Landscape characterization of Sariska National Park (India) and its surroundings     

JOSHI Pawan Kumar  NARULA Sheena  RAWAT Asha  GHOSH Aniruddha 《地球空间信息科学学报》2011,14(4):303-310

Landscape characterization gives an overall information on the status of Land Use and Land Cover(LULC),changes in its composition and the impact of natural and human influences operating at different spatial and temporal scales.This information can be used to monitor changes in natural forest resources and protected areas,delineate potential conservation areas and can serve in effective management of ecologically fragile landscapes.In the present study,geo-spatial tools were used to characterize the landscape of Sariska National Park and its surroundings.Satellite data was used to prepare LULC maps for 1989 and 2000,change detection analysis and computation of landscape metrics.Climatic data,field records and modeling tools were used to map the po-tential spread of two invasive species,Prosopis juliflora and Adhatoda vasica.The results show that the forest area increased from 1989 to 2000,indicating better management practices.Landscape metrics(PAFRAC,PLADJ and AI)also support this argument.Improvements in the degraded forest can further enhance this effect.The entire reserve however is suitable for the invasion of P.juliflora and A.vasica but is more pronounced in Boswellia serrata and Anogeissus pendula-Acacia catechu(open)forests.A detailed landscape characterization map can help forest managers to make important policy decisions concerning issues such as in-vasive species.  相似文献   

Evaluation of the Diurnal Cycle in the Atmospheric Boundary Layer Over Land as Represented by a Variety of Single-Column Models: The Second GABLS Experiment   总被引：3，自引：3，他引：0  

G. Svensson  A. A. M. Holtslag  V. Kumar  T. Mauritsen  G. J. Steeneveld  W. M. Angevine  E. Bazile  A. Beljaars  E. I. F. de Bruijn  A. Cheng  L. Conangla  J. Cuxart  M. Ek  M. J. Falk  F. Freedman  H. Kitagawa  V. E. Larson  A. Lock  J. Mailhot  V. Masson  S. Park  J. Pleim  S. S?derberg  W. Weng  M. Zampieri 《Boundary-Layer Meteorology》2011,140(2):177-206

We present the main results from the second model intercomparison within the GEWEX (Global Energy and Water cycle EXperiment) Atmospheric Boundary Layer Study (GABLS). The target is to examine the diurnal cycle over land in today??s numerical weather prediction and climate models for operational and research purposes. The set-up of the case is based on observations taken during the Cooperative Atmosphere-Surface Exchange Study-1999 (CASES-99), which was held in Kansas, USA in the early autumn with a strong diurnal cycle with no clouds present. The models are forced with a constant geostrophic wind, prescribed surface temperature and large-scale divergence. Results from 30 different model simulations and one large-eddy simulation (LES) are analyzed and compared with observations. Even though the surface temperature is prescribed, the models give variable near-surface air temperatures. This, in turn, gives rise to differences in low-level stability affecting the turbulence and the turbulent heat fluxes. The increase in modelled upward sensible heat flux during the morning transition is typically too weak and the growth of the convective boundary layer before noon is too slow. This is related to weak modelled near-surface winds during the morning hours. The agreement between the models, the LES and observations is the best during the late afternoon. From this intercomparison study, we find that modelling the diurnal cycle is still a big challenge. For the convective part of the diurnal cycle, some of the first-order schemes perform somewhat better while the turbulent kinetic energy (TKE) schemes tend to be slightly better during nighttime conditions. Finer vertical resolution tends to improve results to some extent, but is certainly not the solution to all the deficiencies identified.  相似文献   

Simulations of Cyclone Sidr in the Bay of Bengal with a high-resolution model: sensitivity to large-scale boundary forcing     

Anil Kumar  James Done  Jimy Dudhia  Dev Niyogi 《Meteorology and Atmospheric Physics》2011,114(3-4):123-137

The predictability of Cyclone Sidr in the Bay of Bengal was explored in terms of track and intensity using the Advanced Research Hurricane Weather Research Forecast (AHW) model. This constitutes the first application of the AHW over an area that lies outside the region of the North Atlantic for which this model was developed and tested. Several experiments were conducted to understand the possible contributing factors that affected Sidr??s intensity and track simulation by varying the initial start time and domain size. Results show that Sidr??s track was strongly controlled by the synoptic flow at the 500-hPa level, seen especially due to the strong mid-latitude westerly over north-central India. A 96-h forecast produced westerly winds over north-central India at the 500-hPa level that were notably weaker; this likely caused the modeled cyclone track to drift from the observed actual track. Reducing the model domain size reduced model error in the synoptic-scale winds at 500?hPa and produced an improved cyclone track. Specifically, the cyclone track appeared to be sensitive to the upstream synoptic flow, and was, therefore, sensitive to the location of the western boundary of the domain. However, cyclone intensity remained largely unaffected by this synoptic wind error at the 500-hPa level. Comparison of the high resolution, moving nested domain with a single coarser resolution domain showed little difference in tracks, but resulted in significantly different intensities. Experiments on the domain size with regard to the total precipitation simulated by the model showed that precipitation patterns and 10-m surface winds were also different. This was mainly due to the mid-latitude westerly flow across the west side of the model domain. The analysis also suggested that the total precipitation pattern and track was unchanged when the domain was extended toward the east, north, and south. Furthermore, this highlights our conclusion that Sidr was influenced from the west side of the domain. The displacement error was significantly reduced after the domain size from the western model boundary was decreased. Study results demonstrate the capability and need of a high-resolution mesoscale modeling framework for simulating the complex interactions that contribute to the formation of tropical cyclones over the Bay of Bengal region.  相似文献   

Neural network estimation of duration of strong ground motion using Japanese earthquake records     

C.R. Arjun  Ashok Kumar 《Soil Dynamics and Earthquake Engineering》2011

The duration of strong motion has a significant influence on the severity of ground shaking. In this work, a combination of average values of four geophysical properties of site (Standard Penetration Test (SPT) blow count, primary wave velocity, shear wave velocity, and density of soil) including hypocentral distance of less than 50 km and magnitudes more than 5.0 from Japanese ground motion records were used for development of neural network model, to estimate duration of strong ground motion. Since majority of strong motion databases provide only average shear wave velocity for site characterization, an attempt has also been made to train the neural network with magnitude, hypocentral distance and average shear wave velocity as three input variables. Results obtained from this study show that the duration of strong motion is mostly dependent on average shear wave velocity rather than other geophysical properties of site.  相似文献   

Peak ground motion predictions in India: an appraisal for rock sites   总被引：1，自引：0，他引：1  

Sankar Kumar Nath  Kiran Kumar Singh Thingbaijam 《Journal of Seismology》2011,15(2):295-315

Proper selection and ranking of Ground Motion Prediction Equations (GMPEs) is critical for successful logic-tree implementation in probabilistic seismic hazard analysis. The present study explores this issue in predicting peak ground accelerations at the rock sites in India. Macroseismic intensity data complemented with limited strong ground-motion recordings are used for the purpose. The findings corroborate the possible conformity between the GMPEs developed for tectonically active shallow crust across the globe. On the other hand, the relevant GMPEs in the intraplate regions cluster into two different groups with the equations of lower ranks catering to higher ground motions. The earthquakes in the subduction zones have significant regional implications. However, affinity in the ground-motion attenuations between the major interface events (M _W > 7.4) in Andaman-Nicobar, Japan and Cascadia, respectively, is noted. This can be also observed for the intraslab events in the Hindukush and Taiwan respectively. Overall, we do not observe any significant advantage with the equations developed using the regional data. These findings are expected to be useful in probabilistic seismic hazard analysis across the study region.  相似文献   

An Environmental Threshold of Soil Test P and Degree of P Saturation of Brazilian Oxisols     

Amlan Kumar Ghosh  Joyce Barbosa  Ivo Ribeiro da Silva 《洁净——土壤、空气、水》2011,39(5):421-427

To develop P management guidelines for poultry litter application in Oxisols of Brazil, the relationship between water soluble P (WSP), soil test P (STP), and degree of P saturation (DPS) needs to be established. The study examined this relationship in Oxisols of Brazil receiving poultry litter. Soils were analyzed for Mehlich‐1 P (M1‐P), WSP, P fractions, P sorption index (PSI), and P saturation based on Mehlich‐1 extractable P, Al, Fe (DPS_M1), and PSI (DPS_PSI). Surface water bodies in the catchment area were examined for inorganic and total P. All the surface water bodies in the catchment area of the sampled plots were highly enriched in inorganic and organic P. Enrichment of soil P fractions following poultry litter application followed the order HCl‐bound > NaOH‐bound > NaHCO₃‐bound fraction. M1‐P was correlated to labile (NaHCO₃‐P_i), and stable P pools (NaOH‐P and HCl‐P) and reflected the cumulative P accumulation in these soils. P saturation indices increased with cumulative P addition and increasing M1‐P. WSP increased with increasing DPS and a change point was noticed at 23% DPS_PSI (equivalent to DPS_M1 of 16.5%) corresponding to M1‐P of 44.5 mg P kg^?1, which could be regarded as threshold for P loss in these soils.  相似文献   

Shallow Crustal Configuration of the Narmada–Son Lineament Transition Zone Near the Sahdol–Katni Area of Central India Using Simultaneous Gravity and Magnetic Observations     

G. K. Ghosh  C. L. Singh 《Pure and Applied Geophysics》2011,168(5):845-860

Gravity and magnetic studies have been carried out to map the different depth formations of alluvium, Gondwana, Vindhyan, Mahakoshal, and the crystalline basement in the Narmada–Son lineament (NSL) near the Sahdol–Katni area, India. Higher elevations in the northern part of the study area have lower gravity; the southern part of the study area, however, is moderately elevated and also has a higher gravity anomaly, which justifies the isostatic adjustment. This indicates the presence of high-density material, for example Mahakoshal rocks, in the upper crust which causes the higher anomaly value. The Mahakoshal rocks are widely exposed at Mau, Chanaura, Nadawar, Khamaria, Umria, and near the Tala–Barhi area and also extend from Sidhi to Agoni village further east of the area. The Mahakoshal rocks are thinner between the river Son and Tikwa village which causes a different gravity anomaly pattern changing from the NNE–SSW direction to the N–S direction. However, the trend of magnetic anomaly follows the same pattern toward the NNE–SSW direction, mainly because of the effect of the crystalline basement. Two magnetic highs are prominent in the Tikwa and Amarpur regions, 800 and 400 nTesla, respectively, because of the presence of the crystalline basement. The depth of the crystalline basement obtained by 2½ D gravity–magnetic modelling varies from 2.7 to 2.9 km. From spectral analysis the average depth of the crystalline basement varies from 2.83 to 3.05 km. The different crustal depth sections obtained by 2½ D simultaneous gravity–magnetic modelling correlate well with other constrained data.  相似文献   

Holocene climate variability from lake sediment core in Larsemann Hills,Antarctica     

Pawan Govil  Abhijit Mazumder  Anoop Tiwari  Sandeep Kumar 《Journal of the Geological Society of India》2011,78(1):30-35

A sediment core (L2) from Larsemann Hills, Antarctica was analyzed for Biogenic Silica (BSi), Sand (%) and Total Organic Carbon (TOC). The 78 cm core length represents the time span of ∼8.3 cal ka BP. The values of BSi from the core show prominent high productivity from ∼8.3 to ∼6 cal ka BP in comparison to less productivity in mid-late Holocene (∼6 cal ka BP to recent). Moreover, high sand (%) infers the glacio-fluvial deposition from ∼8.3 to ∼5 cal ka BP TOC shows little variation through out the core, except in the upper ∼10 cm (∼4 cal ka BP) part wherein it is comparatively high. The increased TOC in the upper part of the core possibly indicates presence of algal mat due to exposure of the lake to the ice free (glacier free) conditions.  相似文献   

Groundwater resources management through flow modeling in lower part of Bhagirathi — Jalangi interfluve,Nadia, West Bengal     

Sudhir Kumar  Subrata Halder  D. C. Singhal 《Journal of the Geological Society of India》2011,78(6):587-598

Groundwater utilization in Nadia district, West Bengal has been subjected to rapid exploitation in the wake of increasing urbanization and production of agricultural commodities. It is, therefore, necessary to evaluate the existing trend and availability of groundwater in time and space and its movement for proper planning in future. In the present study, an attempt has been made develop a groundwater management model using Visual MODFLOW software. The groundwater flow model for the study area was formulated by using input hydrogeological data and appropriate boundary conditions. The groundwater flow pattern of the study area indicates the occurrence of base flow which feed both the Rivers Bhagirathi and Jalangi throughout the year. The computed hydraulic heads were calibrated by comparing with observed groundwater level data for years 2004 to 2006 and were verified with the data of 2007. The outcome of modeling shows that this model can be used for prediction purpose in the future by updating input boundary conditions and hydrologic stresses during the preceding year. The model optimized unit draft for deep tube well as 556.5 m³/day and the same for shallow tube well as 41 m³/day keeping the existing tube well structures in running condition and maintaining the present and recent past trends of groundwater level. The model can be further improved if more spatial and temporal input parameters are available and can be incorporated into the model for more realistic characterization of groundwater flow.  相似文献   

Chemical weathering of the Indo-Gangetic alluvium with special reference to release of fluoride in the groundwater,Unnao district,Uttar Pradesh   总被引：1，自引：0，他引：1  

S. Kumar  A. Saxena 《Journal of the Geological Society of India》2011,77(5):459-477

In the central part of Indo-Gangetic alluvium in the Unnao district, Uttar Pradesh there are many pockets where groundwater shows high fluoride content. Drinking of fluorinated ground water has effected a large population and in many villages more than 80% of the population is suffering from fluorosis. The source of this fluoride appears to be the alluvial sediments deposited in the geological past as no hard rock terrain is present in the nearby areas. The area is dominantly made up of mud with pockets of sand. The sand fraction is made up of quartz, plagioclase, microcline, muscovite and biotite along with some accessory minerals like garnet, epidote, chlorite, tourmaline, hornblende, kyanite and a few opaque minerals. Moreover, the fluoride content in the groundwater varies both spatially and with depth indicating a sporadic occurrence. The surface water is devoid of high content of fluoride but is reported in hand pumps and in the dug wells. This paper deals with the geochemical study of the sediments up to a depth of 45m as most of the hand pumps are up to this depth to understand the source of fluoride. ¹⁴C dates of calcretes have suggested that the 45 m thick succession must have been formed in about 45000 years.  相似文献