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1
Mishra, Asheesh Shivam, Prakash Nautiyal et Vijay Prakash Semwal. « Distributional Patterns of Benthic Macro-invertebrate Fauna in the Glacier Fed Rivers of Indian Himalaya ». Our Nature 11, no 1 (24 juin 2013) : 36–44. http://dx.doi.org/10.3126/on.v11i1.8242.
Texte intégralRésumé :
Large-scale distributional pattern for the benthic macro-invertebrate fauna was determined in the glacier fed Himalayan and Trans-Himalayan rivers and streams of India at the elevation range of 2000-3000 m asl. In Trans-Himalaya the family Heptageniidae (Ephemeroptera) alone (Chandra and Bhaga) or in combination with Chironomidae (Diptera) in similar proportions (Chenab) or Diptera alone (Miyar) dominated the assemblages. Its influence seems to extend to Rupin drainage in the Himalaya where Chironomidae alone dominated the assemblages. Except for this Himalayan river. Various families of Trichoptera attained highest abundance in other rivers of the Himalaya. Thus, Leptoceridae in combination with Limnephilidae (Alaknanada at Tapovan) and Heptageniidae and Baetidae (Alaknanada at Mana) is the only instance of similarity in abundant taxa by virtue of same river. The Mandakini was partially similar to Alaknanda by virtue of abundant Limnephilidae. The Bhagirathi was characterized by abundance of Philopotamidae. Thus, assemblages exhibit greater variability in the Himalayan rivers than Trans-Himalayan rivers and are hence entirely different, as also evident from the cluster analysis. This present hypothesis is not applicable to explain the macro-invertebrate assemblages in Himalayan and Trans-Himalayan region.DOI: http://dx.doi.org/10.3126/on.v11i1.8242 Our Nature Vol.11(1) 2013: 36-44
2
Thayyen, R. J., et J. T. Gergan. « Role of glaciers in watershed hydrology : ''Himalayan catchment'' perspective ». Cryosphere Discussions 3, no 2 (15 juillet 2009) : 443–76. http://dx.doi.org/10.5194/tcd-3-443-2009.
Texte intégralRésumé :
Abstract. A large number of Himalayan glacier catchments are under the influence of humid climate with snowfall in winter (November–April) and South-West monsoon in summer (June–September) dominating the regional hydrology. Such catchments are defined as ''Himalayan catchment'', where the glacier melt water contributes to the river flow during the period of annual high flows produced by the monsoon. Other two major glacio-hydrological regimes of the Himalaya are winter snow dominated Alpine catchments of the Kashmir and Karakoram region and cold-arid regions of the Ladakh mountain range. Factors influencing the river flow variations in a ''Himalayan catchment'' were studied in a micro scale glacier catchment in the Garhwal Himalaya, covering an area of 77.8 km2. Discharge data generated from three hydrometric stations established at different altitudes of the Din Gad stream during the summer ablation period of 1998, 1999, 2000, 2001, 2003 and 2004. These data has been analysed along with winter/summer precipitation, temperature and mass balance data of the Dokriani glacier to study the role of the glacier and precipitation in determining the runoff variations along the stream continuum from the glacier snout to 2360 m a.s.l. Study shows that the inter-annual runoff variations in a ''Himalayan glacier catchment'' is directly linked with the precipitation rather than mass balance changes of the glacier. Study suggest that warming induced initial increase of glacier degraded runoff and subsequent decline is a glaciers mass balance response and cannot be translated as river flow response in a ''Himalayan catchment'' as suggested by the IPCC, 2007. Study also suggest that the glacier runoff critically influence the headwater river flows during the years of low summer discharge and proposes that the Himalayan catchment could experience higher river flows and positive glacier mass balance regime together in association with strong monsoon. This paper intended to highlight the importance of creating credible knowledge on the Himalayan cryospheric processes to develop a global outlook on river flow response to cryospheric change and locally sustainable water resources management strategies.
3
Baloori, S. S., Pallavi Upreti et Jyotsna Kukreti. « A COMPREHENSIVE WATER QUALITY REVIEW OF RIVER YAMUNA WITH SPECIAL REFERENCE TO WATER QUALITY INDEX IN THE HIMALAYAN REGION OF INDIA ». International Journal of Advanced Research 10, no 05 (31 mai 2022) : 407–17. http://dx.doi.org/10.21474/ijar01/14722.
Texte intégralRésumé :
India with 4% of fresh water resources is facing a dual challenge of water scarcity and pollution. Several rivers in India originate from Himalayan systems and forms the basis of Indias Economy. River contamination and diminishing water quality is reducing populations accessibility to clean and safe drinking Water. As one of the significant perennial tributaries of The Ganga Water systems, River Yamuna passes through the heartlands of thegreat North India Plains sustaining cities, feeding millions. Since Yamuna passes through major urban settlement it is heavily polluted with untreated industrial waste, sewage, domestic waste making its way into the river. The study presents a comprehensive reviewof the water quality assessmentsof theriver Yamuna with special reference to Water Quality Index based on severalhydrological parameters. Based on the levels of contamination the whole stretch of Yamuna from its source (at Uttarakhand) till its confluence with Ganga (at Allahabad) has been divided into 5 segments. While all the lower stretches depict high to very high pollution levels, the upper segment of the river in the Himalayas show good water quality. Water quality parameters of river Yamuna depict that BOD, DO and COD levels are not in range of permissible limits in Delhi segment but it falls under permissible limits range in Himalayan segment. Other than these parameters, ammonia, TKN and other organic and inorganic matters fall under the desired standards in Himalayan region of Yamuna.
4
Pangali Sharma, Til Prasad, Jiahua Zhang, Narendra Raj Khanal, Foyez Ahmed Prodhan, Basanta Paudel, Lamei Shi et Nirdesh Nepal. « Assimilation of Snowmelt Runoff Model (SRM) Using Satellite Remote Sensing Data in Budhi Gandaki River Basin, Nepal ». Remote Sensing 12, no 12 (17 juin 2020) : 1951. http://dx.doi.org/10.3390/rs12121951.
Texte intégralRésumé :
The Himalayan region, a major source of fresh water, is recognized as a water tower of the world. Many perennial rivers originate from Nepal Himalaya, located in the central part of the Himalayan region. Snowmelt water is essential freshwater for living, whereas it poses flood disaster potential, which is a major challenge for sustainable development. Climate change also largely affects snowmelt hydrology. Therefore, river discharge measurement requires crucial attention in the face of climate change, particularly in the Himalayan region. The snowmelt runoff model (SRM) is a frequently used method to measure river discharge in snow-fed mountain river basins. This study attempts to investigate snowmelt contribution in the overall discharge of the Budhi Gandaki River Basin (BGRB) using satellite remote sensing data products through the application of the SRM model. The model outputs were validated based on station measured river discharge data. The results show that SRM performed well in the study basin with a coefficient of determination (R2) >0.880. Moreover, this study found that the moderate resolution imaging spectroradiometer (MODIS) snow cover data and European Centre for Medium-Range Weather Forecasts (ECMWF) meteorological datasets are highly applicable to the SRM in the Himalayan region. The study also shows that snow days have slightly decreased in the last three years, hence snowmelt contribution in overall discharge has decreased slightly in the study area. Finally, this study concludes that MOD10A2 and ECMWF precipitation and two-meter temperature products are highly applicable to measure snowmelt and associated discharge through SRM in the BGRB. Moreover, it also helps with proper freshwater planning, efficient use of winter water flow, and mitigating and preventive measures for the flood disaster.
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Verma, Jyoti, Prakash Nautiyal et Prateek Srivastava. « Diatoms of the Cymbella sensu lato species of the two different eco-regions of the Indian Mountain Rivers ». Annals of Plant Sciences 6, no 10 (1 octobre 2017) : 1705. http://dx.doi.org/10.21746/aps.2017.6.10.4.
Texte intégralRésumé :
This paper describes Cymbella sensu lato (Cymbopleura, Delicata, Encyonema, Encyonopsis and Reimeria) species from two different ecoregions of India. In the present study, twenty-six diatom taxa belonging to the genus Cymbella sensu lato were identified. In the flora nineteen species were recorded from the Vindhya region while eleven from the Himalaya. All of them were first records for the Vindhyan rivers. Seven taxa were new records for the Himalayan river.
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Khanal, Laxman, Mukesh Kumar Chalise et Xuelong Jiang. « ECOLOGICAL NICHE MODELLING OF HIMALAYAN LANGUR (Semnopithecus entellus) IN SOUTHERN FLANK OF THE HIMALAYA ». Journal of Institute of Science and Technology 23, no 1 (30 décembre 2018) : 1–9. http://dx.doi.org/10.3126/jist.v23i1.22142.
Texte intégralRésumé :
The species and subspecies status of various populations of the Himalayan langur (Semnopithecus entellus) have been disputed in many literatures. Before delineating the taxonomic boundaries, it is important to identify the potential distribution areas of extant populations of the species. Ecological niche modeling (ENM) can be coupled with the systematic survey of species presence to identify the species’ potential distribution range. Therefore, we did extensive survey and population census of the Himalayan langur across three major river basins (Koshi, Gandaki and Karnali) of Nepal and analyzed the population patterns. In addition, we also modelled the ecological niche of the species by using maximum entropy (MaxEnt) algorithm. We counted a total of 559 individuals from 33 troops that accounted the average troop size of 16.94 (±8.39) individuals. Within Nepal territory, the highest population of langurs was observed from the Gandaki River basin followed by the Karnali River basin. We revealed that Himalayan langurs have a wide range of altitudinal (49 m - 4190 m above sea level) distributions from Bhutan to Kashmir across southern flank of the Himalaya. We warrant for the detail distribution assessment and taxonomic analysis of Himalayan langurs using ecological, morphological and genetic variables.
7
Montgomery, David R., et Drew B. Stolar. « Reconsidering Himalayan river anticlines ». Geomorphology 82, no 1-2 (décembre 2006) : 4–15. http://dx.doi.org/10.1016/j.geomorph.2005.08.021.
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Kattel, Giri R. « Changing Ecological and Hydrological Conditions in the Himalayan Mountains and Measures of Future Adaptation ». Jalawaayu 1, no 1 (21 avril 2021) : 15–24. http://dx.doi.org/10.3126/jalawaayu.v1i1.36447.
Texte intégralRésumé :
The Himalayan mountains are one of the important geographical settings of the planet Earth for the source of global freshwaters. The freshwaters from the Himalayas are life supporting systems of the millions of people residing in downstream Asia. However, the high-altitude mountains of the Himalayas have gone through considerable transformations in hydrology and ecology over the recent past. In the 21st century, the hydrological flow regimes of glacial-fed rivers are threatened by both climate change and human disturbances. Rapidly changing temperature and the frequency, duration and timing of monsoonal precipitation have altered glacier melt, river flow, flood, and downstream volume of water. As a result, the ecosystems and biodiversity as well as irrigation-dependent agriculture in the region is profoundly impacted. The fundamental challenge today is therefore to address the issue of water resources through understanding of hydrological and ecological changes of lake and river systems in the region. Ecohydrology is a sustainability concept, which addresses water resource management through understanding of water cycle, including hydrological processes of rivers and lakes and the structure, and function of ecosystems. Putting ecohydrology at the center of the water resource management program, this mini review discusses rapid ecological and hydrological changes of freshwater systems in the Himalayan mountains and suggested some of the key future adaptation strategies of water resources to rapidly changing regional environment.
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Liang, Wendong, Eduardo Garzanti, Sergio Andò, Paolo Gentile et Alberto Resentini. « Multimineral Fingerprinting of Transhimalayan and Himalayan Sources of Indus-Derived Thal Desert Sand (Central Pakistan) ». Minerals 9, no 8 (26 juillet 2019) : 457. http://dx.doi.org/10.3390/min9080457.
Texte intégralRésumé :
As a Quaternary repository of wind-reworked Indus River sand at the entry point in the Himalayan foreland basin, the Thal Desert in northern Pakistan stores mineralogical information useful to trace erosion patterns across the western Himalayan syntaxis and the adjacent orogenic segments that fed detritus into the Indus delta and huge deep-sea fan throughout the Neogene. Provenance analysis of Thal Desert sand was carried out by applying optical and semi-automated Raman spectroscopy on heavy-mineral suites of four eolian and 11 fluvial sand samples collected in selected tributaries draining one specific tectonic domain each in the upper Indus catchment. In each sample, the different types of amphibole, garnet, epidote and pyroxene grains—the four dominant heavy-mineral species in orogenic sediment worldwide—were characterized by SEM-EDS spectroscopy. The chemical composition of 4249 grains was thus determined. Heavy-mineral concentration, the relative proportion of heavy-mineral species, and their minerochemical fingerprints indicate that the Kohistan arc has played the principal role as a source, especially of pyroxene and epidote. Within the western Himalayan syntaxis undergoing rapid exhumation, the Southern Karakorum belt drained by the Hispar River and the Nanga Parbat massif were revealed as important sources of garnet, amphibole, and possibly epidote. Sediment supply from the Greater Himalaya, Lesser Himalaya, and Subhimalaya is dominant only for Punjab tributaries that join the Indus River downstream and do not contribute sand to the Thal Desert. The detailed compositional fingerprint of Thal Desert sand, if contrasted with that of lower course tributaries exclusively draining the Himalaya, provides a semi-actualistic key to be used, in conjunction with complementary provenance datasets and geological information, to reconstruct changes in paleodrainage and unravel the relationship between climatic and tectonic forces that controlled the erosional evolution of the western Himalayan-Karakorum orogen in space and time.
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Shisode, Nileema Raju. « To study the dfferent sorces of water and its qualities with health perspective ». Journal of Preventive Medicine and Holistic Health 8, no 1 (15 juin 2022) : 3–8. http://dx.doi.org/10.18231/j.jpmhh.2022.002.
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Water is a life. Drinking water is very important to stay healthy. In Ayurveda different sources of water are described, among them divya jal-rain water is considered as very pure. In India we consider river as a Goddess. Himalaya, Himalayan Rivers are considered as holy. Clean, pure, sweet, light, satisfying, tridosha balancing, strength giving water is considered as pure and holy. Water from late monsoon rain water, autumn rain water, big lakes, upper Himalaya river water, and fountain water is considered as pure. Impure water we can identify with our five sense organs. Sun rays, air, fire, are methods to purify water. Katak is a herb which purifies water by sedimentation of dirt.to flavor water different herbs and spices are used. Properties of water changes according to its origin, land, soil and season.
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Sahu, Netrananda, Takahiro Sayama, Atul Saini, Arpita Panda et Kaoru Takara. « Understanding the Hydropower and Potential Climate Change Impact on the Himalayan River Regimes—A Study of Local Perceptions and Responses from Himachal Pradesh, India ». Water 12, no 10 (30 septembre 2020) : 2739. http://dx.doi.org/10.3390/w12102739.
Texte intégralRésumé :
The Himalayas have become synonymous with the hydropower developments for larger electricity demands of India’s energy sector. In the Himachal Himalayas though, there are only three large storage dams with more than 1000 megawatts (hereafter MW) capacity that have very serious environmental issues. However, hundreds of small runoff-river hydropower plants across the Himachal Himalayas are a serious threat to the river regimes and Himalayan biota. There are 965 identified hydropower projects (hereafter HPPs) having a potential capacity of 27,436 MW in the Himachal Pradesh as of December 2019 as per the Directorate of Energy of the state. Out of the 965 identified, 216 are commissioned, including less than 5 MW plants, with an installed capacity of 10,596 MW, and were operational by December 2019. Only 58 projects are under construction among the identified with an installed capacity of 2351 MW, 640 projects are in various stages of clearance and investigation with an installed capacity 9260 MW, 30 projects are to be allotted with 1304 MW installed capacity, and merely four projects are disputed/cancelled with installed capacity of 50.50 MW. The large number of HPPs are sanctioned without proper consideration of negative environmental and geohazard impacts on the Himalayan terrestrial biota. In this work, our focus was on the hydropower and climate change impact on the Himalayan river regimes of the Chenab, the Ravi, the Beas, the Satluj, and the Yamuna river basins. We analyzed basin-wise rainfall, temperature, and soil moisture data from 1955 to 2019 to see the trend by applying the Mann–Kendall test, the linear regression model, and Sen’s slope test. A basin-wise hazard zonation map has been drawn to assess the disaster vulnerability, and 12 hydropower sites have been covered through the primary survey for first-hand information of local perceptions and responses owing to hydropower plants.
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Rasul, Golam. « Why Eastern Himalayan countries should cooperate in transboundary water resource management ». Water Policy 16, no 1 (27 août 2013) : 19–38. http://dx.doi.org/10.2166/wp.2013.190.
Texte intégralRésumé :
Bangladesh, Bhutan, India, and Nepal in the Eastern Himalayas are interconnected by the common river systems of the Ganges, Brahmaputra, and Meghna (GBM). The GBM basin is home to approximately 700 million people, comprising over 10% of the world's population. The economy and environment of the region depend on water, but while the need for water is increasing, poor management and climate-related effects are making water supplies erratic. Upstream–downstream interdependencies necessitate developing a shared river system in an integrated manner through collaboration of the riparian countries. This paper examines the opportunities for, and potential benefits of, regional cooperation in water resource management. It suggests that the benefits can increase considerably when a regional (river basin) perspective is adopted that promotes optimum use of water resources for consumptive and non-consumptive use. Regional cooperation can bring additional economic, environmental, social, and political benefits through multi-purpose river projects, which help by storing monsoon water, mitigating the effects of floods and droughts, augmenting dry season river flows, expanding irrigation and navigation facilities, generating hydropower, and enhancing energy and environmental security. A broader framework to facilitate regional cooperation in transboundary rivers in the Eastern Himalayan region is suggested.
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Thayyen, R. J., et J. T. Gergan. « Role of glaciers in watershed hydrology : a preliminary study of a "Himalayan catchment" ; ». Cryosphere 4, no 1 (9 février 2010) : 115–28. http://dx.doi.org/10.5194/tc-4-115-2010.
Texte intégralRésumé :
Abstract. A large number of Himalayan glacier catchments are under the influence of humid climate with snowfall in winter (November–April) and south-west monsoon in summer (June–September) dominating the regional hydrology. Such catchments are defined as "Himalayan catchment", where the glacier meltwater contributes to the river flow during the period of annual high flows produced by the monsoon. The winter snow dominated Alpine catchments of the Kashmir and Karakoram region and cold-arid regions of the Ladakh mountain range are the other major glacio-hydrological regimes identified in the region. Factors influencing the river flow variations in a "Himalayan catchment" were studied in a micro-scale glacier catchment in the Garhwal Himalaya, covering an area of 77.8 km2. Three hydrometric stations were established at different altitudes along the Din Gad stream and discharge was monitored during the summer ablation period from 1998 to 2004, with an exception in 2002. These data have been analysed along with winter/summer precipitation, temperature and mass balance data of the Dokriani glacier to study the role of glacier and precipitation in determining runoff variations along the stream continuum from the glacier snout to 2360 m a.s.l. The study shows that the inter-annual runoff variation in a "Himalayan catchment" is linked with precipitation rather than mass balance changes of the glacier. This study also indicates that the warming induced an initial increase of glacier runoff and subsequent decline as suggested by the IPCC (2007) is restricted to the glacier degradation-derived component in a precipitation dominant Himalayan catchment and cannot be translated as river flow response. The preliminary assessment suggests that the "Himalayan catchment" could experience higher river flows and positive glacier mass balance regime together in association with strong monsoon. The important role of glaciers in this precipitation dominant system is to augment stream runoff during the years of low summer discharge. This paper intends to highlight the importance of creating credible knowledge on the Himalayan cryospheric processes to develop a more representative global view on river flow response to cryospheric changes and locally sustainable water resources management strategies.
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Arora, Manohar, N. K. Goel, Pratap Singh et R. D. Singh. « Regional flow duration curve for a Himalayan river Chenab ». Hydrology Research 36, no 2 (1 avril 2005) : 193–206. http://dx.doi.org/10.2166/nh.2005.0014.
Texte intégralRésumé :
This study is carried out with the objective of examining the effect of altitude on water availability estimates for the various sub-basins of the Chenab river basin (mean elevation of the basin is 3600 m), which is a snow-fed Himalayan river basin located in the western Himalayas. This basin covers all three Himalayan ranges, i.e. outer, middle and greater Himalayas. For this study, the daily flow data of 11 gauging sites varying from 14 years to 23 years in the Chenab river basin are utilised. The other important information related to the physiography, hydrology and meteorology, etc, for the region are derived from the available literature and maps. The daily flow data of nine gauging sites are utilised for developing the regional relationships for water availability computations. These relationships are tested over the remaining two gauging sites. The regional relationships are developed using three different approaches. These approaches include: (i) parameter regionalisation for individual gauged sites of selected probability distribution, (ii) regionalisation of dependable flows and (iii) parameter regionalisation for the region as a whole of the selected probability distribution. The different methods are compared and discussed in detail. It is observed that the flow for a given dependability increases with catchment area and decreases with altitude. The flows of the catchments at higher altitudes exhibit larger variability in comparison to the catchments at lower altitudes. The regional relationships are recommended for the use of field engineers.
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Wiejaczka, Łukasz, Paweł Prokop, Rafał Kozłowski et Subir Sarkar. « Reservoir’s Impact on the Water Chemistry of the Teesta River Mountain Course (Darjeeling Himalaya) ». Ecological Chemistry and Engineering S 25, no 1 (1 mars 2018) : 73–88. http://dx.doi.org/10.1515/eces-2018-0005.
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Abstract The article presents the role of the newly built reservoir in the formation of the hydrochemistry of water of the Teesta River (a tributary of the Brahmaputra) in its Himalayan course. Field research were performed in the post-monsoon season of the period 2013-2015. Sampling and measuring points were located in five points over 43 km of the Teesta River in the Darjeeling Himalaya. Analysis of water along of river longitudinal profile above and below the reservoir suggest that the reservoir caused decrease most of the basic ions concentrations (Cl−, K+, Na+, Mg2+, NO3− and PO43−). An inverse trend was observed only with respect to Ca2+, SO42− and NH4+. The dam does not influent on the F− concentration. The reservoir causes minor enrichment most of the heavy metals such Cu, Ni, Zn, Cr, Cd and Sr. The lower enrichment of Teesta water below the dam indicates the water self-purification processes for metals by the Teesta Reservoir. The changes of physicochemical properties and concentrations of ions caused by the reservoir are usually normalised by environmental factors before the Teesta River outlet from the Himalayas (within 15 km of the river).
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Kumar, Susheel, et Nitin Sharma. « The seismicity of central and north-east Himalayan region ». Contributions to Geophysics and Geodesy 49, no 3 (1 septembre 2019) : 265–81. http://dx.doi.org/10.2478/congeo-2019-0014.
Texte intégralRésumé :
Abstract The Himalayan range extends upto 2400 km arc from Indus river valley in the west to Brahmaputra river valley in the east of India. Due to distinct geological structures of Himalayan seismic belt, seismicity in Himalaya is inhomogeneous. The inhomogeneity in seismicity is responsible for a number of seismic gaps in the Himalayan seismic belt. Thus Iin the present study, we proposed the study of spatial and temporal evolution of seismicity in entire central and north-east Himalayan region by using Gutenberg-Richter relationship. A detailed study on the behavior of natural seismicity in and around the seismic gap regions is carried out. The study region is segmented in four meridional regions (A) 80°E to 83.5°E, (B) 83.5°E to 87.5°E, (C) 87.5°E to 90°E and (D) 90°E to 98°E along with a fixed latitude belt. The homogeneous catalogue with 3 ≤ Mb ≤ 6.5 is used for the spatial and temporal analysis of seismicity in terms of b-value. It is find out that pockets of lower b-values are coinciding over and around stress accumulated regions. The observed low b-value before occurrence of the Nepal earthquake of 25th April, 2015 supports the argument of impending occurrence of moderate to large magnitude earthquake in Sikkim and north-east Himalayan region in future.
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Sigdel, Ashok, et Tetsuya Sakai. « Sedimentary facies analysis of the fluvial systems in the Siwalik Group, Karnali River section, Nepal Himalaya, and their significance for understanding the paleoclimate and Himalayan tectonics ». Journal of Nepal Geological Society 51 (31 décembre 2016) : 11–26. http://dx.doi.org/10.3126/jngs.v51i0.24084.
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Fluvial sediments of the Siwalik successions in the Himalayan Foreland Basin are one of the most important continental archives for the history of Himalayan tectonics and climate change during the Miocene Period. This study reanalyzes the fluvial facies of the Siwalik Group along the Karnali River, where the large paleo-Karnali River system is presumed to have flowed. The reinterpreted fluvial system comprises fine-grained meandering river (FA1), flood-flow dominated meandering river with intermittent appearance of braided rivers (FA2), deep and shallow sandy braided rivers (FA3, FA4) to gravelly braided river (FA5) and finally debris-flow dominated braided river (FA6) facies associations, in ascending order. Previous work identified sandy flood-flow dominated meandering and anastomosed systems, but this study reinterprets these systems as a flood-flow dominated meandering river system with intermittent appearance of braided rivers, and a shallow sandy braided system, respectively. The order of the appearance of fluvial depositional systems in the Karnali River section is similar to those of other Siwalik sections, but the timing of the fluvial facies changes differs. The earlier appearance (3-4 Ma) of the flood-flow dominated meandering river system in the Karnali River section at about 13.5 Ma may have been due to early uplift of the larger catchment size of the paleo-Karnali River which may have changed the precipitation pattern i.e. intensification of the Indian Summer Monsoon. The change from a meandering river system to a braided river system is also recorded 1 to 3 Ma earlier than in other Siwalik sections in Nepal. Differential and diachronous activities of the thrust systems could be linked to change in catchment area as well as diachronous uplift and climate, the combination of which are major probable causes of this diachronity.
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Ahluwalia, Rajeev Saran, S. P. Rai, Sanjay K. Jain, Bhishm Kumar et D. P. Dobhal. « Assessment of snowmelt runoff modelling and isotope analysis : a case study from the western Himalaya, India ». Annals of Glaciology 54, no 62 (2013) : 299–304. http://dx.doi.org/10.3189/2013aog62a133.
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AbstractThe major river systems of India, i.e. the Indus, Ganga and Brahmaputra river systems originating in the Himalayan region, are considered the lifeline of the Indian subcontinent. The main sources maintaining the flow of the Himalayan rivers are snow/glacial melt runoff, rainfall runoff and base flow. The Beas River originates from Beas Kund Glacier in the Himalayan region and flows down to join the Sutlej River, which is a tributary of the Indus River system. In the present study two approaches, namely hydrologic modelling and isotope analysis, have been applied to estimate the contribution of snow and glacier melt. Samples of streamflow, rainfall and snow for isotopic analysis were collected daily from April to September and weekly from October to March during 2010 and 2011. The isotope analysis of samples reveals that the snow/glacier melt contribution to the Beas River at Manali is 50% of the total flow during these 2 years. Snowmelt runoff modelling has been carried out using the SNOWMOD model, and the snow/glacier melt runoff contribution is calculated to be 52% of the total flow during the same period. These findings indicate that the results obtained from the two approaches are similar.
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Dahlquist, Maxwell P., et A. Joshua West. « The imprint of erosion by glacial lake outburst floods in the topography of central Himalayan rivers ». Earth Surface Dynamics 10, no 4 (14 juillet 2022) : 705–22. http://dx.doi.org/10.5194/esurf-10-705-2022.
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Abstract. In steep landscapes, river incision sets the pace of landscape evolution. Transport of coarse sediment controls incision by evacuating material delivered to river channels by landslides. However, large landslide-derived boulders that impede bedrock erosion are immobile even in major runoff-driven floods. Glacial lake outburst floods (GLOFs) mobilize these boulders and drive incision, yet their role in regional-scale erosion is poorly understood, largely because of their rarity. Here, we find a topographic signature consistent with widespread GLOF erosion in the Nepal Himalaya. Our interpretations emerge from the analysis of normalized channel steepness patterns, knickpoint distributions, and valley wideness. In rivers with glaciated headwaters that generate GLOFs, valleys stay narrow and relatively free of sediment, with bedrock often exposed to erosion. In turn, tributaries to these valleys are steep, allowing less efficient erosional regimes to keep pace with GLOF-driven incision. Where GLOFs are less frequent, valleys are more alluviated and incision stalls. Our results suggest that the extent of headwater glaciation may play an important role in the erosion of Himalayan river valleys and deserves more attention in future work.
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Arfanuzzaman, Md. « Economics of transboundary water : an evaluation of a glacier and snowpack-dependent river basin of the Hindu Kush Himalayan region ». Water Policy 20, no 1 (21 décembre 2017) : 90–108. http://dx.doi.org/10.2166/wp.2017.071.
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Abstract The Himalayan rivers are recognized as a reliable source of water supply in the countries of the Hindu Kush Himalayan (HKH) region. Increasing need for food and energy for the growing population of the HKH region has stimulated water harvesting from the transboundary rivers and triggered water conflict, environmental degradation and socio-economic turmoil among the riparian nations. Teesta is one such mighty trans-Himalayan river flowing through India and Bangladesh and is recognized as a basin where there is increasing tension between these two nations. Due to upstream interventions including barrage, dam and hydropower construction, the lower riparian region of Bangladesh faces acute water stresses, which hamper the agricultural, fisheries and livelihood activities of the river-dependent communities and impede the economic prosperity of the greater north-west region. The study provides a robust outline of the transboundary nexus between India and Bangladesh, and identifies upstream intervention-induced economic loss and ecological deterioration in the lower Teesta basin. To encourage water collaboration between the riparian states, the study estimates the benefit of transboundary co-operation for the larger socio-economic prosperity and environmental sustainability in the Teesta basin of the Himalayan region, which is decidedly applicable to similar basins in the HKH region and the rest of the world.
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Biswas, Atrayee, Dipanjan Das Majumdar et Sayandeep Banerjee. « Morphometry Governs the Dynamics of a Drainage Basin : Analysis and Implications ». Geography Journal 2014 (7 mai 2014) : 1–14. http://dx.doi.org/10.1155/2014/927176.
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Mountainous rivers are the most significant source of water supply in the Himalayan provinces of India. The drainage basin dynamics of these rivers are controlled by the tectonomorphic parameters, which include both surface and subsurface characteristics of a basin. To understand the drainage basin dynamics and their usefulness in watershed prioritisation and management in terms of soil erosion studies and groundwater potential assessment and flood hazard risk reduction in mountainous rivers, morphometric analysis of a Himalayan River (Supin River) basin has been taken as a case study. The entire Supin River basin has been subdivided into 27 subwatersheds and 36 morphometric parameters have been calculated under four broad categories: drainage network, basin geometry, drainage texture, and relief characteristics, each of which is further grouped into five different clusters having similar morphometric properties. The various morphometric parameters have been correlated with each other to understand their underlying relationship and control over the basin hydrogeomorphology. The result thus generated provides adequate knowledge base required for decision making during strategic planning and delineation of prioritised hazard management zones in mountainous terrains.
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Buckton, Sebastian T., et Steve J. Ormerod. « Niche segregation of Himalayan river birds ». Journal of Field Ornithology 79, no 2 (juin 2008) : 176–85. http://dx.doi.org/10.1111/j.1557-9263.2008.00160.x.
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Jayaraman, K. S. « Lost Himalayan river found in Rajasthan ». Nature 330, no 6150 (décembre 1987) : 683. http://dx.doi.org/10.1038/330683a0.
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Thapliyal, Madhu, Bipin Kumar Sati, Ravi Kumar, Tribhuwan Chandra et Ashish Thapliyal. « DNA barcoding of fishes from River Song, Dehradun, Uttarakhand using mitochondrial cytochrome-c oxidase-I gene ». Environment Conservation Journal 14, no 3 (21 décembre 2013) : 113–21. http://dx.doi.org/10.36953/ecj.2013.14320.
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The entire Himalayan region is well known as a global hotspot for biodiversity. Many workers have documented different aspect of biodiversity. The Uttarakhand Himalaya region, a part of Himalayan system, is very rich in fresh water aquatic biodiversity because it has many fresh water streams and rivers within a short distance of 200 miles. All these fresh water bodies harbor diverse aquatic fauna with fishes being the most extensively studied. There are many fish species reported by many authors in Uttarakhand. Many of the fishes have similar morphological characters (morpho-metrics) and are difficult to identify. Attempts have been made to generate the DNA barcode of fishes but most of the attempt are limited to major rivers i.e. the Ganges and the Yamuna. Besides these two prominent river (the Ganges & the Yamuna), there are many supporting streams and small tributaries that are also inhabited by many species. No “long term” and “entire river scan” for fish species has ever been conducted in Uttarakhand. Our research aims to generate a molecular database (DNA Barcode) for entire fish species fauna in each small river/stream of Uttarakhand. Using a combination of morphometric & DNA bar-coding data will provide an efficient method for species level identification and contributes considerably to taxonomic and biodiversity research. The present study is first step towards establishing molecular taxonomy database of Uttarakhand based upon the bar coding pattern of cytochrome c oxidase I (COI) gene. We carried out an “entire river scan” of River Song (a tributary of river Ganges). 50 samples were collected from various sampling sites along the entire stretch of river and analyzed. Data was uploaded into the BOLD database and the analysis of data using this database suggests that the genetic variability (K2P distance) distribution of 50 individuals belonging with 15 species.The average intraspecific variation using K2P and NJ methods/models was assessed. The mean intraspecific distance was less than 1.45% for 32% of species. Mean K2P distance within species, genus and family was 0.1%, 16.3% and 21.70% respectively. Our results suggest that River Song has diverse fish fauna with substantial genetic diversity. Data from Barillius species suggests that this species has a very high variation. There is ahighly probability that as all the rivers are scanned new data on endemic and exotic fish fauna diversity will emerge which would be helpful in conservation efforts.
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Alford, D., et R. Armstrong. « The role of glaciers in stream flow from the Nepal Himalaya ». Cryosphere Discussions 4, no 2 (1 avril 2010) : 469–94. http://dx.doi.org/10.5194/tcd-4-469-2010.
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Abstract. Recent concerns related to the potential impacts of the retreat of Himalayan glaciers on the hydrology of rivers originating in the catchment basins of the Himalaya have been accompanied by few analyses describing the role of glaciers in the hydrologic regime of these mountains. This is, at least in part, a result of the relative inaccessibility of the glaciers of the Himalaya, at altitudes generally between 4000–7000 m, and the extreme logistical difficulties of: 1) reaching the glaciers, and 2) conducting meaningful research once they have been reached. It is apparent that an alternative to traditional "Alpine" glaciology is required in the mountains of the Hindu Kush-Himalaya region. The objectives of the study discussed here have been to develop methodologies that will begin to quantify the role of complete glacier systems in the hydrologic regime of the Nepal Himalaya, and to develop estimates of the potential impact of a continued retreat of these glacier, based on the use of disaggregated low-altitude data bases, topography derived from satellite imagery, and simple process models of water and energy exchange in mountain regions. While the extent of mesoscale variability has not been established by studies to date, it is clear that the dominant control on the hydrologic regime of the tributaries to the Ganges Basin from the eastern Himalaya is the interaction between the summer monsoon and the 8000 m of topographic relief represented by the Himalayan wall. All the available evidence indicates that the gradient of specific runoff with altitude resulting from this interaction is moderately to strongly curvilinear, with maximum runoff occurring at mid-altitudes, and minima at the altitudinal extremes. At the upper minimum of this gradient, Himalayan glaciers exist in what has been characterized as an "arctic desert". The methodologies developed for this study involve the relationship between area-altitude distributions of catchment basins and glaciers, based on Shuttle Radar Topography Mission (SRTM3) data and water and energy exchange gradients. Based on these methodologies, it is estimated that the contribution of glacier annual melt water to annual stream flow into the Ganges Basin from the glacierized catchments of the Nepal Himalaya represents approximately 4% of the total annual stream flow volume of the rivers of Nepal, and thus, is a minor component of the annual flow of the Ganges River. The models developed for this study indicate that neither stream flow timing nor volume of the rivers flowing into the Ganges Basin from Nepal will be affected materially by a continued retreat of the glaciers of the Nepal Himalaya.
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ZENTMYER, R., P. M. MYROW et D. L. NEWELL. « Travertine deposits from along the South Tibetan Fault System near Nyalam, Tibet ». Geological Magazine 145, no 6 (9 septembre 2008) : 753–65. http://dx.doi.org/10.1017/s0016756808005323.
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AbstractA newly investigated travertine deposit in southern Tibet provides a window into Holocene hydrological, geomorphic and climatic processes near the boundary of the Tibetan Plateau and High Himalaya. Travertine, deposited as a result of the degassing of CO2-rich groundwater as it emerges on the Earth's surface, is in many cases formed along the trace of major crustal-scale faults in primarily extensional tectonic regimes. A travertine platform measuring roughly 1 km by 0.5 km exists near the town of Nyalam in southern Tibet along a major Himalayan down-to-the-N normal fault, the South Tibetan Fault System. A wide variety of travertine depositional textures and features are recorded in the platform on a series of terraces. Active travertine deposition was observed from spring mounds and seeps along the base of the platform at the modern river level. Palaeotemperatures of spring water, calculated from δ18O of the travertine, range from 9 to 25 °C, which closely matches the temperatures recorded from modern springs in the area. A complex geomorphological landscape records interaction between growing alluvial fans, travertine accumulation, and a rapidly down-cutting river with associated fluvial terraces. River incision was contemporaneous with travertine deposition, as indicated by cemented fluvial river gravel layers interbedded with travertine. High 87Sr/86Sr ratios in the travertine (mean of 0.7168) indicate subsurface fluid interaction with radiogenic crystalline rocks of the underlying Greater Himalaya. Uranium-series ages of the travertine platform range from 5400 a (±950 a) to 11600 a (±1000 a), and indicate a younging progression from higher terraces near the valley wall to lower terraces at present-day river level. Travertine that overlies a river gravel terrace 18 m above river level formed at 11600 a. This date yields a local incision rate of 1.6 mm a−1, consistent with estimated fluvial incision rates in the High Himalaya. The range of our U-series ages coincides with an interval of higher precipitation associated with greater intensity of the Indian monsoon, which led to elevated spring discharge and carbonate precipitation in this part of the High Himalayas.
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Huber, Marius L., Maarten Lupker, Sean F. Gallen, Marcus Christl et Ananta P. Gajurel. « Timing of exotic, far-traveled boulder emplacement and paleo-outburst flooding in the central Himalayas ». Earth Surface Dynamics 8, no 3 (22 septembre 2020) : 769–87. http://dx.doi.org/10.5194/esurf-8-769-2020.
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Abstract. Large boulders, ca. 10 m in diameter or more, commonly linger in Himalayan river channels. In many cases, their lithology is consistent with source areas located more than 10 km upstream, suggesting long transport distances. The mechanisms and timing of “exotic” boulder emplacement are poorly constrained, but their presence hints at processes that are relevant for landscape evolution and geohazard assessments in mountainous regions. We surveyed river reaches of the Trishuli and Sunkoshi, two trans-Himalayan rivers in central Nepal, to improve our understanding of the processes responsible for exotic boulder transport and the timing of emplacement. Boulder size and channel hydraulic geometry were used to constrain paleo-flood discharge assuming turbulent, Newtonian fluid flow conditions, and boulder exposure ages were determined using cosmogenic nuclide exposure dating. Modeled discharges required for boulder transport of ca. 103 to 105 m3 s−1 exceed typical monsoonal floods in these river reaches. Exposure ages range between ca. 1.5 and 13.5 ka with a clustering of ages around 4.5 and 5.5 ka in both studied valleys. This later period is coeval with a broader weakening of the Indian summer monsoon and glacial retreat after the Early Holocene Climatic Optimum (EHCO), suggesting glacial lake outburst floods (GLOFs) as a possible cause for boulder transport. We, therefore, propose that exceptional outburst events in the central Himalayan range could be modulated by climate and occur in the wake of transitions to drier climates leading to glacier retreat rather than during wetter periods. Furthermore, the old ages and prolonged preservation of these large boulders in or near the active channels shows that these infrequent events have long-lasting consequences on valley bottoms and channel morphology. Overall, this study sheds light on the possible coupling between large and infrequent events and bedrock incision patterns in Himalayan rivers with broader implications for landscape evolution.
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Valdiya, K. S. « Emergence and evolution of Himalaya : reconstructing history in the light of recent studies ». Progress in Physical Geography : Earth and Environment 26, no 3 (septembre 2002) : 360–99. http://dx.doi.org/10.1191/0309133302pp342ra.
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India collided with mainland Asia at 65 Ma. The pressure rose to 9-11 kbar in the collision zone. As the Indian lithosphere bent down and its upper crust buckled up as an upwarp in the period 35-45 Ma, the southern margin of Asia became the water-divide of the Himalayan rivers. A variety of Eurasian fauna migrated to the Indian landmass. The southern margin of the Himalayan province synchronously sagged to give rise to the foreland basin that was linked with the Indian sea. In this Paleocene foreland basin 48-49 Ma ago, the whales from one of the species of the immigrant terrestrial mammals evolved. The sea retreated from the Himalayan province by the early Miocene, even as the crust broke up along faults 20-22 million years ago. The basement rocks, which had attained high-grade metamorphism at 600-800°C and 6-10 kbar, were thrust up to give rise to what later became the Himādri or Great Himalaya. Differential melting of the high-grade metamorphic rocks of the Himadri extensively produced 21 ± 1 Maold granites. Rivers carried detritus generated by the denudation of the fast emerging Himalaya and deposited it in the foreland basin which turned fluvial around 23 Ma. Another fluvial foreland basin, the Siwalik, was formed at ~18 Ma in front of the rapidly rising orogen and was filled by river-borne sediments at the rate of 20-30 cm year-1 in the early stage and at 50-55 cm year-1 later when the Himadri was uplifted and briskly exhumed in the Late Miocene (9-7.5 Ma). The Himadri then became high enough to cause disruption of wind circulation, culminating in the onset of monsoon. The climate change that followed caused migration of a variety of quadrupeds from Africa and Eurasia, bringing about considerable faunal turnovers in the Siwalik life. Spasmodic uplift of the outer ranges of the Lesser Himalaya and tectonic convulsion in the Siwalik domain at 1.6 Ma resulted in widespread landslides with debris flows and emplacement of the Upper Siwalik Boulder Conglomerate. Strong tectonic movements at 0.8 Ma caused the partitioning of the foreland basin into the rising Siwalik Hills and the subsiding IndoGangetic Plains, and also the initiation of glaciation in the uplifted domain of the Great Himalaya. After the end of the Pleistocene ice age around 0.2 Ma, there was oscillation of dry-cold and wet-warm climates. This climatic vicissitude is recorded in the sediments of the lakes that had formed because of reactivation of faults crossing rivers and streams. Activeness of faults, continuing uplift and current seismicity imply ongoing strain-buildup in the Himalayan domain.
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Wulf, H., B. Bookhagen et D. Scherler. « Climatic and geologic controls on suspended sediment flux in the Sutlej River Valley, western Himalaya ». Hydrology and Earth System Sciences 16, no 7 (20 juillet 2012) : 2193–217. http://dx.doi.org/10.5194/hess-16-2193-2012.
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Abstract. The sediment flux through Himalayan rivers directly impacts water quality and is important for sustaining agriculture as well as maintaining drinking-water and hydropower generation. Despite the recent increase in demand for these resources, little is known about the triggers and sources of extreme sediment flux events, which lower water quality and account for extensive hydropower reservoir filling and turbine abrasion. Here, we present a comprehensive analysis of the spatiotemporal trends in suspended sediment flux based on daily data during the past decade (2001–2009) from four sites along the Sutlej River and from four of its main tributaries. In conjunction with satellite data depicting rainfall and snow cover, air temperature and earthquake records, and field observations, we infer climatic and geologic controls of peak suspended sediment concentration (SSC) events. Our study identifies three key findings: First, peak SSC events (≥ 99th SSC percentile) coincide frequently (57–80%) with heavy rainstorms and account for about 30% of the suspended sediment flux in the semi-arid to arid interior of the orogen. Second, we observe an increase of suspended sediment flux from the Tibetan Plateau to the Himalayan Front at mean annual timescales. This sediment-flux gradient suggests that averaged, modern erosion in the western Himalaya is most pronounced at frontal regions, which are characterized by high monsoonal rainfall and thick soil cover. Third, in seven of eight catchments, we find an anticlockwise hysteresis loop of annual sediment flux variations with respect to river discharge, which appears to be related to enhanced glacial sediment evacuation during late summer. Our analysis emphasizes the importance of unconsolidated sediments in the high-elevation sector that can easily be mobilized by hydrometeorological events and higher glacial-meltwater contributions. In future climate change scenarios, including continuous glacial retreat and more frequent monsoonal rainstorms across the Himalaya, we expect an increase in peak SSC events, which will decrease the water quality and impact hydropower generation.
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Thakur, P. K., P. R. Dhote, A. Roy, S. P. Aggarwal, B. R. Nikam, V. Garg, A. Chouksey et al. « SIGNIFICANCE OF REMOTE SENSING BASED PRECIPITATION AND TERRAIN INFORMATION FOR IMPROVED HYDROLOGICAL AND HYDRODYNAMIC SIMULATION IN PARTS OF HIMALAYAN RIVER BASINS ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B3-2020 (21 août 2020) : 911–18. http://dx.doi.org/10.5194/isprs-archives-xliii-b3-2020-911-2020.
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Abstract. The Himalayan region are home to the world’s youngest and largest mountains, and origins of major rivers systems of South Asia. The present work highlight the importance of remote sensing (RS) data based precipitation and terrain products such as digital elevation models, glacier lakes, drainage morphology along with limited ground data for improving the accuracy of hydrological and hydrodynamic (HD) models in various Himalayan river basins such as Upper Ganga, Beas, Sutlej, Teesta, Koshi etc. The satellite based rainfall have mostly shown under prediction in the study area and few places have are also showing over estimation of rainfall. Hydrological modeling results were most accurate for Beas basin, followed by Upper Ganga basin and were least matching for Sutlej basin. Limited ground truth using GNSS measurements showed that digital elevation model (DEM) for carto version 3.1 is most accurate, followed by ALOS-PALSAR 12.5 DEM as compared to other open source DEMs. Major erosion and deposition was found in Rivers Bhagirathi, Alakhnanda, Gori Ganga and Yamuna in Uttarakhand state and Beas and Sutlej Rivers in Himachal Pradesh using pre and post flood DEM datasets. The terrain data and river cross section data showed that river cross sections and water carrying capacity before and after 2013 floods have changed drastically in many river stretches of upper Ganga and parts of Sutlej river basins. The spatio-temporal variation and evolution of glacier lakes was for lakes along with GLOF modeling few lakes of Upper Chenab, Upper Ganga, Upper Teesta and Koshi river basin was done using time series of RS data from Landsat, Sentinel-1 and Google earth images.
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Zaheer, Muhammad, Muhammad Rustam Khan, Muhammad Saleem Mughal, Hammad Tariq Janjuhah, Panayota Makri et George Kontakiotis. « Petrography and Lithofacies of the Siwalik Group in the Core of Hazara-Kashmir Syntaxis : Implications for Middle Stage Himalayan Orogeny and Paleoclimatic Conditions ». Minerals 12, no 8 (21 août 2022) : 1055. http://dx.doi.org/10.3390/min12081055.
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The present field and petrographic investigations of the Tortonian to Gelasian Siwalik Group in the core of the Hazara-Kashmir Syntaxis have been carried out to comprehend the middle stage Himalayan orogeny that resulted from the collision of Indian and Asian plates. The Chinji, Nagri, Dhok Pathan, and Soan Formations of the Siwalik Group were deposited by river meandering flood plains, braided rivers, and alluvial fan systems, respectively. The Siwalik Group is classified into seven major facies and many minor facies based on sedimentological properties. According to the petrographic analysis, the Siwalik Group sandstone is classified as litharenite and feldspathic litharenite petrofacies. The sandstone of the Siwalik Group is texturally mature, but compositionally it is immature. The data shown on the tectonic discrimination diagrams point to a recycled orogen provenance field for the Siwalik sandstone. In addition to quartz and feldspar, the sandstone includes clasts of volcanic, metamorphic, and sedimentary rock types. The igneous and metamorphic rock clasts were derived from the Lesser and Higher Himalayas. The sedimentary lithic fragments, on the other hand, are derived from both the earlier molasse and pre-molasse rocks. The presence of lithic fragments of the earlier molasse sandstone in the Siwalik sandstone indicates that the Siwalik Group sandstones were deposited during the Middle Stage of the Himalayan orogeny. The paleoclimatic conditions were semi-arid to semi-humid during the Siwalik Group’s deposition. The presence of clay minerals in the shale reveals the intense chemical weathering processes that occurred during their deposition on the flood plains of the river meandering system.
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Pal, I., U. Lall, A. W. Robertson, M. A. Cane et R. Bansal. « Predictability of Western Himalayan river flow : melt seasonal inflow into Bhakra Reservoir in northern India ». Hydrology and Earth System Sciences 17, no 6 (5 juin 2013) : 2131–46. http://dx.doi.org/10.5194/hess-17-2131-2013.
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Abstract. Snowmelt-dominated streamflow of the Western Himalayan rivers is an important water resource during the dry pre-monsoon spring months to meet the irrigation and hydropower needs in northern India. Here we study the seasonal prediction of melt-dominated total inflow into the Bhakra Dam in northern India based on statistical relationships with meteorological variables during the preceding winter. Total inflow into the Bhakra Dam includes the Satluj River flow together with a flow diversion from its tributary, the Beas River. Both are tributaries of the Indus River that originate from the Western Himalayas, which is an under-studied region. Average measured winter snow volume at the upper-elevation stations and corresponding lower-elevation rainfall and temperature of the Satluj River basin were considered as empirical predictors. Akaike information criteria (AIC) and Bayesian information criteria (BIC) were used to select the best subset of inputs from all the possible combinations of predictors for a multiple linear regression framework. To test for potential issues arising due to multicollinearity of the predictor variables, cross-validated prediction skills of the best subset were also compared with the prediction skills of principal component regression (PCR) and partial least squares regression (PLSR) techniques, which yielded broadly similar results. As a whole, the forecasts of the melt season at the end of winter and as the melt season commences were shown to have potential skill for guiding the development of stochastic optimization models to manage the trade-off between irrigation and hydropower releases versus flood control during the annual fill cycle of the Bhakra Reservoir, a major energy and irrigation source in the region.
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Pal, I., U. Lall, A. W. Robertson, M. A. Cane et R. Bansal. « Predictability of Western Himalayan River flow : melt seasonal inflow into Bhakra Reservoir in Northern India ». Hydrology and Earth System Sciences Discussions 9, no 7 (4 juillet 2012) : 8137–72. http://dx.doi.org/10.5194/hessd-9-8137-2012.
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Abstract. Snowmelt dominated streamflow of the Western Himalayan Rivers is an important water resource during the dry pre-monsoon spring months to meet the irrigation and hydropower needs in Northern India. Here we study the seasonal prediction of melt-dominated total inflow into the Bhakra Dam in Northern India based on statistical relationships with meteorological variables during the preceding winter. Total inflow into the Bhakra dam includes the Satluj River flow together with a flow diversion from its tributary, the Beas River. Both are tributaries of the Indus River that originate from the Western Himalayas, which is an under-studied region. Average measured winter snow volume at the upper elevation stations and corresponding lower elevation rainfall and temperature of the Satluj River basin were considered as empirical predictors. Akaike Information Criteria (AIC) and Bayesian Information Criteria (BIC) were used to select the best subset of inputs from all the possible combinations of predictors for a multiple linear regression framework. To test for potential issues arising due to multi-collinearity of the predictor variables, cross-validated prediction skills of best subset were also compared with the prediction skills of Principal Component Regression (PCR) and Partial Least Squares Regression (PLSR) techniques, which yielded broadly similar results. As a whole, the forecasts of the melt season at the end of winter and as the melt season commences were shown to have potential skill for guiding the development of stochastic optimization models to manage the trade-off between irrigation and hydropower releases versus flood control during the annual fill cycle of the Bhakra reservoir, a major energy and irrigation source in the region.
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Pal, Ranjana, Aashna Sharma, Vineet Kumar Dubey, Tapajit Bhattacharya, Jeyaraj Antony Johnson, Kuppusamy Sivakumar et Sambandam Sathyakumar. « A rare photographic record of Eurasian Otter Lutra lutra with a note on its habitat from the Bhagirathi Basin, western Himalaya, India ». Journal of Threatened Taxa 13, no 13 (26 novembre 2021) : 20072–77. http://dx.doi.org/10.11609/jott.6937.13.13.20072-20077.
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The Eurasian Otter Lutra lutra is an elusive, solitary animal that has one of the widest distributions of all palearctic mammals. Once widely distributed in Asia, the Eurasian Otter population is now vulnerable to urbanization, pollution, poaching, and dam construction. Eurasian Otter distribution in the Indian Himalayan rivers is little explored, and information from this high-altitude riverine ecosystem is sparse. This publication reports a rare photographic record of the Eurasian Otter which confirms its presence in the high-altitude temperate forest of the Upper Bhagirathi Basin, western Himalayan region. The otter was recorded during investigations of terrestrial and aquatic fauna in the Bhagirathi Basin (7,586 km2, 500–5,000 m) of Uttarakhand State, India from October 2015 to May 2019. Among aquatic fauna, Brown Trout were found to be abundant in high altitude river stretches, with a catch per unit effort of 1.02 kg h–1. Additionally, 26 families of freshwater macroinvertebrates underscored a rich diet available for the Brown Trout, which in turn is a potential food source for the otters. The riverine ecosystem is undergoing dramatic changes because of the increasing demand for hydropower plants in the Bhagirathi Basin. Although mitigation measures are currently in place for fish, the presence of otters further necessitates the need for targeted management for high-altitude Himalayan rivers. There is an imperative need for intensive otter surveys using methods such as camera traps in riparian habitats along the Bhagirathi River and its tributaries.
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Ojha, Hemant, Kaustuv Raj Neupane, Chandra Lal Pandey, Vishal Singh, Roshan Bajracharya et Ngamindra Dahal. « Scarcity Amidst Plenty : Lower Himalayan Cities Struggling for Water Security ». Water 12, no 2 (19 février 2020) : 567. http://dx.doi.org/10.3390/w12020567.
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In recent years, growing water insecurity in the Himalayan region has attracted new scientific research and fresh attention on policy. In this paper, we synthesize field research evidence from a sample of five Himalayan cities—three in Nepal and two in the western Indian Himalayas—on various forms of water insecurity and cities’ responses to such challenges. We gathered evidence from a field research conducted in these cities between 2014 and 2018. We show how different types of Himalayan towns (mainly hilltop, foot hill, river side, touristic, and regional trading hub) are struggling to secure water for their residents and tourists, as well as for the wider urban economy. We found that even though the region receives significant amounts of precipitation in the form of snow and rainfall, it is facing increasing levels of water insecurity. Four of the five towns we studied are struggling to develop well-performing local institutions to manage water supply. Worse still, none of the cities have a robust system of water planning and governance to tackle the water challenges emerging from rapid urbanization and climate change. In the absence of a coordinated water planning agency, a complex mix of government, community, and private systems of water supply has emerged in the Himalayan towns across both Nepal and India. There is clearly a need for strengthening local governance capacity as well as down-scaling climate science to inform water planning at the city level.
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Dey, Saptarshi, Rasmus C. Thiede, Arindam Biswas, Naveen Chauhan, Pritha Chakravarti et Vikrant Jain. « Implications of the ongoing rock uplift in NW Himalayan interiors ». Earth Surface Dynamics 9, no 3 (2 juin 2021) : 463–85. http://dx.doi.org/10.5194/esurf-9-463-2021.
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Abstract. The Lesser Himalaya exposed in the Kishtwar Window (KW) of the Kashmir Himalaya exhibits rapid rock uplift and exhumation (∼3 mm yr−1) at least since the late Miocene. However, it has remained unclear if it is still actively deforming. Here, we combine new field, morphometric and structural analyses with dating of geomorphic markers to discuss the spatial pattern of deformation across the window. We found two steep stream segments, one at the core and the other along the western margin of the KW, which strongly suggest ongoing differential uplift and may possibly be linked to either crustal ramps on the Main Himalayan Thrust (MHT) or active surface-breaking faults. High bedrock incision rates (>3 mm yr−1) on Holocene–Pleistocene timescales are deduced from dated strath terraces along the deeply incised Chenab River valley. In contrast, farther downstream on the hanging wall of the MCT, fluvial bedrock incision rates are lower (<0.8 mm yr−1) and are in the range of long-term exhumation rates. Bedrock incision rates largely correlate with previously published thermochronologic data. In summary, our study highlights a structural and tectonic control on landscape evolution over millennial timescales in the Himalaya.
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Lupker, Maarten, Christian France-Lanord et Bruno Lartiges. « Impact of sediment–seawater cation exchange on Himalayan chemical weathering fluxes ». Earth Surface Dynamics 4, no 3 (12 août 2016) : 675–84. http://dx.doi.org/10.5194/esurf-4-675-2016.
Texte intégralRésumé :
Abstract. Continental-scale chemical weathering budgets are commonly assessed based on the flux of dissolved elements carried by large rivers to the oceans. However, the interaction between sediments and seawater in estuaries can lead to additional cation exchange fluxes that have been very poorly constrained so far. We constrained the magnitude of cation exchange fluxes from the Ganga–Brahmaputra river system based on cation exchange capacity (CEC) measurements of riverine sediments. CEC values of sediments are variable throughout the river water column as a result of hydrological sorting of minerals with depth that control grain sizes and surface area. The average CEC of the integrated sediment load of the Ganga–Brahmaputra is estimated ca. 6.5 meq 100 g−1. The cationic charge of sediments in the river is dominated by bivalent ions Ca2+ (76 %) and Mg2+ (16 %) followed by monovalent K+ (6 %) and Na+ (2 %), and the relative proportion of these ions is constant among all samples and both rivers. Assuming a total exchange of exchangeable Ca2+ for marine Na+ yields a maximal additional Ca2+ flux of 28 × 109 mol yr−1 of calcium to the ocean, which represents an increase of ca. 6 % of the actual river dissolved Ca2+ flux. In the more likely event that only a fraction of the adsorbed riverine Ca2+ is exchanged, not only for marine Na+ but also Mg2+ and K+, estuarine cation exchange for the Ganga–Brahmaputra is responsible for an additional Ca2+ flux of 23 × 109 mol yr−1, while ca. 27 × 109 mol yr−1 of Na+, 8 × 109 mol yr−1 of Mg2+ and 4 × 109 mol yr−1 of K+ are re-absorbed in the estuaries. This represents an additional riverine Ca2+ flux to the ocean of 5 % compared to the measured dissolved flux. About 15 % of the dissolved Na+ flux, 8 % of the dissolved K+ flux and 4 % of the Mg2+ are reabsorbed by the sediments in the estuaries. The impact of estuarine sediment–seawater cation exchange appears to be limited when evaluated in the context of the long-term carbon cycle and its main effect is the sequestration of a significant fraction of the riverine Na flux to the oceans. The limited exchange fluxes of the Ganga–Brahmaputra relate to the lower than average CEC of its sediment load that do not counterbalance the high sediment flux to the oceans. This can be attributed to the nature of Himalayan river sediment such as low proportion of clays and organic matter.
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Wahid, S. M., A. B. Shrestha, M. S. R. Murthy, M. Matin, J. Zhang et O. Siddiqui. « Regional Water Security in the Hindu Kush Himalayan Region : Role of Geospatial Science and Tools ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-8 (28 novembre 2014) : 1331–40. http://dx.doi.org/10.5194/isprsarchives-xl-8-1331-2014.
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The Hindu Kush Himalayan (HKH) region is the source of ten large Asian river systems – the Amu Darya, Indus, Ganges, Brahmaputra (Yarlungtsanpo), Irrawaddy, Salween (Nu), Mekong (Lancang), Yangtse (Jinsha), Yellow River (Huanghe), and Tarim (Dayan), - and provides water, ecosystem services, and the basis for livelihoods to a population of around 0.2 billion people in the region. The river basins of these rivers provide water to 1.3 billion people, a fifth of the world’s population. Against this background, a comprehensive river basin program having current focus on the Koshi and Indus basins is launched at the International Center for Integrated Mountain Development (ICIMOD) as a joint scientific endeavour of several participating institutions from four regional countries of the HKH region. The river basin approach aims is to maximize the economic and social benefits derived from water resources in an equitable manner while conserving and, where necessary, restoring freshwater ecosystems, and improved understanding of upstream-downstream linkages. In order to effectively support river basin management satellite based multi sensor and multi temporal data is used to understand diverse river basin related aspects. We present here our recent experiences and results on satellite based rainfall and run off assessments, land use and land cover change and erosion dynamics, multi thematic water vulnerability assessments, space based data streaming systems for dynamic hydrological modelling, and potential applications of agent based models in effective local water use management.
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Wulf, H., B. Bookhagen et D. Scherler. « Climatic and geologic controls on suspended sediment flux in the Sutlej River Valley, western Himalaya ». Hydrology and Earth System Sciences Discussions 9, no 1 (11 janvier 2012) : 541–94. http://dx.doi.org/10.5194/hessd-9-541-2012.
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Abstract. The sediment flux through Himalayan rivers directly impacts water quality and is important for sustaining agriculture as well as maintaining drinking-water and hydropower generation. Despite the recent increase in demand for these resources, little is known about the triggers and sources of extreme sediment flux events, which lower water quality and account for extensive hydropower reservoir filling and turbine abrasion. Here, we present a comprehensive analysis of the spatiotemporal trends in suspended sediment flux based on daily data during the past decade (2001–2009) from four sites along the Sutlej River and from four of its main tributaries. In conjunction with satellite data depicting rainfall and snow cover, air temperature, earthquake records, and Schmidt hammer rock strength measurements, we infer climatic and geologic controls of peak suspended sediment concentration (SSC) events. Our study identifies three key findings: First, peak SSC events (≥99th SSC percentile) coincide frequently (57–80%) with heavy rainstorms and account for about 30% of the suspended sediment flux in the semi-arid to arid interior of the orogen. Second, we observe an increase of suspended sediment flux from the Tibetan Plateau to the Himalayan front at mean annual timescales. This sediment-flux gradient suggests that averaged, modern erosion in the western Himalaya is most pronounced at frontal regions, which are characterized by high monsoonal rainfall and thick soil cover. Third, in seven of eight catchments we find an anticlockwise hysteresis loop of annual sediment flux, which appears to be related to enhanced glacial sediment evacuation during late summer. Our analysis emphasizes the importance of unconsolidated sediments in the high-elevation sector that can easily be mobilized by hydrometeorological events and higher glacial-meltwater contributions.
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Saha, Ujwal Deep, et Soma Bhattacharya. « Reconstructing the channel shifting pattern of the Torsa River on the Himalayan Foreland Basin over the last 250 years ». Bulletin of Geography. Physical Geography Series 16, no 1 (18 juin 2019) : 99–114. http://dx.doi.org/10.2478/bgeo-2019-0007.
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Abstract The varied physiography, incidences of high seasonal discharge, influences of neo-tectonic activity and the young geological foundation with less consolidated cohesive and non-cohesive sediment have left the Himalayan foreland basin a formidable ground, where silt-laden rivers tend to migrate frequently. A set of maps prepared after 1764, space photographs captured in 1970 and current satellite images from 2015 and 2017 were studied to reconstruct the fluvial dynamics of the Torsa River on the foreland basin of Sikkim-Bhutan Himalaya considering a time span of nearly 250 years. Evidence collected from colonial literature, the above-mentioned satellite images and a field survey, were combined to verify results taken from the old maps used as the base of the study. The application of satellite remote sensing and analysis of the topographic signatures of the palaeo-courses in the form of the palaeo-levee, abandoned courses and ox-bow lakes were the major operational attributes in this study. As a consequence of the channel migration of Torsa River since 1764, the historical floodplain of Torsa has been topographically marked by beheaded old distributaries, a misfit channel system and the presence of abandoned segments. Morphometric changes in the old courses, major flood events and neo-tectonic activity guided an overall trend of channel migration eastwards and has led to a couple of channel oscillation events in the Torsa River over the last 250 years. The mechanism of the avulsion events was thoroughly driven by sedimentation-induced channel morphometric changes and occasional high discharge.
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Tsering, Tenzin, Mika Sillanpää, Satu-Pia Reinikainen et Mahmoud Abdel Wahed. « Metal Fractionation in Surface Sediments of the Brahmaputra River and Implications for Their Mobilization ». International Journal of Environmental Research and Public Health 17, no 24 (9 décembre 2020) : 9214. http://dx.doi.org/10.3390/ijerph17249214.
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The Brahmaputra River is the largest tropical river in India that flows along the Himalayan regions and it is the lifeline of millions of people. Metal fractionation in the Brahmaputra River’s surface sediments and its correlation with turbidity are assessed in this study. The interaction between metal fractions and the overlying water is studied using multivariate statistical analyses. The strong positive correlation between NH4 of the overlying water and the exchangeable fractions in sediments signifies that the metals in the exchangeable fractions can be substituted by NH4. Subsequently, these metals can be released into the overlying water. The fluctuation in turbidity from 73 to 875 NTU indicates a large variation in the suspended matter concentration, and a higher concentration of suspended matter could provide attachment sites for pollutants such as metals. Significant variation in turbidity manifests a potentially high risk of pollution. In addition, the observation of local people along the Brahmaputra River turning its color to muddy indicates the need for continuous monitoring of water quality and an assessment of pollution is crucial. Although the Brahmaputra River’s risk assessment code is at low risk, the exchangeable fractions of Ni and Zn are present at all sites. Thus, the Brahmaputra River requires early preventive measures and management strategies to control metal pollution. This study contributes to an understanding of the fluctuation of turbidity of a tropical river. We provide baseline data for policymakers, and the importance of further intensive studies on metal pollution in the Himalayan Rivers is highlighted.
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Gupta, Nishikant, Mark Everard, Ishaan Kochhar et Vinod Kumar Belwal. « Avitourism opportunities as a contribution to conservation and rural livelihoods in the Hindu Kush Himalaya - a field perspective ». Journal of Threatened Taxa 11, no 10 (26 août 2019) : 14318–27. http://dx.doi.org/10.11609/jott.4911.11.10.14318-14327.
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The Hindu Kush Himalaya is a biodiversity hotspot subject to multiple anthropogenic stressors, including hydropower plants, pollution, deforestation and wildlife poaching, in addition to changing climate. Bird photography tourism, as a locally important element of avitourism, has the potential to integrate sustainable development and wildlife conservation. We conducted field surveys around the reaches of four Indian Himalayan rivers—the Kosi, western Ramganga, Khoh, and Song—outside of protected national parks (the Corbett and Rajaji tiger reserves) to ascertain the distribution of bird species along river corridors that could be sites of avitourism. Species richness along the surveyed reaches were: Kosi (79), western Ramganga (91), Khoh (52), and Song (79). This study contributes critical data to the existing baseline information on the avifaunal species of Uttarakhand. It further discusses the possibility of developing avitourism for knowledge generation on species distribution and innovative livelihood options for local communities in Uttarakhand, reinforcing local vested interest in bird conservation. The findings have generic applicability worldwide.
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Gupta, Nishikant, Mark Everard, Ishaan Kochhar et Vinod K. Belwal. « Avitourism opportunities as a contribution to conservation and rural livelihoods in the Hindu Kush Himalaya - a field perspective ». Journal of Threatened Taxa 11, no 10 (26 août 2019) : 14328–33. http://dx.doi.org/10.11609/jott.4911.11.10.14328-14333.
Texte intégralRésumé :
The Hindu Kush Himalaya is a biodiversity hotspot subject to multiple anthropogenic stressors, including hydropower plants, pollution, deforestation and wildlife poaching, in addition to changing climate. Bird photography tourism, as a locally important element of avitourism, has the potential to integrate sustainable development and wildlife conservation. We conducted field surveys around the reaches of four Indian Himalayan rivers—the Kosi, western Ramganga, Khoh, and Song—outside of protected national parks (the Corbett and Rajaji tiger reserves) to ascertain the distribution of bird species along river corridors that could be sites of avitourism. Species richness along the surveyed reaches were: Kosi (79), western Ramganga (91), Khoh (52), and Song (79). This study contributes critical data to the existing baseline information on the avifaunal species of Uttarakhand. It further discusses the possibility of developing avitourism for knowledge generation on species distribution and innovative livelihood options for local communities in Uttarakhand, reinforcing local vested interest in bird conservation. The findings have generic applicability worldwide.
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Bhargava, Devendra Swaroop. « Nature and the Ganga ». Environmental Conservation 14, no 4 (1987) : 307–18. http://dx.doi.org/10.1017/s0376892900016829.
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The Ganga's unique and numerous virtues appear to be based on myths, but the reasons for its importance are traceable to scientific premises. The Ganga, symbolizing Indian culture and civilization, is regarded by the Hindus as the holiest amongst the rivers, and it is the Indo-Gangetic plain's most significant river owing to its mighty basin and course, and extraordinarily high self-purifying powers. The Ganga originates from Gangori in the Uttrakhand Himalayan glacier as an upland stream, emerges as a river of the plains at Rishikesh, and, after traversing almost the entirety of India from West to East, finally merges into the Bay of Bengal.
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DAS, SHYAMAL CHANDRA SUKLA, AMANULLAH KHAN, ABSAR ALAM, VINEET KUMAR DUBEY et KRIPAL DATT JOSHI. « Piscine diversity, Community structure and Distribution patterns of the West Ramganga River : A mid-Himalayan tributary of River Ganga ». Indian Journal of Animal Sciences 90, no 1 (18 février 2020) : 109–15. http://dx.doi.org/10.56093/ijans.v90i1.98240.
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The study documents the fish diversity, assemblage structure, distributional pattern and composition at different sampling sites along the stretches of the West Ramganga river of mid-Himalayas between 138 and 777 meters above sea level. Altogether 92 fish species representing 8 orders, 23 families and 64 genera were recorded. The most dominant family was Cyprinidae with 47 species (51%) followed by Bagridae with 7 fish species (8%). Labeo was the most dominant genera with 9 species, followed by Barilius (6), Garra and Mystus (4 species each). Species richness showed a trend of rapid decline along the altitude with highest records in the lowland sites, where ~93% of the total fish species recorded were between 138 and 320 masl. The Shannon Wiener Index (H’) was found to be maximum at R6 (3.254) followed by R7 (3.24) and R8 (3.074) sites, all constituting the lowland stretch of the river. Species composition showed a distinct assemblage of cold-water specific genera at higher elevation sites based on clustering As per IUCN status, one species each of endangered (Tor putitora) and vulnerable (Schizothorax richardsonii) category was reported from the river, while 6 species reported, fell into near threatened category (Tor tor, Labeo pangusia, Wallago attu, Ompok pabda, Hypophthalmichthys molitrix, Bagarius bagarius and Ailia colia). The high fish species richness in the river Ramganga provides an updated information for the policy makers to plan suitable conservation measures which is currently lacking in most of the threatened freshwater ecosystems especially in the Himalayan river basin.
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Quincey, Duncan J., Paul Kay, John Wilkinson, Laura J. Carter et Lee E. Brown. « High concentrations of pharmaceuticals emerging as a threat to Himalayan water sustainability ». Environmental Science and Pollution Research 29, no 11 (8 janvier 2022) : 16749–57. http://dx.doi.org/10.1007/s11356-021-18302-8.
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Abstract The sixth UN Sustainable Development Goal, Clean Water and Sanitation, directly underpins other goals of Health, Life in Water and Sustainable Cities. We highlight that poor sanitation, exemplified through some of the highest concentrations of pharmaceuticals ever detected in rivers, will amplify societal and environmental stress where climate-induced reductions in flow are predicted. Rapidly growing urban centres with inadequate water treatment works will need to prioritise water quality improvement before supply reductions become a reality. For 23 river locations within Kathmandu City and the Annapurna region, Nepal, we show the presence of 28 of 35 monitored human-use pharmaceuticals. Concentrations of antibiotics measured in this sampling campaign in both Kathmandu City (sulfamethazine, metronidazole and ciprofloxacin) and rural locations (ciprofloxacin) are in excess of predicted no effect concentrations, suggesting these sites are at risk of proliferating antimicrobial resistance as well as affecting other ecotoxicological endpoints. It is anticipated that climate-induced reductions in flow combined with contaminated river systems will amplify future societal and environmental stress.
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Penny, Gopal, Zubair A. Dar et Marc F. Müller. « Climatic and anthropogenic drivers of a drying Himalayan river ». Hydrology and Earth System Sciences 26, no 2 (24 janvier 2022) : 375–95. http://dx.doi.org/10.5194/hess-26-375-2022.
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Abstract. Streamflow regimes are rapidly changing in many regions of the world. Attribution of these changes to specific hydrological processes and their underlying climatic and anthropogenic drivers is essential to formulate an effective water policy. Traditional approaches to hydrologic attribution rely on the ability to infer hydrological processes through the development of catchment-scale hydrological models. However, such approaches are challenging to implement in practice due to limitations in using models to accurately associate changes in observed outcomes with corresponding drivers. Here we present an alternative approach that leverages the method of multiple hypotheses to attribute changes in streamflow in the Upper Jhelum watershed, an important tributary headwater region of the Indus basin, where a dramatic decline in streamflow since 2000 has yet to be adequately attributed to its corresponding drivers. We generate and empirically evaluate a series of alternative and complementary hypotheses concerning distinct components of the water balance. This process allows a holistic understanding of watershed-scale processes to be developed, even though the catchment-scale water balance remains open. Using remote sensing and secondary data, we explore changes in climate, surface water, and groundwater. The evidence reveals that climate, rather than land use, had a considerably stronger influence on reductions in streamflow, both through reduced precipitation and increased evapotranspiration. Baseflow analyses suggest different mechanisms affecting streamflow decline in upstream and downstream regions, respectively. These findings offer promising avenues for future research in the Upper Jhelum watershed, and an alternative approach to hydrological attribution in data-scarce regions.
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Saikia, Dipankar, M. Ravi Kumar et Arun Singh. « Palaeoslab and plume signatures in the mantle transition zone beneath Eastern Himalaya and adjoining regions ». Geophysical Journal International 221, no 1 (9 janvier 2020) : 468–77. http://dx.doi.org/10.1093/gji/ggaa012.
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SUMMARY A comprehensive data set of 73 876 high quality receiver functions computed using waveforms recorded by 327 broad-band seismic stations is used to investigate the mantle transition zone (MTZ) structure beneath the eastern Himalaya, southern Tibet, Assam valley and the previously unexplored Burmese arc and Bengal basin regions. A highly variable and perturbed mantle transition zone, with depressed 410 and 660 km discontinuities, is observed beneath the Bengal basin and to the east of the eastern Himalayan syntaxis. The 410 is elevated by ∼10 km along the Himalayan collision front, while it deviates in the range of ±5 km beneath most parts of Tibet and the Himalayan Foredeep. In northern Tibet and along the Red River Fault, delayed conversions from the 410 reveal a deepening of more than 10 km. The 410 and 660 km discontinuities are uplifted by nearly 10 km beneath the Arunachal Himalaya, due to the presence of a subducting Indian lithosphere, as evident in the regional tomographic images. We observe a thick (>20 km) transition zone beneath the Burmese Arc and close to the Tengchong volcano. An uplifted 410 together with a depressed 660 km discontinuity requires presence of lithospheric slabs within the MTZ. Delayed P-to-s conversions from the 410 and 660 km discontinuities in the proximity of the Jinsha suture zone seem to be consistent with the earlier results that invoke flow of a hot Tibetan asthenosphere into the mantle transition zone, as an explanation. Interestingly, results from the Bengal basin reveal a deepening (∼10 km) of both the 410 and 660 km discontinuities. Similar results from other plume affected regions prompt us to interpret this as a signature of the Kergulean plume.
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Azam, Mohd Farooq, Jeffrey S. Kargel, Joseph M. Shea, Santosh Nepal, Umesh K. Haritashya, Smriti Srivastava, Fabien Maussion et al. « Glaciohydrology of the Himalaya-Karakoram ». Science 373, no 6557 (10 juin 2021) : eabf3668. http://dx.doi.org/10.1126/science.abf3668.
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Understanding the response of Himalayan-Karakoram (HK) rivers to climate change is crucial for ~1 billion people who partly depend on these water resources. Policy-makers tasked with sustainable water resources management require an assessment of the rivers’ current status and potential future changes. We show that glacier and snow melt are important components of HK rivers, with greater hydrological importance for the Indus basin than for the Ganges and Brahmaputra basins. Total river runoff, glacier melt, and seasonality of flow are projected to increase until the 2050s, with some exceptions and large uncertainties. Critical knowledge gaps severely affect modeled contributions of different runoff components, future runoff volumes, and seasonality. Therefore, comprehensive field observation–based and remote sensing–based methods and models are needed.
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Rai, Raju, Basanta Paudel, Gu Changjun et Narendra Raj Khanal. « Change in the Distribution of National Bird (Himalayan Monal) Habitat in Gandaki River Basin, Central Himalayas ». Journal of Resources and Ecology 11, no 2 (3 avril 2020) : 223. http://dx.doi.org/10.5814/j.issn.1674-764x.2020.02.010.
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