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151.
152.
Geomorphic processes operate at multiple spatio-temporal scales and different levels of hierarchy. It is therefore necessary to understand the linkages of landscapes across various scales and levels to gain insights into their interactions and feedbacks. Connectivity is an emergent property of the hydro-geomorphic systems, and it is gradually evolving into a unifying concept in geomorphology. The connectivity approach has the potential to be applied extensively to diverse hydro-geomorphic systems of India to understand their complexity as well as for designing effective management practices for river systems and wetlands, optimizing water resources for agriculture, and monitoring and restoration of habitats. Studies on connectivity, particularly in geomorphic context, have been growing steadily in India, albeit at a much slower pace compared to the global trends. This article undertakes a brief overview of the global developments particularly in terms of providing some clarity among the different types of geomorphic connectivity and their inter-relationships and feedbacks. We then take stock of the connectivity research in India in recent years as applied in different hydrogeomorphic systems across the country. We utilize a number of Indian case studies to illustrate the important developments and applications of connectivity concepts, and also present future perspective of this important field with special relevance to India. © 2020 John Wiley & Sons, Ltd. 相似文献
153.
D. V. Reddy P. Nagabhushanam M. R. Rao D. S. Mitra B. M. Tripati S. K. Sinha B. Bhadu 《Journal of the Geological Society of India》2011,77(3):239-242
The Oil and Natural Gas Corporation Limited (ONGC), India, embarked upon exploration and exploitation of deep groundwater
under the project named as “Saraswati” in arid Thar desert, Rajasthan, with a societal mission of providing water to the local
people and cattle. A 555 m deep well drilled by the ONGC near Jaisalmer town in 2006 encountered a potential aquifer at a
depth of 450–500 m. Radiocarbon dating of this well water indicated paleorecharge to be >40,000 yr BP (uncorrected) (Before
Present with respect to 1950 AD), while the medium depth (∼200 m) well waters around that area showed an age range of ∼9,000
to 17,000 yr BP (uncorrected). These waters represent pre-Saraswati era recharge, because the mighty Saraswati flowed in this
region between 7000–4000 yr BP. The stable isotope (δD and δ18O) and Total Dissolved Solids (TDS) data of these waters clearly indicated absence of communication between the two aquifers
(deep and medium depth). However, the extension of this deep aquifer needs to be determined. 相似文献
154.
Hydrochemistry and quality assessment of groundwater in part of NOIDA metropolitan city,Uttar Pradesh 总被引:1,自引:0,他引:1
Abhay Kumar Singh B. K. Tewary A. Sinha 《Journal of the Geological Society of India》2011,78(6):523-540
An attempt has been made to study the groundwater geochemistry in part of the NOIDA metropolitan city and assessing the hydrogeochemical
processes controlling the water composition and its suitability for drinking and irrigation uses. The analytical results show
that Na and Ca are the major cations and HCO3 and Cl are the major anions in this water. The higher ratios of Na+K/TZ+ (0.2–0.7), Ca+Mg/HCO3 (0.8–6.1); good correlation between Ca-Mg (0.75), Ca-Na (0.77), Mg-Na (0.96); low ratio of Ca+Mg/Na+K (1.6), Ca/Na (1.03),
Mg/Na (0.64), HCO3/Na (1.05) along with negative correlation of HCO3 with Ca and Mg signify silicate weathering with limited contribution from carbonate dissolution. The hydro-geochemical study
of the area reveals that many parameters are exceeding the desirable limits and quality of the potable water has deteriorated
to a large extent at many sites. High concentrations of TDS, Na, Cl, SO4, Fe, Mn, Pb and Ni indicate anthropogenic impact on groundwater quality and demand regional water quality investigation and
integrated water management strategy. SAR, %Na, PI and Mg-hazard values show that water is of good to permissible quality
and can be used for irrigation. However, higher salinity and boron concentration restrict its suitability for irrigation uses
at many sites. 相似文献
155.
N. V. Chalapathi Rao Anup K. Sinha Suresh Kumar Rajesh K. Srivastava 《Journal of the Geological Society of India》2013,81(6):733-736
We report a rare accessory groundmass mineral of K-rich titanate, having a composition close to that of potassium triskaidecatitanate (K2Ti13O27), from an underground drill-core sample of ultrapotassic rock from southwestern part of the Jharia coal field in the Damodar valley, at the northern margin of the Singhbhum craton, Eastern India. Potassium triskaidecatitanate is regarded as a typomorphic mineral of orangeites (Group II kimberlites) of Kaapvaal craton, southern Africa, and its occurrence in the Jharia ultrapotassic rock is significant since ultrapotassic suite of rocks elsewhere from the Damodar valley have been recently suggested to be peralkaline lamproites based on mineral-genetic classification. The important role played by a unique geodynamic setting (involving a thinned metasomatised lithospheric mantle and inheritance of an Archaean subduction component) at the northern margin of the Singhbhum craton in deciding the petrological diversity of the early Cretaceous ultrapotassic intrusives from the Damodar valley is highlighted in this study. 相似文献
156.
D. G. Kaskaoutis E. E. Houssos D. Goto A. Bartzokas P. T. Nastos P. R. Sinha S. K. Kharol P. G. Kosmopoulos R. P. Singh T. Takemura 《Climate Dynamics》2014,43(9-10):2313-2331
The present study focuses on identifying the main atmospheric circulation characteristics associated with aerosol episodes (AEs) over Kanpur, India during the period 2001–2010. In this respect, mean sea level pressure (MSLP) and geopotential height of 700 hPa (Z700) data obtained from the NCEP/NCAR Reanalysis Project were used along with daily Terra-MODIS AOD550 data. The analysis identifies 277 AEs [AOD500 > \( \overline{AOD} \) 500 + 1STDEV (standard deviation)] over Kanpur corresponding to 13.2 % of the available AERONET dataset, which are seasonally distributed as 12.5, 9.1, 14.7 and 18.6 % for winter (Dec–Feb), pre-monsoon (Mar–May), monsoon (Jun–Sep) and post-monsoon (Oct–Nov), respectively. The post-monsoon and winter AEs are mostly related to anthropogenic emissions, in contrast to pre-monsoon and monsoon episodes when a significant component of dust is found. The multivariate statistical methods Factor and Cluster Analysis are applied on the dataset of the AEs days’ Z700 patterns over south Asia, to group them into discrete clusters. Six clusters are identified and for each of them the composite means for MSLP and Z700 as well as their anomalies from the mean 1981–2010 climatology are studied. Furthermore, the spatial distribution of Terra-MODIS AOD550 over Indian sub-continent is examined to identify aerosol hot-spot areas for each cluster, while the SPRINTARS model simulations reveal incapability in reproducing the large anthropogenic AOD, suggesting need of further improvement in model emission inventories. This work is the first performed over India aiming to analyze and group the atmospheric circulation patterns associated with AEs over Indo-Gangetic Plains and to explore the influence of meteorology on the accumulation of aerosols. 相似文献
157.
158.
A. K. Shukla K. N. Babu R. P. Prajapati N. M. Suthar Ajai A. Sinha 《Marine Geodesy》2013,36(2):203-218
A pair of buoys (system), MET and OPTICAL, consisting of fully automated hyperspectral radiometers, fluorometer, and meteorological sensors, has been realized and deployed in deep ocean case-I site at Kavaratti in Lakshadweep, Arabian Sea, for preprogrammed in situ data collection and transmission via INSAT-3C satellite. The buoy of described configuration is capable of measuring in-water optical and biological parameters in an unattended manner for long-term time series with less vertical tilt. A robotic sun/sky photometer installed on Kavaratti Island simultaneously provides information on aerosols over the site. A combination of these parameters available hourly in real time throughout the day from unattended systems in the ocean as well as on island provides an ideal reference site. The paper reports recent collection of bio-optical marine observations over the site and use of the data for OCM-2 vicarious calibration and validation of geophysical products. 相似文献
159.
Influence of Carbon and Microbial Community Priming on the Attenuation of Uranium in a Contaminated Floodplain Aquifer 下载免费PDF全文
P.J. Mouser L.A. N'Guessan N.P. Qafoku M. Sinha K.H. Williams M. Dangelmayr C.T. Resch A. Peacock Z. Wang L. Figueroa P.E. Long 《Ground water》2015,53(4):600-613
The capacity for subsurface sediments to sequester radionuclide contaminants, such as uranium (U), and retain them after bioremediation efforts are completed is critical to the long‐term stewardship of re‐mediated sites. In U bioremediation strategies, carbon amendment stimulates bioreduction of U(VI) to U(IV), immobilizing it within the sediments. Sediments enriched in natural organic matter are naturally capable of sequestering significant U, but may serve as sources to the aquifer, contributing to plume persistence. Two types of organic‐rich sediments were compared to better understand U release mechanisms. Sediments that were artificially primed for U removal were retrieved from an area previously biostimulated while detrital‐rich sediments were collected from a location never subject to amendment. Batch incubations demonstrated that primed sediments rapidly removed uranium from the groundwater, whereas naturally reduced sediments released a sizeable portion of U before U(VI)‐reduction commenced. Column experiments confirmed that U release persisted for 65 pore volumes in naturally reduced sediments, demonstrating their sink‐source behavior. Acetate addition to primed sediments shifted the microbial community from sulfate‐reducing bacteria within Desulfobacteraceae to the iron‐reducing Geobacteraceae and Firmicutes, associated with efficient U(VI) removal and retention, respectively. In contrast, Geobacteraceae communities in naturally reduced sediments were replaced by sequences with similarity to Pseudomonas spp. during U release, while U(VI) removal only occurred with enrichment of Firmicutes. These investigations stress the importance of characterizing zones with heterogeneous carbon pools at U‐contaminated sites prior to the determination of a remedial strategy to identify areas, which may contribute to long‐term sourcing of the contaminants. 相似文献
160.
In this study, sensitivity of the Indian summer monsoon simulation to the Himalayan orography representation in a regional climate model (RegCM) is examined. The prescribed height of the Himalayan orography is less in the RegCM model than the actual height of the Himalayas. Therefore, in order to understand the impact of the Himalayan orography representation on the Indian summer monsoon, the height of the Himalayan orography is increased (decreased) by 10 % from its control height in the RegCM model. Three distinct monsoon years such as deficit (1987), excess (1988) and normal rainfall years are considered for this study. The performance of the RegCM model is tested with the use of a driving force from the reanalysis data and a global model output. IMD gridded rainfall and the reanalysis-2 data are used as verification analysis to validate the model results. The RegCM model has the potential to represent mean rainfall distribution over India as well as the upper air circulation patterns and some of the semi-permanent features during the Indian summer monsoon season. The skill of RegCM is reasonable in representing the variation in circulation and precipitation pattern and intensity during two contrasting rainfall years. The simulated seasonal mean rainfall over many parts of India especially, the foothills of the Himalaya, west coast of India and over the north east India along with the whole of India are more when the orography height is increased. The low level southwesterly wind including the Somali jet stream as well as upper air circulation associated with the tropical easterly jet stream become stronger with the enhancement of the Himalayan orography. Statistical analysis suggests that the distribution and intensity of rainfall is represented better with the increased orography of RegCM by 10 % from its control height. Thus, representation of the Himalayan orography in the model is close to actual and may enhance the skill in seasonal scale simulation of the Indian summer monsoon. 相似文献