Soil and water conservation measures improve soil carbon sequestration and soil quality under cashews   总被引：2，自引：1，他引：1  

Gopal Ramdas Mahajan  Bappa Das  Sandrasekaran Manivannan  Begur Lakshminarasimha Manjunath  Ram Ratan Verma  Sujeet Desai  Rahul Mukund Kulkarni  Ashish Marotrao Latare  Reshma Sale  Dayesh Murgaonkar  Kiran Puna Patel  Shaiesh Morajkar  Ashwini Desai  Natasha Barnes  Heena Mulla 《国际泥沙研究》2021,36(2):190-206

Land degradation is becoming a serious problem in the west coast region of India where one of the world's eight biodiversity hotspots,the‘Western Ghats’,is present.Poor land management practices and high rainfall have led to increasing problems associated with land degradation.A long-term(13-year)experiment was done to evaluate the impact of soil and water conservation measures on soil carbon sequestration and soil quality at three different depths under cashew nut cultivation on a 19%slope.Five soil and water conservation measures-continuous contour trenches,staggered contour trenches,halfmoon terraces,semi-elliptical trenches,and graded trenches all with vegetative barriers of Stylosanthes scabra and Vetiveria zizanoides and control were evaluated for their influence on soil properties,carbon sequestration,and soil quality under cashews.The soil and water conservation measures improved significantly the soil organic carbon,soil organic carbon stock,carbon sequestration rate and microbial activity compared to the control condition(without any measures).Among the measures tested,continuous contour trenches with vegetative barriers outperformed the others with respect to soil organic carbon stock,sequestration rate,and microbial activity.The lower metabolic quotient with the measures compared to the control indicated alleviation of environmental stress on microbes.Using principal component analysis and a correlation matrix,a minimum dataset was identified as the soil available nitrogen,bulk density,basal soil respiration,soil pH,acid phosphatase activity,and soil available boron and these were the most important soil properties controlling the soil quality.Four soil quality indices using two summation methods(additive and weighted)and two scoring methods(linear and non-linear)were developed using the minimum dataset.A linear weighted soil quality index was able to statistically differentiate the effect of soil and water conservation measures from that of the control.The highest value of the soil quality index of 0.98 was achieved with continuous contour trenches with a vegetative barrier.The results of the study indicate that soil and water conservation measures for cashews are a potential strategy to improve the soil carbon sequestration and soil quality along with improving crop productivity and reducing the erosion losses.  相似文献   

Soft computing and GIS for landslide susceptibility assessment in Tawaghat area, Kumaon Himalaya, India   总被引：6，自引：4，他引：2  

D. Ramakrishnan  T. N. Singh  A. K. Verma  Akshay Gulati  K. C. Tiwari 《Natural Hazards》2013,65(1):315-330

This paper mainly presents a case study of landslide vulnerability zonation along Tawaghat-Mangti route corridor in Kumaon Himalaya, India. An attempt is made to predict landslide susceptibility using back-propagation neural network (BPNN) and propose a suitable model for that zone, which can be successfully implemented for the prevention of slides. Various landslide affecting parameters such as lithology, slope, aspect, structure, geotechnical properties, land use, landslide inventory, and distance from recorded epicenter are used to model the landslide susceptibility. The database on the above parameters derived from satellite imageries, topographic maps, and field work are integrated in the GIS to generate an information layer. Database of this information layer is used to train, test, and validate the BPNN model. A three-layered BPNN with an input layer, two hidden layers, and one output layer is found to be optimal. The developed model demonstrates a promising result, and the prediction accuracy has been found to be 80?% in the field.  相似文献   

Probabilistic seismic hazard analysis for Kakrapar atomic power station, Gujarat, India   总被引：1，自引：1，他引：0  

William K. Mohanty  Akhilesh K. Verma 《Natural Hazards》2013,69(1):919-952

Seismic ground motion caused by earthquakes mainly affects the constructions and structures around its area of influence. In this context, the probabilistic seismic hazard analysis (PSHA) is a scientific step towards the safety analysis of any major construction such as nuclear power plant. Thus, the present study focused to estimate seismic hazard level at different probabilities for Kakrapar nuclear power plant located in the Western India. The hazard curves for the study area are developed following the procedure of PSHA suggested by Cornell–McGuire. Three source zones, Narmada-Tapti zone (NTZ), Rann of Kuchchh (ROK), and west passive margin (WPM), are classified on the basis of seismicity and tectonic setting of the study area. The estimated maximum magnitude (m _max) for NTZ, ROK, and WPM are 6.9 ± 0.57, 6.5 ± 0.64, and 6.1 ± 0.64, respectively. Logic tree approach has been used for the development of hazard curves to account the epistemic uncertainties associated with the analysis. For maximum credible earthquake [MCE, i.e., the probability of exceedance of 2 % in 50 years (return period of ~2,500 years)], the peak spectral acceleration (i.e., PSA at 0.2 s) expected around 5 km of the Kakrapar nuclear power plant (site) is 0.23 g from all source zones; however, at exact site location, it is 0.18 g. The PSA values due to NTZ, ROK, and WPM based on MCE are 0.22, 0.065, and 0.052 g, respectively. In case of design-based earthquake (DBE, i.e., 50 % probability in 50 years (return period of ~110 years)), the calculated maximum spectral acceleration (SA) from all source zones is about 0.045 g. The PSA distribution for the DBE from the NTZ has reached a maximum value of 0.042 g; however, PSA for ROK and WPM is considerably low with a maximum value of 0.022 and 0.021 g, respectively. Considering the MCE and DBE, the estimated PSA at 0.2 s has a highest value of ~0.23 g from all source zones. Spectral accelerations (SAs) correspond to different periods are presented, and SA plots for NTZ zone can be considered as response spectra for the KAPS site. Deaggregation of PSHA in the present study is also discussed. PGA values reported in seismic zonation map and global seismic hazard analysis program around the present study area range from 0.05 to 0.2 g which is slightly lower than the peak acceleration obtained in this study. The results of this study would facilitate in the performance of the site-specific seismic probabilistic safety analysis.  相似文献   

Aerosol particle behavior during Dust Storm and Diwali over an urban location in north western India     

Prakash  Divya  Payra  Swagata  Verma  Sunita  Soni  Manish 《Natural Hazards》2013,69(3):1767-1779

In this study, the aerosol behavior during two contradictory events, i.e., dust storm (DS) and Diwali (DW) has been studied over Jaipur. The aerosol particle number concentration shows distinct features between DS and DW events. The total ANC was found minimum during DS while maximum during DW. The 24 h mean of total ANC was 9.15 × 10⁴ (±7.71 × 10⁴) and 5.38 × 10⁵ (±3.73 × 10⁵ particles/l) during DS and DW, respectively. The total ANC increases from 7.78 × 10⁴ to 5.32 × 10⁵ and 3.52 × 10⁵ to 1.70 × 10⁶ particles/l in 24 h during DS and DW, respectively. In DS, the ANC in coarse mode (2 < particle diameter < 20 μm) is significantly high while in DW, the ANC in fine mode (0.3 < particle diameter < 2 μm) exhibits higher concentration. During dust episode, a significant change in ANC (3.0 × 10³ to 1.12 × 10⁵ particles/l) was observed for the particle of size range in 2.0–20 μm with a slight increase in particles number concentration (7.48 × 10⁴ to 4.20 × 10⁵ particles/l) in 0.3–2.0 μm range is also observed. During DS, the fine and coarse mode particles increased 4.61 and 36.44 times while during DW, it increased 3.83 and 0.95 times, respectively. The relatively high particle levels during DW are attributed for two reasons: local emissions due to burning of fire crackers and meteorological conditions, i.e., low wind speeds and low mixing-layer heights lead to relatively high particle concentrations.

  相似文献   

Fluid inclusion study of the Higher Himalayan quartzitic pelites, Garhwal Himalaya, India: Implications for recrystallization history of metasediments     

Himanshu K. Sachan  Anubhooti Saxena  Preeti Verma  Santosh K. Rai  Aditya Kharya 《Journal of the Geological Society of India》2013,82(5):509-518

Quartzitic pelites forms a part of Higher Himalayan Crystalline of higher geotectonic zone in Garhwal Himalaya. Quartzitic pelites (locally known as Pandukeshwar Quartzite) in Garhwal Himalaya is sandwiched between high grade metamorphic rocks of Central Crystallines and Badrinath Formation. Fluid inclusion studies are carried out on the detrital, and recrystallized quartz grains of quartzitic pelites to know about the fluid phases present during recrystallization processes at the time of maximum depth of burial. The quartzitic pelite (Pandukeshwar Quartzite) essentially consists of recrystallised quartz with accessory minerals like mica and feldspar. Fluid microthermometry study reveals the presence of three types of fluids: (i) high-salinity brine, (ii) CO₂-H₂O and (iii) H₂O-NaCl. These fluids were trapped during the development of grain and recrystallization processes. The high saline brine inclusions and CO₂-H₂O fluid with the density of 0.90 to 0.97 gm/cm³ are remnants of provenance area. CO₂ density in detrital quartz grains characterise the protolith of the sandstone as granite or metamorphic rock. The H₂O-NaCl fluids involved in the recrystallization processes at temperature-pressure of 430-350°C; 4.8 to 0.5 Kbars as constrained by fluid isochores of CO₂-H₂O and H₂O-NaCl inclusions and bulging and subgrain development during recrystallization processes. The re-equilibration of the primary fluid due to elevated internal and confining pressure is evident from features like ‘C’ shaped cavities, stretching of the inclusions, their migration and decrepitation clusters. The observed inclusion morphology revealed that the rocks were exhumed along an isothermal decompression path.  相似文献   

Vegetation Dynamics from Denoised NDVI Using Empirical Mode Decomposition     

Rahul Verma  Subashisa Dutta 《Journal of the Indian Society of Remote Sensing》2013,41(3):555-566

A novel approach to study vegetation dynamics is introduced, using the Empirical Mode Decomposition (EMD) to analyze NDVI time series. The NDVI time series which is nonlinear and nonstationary can be decomposed by EMD into components called intrinsic mode functions (IMFs), based on inherent temporal scales. The highest frequency component which has been found to represent noise is subtracted from the original NDVI series; thus smoothing the noisy signal. The different key features describing vegetation phenology have been extracted by analyzing the noise free signal. The lowest frequency component (last IMF) is the trend in the NDVI series. The trend in the series has been identified finding the Sen’s slope of last IMF, and the non-parametric seasonal Mann–Kendall test has been used to confirm the significance of the observed trend. The method has been applied on per–pixel basis to the SPOT Vegetation NDVI product covering Northeast India and surrounding regions for the time span of 1998–2009. Results show that the method has performed well in identifying the pixel clusters with significant trends. Hotspot regions with severe vegetation degeneration have been identified, and the relationship of the observed trends with the expected causative variables such as land use and land cover, topographic relief, and anthropogenic causes has been explored. The spatial locations of these critical regions closely matches with the findings of the previous studies carried out locally in the region, mainly indicating the shifting cultivation practice to be the main cause for land cover change.  相似文献   

Internal sedimentary architecture and coastal dynamics as revealed by ground penetrating radar, Kachchh coast, western India     

Shashi B. Shukla  Vikas M. Chowksey  Siddharth P. Prizomwala  Vishal M. Ukey  Nilesh P. Bhatt  Deepak M. Maurya 《Acta Geophysica》2013,61(5):1196-1210

The coastline constitutes a very sensitive geomorphic domain which is constantly subjected to dynamic coastal processes and stores vital information regarding past sea level fluctuations. A ground-penetrating radar (GPR) survey was carried out along the northern coast of the Gulf of Kachchh which is one of the largest macrotidal inlets of the Arabian Sea, Western India. Our studies have delineated several radar surfaces and radar facies which reflect the internal architecture and sediment body geometry, which can be related to the processes acting along this coastline. Various radar facies, namely, beach ridge (Br), washover (Wo), coastal dune (Cd), swale (Sw), berm plain (Bp), and sandsheet facies (Ss) have been identified. The GPR studies successfully documented the subsurface presence of ancient beach ridge system towards the sea, and the coastal dunes towards the land side. The results are suggestive of signatures of changes in sea level and the coastline being prone to high energy events in the recent past. The GPR has been found to be an important non-invasive geophysical tool in the study of past coastal dynamics.  相似文献   

Science and technology based earthquake risk reduction strategies: The Indian scenario     

Brijesh K. Bansal  Mithila Verma 《Acta Geophysica》2013,61(4):808-821

Science and Technology (S & T) interventions are considered to be very important in any effort related to earthquake risk reduction. Their three main components are: earthquake forecast, assessment of earthquake hazard, and education and awareness. In India, although the efforts towards earthquake forecast were initiated about two decades ago, systematic studies started recently with the launch of a National Program on Earthquake Precursors. The quantification of seismic hazard, which is imperative in the present scenario, started in India with the establishment of first seismic observatory in 1898 and since then a substantial progress has been made in this direction. A dedicated education and awareness program was initiated about 10 years ago to provide earthquake education and create awareness amongst the students and society at large. The paper highlights significant S & T efforts made in India towards reduction of risk due to future large earthquakes.  相似文献   

Thermal decomposition pattern and particle size estimation of iron minerals associated with the Cretaceous‐Tertiary boundary at Gubbio     

H. C. Verma  C. Upadhyay  A. Tripathi  R. P. Tripathi  N. Bhandari 《Meteoritics & planetary science》2002,37(7):901-909

Abstract— Mössbauer studies of the samples from the Cretaceous‐Tertiary (K‐T) boundary layer at Gubbio, Italy show that iron appears mainly in two phases, magnetically ordered hematite and a paramagnetic silicate phase. The average particle size of hematite is estimated to be in the range of 16 to 27 nm from transmission electron micrographs and lack of a Morin transition. The hyperfine magnetic field at the iron nucleus is observed to be somewhat less than that of bulk hematite, which may be explained by collective magnetic excitation. Stepwise heating up to 1000°C shows a decomposition pattern of the paramagnetic phase, which suggests it to be a tri‐octahedral layer silicate. The iron‐bearing phases found in the bulk sedimentary K‐T boundary material are different from those found in the spherules separated from this material indicating that the redox conditions changed rapidly after the impact, becoming more oxidizing during the period these bulk phases were formed.  相似文献   

Solar x-ray spectrometer (SOXS) mission – Low energy payload – First results     

Rajmal Jain  Vishal Joshi  S. L. Kayasth  Hemant Dave  M. R. Deshpande 《Journal of Astrophysics and Astronomy》2006,27(2-3):175-192

We present the first results from the ‘Low Energy Detector’ pay-load of ‘Solar X-ray Spectrometer (SOXS)’ mission, which was launched onboard GSAT-2 Indian spacecraft on 08 May 2003 by GSLV-D2 rocket to study the solar flares. The SOXS Low Energy Detector (SLD) payload was designed, developed and fabricated by Physical Research Laboratory (PRL) in collaboration with Space Application Centre (SAC), Ahmedabad and ISRO Satellite Centre (ISAC), Bangalore of the Indian Space Research Organization (ISRO). The SLD payload employs the state-of-the-art solid state detectors viz., Si PIN and Cadmium-Zinc-Telluride (CZT) devices that operate at near room temperature (-20°C). The dynamic energy range of Si PIN and CZT detectors are 4–25 keV and 4–56 keV respectively. The Si PIN provides sub-keV energy resolution while CZT reveals ∼1.7keV energy resolution throughout the dynamic range. The high sensitivity and sub-keV energy resolution of Si PIN detector allows the measuring of the intensity, peak energy and equivalent width of the Fe-line complex at approximately 6.7 keV as a function of time in all 8 M-class flares studied in this investigation. The peak energy (E _p) of Fe-line feature varies between 6.4 and 6.8 keV with increase in temperature from 9 to 34 MK. We found that the equivalent width (ω) of Fe-line feature increases exponentially with temperature up to 20 MK but later it increases very slowly up to 28 MK and then it remains uniform around 1.55 keV up to 34 MK. We compare our measurements ofw with calculations made earlier by various investigators and propose that these measurements may improve theoretical models. We interpret the variation of both E_pand ω with temperature as the changes in the ionization and recombination conditions in the plasma during the flare interval and as a consequence the contribution from different ionic emission lines also varies.  相似文献