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Debashis Chakraborty Dibyendu Dutta H Chandrasekharan 《Journal of the Indian Society of Remote Sensing》2001,29(3):115-128
The vegetation dynamics and land use/land cover types of Birantiya Kalan watershed located in the arid tracts of western Rajasthan have been characterized and evaluated using Remote Sensing and Geographical Information System (GIS). The watershed under study falls in the transitional plain of Luni Basin and is characterized by Aravali ranges in the eastern half and vast alluvial plains in the west. The land use/land cover types, as identified are cropland, fallow, forest, land with scrub, land without scrub, sandy area and the water body. Land with scrub occupied maximum area (39% area of the watershed) in 1996 in place of crop land which was dominant (43% of total area) in the year 1988. During eight years period, seasonal fallow land increased significantly and the areal extent of water body decreased to almost half. Vegetation vigour types have been classified into very poor, poor. moderate, good and very good categories. Moderate vigour type reduced from 62 to 27% and poor type increased from 34 to 68% during the period 1988 to 1996. Other vegetation vigour types have not shown any significant changes. To quantify the changes over the years in both vegetation and land use/land cover, weightages have been given to each type and composite values of both vegetation vigour and land use types for 1996 and 1988 have been calculated. It has been observed that the ratio for vegetation vigour has been found to be 0.85 showing that the overall vegetation have not improved after the treatment. The ratio for land use is found to be 1.01, which indicates negligible change in land use. 相似文献
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Natural Hazards - In a globally competitive market, companies attempt to foresee the occurrences of any catastrophe that may cause disruptions in their supply chains. Indian subcontinent is prone... 相似文献
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Directional dependence of horizontal wind direction fluctuations (Σθ) is studied at the coastal site of Madras Atomic Power Project, Kalpakkam with significant inhomogeneity in roughness element distribution around the location of measurement. Σθ is measured by a potentiometric wind vane mounted on a 30 m meteorological tower. Values of Σθ showed as high as threefold variation for the same atmospheric stability depending on the effective roughness length of the upwind sector. Average Σθ values separated for sea- and land-breeze conditions, when correlated with Pasquill stability categories showed a monotonic decrease with increasing stability for land breeze but was found to increase for change from D to F category during sea breezes presumably due to the influence of an internal boundary-layer development. 相似文献
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Hema Chandrasekharan Nair Damodaran Padmalal Ammini Joseph Vinod Padmakumari Gopinthan 《Arabian Journal of Geosciences》2018,11(4):73
The present study deals with the hydrogeochemistry and water quality of shallow aquifers in two important river basins—the Ithikkara and Kallada river basins—draining the south western flanks of Western Ghats in Kerala, South West India. Well water samples were collected from 20 dug wells with a depth range of 1 m below ground level (mbgl) to 18.2 mbgl during pre-monsoon, monsoon, and post-monsoon seasons of the year 2011–2012. These samples were analyzed for various physico-chemical parameters following standard methods and were evaluated for their interrelations and drinking water suitability. The pH of the water samples shows wide variation from highly acidic to highly alkaline water. About 80% of pre-monsoon samples recorded Fe2+ concentration above the permissible limit of drinking water standard. Water Quality Index (WQI) shows that majority of the well water samples fall in the category of excellent–good for drinking purpose. The results of the irrigation suitability assessment using the procedures like Percent Sodium, Sodium Absorption Ratio, Residual Sodium Carbonate, Kelly Index, Permeability Index, and Magnesium Hazard reveal that the well waters of the study area are fit for irrigation purpose. Na+/Cl? ratio reflects the release of sodium to water due to silicate weathering. The samples have a Ca2+/Mg2+ ratio equal or greater than 2 indicating the effect of silicate minerals in contributing Ca2+ and Mg2+ ions to the well water. The saturation indices reveal that groundwater is supersaturated with SiO2. Among the causative factors that determine the hydrochemical quality of well water samples, silicate weathering plays a pivotal role with significant input of ions from anthropogenic sources. 相似文献
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Geo-limis - a decision support system for minimizing locust impact in republic of kazakhstan 总被引：1，自引：0，他引：1
Dutta D. Bhatawdekar S. Chandrasekharan B. Sharma J. R. Adiga S. Wood Duncan Mccardle Adrian 《Journal of the Indian Society of Remote Sensing》2004,32(1):25-47
Desert locusts (DL) are serious problem during April to August in the deserts and semi-deserts of Republic of Kazakhstan and
causing extensive crop damage. There is no institutional and functional mechanism to forecast the habitat of locusts and most
of the area remains unnoticed after laying eggs. The key to improve DL forecasting and control depends on the collection and
generation of historical database on locusts, weather and habitat from affected region. Looking at the problem, a Spatial
Decision Support Systems (DSS) has been developed on ARC/INFO GIS with ergonomic user interface for ingestion and subsequent
analysis of locust related information vis-à-vis bio-physical and climatic data acquired from various satellite sensors and
hydromet weather server respectively, to identify high frequency breeding areas well before the physiological development
is completed. Weather based analytical models for physiological development of DL has been dovetailed with the SDSS for facilitating
historic and present data analysis in relation to locust activity. This has augmented the surveying capability and better
forecasting. 相似文献
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Partha Pratim Adhikary Ch. Jyotiprava Dash H. Chandrasekharan T. B. S. Rajput S. K. Dubey 《Arabian Journal of Geosciences》2012,5(6):1423-1434
Intensive agriculture by indiscriminate use of agrochemicals, sewage water, and polluted drain water has posed a serious threat to groundwater quality in some peri-urban areas of Delhi like Najafgarh block. The objective of the study was to determine the groundwater quality and to map their spatial variation in terms of suitability for irrigation and drinking purpose. Ordinary kriging method was used for preparation of thematic maps of groundwater quality parameters such as electrical conductivity, sodium adsorption ratio, bicarbonate, magnesium/calcium ratio, total dissolved solids, chloride, nitrate and hardness. Exponential semivariogram model was best fitted for all quality parameters except chloride and hardness, where spherical model fitted best. Pollution level was highest at south and south-eastern part of the study area. Better quality groundwater may be expected at the northern and western part. High salinity was due to high chloride concentration in the groundwater. Nitrate pollution level was found to be very alarming and need immediate interventions. High dissolved solids and hardness made the groundwater unsuitable for drinking. There were negligible sodium and bicarbonate hazard in the study area. The groundwater quality index was devised to analyse the combined impact of different quality parameters on irrigation and drinking purposes. The irrigation water quality index and drinking water quality index distribution maps delineated an area of 47.29 and 6.54 km2 suitable for irrigation and drinking, respectively. These safe zones were found as a small strip along the northern boundary and a very small pocket at the western side of the study area. 相似文献
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