Characterization of suspended sediment in Meltwater from Glaciers of Garhwal Himalaya          下载免费PDF全文

Deepak Srivastava  Amit Kumar  Akshaya Verma  Siddharth Swaroop 《水文研究》2014,28(3):969-979

Glacierised basins are significant sources of sediments generated by glacial retreat. Estimation of suspended sediment transfer from glacierised basins is very important in reservoir planning for hydropower projects in Himalaya. The present study indicates that storage and release of sediment in proglacial streams may categorise the pattern of suspended sediment transfer from these basins. Assessment of suspended sediment concentration (SSC), suspended sediment load (SSL) and yield has been undertaken for Dunagiri Glacier basin located in Garhwal Himalaya (30^o33'20”N, 79^o53'36”E), and its results are compared with the Gangotri and Dokriani glaciers sharing close proximity. Out of the total drainage basin area, about 14.3 % of the area is glacierised. Data were collected for five ablation seasons (1984–1989, barring 1986). The mean daily SSCs for July, August and September were 333.9, 286.0 and 147.15 mg/l, respectively, indicating highest concentration of mean daily suspended sediment in July followed by August. SSL trends were estimated to be 93.0, 57.0 and 21.3 tonnes. About 59% of the total SSL of the melt period was transported during the months of August and September. Sediment yield for the study basin was computed to be 296.3 t km^?2 yr ^?1. It is observed that the cumulative proportion of SSC precedes the discharge throughout the melt season except in the year 1987. Release of SSL in terms of total load is less in the early part of melt season than in the later stage as compared to that of discharge. Diurnal variations in SSC reach their maximum at 2400 h, and therefore, SSC was found to be high during night (2000–0400 h). There was a good relationship between SSC and SSL with discharge for the ablation seasons (1988 and 1989). Mean monthly SSC and mean monthly SSL provide a good exponentional relationship with mean monthly temperature. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Change detection of linear features in temporally spaced remotely sensed images using edge-based grid analysis     

Arati Paul  V. M. Chowdary  Y. K. Srivastava  D. Dutta  J. R. Sharma 《国际地球制图》2017,32(6):640-654

Automatic change detection of land cover features using high-resolution satellite images, is a challenging problem in the field of intelligent remote sensing data interpretation, and is becoming more and more effective for its applications viz. urban planning and monitoring, disaster assessment etc. In the present study, a change in detection approach based on the image morphology that analyses change in the local image grids is proposed. In this approach, edges from both the images are extracted and grid wise comparison is made by probabilistic thresholding and power spectral density analysis for identifying change area. One of the advantages of the proposed methodology is that the temporal images used in the change analysis need not be radiometrically corrected as analysis is based on edge extractions. The grid-based analysis further reduces the error, which might have been introduced by image mis-registration. The proposed methodology is validated by finding the temporal changes in the linear land cover features in parts of Kolkata city, India using three different image data-sets from LISS IV, Cartosat-1 and Google earth having varied spatial resolutions of 5.8 m, 2.5 m and about 1 m, respectively. The overall accuracy in identifying changes is found to be 64.82, 73.86 and 80.93% for LISS IV, Cartosat-1 and Google earth data-set, respectively.  相似文献   

A comparative analysis of pansharpening techniques on QuickBird and WorldView-3 images     

Snehmani  Ashwagosh Ganju  Satish Kumar  P. K. Srivastava  Hari Ram R P 《国际地球制图》2017,32(11):1268-1284

Nowadays, different image pansharpening methods are available, which combine the strengths of different satellite images that have different spectral and spatial resolutions. These different image fusion methods, however, add spectral and spatial distortions to the resultant images depending on the required context. Therefore, a careful selection of the fusion method is required. Simultaneously, it is also essential that the fusion technique should be efficient to cope with the large data. In this paper, we investigated how different pansharpening algorithms perform, when applied to very high-resolution WorldView-3 and QuickBird satellite images effectively and efficiently. We compared these 27 pansharpening techniques in terms of quantitative analysis, visual inspection and computational complexity, which has not previously been formally tested. In addition, 12 different image quality metrics available in literature are used for quantitative analysis purpose.  相似文献   

Semi-automatic mapping of anthropogenic impervious surfaces in an urban/suburban area using Landsat 8 satellite data     

Atul Kant Piyoosh  Sanjay Kumar Ghosh 《地理信息系统科学与遥感》2017,54(4):471-494

Impervious surfaces have a significant impact on urban runoff, groundwater, base flow, water quality, and climate. Increase in Anthropogenic Impervious Surfaces (AIS) for a region is a true representation of urban expansion. Monitoring of AIS in an urban region is helpful for better urban planning and resource management. Cost effective and efficient maps of AIS can be obtained for larger areas using remote sensing techniques. In the present study, extraction of AIS has been carried out using Double window Flexible Pace Search (DFPS) from a new index named as Normalized Difference Impervious Surface Index (NDAISI). NDAISI is developed by enhancing Biophysical Composition Index (BCI) in two stages using a new Modified Normalized Difference Soil Index (MNDSI). MNDSI has been developed from Band 7 and Band 8 (PAN) of Landsat 8 data. In comparison to existing impervious surface extraction methods, the new NDAISI approach is able to improve Spectral Discrimination Index (SDI) for bare soil and AIS significantly. Overall accuracy of mapping of AIS, using NDAISI approach has been found to be increased by nearly 23% when compared with existing impervious surface extraction methods.  相似文献   

Hydrochemistry and sediment characteristics of polar periglacial lacustrine environments on Fisher Island and Broknes Peninsula,East Antarctica     

Raj esh Asthana  Prakash Kumar Shrivastav  Hari Bahadur Srivastava  Mirza Javed Beg  Pradeep Kumar 《极地研究(英文版)》2013,(4):281-295

Fisher Island and Broknes Peninsula in the Larsemann Hills constitute part of a polar lowland periglacial environment between marine and glacial ecosystems. The landscape is characterized by gently rolling hills and broad valleys interspersed with lakes formed in glacially scoured basins. We analyzed the physieochemical parameters and the ionic constituents of water samples from 10 lakes in each of these two locations. Our results showed considerable differences between the two regions and demon- strated the influence of lithology and processes including weathering, evaporation, and atmospheric precipitation. All major cations and anions in the lake waters showed positive correlations indicating balanced ionic concentrations. Unconsolidated sediments were sparsely distributed and scattered over glacial deposits, valley fills, and occasional moraine ridges. The type and rate of sedi- mentation was mainly controlled by surface run-off and aeolian influx. The sediment samples from lake beds and the catchment area on Fisher Island were immature and poorly to very poorly sorted, consisting of gravelly sand with negligible silt and finer fractions. Sediments had a polymodal grain size distribution with the two major populations lying between -2 and 1 phi and be- tween 0 and 1.5 phi. The sediments were lithic arenite to arkosic in composition and the microtextures imprinted over quartz grains were dominated by mechanical textures resulting from several stages of glacial crushing and grinding. The presence of deep disso- lution cavities, cryptocrystalline precipitation, and euhedral crystal growth signified the effect of chemical activity after the deposition of grains in the lacustrine environment.  相似文献   

Mycorrhizal Colonization Affects the Survival of Vetiveria zizanioides (L.) Nash Grown in Water Containing As(III)     

Jatin Srivastava  Dinesh Shukla  Vishal Chand  Ram Naraian  Harish Chandra  Anant R. Nautiyal 《洁净——土壤、空气、水》2010,38(8):771-774

The presence of arsenic (As) in water is of great public concern. Arsenic exists in three common valence states viz., As(0) metalloid arsenic, As(III) (arsenite) and As(V) (arsenate). Arsenite [As(III)] is the most toxic form among arsenicals which, predominates in anaerobic conditions, generally in flooded soils and in the water with high BOD. Experiments were conducted to investigate the effect of As(III) on the mycorrhization in vetiver (Vetiveria zizanioides (L.) Nash) grass in hydroponics. Studies showed significant alteration in the mycorrhizal colonization in the roots of vetiver exposed to higher concentrations of As(III) starting from 1.0, 2.0, 3.0, 4.0 to 5.0 mg/L prepared in 5% Hoagland nutrient solution without addition of phosphate ions. Considerable reduction in the mycorrhizal intensity (M) was observed in all the treatment sets as compared to the control suggesting a negative impact of the As(III) on the mycorrhizal association. Simultaneously, the study also showed that, As(III) is toxic to the vetiver plants having mycorrhizal association however plants with non‐mycorrhizal (cleansed) roots were found to be able to survive for a longer period exposed to As(III).  相似文献   

A micromorphological record of contemporary and relict pedogenic processes in soils of the Indo‐Gangetic Plains: implications for mineral weathering,provenance and climatic changes          下载免费PDF全文

Pankaj Srivastava  Manini Aruche  Ajay Arya  Dilip K. Pal  Lalan P. Singh 《地球表面变化过程与地形》2016,41(6):771-790

Micromorphology has important application in earth surface process and landform studies particularly in alluvial settings such as the Indo‐Gangetic Plains (IGP) with different geomorphic surfaces to identify climatic changes and neotectonic events and their influence on pedogenesis. The soils of the IGP extending from arid upland in the west to per humid deltaic plains in the east developed on five geomorphic surfaces namely QIG1 to QIG5 originating during the last 13.5 ka. Four soil‐geomorphic systems across the entire IGP are identified as: (i) the western Yamuna Plains/Uplands, (ii) the Yamuna‐Ganga Interfluve, (iii) the Ganga‐Ghaghara Interfluve, and (iv) the Deltaic Plains. Thin section analysis of the soils across the four soil‐geomorphic systems provides a record of provenance, mineral weathering, pedogenic processes and polygenesis in IGP. The soils over major parts of the IGP dominantly contain muscovite and quartz and small fraction of highly altered feldspar derived from the Himalayas. However, soils in the western and eastern parts of the IGP contain large volumes of fresh to weakly altered plagioclase and smectitic clay derived from the Indian craton. The soils in western Yamuna Plains/Uplands dominated by QIG2–QIG3 geomorphic surfaces and pedogenic carbonate developed in semi‐arid climate prior to 5 ka. However, soils of the central part of the IGP in the Yamuna‐Ganga Interfluve and Ganga‐Ghaghara Interfluve regions with dominance of QIG4–QIG5 surfaces are polygenetic due to climate change over the last 13.5 ka. The clay pedofeatures formed during earlier wet phase (13.5–11 ka) show degradation, loss of preferred orientation, speckled appearance in contrast with the later phase of wet climate (6.5–4 ka). The soils over the deltaic plains with dominance of vertic features along with clay pedofeatures suggest that illuviation of fine clay is an important pedogenic process even in soils with shrink‐swell characteristics. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Evaluation of a regional strain gradient in mylonitic quartzites from the footwall of the Main Central Thrust Zone (Garhwal Himalaya,India): Inferences from finite strain and AMS analyses     

Nihar R. Tripathy  Hari B. Srivastava  Manish A. Mamtani 《Journal of Asian Earth Sciences》2009,34(1):26-37

The footwall of the Main Central Thrust (MCT) Zone along the Bhagirathi valley comprises a wide zone of mylonitic quartzite and deep-level tectonites. The systematic variation of finite strain parameters (Es, k and v) in the mylonites indicates heterogeneous deformation, which is determined to vary between, simple shear and non-coaxial flattening type. In such a strain regime the outer boundary of the quartz clasts are no longer preserved thus leading to an error in finite strain measurement.In order to supplement the finite strain studies, Anisotropy of Magnetic Susceptibility (AMS) analyses were carried out on the mylonitic quartzites. A systematic variation in degree of anisotropy (P′) with distance from the MCT is documented and is interpreted to be tectonic in origin. Based on these results it is concluded that P′ can be used as a strain-intensity gauge at least on an outcrop scale, where a systematic variation in P′ values from one part of the outcrop to the other can be established. However, the quantitative relation between principal axes of finite strain ellipsoid and AMS axes, magnitude of principal susceptibility difference (ΔK₁ and ΔK₃) and finite strain magnitude (ε₁=ln 1 + e₁ and ε₃=ln 1 + e₃) were related by a logarithmic relationship with a correlation coefficient of 0.844.  相似文献   

International dune atlas meeting     

H. S. Saini  Nilesh Bhatt  Pradeep Srivastava 《Journal of the Geological Society of India》2012,80(5):742-742

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Soil chemical changes resulting from irrigating with petrochemical effluents   总被引：1，自引：0，他引：1  

N. K. Sharma  S. Bhardwaj  P. K. Srivastava  Y. J. Thanki  P. K. Gadhia  M. Gadhia 《International Journal of Environmental Science and Technology》2012,9(2):361-370

Irrigating food crops with treated wastewater is a popular management option in India. This study evaluated the impacts of land application of treated petrochemical effluent on soil chemical properties. Soil samples were collected from different depths from sites irrigated with petrochemical effluent for 2?years and from control sites. The effluent collected was analysed for different physic?Cchemical properties and its impact on Lagenaria siceraria (Bottle gourd) growth. 100% concentrated effluent was used for the study and compared with the control. It was observed that application of effluent significantly increased the major cations and anions in the field. On the basis of the study, it may be suggested that treated petrochemical effluent can be used as an alternate source for irrigating crops as it increases the nutrient content of the soil. The overall application indicates a lavishing growth of L. siceraria crop in petrochemical irrigated soil than control sites. This study provides information for better understanding of changes in soil properties due to land application of petrochemical effluent. These changes must be considered in developing possible criteria for preserving delicate ecosystems.  相似文献