Socio-economic and Environmental Implications of the Hydroelectric Projects in Uttarakhand Himalaya, India   总被引：1，自引：1，他引：0  

Naresh Rana S.P. Sati Y.P. Sundriyal Madan Mohan Doval Navin Juyal 《山地科学学报》2007,4(4):344-353

This paper deals with detailed analysis of the fiasco created by the Tehri High Dam in Uttarakhand, India, particularly in terms of resettlement and rehabilitation of the local inhabitants. Aspects pertaining to the environmental issues are also discussed. Currently, the river valleys in Uttarakhand state of India are the targets of increasing hydroelectric projects. Virtually all rivers are being exploited for generating environmental friendly power. Having being learned the hard lesson from Tehri Dam, it has been decided to opt for such schemes in which comparatively little submergence and tempering with the fragile eco-systems is involved.However, our observations suggest that even in such schemes if due care is not taken they may turn out to be a failure.  相似文献   

2-D deformation analysis of a half-space due to a long dip-slip fault at finite depth     

Sushil K. Tomar  Naresh K. Dhiman 《Journal of Earth System Science》2003,112(4):587-596

Closed form analytical expressions of stresses and displacements at any field point due to a very long dip-slip fault of finite width buried in a homogeneous, isotropic elastic half-space, are presented. Airy stress function is used to derive the expressions of stresses and displacements which depend on the dip angle and depth of the upper edge of the fault. The effect of dip angle and depth of the upper edge of the fault on stresses and displacements is studied numerically and the results obtained are presented graphically. Contour maps for stresses and displacements are also presented. The results of Rani and Singh (1992b) and Freund and Barnett (1976) have been reproduced.  相似文献   

The Congo basin zonal overturning circulation     

Naresh Neupane 《大气科学进展》2016,33(6):767-782

The Gulf of Guinea in the equatorial Atlantic is characterized by the presence of strong subsidence at certain times of the year. This subsidence appears in June and becomes well established from July to September. Since much of theWest African monsoon flow originates over the Gulf, Guinean subsidence is important for determining moisture sources for the monsoon. Using reanalysis products, I contribute to a physical understanding of what causes this seasonal subsidence, and how it relates to precipitation distributions across West Africa.There is a seasonal zonal overturning circulation above the Congo basin and the Gulf of Guinea in the ERA-Interim, ERA-40, NCEP2, and MERRA reanalyses. The up-branch is located in the Congo basin around 20°E. Mid-tropospheric easterly flows constitute the returning-branch and sinking over the Gulf of Guinea forms the down-branch, which diverges at 2°W near the surface, with winds to the east flowing eastward to complete the circulation. This circulation is driven by surface temperature differences between the eastern Gulf and Congo basin. Land temperatures remain almost uniform, around 298 K, throughout a year, but the Guinean temperatures cool rapidly from 294 K in May to about 290 K in August. These temperature changes increase the ocean/land temperature contrast, up to 8 K, and drive the circulation.I hypothesize that when the overturning circulation is anomalously strong, the northward moisture transport and Sahelian precipitation are also strong. This hypothesis is supported by ERA-Interim and PERSIANN-CDR (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record) data.  相似文献   

Seismicity and stress inversion study in the Kangra–Chamba region of north-west Himalaya     

Dilip Kumar Yadav  Devajit Hazarika  Naresh Kumar 《Natural Hazards》2016,81(2):1393-1404

  相似文献   

Investigation of azimuthal variation in S-wave velocity in the western part of the Himalayas-Tibet Indo-Gangetic plains region using surface waves     

Sagarika Mukhopadhyay  Amit Kumar  Naresh Kumar 《《地质学报》英文版》2018,92(Z1):53-53

  相似文献   

Late Quaternary fluvial aggradation and incision in the monsoon‐dominated Alaknanda valley,Central Himalaya,Uttrakhand, India     

Navin juyal  Yaspal Sundriyal  Naresh rana  Shipra chaudhary  Ashok k. Singhvi 《第四纪科学杂志》2010,25(8):1293-1304

The present study aims to explain the spatial and temporal variability in phases of aggradation/incision in response to changes in climate and seismicity during the late Quaternary in the Alaknanda River valley (a major tributary of the river Ganges or Ganga). Geomorphology, stratigraphy and optical dating of the fluvial sediment reveal that the oldest fluvial landforms preserved in the south of the Main Central Thrust are debris flow terraces developed during the early part of pluvial Marine Isotopic Stage 3. Following this, a period of accelerated incision/erosion owing to an increase in uplift rate and more intense rainfall occurred. In the Lesser Himalaya, three phases of valley fill aggradation around 26 ± 3 ka, 18 ± 2 ka and 15 ± 1 ka and 8 ± 1 ka occurred in response to changes in monsoon intensity and sediment flux. The last phase was regionally extensive and corresponds to a strengthening of the early Holocene Indian Summer Monsoon. A gradual decline in the monsoon strength after 8 ± 1 ka resulted in reduced fluvial discharge and lower sediment transport capacity of the Alaknanda River, leading to valley fill incision and the development of terraces. The study suggests that fluvial dynamics in the Alaknanda valley were modulated by monsoon variability and the role of tectonics was subordinate, limited to providing accommodation space and post‐deposition modification of the fluvial landforms. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Recurvature dynamics of a typhoon   总被引：1，自引：0，他引：1  

T. N. Krishnamurti  H. S. Bedi  K. S. Yap  D. Oosterhof  G. Rohaly 《Meteorology and Atmospheric Physics》1992,50(1-3):105-126

Summary In this paper we present some recent work on typhoon prediction with a high resolution global model. The emphasis of this paper is on typhoon recurvature. Here we include examples of successful typhoon recurvature track forecasts made from a very high resolution global spectral model. The main objective of this study however is to go beyond the forecasts, i.e. to interrogate the history tapes and to diagnose residue-free budgets of the divergence and vorticity. The premise of this paper is that the recurvature of the typhoons depends on both the usual advection of vorticity by the layer mean winds and the advection of divergence in the outflow layers of the storm.The region immediately outside the heavy rain area of the storm experiences large values of divergent outflows which contribute a significant advection of divergence. Through the Dine's compensation this region must, in consort, experience an enhancement of low level convergence and of deep convection, thus contributing to the storm motion. We distinguish two facets of storm motion and recurvature, one based on the conventional steering that invokes the advection of vorticity by a vertical integrated flow, the other is the generation mechanism proposed here. During recurvature the storm appears to move in a direction which is influenced by the rotational and the divergent flow dynamics. Increased vertical resolution in the outflow layer is shown to resolve stronger amplitudes in the outflow layer divergence and thus to contribute to improved forecasts of recurvature. A number of processes seem to simultaneously evolve, these include the strong advection of divergence part of the wind, enhancement of cumulus convection over this region, an enhancement of lower tropospheric convergence, generation of vorticity of the lower troposphere and the attendant recurvature.With 16 Figures  相似文献   

Meandering valley of Karjan-Terav rivers in district broach,Gujarat     

Naresh Bedi 《Journal of the Indian Society of Remote Sensing》1980,8(2):1-5

Karjan river is an important tributary of Narmada in Gujarat. Along with one of its own tributaries, called Terav it has carved a “meandering valley” across the block faulted rldge and valley Deccan Trap topography, south of Narmada. Karjan originates at Bardipada, which is much nearer to Tapti river than Narmada and in the initial stretches its channel is consequent to faults and fractures. However, before emerging on to the alluvial plain in north it has a sinuous valley. With confines of this valley the present stream channel wanders back and forth and has incised deep into various Deccan Trap flows. The geometry of such meanders shows that this is an symmetric meandering valley. The valley as such is an antecedent one in which the present stream channel is ur.derfit and ingrown. Natural fluvial processes, accelerated by dynamic rejuvenation of the area and wetter climatic phases during Pleistocene and Holocene seem to have carved this meandering valley and integrated the drainage.  相似文献   

Organization of convection and monsoon forecasts     

Prof. Dr. T. N. Krishnamurti  H. S. Bedi  Wei Han 《Meteorology and Atmospheric Physics》1998,67(1-4):117-134

Summary In this paper we address the issue of monsoon forecasts in relation to the organization of convection. Given a physical initialization procedure, within a data assimilation, it is possible to use the detailed distribution of rainfall from mesoconvective precipitating elements to define the initial state of a global model. If that is carried out using a very high resolution model then the initial state can carry within it an organization of convection within the resolvable scales. Then the impact of physical initialization on the maintenance and prediction of tropical weather such as the monsoon can be determined. Lacking such an initialization, one can expect the convectively driven energetics to be biased, and a slow degradation of the forecasts can follow. Several examples of forecasts at different resolutions are discussed here. The main findings of this study are that improved forecast results are obtained when physical initialization is invoked where the observed rain and the model resolution are comparable, i.e. the footprint of the highest resolutions rainfall estimates obtained from satellite based data sets (principally we use the SSM/I instrument over the oceans). At this resolution, we note that the model is able to carry an organization of convection in the initialization and in the forecasts through the medium-range time scale.We have compared our results of monsoon studies at a resolution T255 with those at resolution T62. The transform grid separation at the resolution T255 is approximately 50 km and at the resolution T62, it is approximately 200 km. We find that the model at the higher resolution (T255) performs better and has more realistic energy conversions for the convectively driven synoptic scale monsoon.An organization of convection, at the synoptic scales, is not seen in the forecasts at lower resolutions, T62, where the rainfall patterns are generally much broader and tend to be more zonal. Such organization appears more realistic at the resolution T255. Variances of the energy conversion, calculated in the two-dimensional spectral space, from physically initialized short range forecasts at the higher resolution are seen to be largest on the scales of the monsoon. Similar calculations for the reanalyzed fields at lower resolutions show the spectral distribution of variances to be biased towards local Hadley scale overturnings.With 12 Figures  相似文献   

Estimates of source parameters of <Emphasis Type="Italic">M</Emphasis>4.9 Kharsali earthquake using waveform modelling     

Ajay Paul  Naresh Kumar 《Journal of Earth System Science》2010,119(5):731-743

This paper presents the computation of time series of the 22 July 2007 M 4.9 Kharsali earthquake. It occurred close to the Main Central Thrust (MCT) where seismic gap exists. The main shock and 17 aftershocks were located by closely spaced eleven seismograph stations in a network that involved VSAT based real-time seismic monitoring. The largest aftershock of M 3.5 and other aftershocks occurred within a small volume of 4 × 4 km horizontal extent and between depths of 10 and 14 km. The values of seismic moment (M _∘) determined using P-wave spectra and Brune’s model based on f ² spectral shape ranges from 10¹⁸ to 10²³ dyne-cm. The initial aftershocks occurred at greater depth compared to the later aftershocks. The time series of ground motion have been computed for recording sites using geometric ray theory and Green’s function approach. The method for computing time series consists in integrating the far-field contributions of Green’s function for a number of distributed point source. The generated waveforms have been compared with the observed ones. It has been inferred that the Kharsali earthquake occurred due to a northerly dipping low angle thrust fault at a depth of 14 km taking strike N279°E, dip 14° and rake 117°. There are two regions on the fault surface which have larger slip amplitudes (asperities) and the rupture which has been considered as circular in nature initiated from the asperity at a greater depth shifting gradually upwards. The two asperities cover only 10% of the total area of the causative fault plane. However, detailed seismic imaging of these two asperities can be corroborated with structural heterogeneities associated with causative fault to understand how seismogenesis is influenced by strong or weak structural barriers in the region.  相似文献