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Lake bank filtration at Nainital,India: water-quality evaluation 总被引：6，自引：2，他引：4
There are different water-supply schemes in Uttarakhand, India to tap the water from streams, rivers and lakes. At Nainital,
seven tube-wells (depths 22.6–36.7 m), located at a distance of <100 m from the lake, are being used to abstract (1) lake
water after passage through the soil and (2) subsurface water/groundwater flowing towards the lake. Water samples from the
lake and tube-wells were analyzed in monsoon and non-monsoon periods from 1997 to 2006. Total dissolved solids, EC, alkalinity
and hardness were found to be marginally greater in tube-well waters. The difference in hydrochemistry of tube-well water
was mainly due to variation in flow regimes during monsoon and non-monsoon periods. Results clearly indicate that lake water
as such is not potable as it contains unacceptable levels of organic matter in terms of COD (~44 mg/L), coliforms (~15.6 × 104 MPN/100 mL) and nutrients. Coliform bacteria and COD have not been detected in any of the tube-well water samples over the
years. Lake water, treated by sand filters did not conform to drinking water standards. These investigations have led to the
closure of the treatment facility and installation of two tube-wells in addition to the existing five tube-wells.
Résumé Il existe divers projets d’alimentation en eau dans l’état d’Uttarakhand, Inde, afin de capter l’eau de ruisseaux, de rivières et de lacs. A Nainital, sept puits tubés (profondeur de 22.6–36.7 m), situés à une distance < à 100 m du lac, sont utilisés pour prélever (1) de l’eau du lac après transit à travers le sol et (2) de l’eau de sub-surface/eau souterraine s’écoulant vers le lac. Des échantillons d’eau du lac et des puits tubés ont été analysés en périodes de mousson et de celles sans mousson 1997 à 2006. Résidu sec, C.E., alcalinité et dureté ont été trouvés marginalement supérieurs dans l’eau des puits tubés. La différence d’hydrochimie de l’eau des puits tubés était surtout due à la variation des régimes d’écoulement pendant les périodes de mousson et de celles sans mousson. Les résultats indiquent clairement que l’eau du lac en tant que telle n’est pas potable car elle contient des teneurs inacceptables de matière organique en termes de COD (~44 mg/L), de coliformes (~15.6 × 104 MPN/100 mL) et d’éléments nutritifs. Des bactéries coliformes et du COD n’ont été détectés dans aucun des échantillons d’eau de puits tubés au fil des années. L’eau du lac traitée par des filtres à sable ne se conformait pas aux normes de l’eau potable. Ces recherches ont conduit à la fermeture de l’installation de traitement et à l’implantation de deux puits tubés en plus des cinq puits existants.
Resumen En el estado de Uttarakhand, India, existen diferentes esquemas de abastecimiento de agua que explotan agua de arroyos, ríos y lagos. En Nainital, siete pozos (profundidades entre 22.6–36.7 m), ubicados a una distancia de <100 m del lago, se usan para extraer (1) agua del lago luego de su pasaje a través del suelo y (2) agua superficial y subterránea que fluye hacia el lago. En períodos de monzón y de no monzón de 1997 a 2006 se han analizado muestras de agua del lago y de las captaciones. Se halló que el agua de los pozos es ligeramente mayor en términos del total de sólidos disueltos, la conductividad eléctrica, la alcalinidad y la dureza. La diferencia en la hidroquímica del agua de las perforaciones se debe principalmente a la variación de los regímenes de flujo durante los períodos de monzón y de no monzón. Los resultados claramente indican que el agua del lago no es potable por su contenido inaceptable de materia orgánica medida como demanda de carbono orgánico/oxígeno –DCO- (~44 mg/L), coliformes (~15.6 × 104 NMP/100 mL) y nutrientes. En el período, no se han detectado bacterias coliformes ni DCO en las muestras de agua de las captaciones. El agua del lago, tratada con filtros de arena, no conformó los estándares de agua para bebida. Estas investigaciones han demostrado la necesidad de clausurar las instalaciones de tratamiento y la adición de dos captaciones a las cinco ya existentes.相似文献
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Suresh C. Mehrotra 《Astrophysics and Space Science》1981,78(2):463-465
Collision induced vibrational rates of SiO due to H2 are computed using the normalized perturbative, semiclassical approach as described in Paper I (Mehrotra, 1980). The rates are very small as compared to the rates for rotational excitation and are more sensitive to temperature. 相似文献
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Fabio?OrianiEmail authorView author&#;s OrcID profile Raj?Mehrotra Grégoire?Mariethoz Julien?Straubhaar Ashish?Sharma Philippe?Renard 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(2):321-340
Daily rainfall is a complex signal exhibiting alternation of dry and wet states, seasonal fluctuations and an irregular behavior at multiple scales that cannot be preserved by stationary stochastic simulation models. In this paper, we try to investigate some of the strategies devoted to preserve these features by comparing two recent algorithms for stochastic rainfall simulation: the first one is the modified Markov model, belonging to the family of Markov-chain based techniques, which introduces non-stationarity in the chain parameters to preserve the long-term behavior of rainfall. The second technique is direct sampling, based on multiple-point statistics, which aims at simulating a complex statistical structure by reproducing the same data patterns found in a training data set. The two techniques are compared by first simulating a synthetic daily rainfall time-series showing a highly irregular alternation of two regimes and then a real rainfall data set. This comparison allows analyzing the efficiency of different elements characterizing the two techniques, such as the application of a variable time dependence, the adaptive kernel smoothing or the use of low-frequency rainfall covariates. The results suggest, under different data availability scenarios, which of these elements are more appropriate to represent the rainfall amount probability distribution at different scales, the annual seasonality, the dry-wet temporal pattern, and the persistence of the rainfall events. 相似文献
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Neerja Jha Pauline Sabina K. Rajni Tewari N. C. Mehrotra 《Journal of the Geological Society of India》2011,77(2):137-148
42 genera of palynomorphs have been reported from the qualitative and quantitative analysis of the palynoflora from both open
cast mine and bore holes viz., Ballarpur open cast mine, Durgapur open cast mine and Bore hole CMWNM-57 on barrier between
Kawadi/Majri open cast and Hindustan Lalpeth Colliery from the Wardha valley coalfield of Wardha basin. Two palynoassemblages
have been recorded i.e., an Upper Karharbari palynoassemblage comprising dominance of radial monosaccate genus Parasaccites and subdominance of nonstriate disaccate genus Scheuringipollenites and a Lower Barakar palynoassemblage consisting of dominance of Scheuringipollenites and subdominance of striate disaccates chiefly Faunipollenites, suggesting an Early Permian age (Late Sakmarian to Early Artinskian) to the sediments. It is further authenticated by the
occurrence of palynotaxa viz., Crucisaccites, Caheniasaccites, Indotriradites and Tiwariasporis. Upper Karharbari Formation has been demarcated for the first time in lithologically designated Barakar Formations in Ballarpur,
Durgapur, Majri and Hindustan Lalpeth Colliery while the sample 57/2 of bore hole CMWNM from Kawadi area may belong to the
Kamthi Formation on the basis of pinkish yellowish coarse grained to medium grained sandstone. An attempt has been made to
correlate these palynoassemblages with other Lower Gondwana basins of Early Permian affinity. 相似文献
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Information about the surface ice velocity is one of the important parameters for Mass balance and Glacier dynamics. This study estimates the surface ice velocity of Chhota Shigri glacier using Landsat (TM/ETM+) and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) temporal data-sets from a period of 2009 to 2016 and 2006 to 2007, respectively. A correlation based Particle Image Velocimetry (PIV) technique has been used for the estimation of surface ice velocity. This technique uses multiple window sizes in the same data-set. Four window sizes (low, medium, high, very high) are used for each image pair. Estimated results have been compared with the published data. The outcomes attained from the medium window size closely matches with the published results. The estimated mean surface ice velocities of medium window size are 24 and 28.5 myr?1 for 2009/2010 and 2006/2007 images pair. Highest velocity is observed in middle part of the glacier while lowest in the accumulation zone of the glacier. 相似文献
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Anumeha Shukla Rakesh Chandra Mehrotra 《Journal of the Geological Society of India》2016,87(5):520-524
Thick lignite deposits on the western margin of India were preserved on account of thick vegetation which got buried underneath due to tectonic activities that occurred in northwestern part of India during the early Palaeogene. Study of the fossil flora preserved in these beds is important to deduce the palaeoclimate of the region. Therefore, a field work was undertaken to collect plant fossils from the Tarkeshwar lignite mine, Surat district, Gujarat (western India) which is still unexplored as far as the plant mega-remains are concerned. A fossil wood is systematically described from the Cambay Shale Formation of the mine considered to be of early Eocene in age. It shows close affinities with Holigarna (Anacardiaceae), particularly with H. beddomei and H. grahamii. This genus is evergreen in nature and grows in the Indo-Malayan region, while both the modern analogues of the fossil are endemic to semi-evergreen to evergreen forests ofWestern Ghats, south India, located at the equator. This not only confirms the palaeolatitudinal position of the Indian subcontinent at the equator during the early Palaeogene, but also indicates the presence of equatorial rain forest in the Indian subcontinent during the period. Based on the timetree, Sapindales started to diverge in the early Palaeocene (62–57 Ma) as its oldest fossil is from the K-Pg boundary. Discovery of the present anacardiaceous fossil (belonging to Sapindales) from the early Eocene strengthens the above phylogenetic view. 相似文献
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For the first time a rich assemblage of legume fruits is described from the Late Oligocene sediments of the Makum as well
as Dilli-Jeypore coalfields of Assam. A new genus Buteocarpon has been instituted for the fossil fruits resembling Butea Roxb. of the family Fabaceae. In addition, six new species of the genus Leguminocarpon Goeppert are also described. Their presence indicates a warm and humid climate in the region during the deposition of the
sediments. 相似文献
10.
Vartika Singh Anjum Farooqui Naresh. C. Mehrotra Dhruv Sen Singh Rajni Tewari Neerja Jha Ratan Kar 《Journal of the Geological Society of India》2011,78(2):109-116
Subsurface sediments of a 120 cm deep trench from Ny-Alesund, Svalbard, were analysed for pollenspores and other organic matter
contents. This study is supported by two AMS 14C dates (27, 200 yrs BP and 8,762 yrs BP) at the bottom and topmost litho-unit of the trench, respectively. The pollen record
provides an evidence of a warm interval at about 27,200 yr BP (Late Weichselian and MIS 3) and cooling episode around 8,762
yr BP. This is also supported by the amount and type of organic matter as well as sediment type and depositional history of
the trench sediments. 相似文献