Effect of geojute technique on density,diversity and carbon stock of plant species in landslide site of North West Himalaya     

Harsh Mehta  Raj Kumar  M. Ayub Dar  G. P. Juyal  Sridhar Patra  Sneha Dobhal  A. C. Rathore  Rajesh Kaushal  P. K. Mishra 《山地科学学报》2018,15(9):1961-1971

Mountainous regions of the globe experience landslides due to heavy rainfall and unplanned construction on slopes. Geojute is adopted globally as a landslide rehabilitation measure, but its impact on natural vegetation development is poorly understood. The present study was conducted to examine the impact of geojute application on vegetation restoration, ecology and carbon stock in a recently occurred landslide, during 2012. The results revealed that the geojute application improved the richness, diversity, density and basal area of plant species at the landslide site. Likewise, biomass production, carbon stock and carbon sequestration of plant species was observed significantly higher in geojute treatments compared to control (without geojute treatment). Moreover, significant improvement in soil moisture was recorded beneath the geojute treatments. Further, results showed that the geojute is highly effective in controlling soil erosion at the landslide site. The findings of this study revealed ecological and environmental benefits of geojute application in term of improvement in vegetation recovery processes, species diversity and carbon sequestration at the landslide site. The scientific outcome of this study can be helpful for planning the rehabilitation measures in landslide affected regions of the globe.  相似文献   

A Petrogenetic Model of Basalts from the Northern Central Indian Ridge: 3-11°S     

Dwijesh RAY  Sridhar D.IYER  Ranadip BANERJEE  Saumitra MISRA  M. WIDDOWSON 《《地质学报》英文版》2007,81(1)

Mid-Ocean Ridge Basalts (MORB) from the Northern Central Indian Ridge (NCIR) were recovered between latitudes 3° and 11°S and are olivine tholeiite with higher abundances of K and Rb.They are of typical transitional MORB (T-MORB) variety and appear to have been generated from an enriched-mantle peridotite source. The primitive NCIR MORBs having Mg# ＞ 0.68 are the product of partial melting at an estimated pressure of ～ 1 GPa. It is inferred that the magma was subsequently modified at a pressure ＞ 1 GPa by crystal fractionation and spinel was the first mineral to crystallize followed by separation of relatively Fe-rich olivine with subsequent decrease in pressure. During progressive fractionation at lower pressure (between 1-0.5 GPa), the bulk composition of the magma became systematically depleted in MgO, and enriched in ∑FeO, TiO2, P2O5 and Na2O. There was,however, limited gradual depletion in Al2O3 and CaO and concomitant enrichment in K2O. With the progressive fractionation these basalts became gradually enriched in V, Co, Y, Zr and to some extent in Sr, and depleted in Ni and Cr. In addition, the ∑REE of the magma also increased with fractionation,without any change in (La/Yb)n value.  相似文献   

Distribution and Origin of Seamounts in the Central Indian Ocean Basin     

Pranab Das  Sridhar D. Iyer  V. N. Kodagali  K. S. Krishna 《Marine Geodesy》2013,36(3):259-269

Approximately 200 seamounts of different dimensions have been identified, from multibeam bathymetry maps of the Central Indian Ocean Basin (CIOB) (9°S to 16°S and 72°E to 80°E), of which 61% form eight chains that trend N-S. The seamounts are clustered above and below 12°S latitude. Area II (9°–12°S) shows a concentration of smaller seamounts (≤400 m height), and area I (12°–15°S) has a mixed population (including both less and more than 400 m height). Inspite of the differences in their height, the seamounts of these eight chains are morphologically (slope angle, flatness, basal width) corelatable. Furthermore, we suggest that height-width ratio could be useful in identifying the style of seamount eruption. The seamount chains in the CIOB probably originated from propagative fractures and were produced between 61 and 52 Ma (chrons A26 to A23) as a result of the interaction between the conjugate crusts of the Central Indian and Southeast Indian Ridges during the Indo-Eurasian collision event.  相似文献   

Explaining the hydroclimatic variability and change in the Salmon River basin     

Venkataramana Sridhar  Xin Jin  W. T. A. Jaksa 《Climate Dynamics》2013,40(7-8):1921-1937

Climate change in the Pacific Northwest and in particular, the Salmon River Basin (SRB), is expected to bring about 3–5 °C rise in temperatures and an 8 % increase in precipitation. In order to assess the impacts due to these changes at the basin scale, this study employed an improved version of Variable Infiltration Capacity (VIC) model, which includes a parallel version of VIC combined with a comprehensive parameter estimation technique, Shuffled Complex Evolution (SCE) to estimate the streamflow and other water balance components. Our calibration (1955–1975) and validation (1976–1999) of the model at the outlet of the basin, White Bird, resulted in an r² value of 0.94 which was considered satisfactory. Subsequent center of timing analysis showed that a gradual advancement of snowmelt induced-peak flow advancing by about 10 days in the future. Historically, the flows have shown a general decline in the basin, and in the future while the magnitudes might not be greatly affected, decreasing runoff of about 3 % over the next 90 years could be expected and timing of peak flow would shift by approximately 10 days. Also, a significant reduction of snow water equivalent up to 25 %, increased evapotranspiration up to 14 %, and decreased soil moisture storages of about 2 % is predicted by the model. A steady decline in SWE/P from the majority of climate model projections for the basin was also evident. Thus, the earlier snowmelt, decreasing soil moisture and increased evapotranspiration collectively implied the potential to trigger drought in the basin and could affect the quality of aquatic habitats and their spawning and a detailed investigation on these impacts is warranted.  相似文献   

Petrological Characteristics and Genesis of the Central Indian Ocean Basin Basalts     

Pranab DAS  Sridhar D. IYER  Sugata HAZRA 《《地质学报》英文版》2012,86(5):1154-1170

The Central Indian Ocean Basin (CIOB) basalts are plagioclase-rich, while olivine and pyroxene are very few. The analyses of 41 samples reveal high FeOT (~10–18 wt%) and TiO2 (~1.4–2.7 wt%) indicating a ferrobasaltic composition. The basalts have high incompatible elements (Zr 63–228 ppm; Nb ~1–5 ppm; Ba ~15–78 ppm; La ~3–16 ppm), a similar U/Pb (0.02–0.4) ratio as the normal mid-oceanic basalt (0.16±0.07) but the Ba/Nb (12.5–53) ratio is much larger than that of the normal mid-oceanic ridge basalt (~5.7) and Primitive Mantle (9.56). Interestingly almost all of the basalts have a significant negative Eu anomaly (Eu/Eu*=0.78–1.00) that may have been a result of the removal of feldspar and pyroxene during crystal fractionation. These compositional variations suggest that the basalts were derived through fractional crystallization together with low partial melting of a shallow seated magma.  相似文献   

Geochemical characterization of oceanic basalts using Artificial Neural Network     

Pranab Das  Sridhar D Iyer 《Geochemical transactions》2009,10(1):13-11

The geochemical discriminate diagrams help to distinguish the volcanics recovered from different tectonic settings but these diagrams tend to group the ocean floor basalts (OFB) under one class i.e., as mid-oceanic ridge basalts (MORB). Hence, a method is specifically needed to identify the OFB as normal (N-MORB), enriched (E-MORB) and ocean island basalts (OIB).  相似文献   

Gold - sulphide mineralization in ultramafic-mafic-granite complex of Jashpur,Bastar craton,central India: Evidences from geophysical studies     

Dewashish Kumar  D. V. Subba Rao  Setbandhu Mondal  K. Sridhar  K. Rajesh  M. Satyanarayanan 《Journal of the Geological Society of India》2017,90(2):147-153

Time Domain Induced Polarization (TDIP) investigation in conjunction with high resolution electrical resistivity tomography surveys carried out at seven sites along a 5.2 km line in Jashpur and Raigarh districts of Chhattisgarh State yielded promising results leading to the demarcation of mineralized zones. These sites are confined to ultramafic-mafic-felsic intrusive complexes representing gabbro-pyroxenite-granite sequences characterized by gold - sulphide mineralization. Two dimensional (2D) geophysical datasets yielded interesting results and a good correlation is found between 2D inverted resistivity tomography and time domain induced polarization (IP) models. Both high resistivity-high chargeability as well as low resistivity-high chargeability conditions have been inferred from these datasets. This observation is consistent with conductive metallic mineralization. Interpretation of the Pharsabahar-Pandripani site, reveals a chargeability magnitude of 9-14 mV/V, which represents a strong metallic conductor associated with gold-sulphide ore body. The results at Samarkachar site are equally significant, showing a good correlation with the presence of a low resistivity and high chargeability zone. Hence, the present study suggests a new scope for application of resistivity and IP tomography surveys for mineral prospecting in favourable geological settings.  相似文献   

Discharge estimation from planform characters of the Shedhi River, Gujarat alluvial plain: Present and past   总被引：1，自引：0，他引：1  

Alpa Sridhar 《Journal of Earth System Science》2007,116(4):341-346

In the absence of long-term hydrologic and streamflow records an understanding of river morphology (present and past) can help delineate changes in magnitudes of water and sediment discharges. The relict drainage system of Gujarat alluvial plain provides an opportunity to reconstruct the palaeochannel morphology-related discharge estimations. In this paper, based on the geomorphological evidence and channel geometry, an attempt has been made to reconstruct the palaeohydrological condition in the Shedhi River during the Holocene. A comparison of the present day channel of the Shedhi River with that of its palaeo counterpart reveals that the former was carrying much higher bankfull discharge (∼5500m³ s⁻¹) as compared to the present (∼200m³ s⁻¹). This is attributed to a larger drainage area and enhanced precipitation in the Shedhi River basin.  相似文献   

Sparse Data Division Using Data Segmentation and Kohonen Network for Neural Network and Geostatistical Ore Grade Modeling in Nome Offshore Placer Deposit   总被引：2，自引：0，他引：2  

Samanta  Biswajit  Bandopadhyay  Sukumar  Ganguli  Rajive  Dutta  Sridhar 《Natural Resources Research》2004,13(3):189-200

In this paper, sparse data problem in neural network and geostatistical modeling for ore-grade estimation was addressed in the Nome offshore placer gold deposit. The problem of sparse data arises because of the random data division into training, validation, and test subsets during ore-grade modeling. In this regard, the possibility of generating statistically dissimilar data subsets by random data division was also explored through a simulation exercise. A combined approach of data segmentation and application of a Kohonen network then was used to solve the data division problem. Two neural networks and five kriging models were applied for grade modeling. The neural network was trained using an early stopping method. Performance evaluation of the models was carried out on the test data set. The study results indicated that all the models that were investigated in this study performed almost equally. It was also revealed that by using the secondary variable watertable depth the neural network and the kriging models slightly improved their prediction precision. Further, the overall R ² of the models was poor as a result of high nugget (noisy) component in ore-grade variation.  相似文献   

Antimicrobial Activity of Seaweeds     

K. R. Sridhar  N. Vidyavathi 《洁净——土壤、空气、水》1991,19(5):455-496

The literature on the bioactivity of seaweeds against bacteria, fungi, viruses and protozoa has been consulted to provide a consolidated report. Information on seaweed metabolites which are antimicrobial in nature is also briefly reported. An appendix provides the details on kind of seaweed, location, period of collection, active compound against microorganisms and reference source. It is possible to derive the details in connection with antimicrobial activity of seaweeds pertaining to regions, seasons, chemical nature and their activity against microorganisms.  相似文献