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1.
Himalayan region has one of the largest concentrations of mountain glaciers whose areal extent is changing due to global warming. In order to assess future changes in glacier extent due to global warming, information about glacier depth and debris cover is important. In this paper, application of ground penetrating radar (GPR) is discussed to assess glacier depth and debris cover. This investigation was carried out at Patseo and Samudratapu glaciers in Himachal Pradesh (West Himalaya). Antennas of frequency 50 and 100 MHz have been used for glacier depth and 500 MHz for moraine depth estimation. GPR signatures of glaciers were collected and further analyzed using velocities of electromagnetic waves in different media. The depth of Patseo glacier was estimated as 40 m. However, depth of the larger Samudra Tapu glacier could not be estimated using 50 and 100 MHz antennas. The depth of moraines was estimated using 500 MHz antenna and it varies from 0.35 cm to 0.85 cm for medial and around 1–2 m for lateral moraine at the experimental site.  相似文献   

2.
Tons basin has the maximum share of glaciers, more than 50 glaciers, as well as glacierised area in Uttarakhand and Himachal Pradesh and the majority of the glaciers are of valley type. One of the important features of the glaciers of Tons valley is the presence of a thick mantle of supraglaciers moraine cover which can be attributed to the terrain characteristics, besides, the avalanche fed nature of the glaciers. The present study is the extraction of Glacio-geomorphological unit of Tons River basin based on the visual interpretation of remote sensing data. It was very much difficult in field, to extract all glacio-geomorphological units in glaciated area, but based on the remote sensing data, it becomes easy to identify. With the help of glacio-geomorphological map it has been found that four most important glaciers which fed the Tons River are Bandarpunch Glacier, Jaundar Bamak glacier, Jhajju Bamak and Tilku glacier. The tributaries of Tons River i.e. Harkidun Gad, Rupin Nadi and Supin Nadi are mainly fed by the mountain glaciers, valley glaciers and glacier lakes. The erosional terraces, glacio-fluvial terraces, open ??U?? shaped valleys, proglacial lake, lateral moraines, terminal moraines, palaeo-cirque and debris/talus cones are well developed in this glaciated regions. Glacio-geomorphic features are very much significant for palaeo-climatic reconstruction, showing variations, temporally and spatially. At the same time, these landforms, which are also altered by processes prevailing during interglacial period, helps in the geo-environment studies and glacier related problems like avalanches, global warming and cloudburst etc.  相似文献   

3.
Peri-glacial studies of the Samudra Tapu glacier reveal three stages of well preserved moraines which are also marked by fluvial overprinting. The signatures of fluvial outwashes over the otherwise morainal deposits have been utilized in estimating the extent of palaeo-lake in the valley of Samudra Tapu glacier of the Chandra basin. Distance and thickness of snout of the glacier and its morainal deposits is estimated by the Laser Range Finder. With the change in the position of the snout there is a change in the extent and orientation of the lake. Recent expedition to the glacier confirms this process to be continuing. The study is important in reconstructing formation of the lake with respect to snout position of the glacier. Based on ground truth, fast melting of the snout is confirmed from year 2004 onwards, with the development of fresh end/terminal moraine. The study reveals that the snout region of the Samudra Tapu glacier is thinning and retreating at an alarming rate and is enlarging the lake extent. The development of fresh terminal moraine has the potential to impound the fast melting glacial waters which in turn can pose serious threat to the downstream regions of the Chandra valley.  相似文献   

4.
The study of advancement and recession of the glaciers in the Himalayas is essential due to their contrasting response towards climatic change. In the present study, Survey of India (SOI) topographical maps of 1962, IRS: LISS-III image of 2001 and LANDSAT-5: TM (Thematic Mapper) image of 2009 were used to analyze the glacier fluctuations in a part of Zanskar valley. The analysis carried out on 212 glaciers indicated decrease of 57 km2 (8 %) of glacier area over many glacier which was partly compensated with area increase by 42 km2 (6 %) in other glaciers, resulting an overall glacier area decrease by only 15 km2 (2 %) from 1962–2001. Due to glacier fragmentation the number of glaciers increased from 212 in 1962 to 238 by 2001. Although majority of glaciers (88 %) exhibited retreat (up to 13 my?1), minor advancement (<15 my?1) also took place in few glaciers during this period. Advancement took place mainly in larger glaciers (2–5 km2 and >5 km2) located over wider altitudinal range (700 m–1,000 m) whereas smaller glaciers (<2 km2) with narrow altitudinal range (100 m–500 m) exhibited retreat. The supraglacial debris analysis indicated that percentage of debris cover over glaciers ranges from 1.43 % to 18.15 %. Smaller glaciers (<2 km2) were debris free in comparison to the larger glaciers (>5 km2). During 2001–2009 majority of the glaciers were apparently stable in terms of their area and snout position indicating less impact of climate forcing in parts of Zanskar valley as compared to other parts of the Himalaya.  相似文献   

5.
This work provides results and analysis of the behavior in a reconstituted debris covered glacier, Horcones Inferior (HIG). This glacier is located at 32° 41′ S and 69° 57′ W in the Aconcagua region, Mendoza, Argentina. The HIG has experienced surges events in 1984 and 2003. GNSS techniques and Digital Terrain Models (DTMs) derived from ASTER optical imagery, were used to detect movements and altimetric changes of the HIG in the 2001–2012 period. Based on a GNSS semi - continuous station, N and E mean velocities of 0.9 cm/d and 1.1 cm/d and in U direction were 1.1 cm/d and 1.5 cm/d were obtained respectively in 2009–2010 period. Additionally, GNSS profiles showed a velocity range between 0.5 cm/d and 2.8 cm/d. Finally, through a DTM comparison the altimetric change before and after the last surge in 2003 was obtained. The applied techniques allowed accurate and reliable change detection of the HIG.  相似文献   

6.
Abstract

SPOT multispectral and panchromatic data were evaluated to determine their utility to detect debris‐load characteristics of the Batura Glacier located in the Karakoram Himalaya. Debris‐depth measurements, surface samples, and ground photography were obtained and used with satellite‐derived information to produce supraglacial debris‐load and discharge estimates. Visual analysis of panchromatic data indicated that structural characteristics of the glacier exhibited unique textures associated with surface structure characteristics. Multispectral analysis revealed that stratified unsupervised classification of principal components can be used to produce classifications depicting supraglacial lithology and shallow debris‐load variability. Debris‐load discharge estimates ranged from 48–97 x 103 m3 yr1. These results indicate that SPOT multispectral data may be used to produce reasonable quantitative estimates of debris‐load characteristics for glacier mass balance and regional denudation studies.  相似文献   

7.
In this study ascending and descending passes interferometric synthetic aperture radar (InSAR) techniques are used for glacier surface velocity estimation in the Himalaya. Single-track interferometric measurements are sensitive to only a single component of the three dimensional (3-D) velocity vectors. European Remote Sensing satellites (ERS-1/2) tandem mission data in ascending and descending tracks provide an opportunity to resolve the three velocity components under the assumption that glacier flow is parallel to its surface. Using the surface slope as an essential input in this technique the velocity pattern of Siachen glacier in Himalaya has been modelled. Glaciers in the Himalayan region maintain excellent coherence of SAR return signals in one-day temporal difference. As a result we could obtain spatially continuous surface velocity field with a precision of fraction of radar wavelength. The results covering the main course of glacier are analysed in terms of spatial and temporal variations. A maximum velocity of 43 cm/day has been observed in the upper middle portion of the glacier. This technique has been found accurate for monitoring the flow rates in this region, suggesting that routine monitoring of diurnal movement Himalayan glaciers would be immensely useful in the present day context of climate change.  相似文献   

8.
In this study an attempt is made for studying the Himalayan glacier features using TerraSAR-X and Indian Remote Sensing Satellite, Linear Imaging Self Scanning System III (IRS LISS –III) images. New generation, synthetic aperture radar (SAR) data from TerraSAR-X (TS-X) sensor provide opportunity for glacier feature studies in Himalayan rugged terrain. Spot Light High resolution mode TS-X data give idea about glacial features which remained untraceable from other existing SAR system. However, presence of speckle noise in SAR images degrades the interpretability of the glacier features. Speckle suppression filters (Lee, Frost, Enhanced Lee, Gamma-Map) are applied on SAR intensity images. On the basis of field sight seeing and insitu observations it is observed that still features are not clear. Hence attempt has been made for fusing multitemporal multispatial speckle reduced TS-X SAR data and multispectral IRS LISS-III data for extracting the glacial features such as crevasses, exposed ice and superaglacier lakes. Principal component analysis (PCA) represents the high spectral resolution data in a linear subspace with minimum information loss. Herein, PCA based image fusion technique is adopted for this study and comparison is made between IHS fusion technique and PCA based technique for glacier studies in the Himalayan region.  相似文献   

9.
为研究泥石流灾害对西藏雅鲁藏布江林芝-加查段沿线的影响与危害,基于遥感手段开展了林芝-加查段沿线泥石流源地物源及冰川水文信息特征的提取研究与分析。研究结果表明:林芝-加查段沿线泥石流源地物源分布具有不均匀性;源地冰川分布具有不平衡性;沿线泥石流源地的物源在冰川融水及冰川型泥石流过后更加发育,积累的松散物质更加丰富,导致泥石流源地物源进一步复活并产生大量新物源,从而使沿线泥石流发生频率增高,规模增大。  相似文献   

10.
The present work evaluates the applicability of operational land imager (OLI) and thermal infrared sensor (TIRS) on-board Landsat 8 satellite. We demonstrate an algorithm for automated mapping of glacier facies and supraglacial debris using data collected in blue, near infrared (NIR), short wave infrared (SWIR) and thermal infrared (TIR) bands. The reflectance properties in visible and NIR regions of OLI for various glacier facies are in contrast with those in SWIR region. Based on the premise that different surface types (snow, ice and debris) of a glacier should show distinct thermal regimes, the ‘at-satellite brightness temperature’ obtained using TIRS was used as a base layer for developing the algorithm. This base layer was enhanced and modified using contrasting reflectance properties of OLI bands. In addition to facies and debris cover characterization, another interesting outcome of this algorithm was extraction of crevasses on the glacier surface which were distinctly visible in output and classified images. The validity of this algorithm was checked using field data along a transect of the glacier acquired during the satellite pass over the study area. With slight scene-dependent threshold adjustments, this work can be replicated for mapping glacier facies and supraglacial debris in any alpine valley glacier.  相似文献   

11.
本文基于30景Sentinel-1影像,首先采用SBAS-InSAR技术反演了2018年4-10月雅鲁藏布江色东普流域灾前冰川形变,并利用非冰雪覆盖的基岩区形变结果进行可靠性检验,得出均方根误差为9 mm,表明SBAS-InSAR技术应用于冰川形变监测具有较高的可靠性。然后分析了升降轨数据对不同坡向形变监测的敏感性,以及冰川碎屑流灾害发生前冰川形变的空间分布与时间演化特征。结果表明,冰川运动的主流线在东西坡交汇的中轴部,研究区平均形变量达-34.8 mm。在典型剖面上,随着海拔逐渐降低,冰川形变呈先缓慢减少,后快速增加,再缓慢减少的趋势,平均形变量为-50.1 mm。冰川碎屑流灾害发生前冰川形变已有明显的加速趋势,可为冰川灾害早期识别提供科学的数据支持。  相似文献   

12.
Glaciers are widely recognized as key indicators of climate change, and melt water obtained from them is an important source of fresh water and for hydropower generation. Regular monitoring of a large number of Himalayan glaciers is important for improving our knowledge of glacier response to climate change. In the present study, Survey of India topographical maps (1966) and Landsat datasets as ETM+ (2000, 2006) and TM (2011) have been used to study glacier fluctuations in Tirungkhad basin. A deglaciation of 26.1% (29.1?km2) in terms of area from 1966 to 2011 was observed. Lower altitude small glaciers (area?<?1?km2) lost more ice (34%), while glaciers with an area <10?km2 lost less (20%). The percentage of change in glacier length was 26% (31.9?km) from 1966 to 2011. The south-facing glaciers showed high percentages of loss. From 2000 to 2011, debris cover has increased by 1.34%. The analysis of the trend in meteorological data collected from Kalpa and Purbani stations was carried out by Mann Kendall non-parametric method. During the last two decades, the mean annual temperature (Tmax and Tmin) has increased significantly, accompanied with a fall in snow water equivalent (SWE) and rainfall. The increasing trend in temperature and decreasing trend in SWE were significant at 95% confidence level. This observation shows that the warming of the climate is probably one of the major reasons for the glacier change in the basin.  相似文献   

13.
Glacial mapping is difficult and hazardous because of the remoteness and inaccessibility of the terrain. In this context, remotely-sensed data from satellites provide valuable information on glaciers and the associated landforms. It is important to note that judicious selection of spectral bands is critical in mapping the glacial features. Glacial landforms in parts of Gangotri glacier, NW Himalaya, have been delineated using selected bands of Landsat Thematic Mapper Data. Digital image processing of Landsat data has helped in identifying the major features of the Gangotri glacier such as accumulation and ablation zones, and glacial moraines. The study shows that Thematic Mapper bands 4, 5 and 7 are more useful in snow mapping because of their distinct spectral discriminability in identifying the glacial features.  相似文献   

14.
Snow physical properties, snow cover and glacier facies are important parameters which are used to quantify snowpack characteristics, glacier mass balance and seasonal snow and glacier melt. This study has been done using C-band synthetic aperture radar (SAR) data of Indian radar imaging satellite, radar imaging satellite-1 (RISAT)-1, to estimate the seasonal snow cover and retrieve snow physical properties (snow wetness and snow density), and glacier radar zones or facies classification in parts of North West Himalaya (NWH), India. Additional SAR data used are of Radarsat-2 (RS-2) satellite, which was used for glacier facies classification of Smudra Tapu glacier in Himachal Pradesh. RISAT-1 based snow cover area (SCA) mapping, snow wetness and snow density retrieval and glacier facies classification have been done for the first time in NWH region. SAR-based inversion models were used for finding out wet and dry snow dielectric constant, dry and wet SCA, snow wetness and snow density. RISAT-1 medium resolution scan-SAR mode (MRS) in HV polarization was used for first time in NWH for deriving time series of SCA maps in Beas and Bhagirathi river basins for years 2013–2014. The SAR-based inversion models were implemented separately for RISAT-1 quad pol. FRS2, for wet snow and dry snow permittivity retrieval. Masks for layover and shadow were considered in estimating final snow parameters. The overall accuracy in terms of R2 value comes out to be 0.74 for snow wetness and 0.72 for snow density based on the limited ground truth data for subset area of Manali sub-basin of Beas River up to Manali for winter of 2014. Accuracy for SCA was estimated to be 95 % when compared with optical remote sensing based SCA maps with error of ±10 %. The time series data of RISAT-1 MRS and hybrid data in RH/RV mode based decompositions were also used for glacier radar zones classification for Gangotri and Samudra Tapu glaciers. The various glaciers radar zones or facies such as debris covered glacier ice, clean or bare glacier ice radar zone, percolation/refreeze radar zone and wet snow, ice wall etc., were identified. The accuracy of classified maps was estimated using ground truth data collected during 2013 and 2014 glacier field work to Samudra Tapu and Gangotri glaciers and overall accuracy was found to be in range of 82–90 %. This information of various glacier radar zones can be utilized in marking firn line of glaciers, which can be helpful for glacier mass balance studies.  相似文献   

15.
To account for the variable response of the Himalayan glaciers towards climatic warming during the recent past, an attempt has been made in the present study to evaluate the changes in glacier area and shift in glacier snout position of selected glaciers in a part of the Greater Himalayan Range (GHR), Jammu & Kashmir (J&K), India. Multi-temporal satellite images of different years viz. 1975, 1989, 1992, 2001 and 2007 were used for mapping the boundaries of glaciers. Among the three observation periods (1975–1989/1992, 1989/1992–2001 and 2001–2007), during 1989/1992–2001 the majority of the glaciers exhibited considerable decrease in area. In contrast during 2001–2007, some glaciers exhibited increase in area indicating comparatively cooler climatic conditions as compared to the previous period. With reference to snout retreat, all the glaciers had a fluctuating trend of retreat during the observation periods although the retreat rate was higher during 1989/1992–2001 in some glaciers.  相似文献   

16.
Using Landsat data at decadal interval (1980–2013), the glacier fluctuations (glacier area, equilibrium line altitude and specific mass balance) of nine benchmark glaciers in Kashmir Himalaya were estimated. The observed changes were related to topographic and climatic variables in order to understand their influence. From the data analysis, it was observed that the glaciers have shrunk by 17%, ELA has shifted upwards (80–300 m) and SMB shows variation in glacier mass loss from ?0.77 to ?0.16 m.w.e. Annual air temperature showed a significant increasing trend, and a slight but insignificant decrease in precipitation was observed during the period. It is evident that in the same climatic regime, varying topography plays a key role in determining the glacier changes. It is believed that the observed changes in the glacier geometry and dynamics, if continued, shall have adverse effect on the streamflows, water supplies and other dependent sectors in the region.  相似文献   

17.
Abstract

This paper documents ongoing glacier retreat in the eastern part of the Granatspitz Mountains (Hohe Tauern Range, Austrian Alps) for the time period 2003–2009 using aerial photogrammetry. Aerial photographs of 2003, 2006, and 2009 were made available by the Hydrological Service of the Regional Government of Salzburg, the Federal Office of Metrology, Surveying and Mapping, Vienna, and the Regional Government of the Tyrol, respectively. High resolution multi-temporal digital elevation models and digital orthophotos of the area of interest were derived using digital photogrammetric methods to provide a sound basis for glaciological research. Glacier outlines of the three glacial stages were mapped interactively. Temporal change in area and surface height of the glaciers mapped clearly document glacier retreat. Glacier mass balance based on the geodetic method was calculated for Stubacher Sonnblickkees (Glacier). Mean annual specific net balance amounts to ?656 mm w.e. for the time period 2003–2009, with a mass balance gradient of 324 mm w.e. (100 m)?1 and an equilibrium-line altitude of 2995 m a.s.l. Digital orthophoto maps and other thematic maps, e.g. showing surface height change, were prepared to support further data interpretation. Both the study area and its spatio-temporal change were visualized with special emphasis on the glaciers in a computer generated video film. Another film (exposure 29 August 2011) shows the lower part of Stubacher Sonnblickkees and its surroundings for reasons of comparison.  相似文献   

18.
Countries like Iran, which are geographically situated in a rather arid and warm regions, will suffer more from global warming than countries located in humid and semi-humid regions. In such environments, analyzing the variations of mountain glaciers can reveal several aspects of climate change patterns more efficiently in comparison to the other geo-indicators. The present study reports some evidence of changes for Alamkouh glacier between 1955 and 2010 based on several mediums to high-resolution satellite images. Considering that most part of the Alamkouh glacier is covered by debris and delineating its actual area is not possible, planimetric change analysis was restricted to the clean-ice regions. The object-oriented classification approach was used to estimate the clean ice areas. This technique takes into account the shapes of the features along with their spectral patterns. Results revealed that clean ice regions of Alamkouh glacier shrank since 1955 with an overall area reduction of about 59 %. Although the general observed trend is a clean ice area reduction, some advancement was detected over the period from 2000 to 2010. During 1992–2000, the maximum reduction in the clean ice area was observed (0.08 km2.a?1). However, clean ice area of the case study has partially increased about 0.028 km2.a?1 from 2000 to 2010. Supra-glacial lake change analysis illustrated that at the surface of the glacier, lakes have been enlarged remarkably in the past 55 years (about 4.75 times greater). In addition, clean ice area and the surface area of supra-glacial lakes oscillated in compliance with each other. The findings revealed that the maximum expansion of supra-glacial lake occurred during 1992–2000, which demonstrate the glacier maximum reduction during this period. This shrinkage in the Alamkouh glacier caused an extensive glacial lake outburst flood in Jun 2011. The results of this study agree with documented changes in other mountain glaciers located in arid and semi-arid environments and they also confirm the application of mountain glaciers in climate variations monitoring over such regions.  相似文献   

19.
The contribution of snow and ice melt towards the water discharges of most of the Himalayan rivers is highly significant. It is, therefore, necessary to monitor the snow accumulation and depletion, and study the melting processes to help in efficient management of water resources. It is also important to compile a glacier inventory for the purpose. The snow bound areas in the Himalaya lie at high altitudes where the terrain is rugged and inaccessible. This renders the conventional methods of study not only difficult but hazardous as well. Remote sensing techniques, therefore, have a vital role to play in these studies for quick results with much less cost. Visual interpretation of Landsat imagery in Beas river basin and use of aerial photographs for glacier inventory in Baspa river basin have been cited as case studies. To perfect the methodology used in various remote sensing techniques, a pilot project approach has been suggested.  相似文献   

20.
Himalayas possess one of the largest resources of snow, ice and glaciers that act as a huge freshwater reservoir. Monitoring the glaciers is important to assess the overall reservoir health of the Himalayas. Samudra Tapu is one of the largest glaciers in Chandra basin of district Lahaul and Spiti, Himachal Pradesh. Based on the field investigations and the remote sensing techniques. features such as accumulation area, ablation area snowline/equilibrium line, moraine-dammed lakes and permanent snowfields were mapped. The glacial terminus was identified using moraine-dammed lake, as lake is located at down streamside of the terminus. The total recession of glacier during the period of 38 years (1962–2000) is about 742 m with an average rate of 19.5 m/yr. In addition, glacial extent is reduced from 73 to 65 km2 between 1962 and 2000. suggesting overall deglaciation of 11%. During field investigation. three stages of glaciation using terminal moraine were identified. These moraines were mapped by merging LISS-II1 and PAN data. At the peak of glaciation. the glacial terminus was extended 3.18 km downstream of terminus position in year 2000. Total area during peak of glaciation period has been observed to be 77.67 km2, which is 12.67 km2 higher than the present glacier extent.  相似文献   

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