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1.
Pradeep Srivastava Indra Bir Singh Shikha Sharma Uma Kant Shukla Ashok Kumar Singhvi 《Geomorphology》2003,54(3-4):279-292
Abandoned channel belts, ponds and point bar deposits of palaeochannels in the interfluve regions of the central Ganga Plain suggest changes in the morphohydrologic conditions during the Latest Pleistocene–Holocene. Stratigraphy of these ponds comprises channel sand at the base overlain by shell-bearing clayey silt. The contact of the two facies marks the phase when channels converted into standing water bodies. Point bar deposits of some palaeochannels are overlain by oxidised aeolian sand, indicating that the channel abandonment possibly occurred due to the desiccation and aridity in the region.Optically stimulated luminescence (OSL) chronometry of the pond sediments suggests that the deposition of the basal channel sand started before 13 ka and continued up to 8 ka. The ponds formed around 8–6 ka when the channel activity ceased. Evidence from the point bar deposits also indicates that the fluvial activity in the region ended sometime during 7–5 ka. This was followed by aeolian aggradation. The present study thus suggests that the hydrologic conditions in the Gangetic plains, i.e. initiation of channels and their abandonment, formation of microgeomorphologic features such as ponds and their eventual siltation, were controlled largely by climatic changes (i.e. monsoon changes) supported by tectonic activity. For the past 2 ka, increasing human and related agricultural activity has substantially accentuated the natural siltation rate of ponds. 相似文献
2.
Sediment samples collected in the Moradabad area, lying in the interfluve of the Ganga and Ramganga Rivers, were analysed for heavy metals, after studying the geomorphology of the area. Geomorphologically, the area can be divided into three terraces - the T0, T1 and T2 surfaces. The rivers on these three surfaces show varying amounts of pollution depending upon the input from industries and urban settlements. The Ramganga River on the T0 surface shows the highest amount of pollution. However, the pollution levels in all these rivers show a downstream dilution effect. The characteristic feature of the vast interfluve area (T2 surface) is the presence of several, independent basins which are closed and rarely interact with each other or with any river. The sediments are redistributed and redeposited within the basin itself, and thus these basins serve as sinks. The sediments of one such basin in the study area show significant concentrations of arsenic, chromium, copper, nickel, lead, zinc and organic carbon. The concentrations of heavy metals in such a basin will show exponential increases with time, because there is no activity to funnel out the sediments and dilute the effect of pollution. This increase will pose more threats, as ultimately it will make its way laterally and vertically through the sediments, thereby polluting groundwater. 相似文献
3.
Indra Bir Singh 《International Journal of Earth Sciences》1979,68(1):342-350
Based on the sedimentological studies and the distribution of fossil-bearing horizons in the Himalaya a new model for the evolution of Himalaya is visualized. It is proposed that the Lesser and Central Himalaya constitute an integral part of the Peninsular Indian shield. The unfossiliferous orthoquartzite-shale-carbonate sequences of Lesser and Central Himalaya represent Precambrian sediments, deposited in a shallow tidal sea. Within the Lesser Himalaya there are thin detached marine fossiliferous horizons of three ages, viz. Carboniferous-Permian, Jurassic-Cretaceous and Eocene, located in a narrow E-W running zone (Dogadda-Subathu Zone), representing deposits of three transgressions in this zone.This zone is analogous to the Narbada Valley zone of the Peninsular India, where rocks of Permian, Cretaceous and Eocene ages are present. This model properly explains the unfossiliferous nature of the Lesser Himalayan sediments and demands the northern limit of Indian Plate north of Himalaya.
Zusammenfassung Aufgrand sedimentologischer Untersuchungen und der Verteilung fossilführender Schichten im Himalaya wird ein neues Modell der Himalayaentwicklung dargestellt. Es wird angenommen, daß der Außen- und Zentralhimalaya fester Bestandteil des indischen Schildes waren. Die fossilleeren Abfolgen von Orthoquarziten, Tonen und Kalken des Außen- und Zentralhimalaya bestehen aus präkambrischen Sedimenten, die ehemals in einem Flachmeer unter Gezeiteneinfluß abgelagert wurden. Im Bereich des Außenhimalaya finden sich geringmächtige Einschaltungen mit mariner Fauna, die dem Permokarbon, Jura/Kreide und Eozän zuzuordnen sind. Sie liegen innerhalb einer schmalen E/W-verlaufenden Zone (Dogadda-Subathu Zone) und entsprechen 3 Transgressionen in diesem Gebiet.Diese Zone ist dem Narbada Valley-Bereich der indischen Halbinsel vergleichbar, wo ebenfalls Ablagerungen aus Perm, Kreide und Eozän angetroffen werden.Durch dieses Modell läßt sich die Art der fossilleeren Sedimente des Außenhimalaya erklären. Es führt zu der Annahme, daß die Nordgrenze der indischen Platte nördlich des Himalaya zu suchen ist.
Résumé Un nouveau modèle de l'évolution de l'Himalaya est présenté, basé sur des études sédimentologiques et sur la répartition des horizons fossilifères, suivant lequel l'Himalaya Central et Externe ferait intégralement partie du boncliez péninsulaire Indien.Les séquences non fossilifères d'orthoquartzites-schistes-carbonates de l'Himalaya Central et Externe représentent des sédiments précambriens déposés dans un environnement marin peu profond soumis aux marées. Dans la région de l'Himalaya Externe, on observe de minces intercalations fossiliferes marines correspondant à trois phases de transgression, au Permo-Carbonifére, au Jurassique-Crétacé et à l'Eocène. Ces horizons sont localisés dans une zone étroite, de direction E-W, la zone de Dogadda-Subathu.Cette zone est comparable à la Valleé de Narbada en Inde péninsulaire, qui comporte également des dépôts permiens, crétacés et éocènes. Le modèle propose permet d'expliquer la nature non fossilifère de la plupart des sédiments de l'Himalaya Externe et conduit á rechercher la limite Nord de la plaque indienne au Nord de l'Himalaya.
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4.
VishwambharPrasadSati 《山地科学学报》2005,2(1):76-85
Agricultural practices are the main stay of the people of Uttranchal. Out of the total population,more than 75% people are engaged either with the main occupation of agriculture or its allied practices,dominated by traditional subsistence cereal farming.Among them, the main crops are rice, wheat, millet,barley, all types of pulses, all types of oilseeds and almost all types of fruits. The crops, vegetables and fruits of all varieties are grown in the different climatic zones such as tropical, temperate, and cold because, the region is characterized by the different altitudinal zones elevated from 200 m to more than 8000m. As a result, different climates are found from hot tropical to sub temperate and chilly cold. Pulses varieties are grown extensively. Among vegetables,potato, onion, carrot, all types of green leaf vegetables,brinzal, pumpkin, ladyfinger, pea, gram, radish,ginger, garlic, etc, are grown widely. All fruit varieties are grown in the different altitudinal zones. The mainfruits are orange, malta (a big size of orange),elephant citrus, lemon and all other types of citrus,apple, stone fruits including peach and pears, manykinds of nuts, and the fruits which are grown in the low lying areas. In spite of feasible climatic conditions,agricultural dominant society, and availability of all types of crops, the production and productivity of these crops are very low, even they are unable to meet the grain-need of the people in Uttaranchal. Agricultural crops are grown almost in all the altitudinal zones -- from the low-lying areas, which are called ‘Ga. ngarh‘, to the highly elevated region,where the legendary term is given as ‘Danda‘. The growing seasons vary according to the heights. The present paper aims to discuss the agricultural practices including cropping season, cropping pattern,land use, production of cropsagricultural system in thisand ecological aspect of Himalayan state and suggest some measures for developing farming system,which could lead the sustainability, in terms of meeting the food grain needs of the people on the one hand and restoring the ecological balance on the other. 相似文献
5.
Vishwambhar Prasad Sati 《山地科学学报》2005,2(4):319-328
Introduction In the Alakananda Basin, undulating terrain constitutes the most fragile elements of the ecosystem. Traditional economy rests on the terraced cultivation with extremely limited viability to expansion and modernization. Consequently, low economic return remains the characteristic feature of the agrarian landscape. It is the common experience that the ecological conditions of the basin are more suited to fruit cultivation rather than cereal farming (Atkinson 1889). Along with frui… 相似文献
6.
Binh Thai Pham Dieu Tien Bui Indra Prakash Long Hoang Nguyen M. B. Dholakia 《Environmental Earth Sciences》2017,76(10):371
Landslide susceptibility assessment using GIS has been done for part of Uttarakhand region of Himalaya (India) with the objective of comparing the predictive capability of three different machine learning methods, namely sequential minimal optimization-based support vector machines (SMOSVM), vote feature intervals (VFI), and logistic regression (LR) for spatial prediction of landslide occurrence. Out of these three methods, the SMOSVM and VFI are state-of-the-art methods for binary classification problems but have not been applied for landslide prediction, whereas the LR is known as a popular method for landslide susceptibility assessment. In the study, a total of 430 historical landslide polygons and 11 landslide affecting factors such as slope angle, slope aspect, elevation, curvature, lithology, soil, land cover, distance to roads, distance to rivers, distance to lineaments, and rainfall were selected for landslide analysis. For validation and comparison, statistical index-based methods and the receiver operating characteristic curve have been used. Analysis results show that all these models have good performance for landslide spatial prediction but the SMOSVM model has the highest predictive capability, followed by the VFI model, and the LR model, respectively. Thus, SMOSVM is a better model for landslide prediction and can be used for landslide susceptibility mapping of landslide-prone areas. 相似文献
7.
Study of regional monsoonal effects on landslide hazard zonation in Cameron Highlands, Malaysia 总被引：1，自引：1，他引：0
Abd Nasir Matori Abdul Basith Indra Sati Hamonangan Harahap 《Arabian Journal of Geosciences》2011,5(5):1069-1084
In general, landslides in Malaysia mostly occurred during northeast and southwest periods, two monsoonal systems that bring heavy rain. As the consequence, most landslide occurrences were induced by rainfall. This paper reports the effect of monsoonal-related geospatial data in landslide hazard modeling in Cameron Highlands, Malaysia, using Geographic Information System (GIS). Land surface temperature (LST) data was selected as the monsoonal rainfall footprints on the land surface. Four LST maps were derived from Landsat 7 thermal band acquired at peaks of dry and rainy seasons in 2001. The landslide factors chosen from topography map were slope, slope aspect, curvature, elevation, land use, proximity to road, and river/lake; while from geology map were lithology and proximity to lineament. Landslide characteristics were extracted by crossing between the landslide sites of Cameron Highlands and landslide factors. Using which, the weighting system was derived. Each landslide factors were divided into five subcategories. The highest weight values were assigned to those having the highest number of landslide occurrences. Weighted overlay was used as GIS operator to generate landslide hazard maps. GIS analysis was performed in two modes: (1) static mode, using all factors except LST data; (2) dynamic mode, using all factors including multi-temporal LST data. The effect of addition of LST maps was evaluated. The final landslide hazard maps were divided into five categories: very high risk, high risk, moderate, low risk, and very low risk. From verification process using landslide map, the landslide model can predict back about 13–16% very high risk sites and 70–93% of very high risk and high risk combined together. It was observed however that inclusion of LST maps does not necessarily increase the accuracy of the landslide model to predict landslide sites. 相似文献
8.
Socio-economic and environmental implications of the hydroelectric projects in Uttarakhand Himalaya, India 总被引：1，自引：1，他引：0
This paper deals with detailed analysis of the fiasco created by the Tehri High Dam in Uttarakhand, India, particularly in terms of resettlement and rehabilitation of the local inhabitants. Aspects pertaining to the environmental issues are also discussed. Currently, the river valleys in Uttarakhand state of India are the targets of increasing hydroelectric projects. Virtually all rivers are being exploited for generating environmental friendly power. Having being learned the hard lesson from Tehri Dam, it has been decided to opt for such schemes in which comparatively little submergence and tempering with the fragile eco-systems is involved.However, our observations suggest that even in such schemes if due care is not taken they may turn out to be a failure. 相似文献
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10.
Age determination of paleotsunami sediments around Lombok Island,Indonesia, and identification of their possible tsunamigenic earthquakes 
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下载免费PDF全文 Aswan Yahdi Zaim Yan Rizal I. Nyoman Sukanta Suci Dewi Anugrah Agus Tri Hascaryo Indra Gunawan Tatok Yatimantoro Weniza Hidayanti Purnomo Hawati Wahyu Dwijo Santoso Nurochim 《地震科学（英文版）》2017,30(2):107-113
Age determination of paleotsunami sediment from Lombok Island, Indonesia, and surrounding area has been carried out using the 210 Pb method in BATAN Jakarta. The basic theory of this method assumes that weathering of sediments, including paleotsunami sediments, will result in 210 Pb enrichment. The principle of this method is to calculate 210 Pb contents accumulation in a particular sedimentation interval from the surface to the deeper buried sediments. The results are then converted into age or depositional time in years ago unit. The dating results from the paleotsunami sediments of the Gawah Pudak(S8°46’2.91’’, E115°56’34.23’’) and Gili Trawangan areas(S8°21’1.38’’, E116°2’36.6’’) indicate the Gawah Pudak sediments were deposited 37 years ago(c. in 1977)and 22 years ago(c. in 1992). Three paleotsunami sediments from Gili Trawangan were deposited 149 years ago(c. in 1865), 117 years ago(c. in 1897) and 42 years ago(c. in 1972). These results are then compared to the available Indonesian earthquake catalogue data. This study reveals that paleotsunami sediments around Lombok Islands, from older to younger, were caused by the 1857 earthquake(epicentre in Bali Sea; M7; S8°00’09.45’’,E115°29’56.41’’), 1897 earthquake(epicentre in Flores Sea;M5.5; S6°47’59.62’’, E120°48’03.5’’ or Sulu Sea earthquake; M8.5; 70 km NW of Basilan Island), the 1975 earthquake(Nusa Tenggara; S10°6’16.61’’, E123°48’09.39’’), 1977 earthquake(in Waingapu, Sumba; M8.0;S11°5’39.34’’, E118°27’50.86’’) and the 1992 earthquake(Flores; M7.8; S8°28’52.11’’, E121°53’44.3’’). 相似文献