Modelling of stream run-off and sediment output for erosion hazard assessment in Lesser Himalaya: need for sustainable land use plan using remote sensing and GIS: a case study     

Pradeep K. Rawat  P. C. Tiwari  C. C. Pant  A. K. Sharama  P. D. Pant 《Natural Hazards》2011,59(3):1277-1297

Assessment and inventory on soil erosion hazard are essential for the formulation of successful hazard mitigation plans and sustainable development. The objective of this study was to assess and map soil erosion hazard in Lesser Himalaya with a case study. The Dabka watershed constitutes a part of the Kosi Basin in the Lesser Himalaya, India, in district Nainital has been selected for the case illustration. The average rate of erosion hazard is 0.68 mm/year or 224 tons/km²/year. Anthropogenic and geo-environmental factors have together significantly accelerated the rate of erosion. This reconnaissance study estimates the erosion rate over the period of 3 years (2006–2008) as 1.21 mm/year (398 tons/km²/year) in the barren land having geological background of diamictite, siltstone and shale rocks, 0.92 mm/year (302 tons/km²/year) in the agricultural land with lithology of diamictite, slates, siltstone, limestone rocks, while in the forest land, it varies between 0.20 mm/year (66 tons/km²/year) under dense forest land having the geology of quartzwacke and quartrenite rocks and 0.40 mm/year (132 tons/km²/year) under open forest/shrubs land having geological setup of shale, dolomite and gypsum rocks. Compared to the intensity of erosion in the least disturbed dense forest, the erosion rate is about 5–6 times higher in the most disturbed agricultural land and barren land, respectively. The erosion hazard zones delineated following scalogram modelling approach. Integrated scalogram modelling approach resulted in severe classes of soil erosion hazard in the study area with numerical values of Erosion Hazard Index (EHI) ranging between 01 (very low hazard) and 5 (very high hazard).  相似文献   

Theoretical studies on OH and Cl initiated hydrogen atom abstraction of HFE-227pc (CF3OCF2CHF2)     

Hari Ji Singh  Pradeep Kumar Rao  Laxmi Tiwari 《Journal of Atmospheric Chemistry》2013,70(3):257-268

The kinetics of hydrogen atom abstraction reactions of HFE-227pc by OH and Cl was studied by ab initio method. The structural optimization and frequency calculation of the titled compound and the species formed during the abstraction reactions were performed with density functional theory using hybrid meta density functional MPWB1K with 6–31?+?G(d,p) basis set. The energy of the species was further refined by making a single point energy calculation at G3B3 level of theory. The standard enthalpies of formation of reactant and the radical formed after H-atom abstraction was calculated using isodesmic method. The rate constants of abstraction reactions were calculated using Conventional Transition State Theory (CTST) and were found to be 1.5?×?10^?15 and 0.53?×?10^?16 cm³molecule^?1 s^?1 for OH and Cl respectively. The calculated value for the abstraction by OH is close to the experimental value of 2.26?×?10^?15 cm³molecule^?1 s^?1 whereas the same for Cl is found to be about five times lower than that of 2.70?×?10^?16 cm³molecule^?1 s^?1. The theoretical studies yielded the enthalpies of formation and the rate constants that are vital in determining the lifetime of HFE-227pc.  相似文献   

On the Structure and Evolution of a Polar Crown Prominence/Filament System     

N. K. Panesar  D. E. Innes  D. J. Schmit  S. K. Tiwari 《Solar physics》2014,289(8):2971-2991

Polar crown prominences, that partially circle the Sun’s poles between 60° and 70° latitude, are made of chromospheric plasma. We aim to diagnose the 3D dynamics of a polar crown prominence using high-cadence EUV images from the Solar Dynamics Observatory (SDO)/AIA at 304, 171, and 193 Å and the Ahead spacecraft of the Solar Terrestrial Relations Observatory (STEREO-A)/EUVI at 195 Å. Using time series across specific structures, we compare flows across the disk in 195 Å with the prominence dynamics seen on the limb. The densest prominence material forms vertical columns that are separated by many tens of Mm and connected by dynamic bridges of plasma that are clearly visible in 304/171 Å two-colour images. We also observe intermittent but repetitious flows with velocity 15 km?s^?1 in the prominence that appear to be associated with EUV bright points on the solar disk. The boundary between the prominence and the overlying cavity appears as a sharp edge. We discuss the structure of the coronal cavity seen both above and around the prominence. SDO/HMI and GONG magnetograms are used to infer the underlying magnetic topology. The evolution and structure of the prominence with respect to the magnetic field seems to agree with the filament-linkage model.  相似文献   

Obituary     

Bijendra Singh  V.M. Tiwari 《Journal of the Geological Society of India》2018,92(3):379-379

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Assessment of Groundwater Quality of the Central Gangetic Plain Area of India Using Geospatial and WQI Techniques     

Dharmendra Kumar Verma  Gouri Sankar Bhunia  Pravat Kumar Shit  Ashwani Kumar Tiwari 《Journal of the Geological Society of India》2018,91(6):743-748

The paper presents results of research to determine the health risk of potentially toxic elements (PTEs) in soils of gold mining area in Ilesha, Southwestern Nigeria. Eighteen top soil samples were collected and analysed for PTEs using ICPMS. The pollution level in soils were assessed using pollution load index (PLI) and potential ecological risk index (PERI). The human health risk was assessed using hazard index (HI), non-carcinogenic risk index and carcinogenic risk index. All the PTEs were higher than crustal average values except Fe and follow the order Mn > Ba > Cr > Zn > Cu > Ni > Pb > Co >Fe > As > Cd. The soil samples can be classified as unpolluted to moderately polluted (0.18-1.23) and low risk (15.28-94.24) based on PLI and PERI respectively. The values of hazard Index (HI) calculated for child and adult population for all the pathways were <1 and pose no obvious non carcinogenic risk to the population except for ingestion pathway where 33% of the samples showed value >1 in child population. As, Co, Cd and Pb constituted high cancer risk in the study area with child at higher risk than adult. The Total Cancer Risk (TCR) in the study area based on all the pathways ranges between 0.19 -3.86 and 0.18-3.58 for child and adult respectively and the ingestion route seems to be the major contributor to excess lifetime cancer risk followed by the dermal pathway.  相似文献   

A 19<Superscript>th</Superscript> Century Baseline Temperature Estimate for Peninsular India from Combined Analysis of Geothermal and Meteorological Records     

Vyasulu V. Akkiraju  Sukanta Roy  V. M. Tiwari  Shalivahan 《Journal of the Geological Society of India》2018,92(5):542-547

Direct information about climate change from meteorological surface air temperature records are available in India only since 1901 A.D. Meteorological surface air temperature (SAT) data for the period 1901–2006 from 49 sites in peninsular India have been combined with the geothermal data from 146 sites to extract a baseline (or pre-observational mean, POM) surface temperature prior to the existence of the observational record in the region. Periodicities of 5, 11 and 22 years in the SAT time series have little influence on the combined analysis to infer long-term climate change. The best estimate of the long-term average temperature for the 19^th Century is 0.7 °C lower than the 1961–1990 mean temperature. Considering the additional warming of 0.38°C relative to the 1961–1990 mean over a 10-year window centred on the year 2000, the hybrid POM-SAT method suggests that the total surface warming in peninsular India from mid-1800s to early- 2000s is about 1.1 °C. The study provides new evidence for significant warming prior to the establishment of widespread meteorological stations in peninsular India.  相似文献   

Spectral Analysis of Magnetic data in the Ajmer-Sambar Sector,North-Central Rajasthan     

K. Satish Kumar  S. Parveen Begum  G. S. Srinivas  M. Shri Hari Rao  P. Prabhakara Prasad  T. Seshunarayna  R. K. Tiwari 《Journal of the Geological Society of India》2018,92(3):368-372

Ajmer-Sambar sector of Delhi fold belt, North-Central Rajasthan has got importance due to its litho characters, structure, metamorphism, magmatism, migmatisation, metallogeny and rich potential of base metal mineralization. This sector is comprised of Delhi sequence of rocks hosted by the Banded Gneisses Complex (BGC). In view of the significance of this region, ground magnetic survey was conducted along six regional profiles to understand the structural features, magnetic nature of the basement and depth to the basement. Analysis of the magnetic data has clearly identified two magnetic lineaments (a) L1 in WNW-ESE direction that appears to represent litho-contact between Kalyanpura sequences in the south to Anasagar migmatite in the north and (b) L2 in NNW to SSE direction south of Parvatsar which is inferred to be a structural control about which the quartzite rocks of Taragarh Formation culminate. An average depth to basement of 3.7 km is estimated through spectral analysis of magnetic data. The maximum depth of the basin 4.5 km is estimated in central part of the study area. The obtained depth results are in good agreement with the Cummulative Total Intensity Magnetic Anomaly field (CTIMAF) and Deep seismic stuides.  相似文献   

Late Quaternary drainage reorganization assisted by surface faulting: The example of the Katrol Hill Fault zone,Kachchh, western India     

Deepak M. Maurya  Prabhuti Tiwari  Mohamedharoon Shaikh  Atul K. Patidar  Naimisha Vanik  Akash Padmalal  Laxman S. Chamyal 《地球表面变化过程与地形》2021,46(7):1268-1293

Drainage reorganization on restricted temporal and spatial scales is poorly-documented. We attempt to decode the relatively complicated mechanism of drainage realignment involving two small rivers that show structurally controlled, highly anomalous channel networks. We provide geomorphic and shallow subsurface evidence using ground-penetrating radar (GPR) for the presence of a buried paleo-valley flowing northward through the wind gap and surface faulting along the range bounding Katrol Hill Fault (KHF) which correlates with the previously known three surface faulting events in last ~30 ka bp . Most of the present river channels and the KHF zone are occupied by aeolian miliolite (local name) which is stratigraphic and lithologic equivalent of the Late Quaternary carbonate rich aeolianite deposits occurring in several parts of the globe. The history of drainage evolution in the study area comprises pre-miliolite, syn-miliolite and post-miliolite phases. Geomorphic evidences show that the paleo-Gangeshwar River flowed north through the wind gap and paleo-valley, while the short paleo-Gunawari occupied the saddle zone to the east of Ler dome prior to and during the phase of miliolite deposition which ended by ~40 ka bp . Southward tilting of the Katrol Hill Range (KHR) due to surface faulting cut off the catchment of the paleo-Gangeshwar River. The abandoned catchment stream extended its channel eastward along the strike through top-down process while the paleo-Gunawari River extended its course westward by headward erosion (bottom-up process). As the channels advanced towards each other they joined to produce the “S”-shaped bend which formed the capture point. We conclude that multiple surface faulting events along the KHF in the last ~30 ka bp , resulted in uplift and tilting of the KHR which caused drainage realignment by river diversion, beheading and river capture. Our study shows that the complexity of drainage reorganization processes is more explicit on shorter rather than longer timescales.  相似文献   

Evidence of self-organization in Sumatra earthquakes: recurrence time and its geodynamical implications   总被引：1，自引：1，他引：0  

Tiwari  R. K.  Krishnaveni  P. 《Natural Hazards》2014,70(1):51-68

Risk reduction as an outcome only takes place if results of risk estimation studies are used to develop action plans for risk-management and risk-reduction strategies. This paper describes an automated model that uses the output of existing earthquake loss estimation methodologies to support decision makers in evaluating a set of competing seismic mitigation strategies and exploring their impact in reducing socio-economic losses of urban settlements. The proposed model is structured to quantify the monetary value of earthquake losses and to find an optimal budget allocation assigned to each mitigation strategy based on user input. The optimization method takes into account both pre- and post-earthquake expenditures, such as costs of building upgrades, critical facility enhancement, temporary shelter provisions, debris removal, hospitalization and human casualty. The system consists of five main modules: (1) building damage function; (2) mitigated damage function; (3) cost estimation function; (4) optimization function; and (5) user interface function. Whereas the optimization function provides the optimal values assigned to each mitigation alternative based on the estimated costs and a defined budget, the user interface allows the decision maker to interact with the software in each step and plan mitigation strategies that best suit the user’s socio-economic requirements and limitations. The outputs of the proposed model are presented with respect to an application in a pilot study area within a vulnerable city district of Tehran, Iran.  相似文献   

Temporal variation of soil radon and thoron concentrations in Mizoram (India), associated with earthquakes     

H. P. Jaishi  S. Singh  R. P. Tiwari  R. C. Tiwari 《Natural Hazards》2014,72(2):443-454

Continuous soil-gas radon and thoron measurements were carried out at 15 days interval along Mat fault in Mizoram (India), which lies in the seismic zone V of the seismic zonation map of India. The study was carried out from March 2012 to February 2013 using LR-115 Type II detectors, manufactured by Kodak Pathe, France. The effect of meteorological parameters on radon and thoron data was taken into consideration. The annual average value of radon and thoron concentration was found to be 621.21 and 590.18 Bq/m³ with a standard deviation of 377.60 and 301.34 Bq/m³, respectively. Inverse correlation coefficient was obtained between radon/thoron concentration and the meteorological parameters except in one case (thoron and relative humidity) which showed a weak positive correlation. Standard deviation method was employed in order to differentiate those anomalies which are solely caused by seismic events and not by meteorological parameters. The data obtained have been correlated with the seismic activities that occurred around the measuring site. Positive correlations were found between radon/thoron data and the earthquakes.  相似文献