above equation had weight values ranging from 0.315 to 4.515. The overall results demonstrate that the use of remote sensing and GIS provide potentially powerful tools to study groundwater resources and design a suitable exploration plan, the thematic maps for the study area. 相似文献
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Sagar S. Salunkhe S. S. Rao I. Prabu V. Raghu Venkataraman Y. V. N. Krishna Murthy Chintamani Sadolikar Supriya Deshpande 《Journal of the Indian Society of Remote Sensing》2018,46(6):915-925
In many flood prone river basins, water inundates vast areas of land causing loss of life and heavy damage to the dwellings in flood plains. It also impacts agricultural productivity and cause severe economic losses. One of the reasons for flooding in plains of Brahmaputra valley in north east India is embankment breaching. In this study, an attempt was made for probabilistic flood hazard modelling of July 2008 embankment breaching scenario of Brahmaputra river at Matmara village, Lakhimpur district in Assam, based on various numerical simulations with the help of Center for Computational Hydro science and Engineering hydro-dynamic model. The methodology was applied over 2146 km2 flood prone area. Data inputs in the study include: Advanced Spaceborne Thermal Emission and Reflection Radiometer Digital Elevation Model, Pre-flood and Post flood satellite images of Landsat Enhanced Thematic Mapper Plus (ETM+) and other ancillary data. The simulation was carried out for various discharge levels based on flood frequency analysis. The result of the model includes spatial variations of inundated water depth and water velocity. The results were validated by comparing it with the post-flood ETM+ data and flood situation status report of National Informatics Centre. Flood hazard maps were prepared by carrying out a spatial analysis of simulated inundation depth and velocity. It was seen that the majority of flooded area fell into the very high and high categories. This information can be used to plan appropriate cost effective flood mitigation schemes. 相似文献
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Combined use of socio economic analysis,remote sensing and GIS data for landslide hazard mapping using ANN 总被引：2，自引：0，他引：2
The term landslide includes a wide range of ground movements, such as slides, falls, flows etc. mainly based on gravity with
the aid of several conditioning and triggering factors. Particularly in the last two decades, there has been an increasing
international interest in the landslide susceptibility, hazard or risk assessments.
In this paper we present a combined use of socioeconomic, remote sensing and GIS data for developing a technique for landslide
susceptibility mapping using artificial neural networks and then to apply the technique to the selected study areas at Nilgiris
district in Tamil Nadu and to analyze the socio economic impact in the landslide locations. 相似文献
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Drainage morphometry of upper Vaigai river sub-basin, Western Ghats, South India using remote sensing and GIS 总被引：1，自引：0，他引：1
The study area is a one of the sub-basin of Vaigai River basin in the Theni and Madurai districts, Western Ghats of Tamil Nadu. The Vaigai sub-basin extends approximately over 849 km2 and it has been sub-divided into 48 watersheds. It lies between 09°30′00″ and 10°00′00″N latitudes and 77°15′10″ and 77°45′00″ E longitudes in the western part of Tamil Nadu, India. It originates at an altitude of 1661m in the Western Ghats of Tamil Nadu in Theni district. The drainage pattern of these watersheds are delineated using geo-coded Indian remote sensing satellite (IRS) ID, linear image self-scanning (LISS) III of geo-coded false colour composites (FCC), generated from the bands 2, 3 and 4 on 1:50,000 scale in the present study. The Survey of India (SOI) toposheets 58G/5, 58 G/6, 58G/9 and 58G/10 on a scale of 1:50,000 scale was used as a base for the delineation of watershed. In the present study, the satellite remote sensing data has been used for updation of drainages and the updated drainages have been used for morphometric analysis. The morphometric parameters were divided in three categories: basic parameters, derived parameters and shape parameters. The data in the first category includes area, perimeter, basin length, stream order, stream length, maximum and minimum heights and slope. Those of the second category are bifurcation ratio, stream length ratio, RHO coefficient, stream frequency, drainage density, and drainage texture, constant of channel maintenance, basin relief and relief ratio. The shape parameters are elongation ratio, circularity index and form factor. The morphometric parameters are computed using ESRI’s ArcGIS package. Drainage density ranges from 1.10 to 4.88 km/km2 suggesting very coarse to fine drainage texture. Drainage frequency varies from 1.45 to 14.70 which is low to very high. The bifurcation ratio ranges from 0.55 to 4.37. The low values of bifurcation ratios and very low values of drainage densities indicate that the drainage has not been affected by structural disturbances and also that the area is covered under dense vegetation cover. Elongation ratio ranges from 0.11 to 0.57. Drainage texture has the minimum of 1.63 and maximum of 11.44 suggesting that the drainage texture is coarse to fine. It is concluded that remote sensing and GIS have been proved to be efficient tools in drainage delineation and updation. In the present study these updated drainages have been used for the morphometric analysis. 相似文献
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P. S. Ramkumar T. Prabu Madhu Girimaji G. Marker leyulu 《Journal of Astrophysics and Astronomy》1994,15(3):343-353
A fast digital signal processor has been designed and built for survey and some observations of pulsars. The processor obtains
spectral information over a bandwidth of 16 MHz (256 channels) every 25μsecs Wedescribethe design ofthisprocessor and present
some test observations made with the Ooty Radio Telescope. 相似文献
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