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151.
The southwestern part of south Shillong plateau (Meghalaya, N-E India), designated as Sylhet Limestone Group is sub-divided into three lithounits i.e., Lakadong, Umlatdoh and Prang formations in ascending order. The Prang Formation is the youngest lithostratigraphic unit of the Sylhet Limestone Group and has been dated as Middle to early Upper Eocene based on the benthic foraminifera studies. Thin section analysis of carbonate rocks from Prang Formation, exposed in the Bholaganj limestone quarry yielded a rich assemblage of calcareous algae. The coralline algal assemblage comprises both non-geniculate and geniculate forms. The green algae are represented by species of Halimeda belonging to the family Halimedaceae. Palaeoecological interpretation based on diversity, growth-form analysis and taphonomic aspects of the algal assemblage indicate that in all probabilities the deposition of Prang Formation occurred in shallow, warm, shelf environment of normal salinity within the transgressive phase. 相似文献
152.
T. J. Majumdar S. K. Pal Amit K. Bhattacharya 《Journal of the Geological Society of India》2012,80(5):685-699
The present study was undertaken with four fold objectives, namely, (i) to estimate land surface temperature using MODIS TIR data; (ii) to calculate relative emissivities from MODIS TIR data; (iii) to identify various lithologies based on relative emissivity and land surface temperature estimation; and finally, (iv) to carry out comparative assessment analysis between the prepared lithological map and the published lithological map. The land surface temperatures for different pixels were estimated using two methods, viz., Reference Channel and Emissivity Normalization; whereas, relative emissivities were calculated by applying three methods, viz., Reference Channel, Emissivity Normalization and Alpha Residual. Lithological maps were subsequently prepared based on the estimated land surface temperatures and relative emissivity values. The present study shows that the Emissivity Normalization method gives the best results for land surface temperature estimation and also for lithological discrimination based on emissivity estimation. Twenty-four lithounits demarcated by the present study match with those of the published map, while four lithounits of the published map could not be identified in the present study. On the other hand, six additional unclassified lithounits could be demarcated in the present study, which need to be crosschecked by field study. 相似文献
153.
Arvind Chandra Pandey Amit Kumar A. T. Jeyaseelan 《Journal of the Indian Society of Remote Sensing》2013,41(1):141-155
In the present study, the Cartosat-I digital elevation model (DEM) was utilized to deduce the vertical characteristics of Ranchi urban area and its relation to long term built-up expansion (1927–2010). The DEM represents moderate variation in terrain relief ranging from 595 m to 754 m with majority of area exhibiting upto 3° of slope and 3° to 6° indicating flat to undulating nature of terrain in Ranchi township. The DEM was used to generate location of sinks within urban area, which are generally delineated along the drainage channels, adjacent to high-rise built-up land and along the elevated road network. The pattern of urban sprawl over the eight decades (1927–2010) were examined with reference to terrain relief zones, which indicated that the built-up growth was mainly taken place over the elevation range of moderate (620–660 m) (67.0%) and high relief (660–680 m) (19.8%) zones. Although earlier preference for built-up development was more in high elevation zones (660–680 m), the low elevation zones (<600–620 m) are now preferred for multistoried built-up land development where better groundwater availability occur. The spatial pattern of vertical growth of built-up land was assessed using contour density obtained from Cartosat-I DEM. The results show that the high density contours predominately correspond to hilly area and high-rise buildings at majority of locations. The urban sprawl pattern and population trend exhibited rapid increase in vertical built-up growth after 1996 indicating beginning of urban densification in Ranchi township. 相似文献
154.
Assessment of Coastal Erosion Vulnerability around Midnapur-Balasore Coast, Eastern India using Integrated Remote Sensing and GIS Techniques 总被引:2,自引:0,他引:2
Adarsa Jana Amit K. Bhattacharya 《Journal of the Indian Society of Remote Sensing》2013,41(3):675-686
Digha coastal region in the northeastern part of the Bay of Bengal is potentially vulnerable to erosional hazard. The present study assessed the coastal erosion vulnerability along this 65 km long coastal stretch located between Rasulpur (Midnapur) and Subarnarekha (Balasore) estuarine complex, which had been subjected to anthropogenic intervention. Multi-resolution Landsat satellite imagery were used for shoreline change study from 1972 to 2010. During this period, accretion was recorded updrift of artificial structures, viz, seawall, groin, pylons and jetties; while, extensive erosion was recorded in downdrift areas of these structures. Assessment was subsequently divided into four categories ranging from “high erosion” to “accretion”. Data from several sources were compiled to map landuse and human activities in the coastal zone. This map was divided into four categories, ranging from “very high capital” to “no capital” landuse. Population density map of the surrounding coastal villages was generated using census data, and divided into four categories ranging from “high density area” to “very low density area”. Subsequently, coastal erosion vulnerability was assessed by combining coastal retreat with landuse type and population density in this study area using simple vector algebraic technique. Zones of vulnerability of different magnitude (viz., very high, high, moderate, and low) have been identified. Furthermore, calculation of “imminent collapse zone (ICZ)” shows that maximum values are around artificial structures and anthropogenic activities. The coastal erosion vulnerability map prepared from this study can be used for proper planning and management of this coastal region. 相似文献
155.
This study demonstrates the use of high resolution WorldView-II satellite data in extraction of built-up land and vegetation using normalized index techniques. The PCA 1 and NIR 2 bands-based built-up index was proposed for extracting built-up land, which exhibit high accuracy. The normalized difference vegetation index based on Red Edge and NIR 2 bands of WorldView-II produced high accuracy inthe estimation of vegetation compared to the use of Red and NIR bands. The grid technique used in estimating built-up and vegetation density from precisely classified images provided better and accurate assessment of built-up and vegetation density in heterogeneous landscape of urban areas. This shows areas of very high to high built-up density are located in the central, western and southern parts, which are primarily devoid of vegetation. This study indicates possibilities of utilizing high resolution satellite data in urban landscape characterization using a grid-based technique. 相似文献
156.
Amit Birenboim Kristian Hegner Reinau Noam Shoval Henrik Harder 《The Professional geographer》2013,65(4):620-629
The notion of consumer and user experience has become dominant in our society in recent years, especially in relation to leisure activities. In this study we used the experience sampling method (ESM) data collection technique in Aalborg Zoo, Denmark, to understand the distribution of subjective experiences within this site. Visitors to the zoo were asked to send phone messages (SMS) about their subjective feelings in real time and to carry with them Global Positioning System (GPS) devices that recorded their movement. This method allowed us to geotag experiences of visitors throughout the zoo compound. The results indicate that the quality of experience of visitors varies both in time and in space. We conclude that there is a need to further explore the effect of place on experiences using repeat, high-resolution measurements. In this regard we believe that geographers, who have a long tradition of studying human–environment relations, have the tools to lead this type of exploration. 相似文献
157.
Amit Birenboim Martin Dijst Floortje E. Scheepers Maartje P. Poelman Marco Helbich 《The Professional geographer》2013,65(3):449-461
Advances in commercial wearable devices are increasingly facilitating the collection and analysis of everyday physiological data. This article discusses the theoretical and practical aspects of using such ambulatory devices for the detection of episodic changes in physiological signals as a marker for mental state in outdoor environments. A pilot study was conducted to evaluate the feasibility of using commercial wearables in combination with location tracking technologies. The study measured physiological signals for fifteen participants, including heart rate, heart rate variability, and skin conductance. Participants’ signals were recorded during an outdoor walk that was tracked using a Global Positioning System logger. The walk was designed to pass through various types of environments including green, blue, and urban spaces, as well as a more stressful road crossing. The data that were obtained were used to demonstrate how biosensor information can be contextualized and enriched using location information. Significant episodic changes in physiological signals under real-world conditions were detectable in the stressful road crossing but not in the other types of environments. The article concludes that despite challenges and limitations of current off-the-shelf wearables, the utilization of these devices offers novel opportunities for evaluating episodic changes in physiological signals as a marker for mental state during everyday activities including in outdoor environments. Key Words: electrodermal activity, GPS, mental state, stress, wearable. 相似文献
158.
Sand dunes as a major proximal dust source for late Pleistocene loess in the Negev Desert, Israel 总被引:3,自引:0,他引:3
Grain size analyses of three hilltop, primary eolian loess sequences in the Negev desert, southern Israel, show a bimodal grain-size distribution at 50-60 μm and 3-8 μm. Using analyses of mineralogy and OSL ages we demonstrate that the coarse mode is composed mostly of quartz grains and its relative magnitude increases regionally with time, suggesting an enhancement of a time-transgressive proximal dust source compared to a distal, Saharan fine-grain dust. The only proximal dust source for large amount of coarse silt quartz grains is the sands that advanced into Sinai and the Negev concurrently with the loess accretion during the late Pleistocene as a result of the exposure of the Mediterranean shelf. We therefore propose that the coarse silt quartz grains were formed through eolian abrasion within the margins of an advancing sand sea. This relationship between desert sand seas as a source for proximal coarse dust and desert margin loess deposits can be applicable to other worldwide deserts such as Northern Africa, China and Australia. 相似文献
159.
Evapotranspiration (ET) is a vital process in land surface atmosphere research. In this study, Surface Energy Balance Algorithm for Land (SEBAL) for the assessment of ET (for 23 December 2010, 8 January 2011, 24 January 2011, 9 February 2011, 25 February 2011, 29 March 2011 and 14 April 2011) from LANDSAT7-ETM+ and validation with Lysimeter data set is illustrated. It is based on the evaporative fraction concept, and it has been applied to LANDSAT7-ETM + (30 m resolution) data acquired over the Indian Agricultural Research Institute’s agricultural farm land. The ET from SEBAL was compared with Lysimeter ET using four statistical tests (root-mean-square error (RMSE), relative root-mean-square error (R-RMSE), mean absolute error (MAE), and normalized root-mean square error (NRMSE)), and each test showed a good correlation between the predicted and observed ET values. Results from this study revealed that the RMSE of crop-growing period was 0.51 mm d?1 for ETSEBAL, i.e. ETSEBAL having good accuracy with respect to observed ETLysimeter. Results were also validated using R-RMSE test, which also proved that ETSEBAL data are having good accuracy with respect to observed ETLysimeter as R-RMSE of crop-growing period is 0.19 mm d?1. MAE (0.19), NRMSE (0.21) and r2 (0.91) tests indicated that model prediction is significant, and model can be effectively used for the estimation of ET from SEBAL as input of remote sensing data sets. Finally, the SEBAL has been useful for remote agricultural land where ground-based data (Lysimeter data) are not available for daily ET (ET24 h) estimation. The temporal study of the ET24 h values analysed has revealed that the highest ET24 h values are owing to the higher development (high greenness) of crops, whereas the lower values are related to the lower development (low greenness) or null crop. 相似文献
160.
Himalayan basins have considerable snow‐ and glacier‐covered areas, which are an important source of water, particularly during summer season. In the Himalayan region, in general, the glacier melt season is considered to be from May to October. Changes in hydrological characteristics of the runoff over the melt season can be understood by studying the variation in time to peak and time lag between melt generation and its emergence as runoff. In the present study, the runoff‐delaying characteristics of Gangotri Glacier, one of the largest glaciers in the Indian Himalayas, have been studied. For this purpose, hourly discharge and temperature data were collected near the snout of the glacier (4000 m) for three ablation seasons (2004–2006). The diurnal variations in discharge and temperature provided useful information on water storage and runoff characteristics of the glacier. In the early stages of the ablation period, poor drainage network and stronger storage characteristics of the glaciers due to the presence of seasonal snow cover resulted in a much delayed response of melt water, providing a higher time lag and time to peak as compared to the peak melt season. A comparison of runoff‐delaying parameters with the discharge ratio clearly indicated that changes in time lag and time to peak are inversely correlated with variations in discharge. Impact of such meltwater storage and delaying characteristics of glaciers on hydropower projects being planned/developed on glacier‐fed streams in India has been discussed. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献