Development of hyperspectral model for rapid monitoring of soil organic carbon under precision farming in the Indo-Gangetic Plains of Punjab,India     

Rajeev Srivastava  Dipak Sarkar  Siddhartha S. Mukhopadhayay  Anil Sood  Manjeet Singh  Ravindra A. Nasre  Sanjay A. Dhale 《Journal of the Indian Society of Remote Sensing》2015,43(4):751-759

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Challenges and adaptations of farming to climate change in the North China Plain     

Hai-Lin Zhang  Xin Zhao  Xiao-Gang Yin  Sheng-Li Liu  Jian-Fu Xue  Meng Wang  Chao Pu  Rattan Lal  Fu Chen 《Climatic change》2015,129(1-2):213-224

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Trace gases at a semi-arid urban site in western India: variability and inter-correlations     

Chinmay Mallik  Shyam Lal  S. Venkataramani 《Journal of Atmospheric Chemistry》2015,72(2):143-164

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Soil Loss Mapping for Sustainable Development and Management of Land Resources in Warora Tehsil of Chandrapur District of Maharashtra: An Integrated Approach Using Remote Sensing and GIS     

M. S. S. Nagaraju  G. P. Obi Reddy  A. K. Maji  Rajeev Srivastava  P. Raja  A. K. Barthwal 《Journal of the Indian Society of Remote Sensing》2011,39(1):51-61

The study area is characterized by low and fluctuating rainfall pattern, thin soil cover, predominantly rain-fed farming with low productivity coupled with intensive mining activities, urbanization, deforestation, wastelands and unwise utilization of natural resources causing human induced environmental degradation and ecological imbalances, that warrant sustainable development and optimum management of land resources. Spatial information related to existing geology, land use/land cover, physiography, slope and soils has been derived through remote sensing, collateral data and field survey and used as inputs in a widely used erosion model (Universal Soil Loss Equation) in India to compute soil loss (t/ha/yr) in GIS. The study area has been delineated into very slight (<5 t/ha/yr), slight (5–10 t/ha/yr), moderate (10–15 t/ha/yr), moderately severe (15–20 t/ha/yr), severe (20–40 t/ha/yr) and very severe (>40 t/ha/yr) soil erosion classes. The study indicate that 45.4 thousand ha. (13.7% of TGA) is under moderate, moderately severe, severe and very severe soil erosion categories. The physiographic unit wise analysis of soil loss in different landscapes have indicated the sensitive areas, that has helped to prioritize development and management plans for soil and water conservation measures and suitable interventions like afforestation, agro-forestry, agri-horticulture, silvipasture systems which will result in the improvement of productivity of these lands, protect the environment from further degradation and for the ecological sustenance.  相似文献   

Characteristics of aerosol optical depth and Ångström parameters over Mohal in the Kullu Valley of Northwest Himalayan Region,India     

Nand Lal Sharma  Jagdish Chand Kuniyal  Mahavir Singh  Manum Sharma  Raj Pal Guleria 《Acta Geophysica》2011,59(2):334-360

The measurements using a ground based multi wavelength radiometer (MWR) at Mohal (31°54′N, 77°07′E, 1154 m AMSL) in the Kullu valley of Northwestern Himalayan region show that the spectral aerosol optical depth (AOD) and turbidity coefficient, β, are high in summer, moderate in monsoon season, low in winter and lowest in autumn, while wavelength exponent, α, has an opposite trend. Average annual value of AOD at 500 nm is 0.24±0.01, 0.43±0.02, and 0.28±0.02; that of β is 0.14±0.01, 0.22±0.02, and 0.17±0.03; and that of α is 1.06±0.09, 1.16±0.10, and 0.86±0.13, respectively, for clear, hazy and partially clear sky days. The considerably greater value of β on hazy days indicates more coarse particles in mountain haze. The fractional asymmetry factor (AF) is more negative in summer and autumn months. The AOD and β have significantly positive correlation with temperature and wind speed, suggesting high AODs and turbidity on hot and windy days.  相似文献   

Holocene Sea Levels and Coastal Change,South-west Viti Levu Island,Fiji     

Kirti K. Lal 《The Australian geographer》2011,42(1):41-51

For the first time, a sediment core spanning the entire Holocene has been analysed from Fiji. The 6 m core was obtained from the floor of an ancient coastal lagoon (palaeolagoon) adjacent to Bourewa, the site of the earliest known human settlement in this island group. The basal sediments, just above bedrock, date from 11 470 cal bp. A major transition occurs around 8000 cal bp where marine influences on palaeolagoon sedimentation increase sharply. Full shallow-water marine conditions are attained around 4630 cal bp and last until 3480 cal bp after which there is a regressive phase. The results agree with the area-specific predictions of sea level in the ICE-4G model, particularly in the timing of the highstand. In addition, the results support the ideas (a) that early human colonisation of Fiji occurred during the late Holocene regression, (b) that the first inhabitants of Bourewa utilised both nearshore marine (reefal) and brackish lagoon food sources, and (c) that the abrupt human abandonment of the area around 2500 cal bp could have been prompted by a reduction in these resources driven largely by sea-level fall.  相似文献   

An evaluation of the universal soil loss equation and field techniques for assessing soil erosion on a tropical alfisol in western Nigeria     

P. W. Mtakwa  R. Lal  R. B. Sharma 《水文研究》1987,1(2):199-209

Four techniques for soil erosion assessment were compared over two consecutive seasons for bare-fallow plots and a maize-cowpea sequence in 1985 at IITA, Ibadan, Nigeria. The techniques used were: tracer (aluminium paint), nails (16 and 25), the rill method, and the Universal Soil Loss Equation (USLE). Soil loss estimated by these techniques was compared with that determined using the runoff plot technique. There was significantly more soil loss (P < 0·01) in bare-fallow than in plots under maize (Zea mays) or cowpea (Vigna unguiculata). In the first season, soil loss from plots sown to maize was 40·2 Mg ha^?1 compared with 153·3 Mg ha^?1 from bare-fallow plots. In the second season, bare-fallow plots lost 87·5 Mg ha^?1 against 39·4 Mg ha^?1 lost from plots growing cowpea. The techniques used for assessing erosion had no influence on the magnitude of soil erosion and did not interfere with the processes of erosion. There was no significant difference (P < 0·05) between soil erosion determined by the nails and the runoff plot technique. Soil loss determined on six plots (three under maize, three bare-fallow) by the rill technique, at the end of the season, was significantly lower (P < 0·05) than that determined by the runoff plot technique. The soil loss estimated by the rill method was 143·2, 108·8 and 121·9 Mg ha^?1 for 11, 11, and 8 per cent slopes respectively, in comparison with 201·5, 162·0, and 166·4 Mg ha^?1 measured by the runoff plot method. Soil loss measured on three bare-fallow plots on 10 different dates by the rill technique was also significantly lower (P < 0·01) than that measured by the runoff plot. In the first season the USLE significantly underestimated soil loss. On 11, 11, and 8 per cent slopes, respectively, soil loss determined by the USLE was 77, 92, and 63 per cent of that measured by the runoff plot. However, in the second season there was no significant difference between soil loss determined by the USLE and that determined by the conventional runoff plot technique.  相似文献   

Global strain rates in western to central Himalayas and their implications in seismic hazard assessment     

Chhavi Choudhary  Mukat Lal Sharma 《Natural Hazards》2018,94(3):1211-1224

The Himalayas has experienced varying rates of earthquake occurrence in the past in its seismo-tectonically distinguished segments which may be attributed to different physical processes of accumulation of stress and its release, and due diligence is required for its inclusion for working out the seismic hazard. The present paper intends to revisit the various earthquake occurrence models applied to Himalayas and examines it in the light of recent damaging earthquakes in Himalayan belt. Due to discordant seismicity of Himalayas, three types of regions have been considered to estimate larger return period events. The regions selected are (1) the North-West Himalayan Fold and Thrust Belt which is seismically very active, (2) the Garhwal Himalaya which has never experienced large earthquake although sufficient stress exists and (3) the Nepal region which is very seismically active region due to unlocked rupture and frequently experienced large earthquake events. The seismicity parameters have been revisited using two earthquake recurrence models namely constant seismicity and constant moment release. For constant moment release model, the strain rates have been derived from global strain rate model and are converted into seismic moment of earthquake events considering the geometry of the finite source and the rates being consumed fully by the contemporary seismicity. Probability of earthquake occurrence with time has been estimated for each region using both models and compared assuming Poissonian distribution. The results show that seismicity for North-West region is observed to be relatively less when estimated using constant seismicity model which implies that either the occupied accumulated stress is not being unconfined in the form of earthquakes or the compiled earthquake catalogue is insufficient. Similar trend has been observed for seismic gap area but with lesser difference reported from both methods. However, for the Nepal region, the estimated seismicity by the two methods has been found to be relatively less when estimated using constant moment release model which implies that in the Nepal region, accumulated strain is releasing in the form of large earthquake occurrence event. The partial release in second event of May 2015 of similar size shows that the physical process is trying to release the energy with large earthquake event. If it would have been in other regions like that of seismic gap region, the fault may not have released the energy and may be inviting even bigger event in future. It is, therefore, necessary to look into the seismicity from strain rates also for its due interpretation in terms of predicting the seismic hazard in various segments of Himalayas.  相似文献   

Exhumation and its mechanisms: A review of exhumation studies in the Himalaya     

Vikas Adlakha  R. C. Patel  Nand Lal 《Journal of the Geological Society of India》2013,81(4):481-502

Exhumation has been recognised as a key factor in understanding the dynamics of a mountain belt. Normal faulting, erosion and ductile thinning are the three basic mechanisms to exhume the deeper high grade metamorphic rocks to the surface. Convergent orogenic belts are characterised by over-thickening of the crust due to thrusting and folding. The interplay of uplift due to over-thickening of crust and climatic-erosion is the most plausible mechanism of exhumation as suggested by the numerical models and analogue experiments. The analysis of 534 thermo-chronological dates through 1D-thermal numerical model in the Himalaya suggest that the exhumation is dominantly due to erosion but the pattern of erosion is controlled by local tectonic activities in different sector of the Himalaya since Miocene, indicating that tectonic force as the prime mechanism of exhumation in Himalaya.  相似文献   

Leaching behavior of lignite fly ash with shake and column tests     

Lal C. Ram  Nishant K. Srivastava  Ramesh C. Tripathi  Sanjay K. Thakur  Awadhesh K. Sinha  Sangeet K. Jha  Reginald E. Masto  Swapan Mitra 《Environmental Geology》2007,51(7):1119-1132

The maximum concentration of the majority of the trace metals in the leachates from shake and column test of lignite fly ash (LFA) was within the prescribed limits; however, total dissolved solids, total hardness, cations and anions (except K⁺), being above the prescribed limits, may lead to the increase in the hardness and salinity in the soil on the disposal of LFA. Present generation of huge amount of fly ash from thermal power plants (TPPs) is a big challenge concerning contamination of soil, crop produce and surface and ground water bodies due to the presence of some of the toxic trace metals in it. The leaching behavior of alkaline LFA (pH, 10.94), from TPP of Neyveli Lignite Corporation (NLC), India, was investigated by shake and column tests using water and sodium acetate buffer. The leaching of trace metals from LFA was governed by their concentrations, association with the ash particles, leaching duration and pH of the leachate (most influencing parameter). The leaching of metals followed the order: buffer column > aqueous column > aqueous shake > buffer shake test.  相似文献