scholarly journals Glacier Area and Snow Cover Changes in the Range System Surrounding Tarim from 2000 to 2020 Using Google Earth Engine

2021 ◽  
Vol 13 (24) ◽  
pp. 5117
Author(s):  
Jing Zhang ◽  
Li Jia ◽  
Massimo Menenti ◽  
Jie Zhou ◽  
Shaoting Ren
Keyword(s):  
Snow Cover ◽  
Tarim Basin ◽  
Reduction Rate ◽  
Google Earth ◽  
Tien Shan ◽  
Relative Reduction ◽  
Landsat 8 ◽  
Glacier Area ◽  
The West ◽  
Snow Cover Area

Glacier and snow are sensitive indicators of regional climate variability. In the early 21st century, glaciers in the West Kunlun and Pamir regions showed stable or even slightly positive mass budgets, and this is anomalous in a worldwide context of glacier recession. We studied the evolution of snow cover to understand whether it could explain the evolution of glacier area. In this study, we used the thresholding of the NDSI (Normalized Difference Snow Index) retrieved with MODIS data to extract annual glacier area and snow cover. We evaluated how the glacier trends related to snow cover area in five subregions in the Tarim Basin. The uncertainty in our retrievals was assessed by comparing MODIS results with the Landsat-5 TM in 2000 and Landsat-8 OLI in 2020 glacier delineation in five subregions. The glacier area in the Tarim Basin decreased by 1.32%/a during 2000–2020. The fastest reductions were in the East Tien Shan region, while the slowest relative reduction rate was observed in the West Tien Shan and Pamir, i.e., 0.69%/a and 1.08%/a, respectively, during 2000–2020. The relative glacier stability in Pamir may be related to the westerlies weather system, which dominates climate in this region. We studied the temporal variability of snow cover on different temporal scales. The analysis of the monthly snow cover showed that permanent snow can be reliably delineated in the months from July to September. During the summer months, the sequence of multiple snowfall and snowmelt events leads to intermittent snow cover, which was the key feature applied to discriminate snow and glacier.

scholarly journals A Conditional Probability Interpolation Method Based on a Space-Time Cube for MODIS Snow Cover Products Gap Filling

2020 ◽  
Vol 12 (21) ◽  
pp. 3577
Author(s):  
Siyong Chen ◽  
Xiaoyan Wang ◽  
Hui Guo ◽  
Peiyao Xie ◽  
Jian Wang ◽  
...  
Keyword(s):  
Snow Cover ◽  
Conditional Probability ◽  
Interpolation Method ◽  
Space Time ◽  
Landsat 8 ◽  
Snow Cover Area ◽  
Northern Xinjiang ◽  
Central Pixel ◽  
Snow Cover Extent ◽  
Snow Condition

Seasonal snow cover is closely related to regional climate and hydrological processes. In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) daily snow cover products from 2001 to 2018 were applied to analyze the snow cover variation in northern Xinjiang, China. As cloud obscuration causes significant spatiotemporal discontinuities in the binary snow cover extent (SCE), we propose a conditional probability interpolation method based on a space-time cube (STCPI) to remove clouds completely after combining Terra and Aqua data. First, the conditional probability that the central pixel and every neighboring pixel in a space-time cube of 5 × 5 × 5 with the same snow condition is counted. Then the snow probability of the cloud pixels reclassified as snow is calculated based on the space-time cube. Finally, the snow condition of the cloud pixels can be recovered by snow probability. The validation experiments with the cloud assumption indicate that STCPI can remove clouds completely and achieve an overall accuracy of 97.44% under different cloud fractions. The generated daily cloud-free MODIS SCE products have a high agreement with the Landsat–8 OLI image, for which the overall accuracy is 90.34%. The snow cover variation in northern Xinjiang, China, from 2001 to 2018 was investigated based on the snow cover area (SCA) and snow cover days (SCD). The results show that the interannual change of SCA gradually decreases as the elevation increases, and the SCD and elevation have a positive correlation. Furthermore, the interannual SCD variation shows that the area of increase is higher than that of decrease during the 18 years.

scholarly journals Snow-Cover Area and Runoff Variation under Climate Change in the West Kunlun Mountains

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2246 ◽  
Author(s):  
Ma ◽  
Yan ◽  
Zhao ◽  
Kundzewicz
Keyword(s):  
Climate Change ◽  
Snow Cover ◽  
River Basin ◽  
River Flow ◽  
Initial Increase ◽  
Runoff Generation ◽  
The West ◽  
Snow Cover Area ◽  
Kunlun Mountains ◽  
West Kunlun

In recent years, the climate in the arid region of Northwest China has become warmer and wetter; however, glaciers in the north slope of the West Kunlun Mountains (NSWKM) show no obvious recession, and river flow is decreasing or stable. This contrasts with the prevalent response of glaciers to climate change, which is recession and initial increase in glacier discharge followed by decline as retreat continues. We comparatively analyzed multi-timescale variation in temperature–precipitation–snow cover-runoff in the Yarkant River Basin (YRK), Karakax River Basin (KRK), Yurungkax River Basin (YUK), and Keriya River Basin (KRY) in the NSWKM. The Mann–Kendall trend and the mutation–detection method were applied to data obtained from an observation station over the last 60 years (1957–2017) and MODIS snow data (2001–2016). NSWKM temperature and precipitation have continued to increase for nearly 60 years at a mean rate of 0.26 °C/decade and 5.50 mm/decade, respectively, with the most obvious trend (R2 > 0.82) attributed to the KRK and YUK. Regarding changes in the average snow-cover fraction (SCF): YUK (SCF = 44.14%) > YRK (SCF = 38.73%) > KRY (SCF = 33.42%) > KRK (SCF = 33.40%). Between them, the YRK and YUK had decreasing SCA values (slope < −15.39), while the KRK and KRY had increasing SCA values (slope > 1.87). In seasonal variation, the SCF of the three of the basins reaches the maximum value in spring, with the most significant performance in YUK (SCF = 26.4%), except for YRK where SCF in spring was lower than that in winter (−2.6%). The runoff depth of all river basins presented an increasing trend, with the greatest value appearing in the YRK (5.78 mm/decade), and the least value in the YUK (1.58 mm/decade). With the runoff response to climate change, temperature was the main influencing factor of annual and monthly (summer) runoff variations in the YRK, which is consistent with the runoff-generation rule of rivers in arid areas, which mainly rely on ice and snow melt for water supply. However, this rule was not consistent for the YUK and KRK, as it was disturbed by other factors (e.g., slope and slope direction) during runoff generation, resulting in disruptions of their relationship with runoff. This research promotes the study of the response of cold and arid alpine regions to global change and thus better serve regional water resources management.

scholarly journals Characterizing the May 2015 Karayaylak Glacier surge in the eastern Pamir Plateau using remote sensing

2016 ◽  
Vol 62 (235) ◽  
pp. 944-953 ◽  
Author(s):  
DONGHUI SHANGGUAN ◽  
SHIYIN LIU ◽  
YONGJIAN DING ◽  
WANQIN GUO ◽  
BAIQING XU ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Branch Length ◽  
Active Phase ◽  
Landsat 8 ◽  
Glacier Area ◽  
Landsat 8 Oli ◽  
The West ◽  
Automatic Feature Extraction ◽  
The Media ◽  
Summer Pasture

ABSTRACTWe investigate an internal surge of Karayaylak Glacier, which was reported by the media in May 2015. To differentiate the May 2015 glacier surge from other glacier advances, we surveyed changes in velocity, crevasses and glacier area using Landsat 8 OLI L1T, ZY-1-02C and Gaofen-1 images from October 2014 to July 2015. The velocity, measured by automatic feature extraction and tracking during the active phase, was 10–100 times the velocity during the quiescent phase, with a maximum of (20.2 ± 0.9) m d−1 (mean ± standard error) from 8 to 15 May 2015 in the west branch of the glacier. The surge initiation and termination took place from 13 April to 16 June 2015. Ice in the west branch (length, 7 km; area, 6.8 km2) of Karayaylak Glacier accelerated down to the east branch, leading to the development of crevasses and ice covering an additional 0.1 km2 of summer pasture on the northwestern side. However, we detected no advance of the glacier's terminus.

scholarly journals Changes in Snow Cover Dynamics over the Indus Basin: Evidences from 2008 to 2018 MODIS NDSI Trends Analysis

2020 ◽  
Vol 12 (17) ◽  
pp. 2782
Author(s):  
Sikandar Ali ◽  
Muhammad Jehanzeb Masud Cheema ◽  
Muhammad Mohsin Waqas ◽  
Muhammad Waseem ◽  
Usman Khalid Awan ◽  
...  
Keyword(s):  
Time Series ◽  
Snow Cover ◽  
River Basins ◽  
Google Earth ◽  
Indus Basin ◽  
Least Squares Regression ◽  
Snow Cover Area ◽  
Standard Product ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Normalized Difference Snow Index

The frozen water reserves on the Earth are not only very dynamic in their nature, but also have significant effects on hydrological response of complex and dynamic river basins. The Indus basin is one of the most complex river basins in the world and receives most of its share from the Asian Water Tower (Himalayas). In such a huge river basin with high-altitude mountains, the regular quantification of snow cover is a great challenge to researchers for the management of downstream ecosystems. In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) daily (MOD09GA) and 8-day (MOD09A1) products were used for the spatiotemporal quantification of snow cover over the Indus basin and the western rivers’ catchments from 2008 to 2018. The high-resolution Landsat Enhanced Thematic Mapper Plus (ETM+) was used as a standard product with a minimum Normalized Difference Snow Index (NDSI) threshold (0.4) to delineate the snow cover for 120 scenes over the Indus basin on different days. All types of errors of commission/omission were masked out using water, sand, cloud, and forest masks at different spatiotemporal resolutions. The snow cover comparison of MODIS products with Landsat ETM+, in situ snow data and Google Earth imagery indicated that the minimum NDSI threshold of 0.34 fits well compared to the globally accepted threshold of 0.4 due to the coarser resolution of MODIS products. The intercomparison of the time series snow cover area of MODIS products indicated R2 values of 0.96, 0.95, 0.97, 0.96 and 0.98, for the Chenab, Jhelum, Indus and eastern rivers’ catchments and Indus basin, respectively. A linear least squares regression analysis of the snow cover area of the Indus basin indicated a declining trend of about 3358 and 2459 km2 per year for MOD09A1 and MOD09GA products, respectively. The results also revealed a decrease in snow cover area over all the parts of the Indus basin and its sub-catchments. Our results suggest that MODIS time series NDSI analysis is a useful technique to estimate snow cover over the mountainous areas of complex river basins.

scholarly journals Theia Snow collection: high resolution operational snow cover maps from Sentinel-2 and Landsat-8 data

2018 ◽  
Author(s):  
Simon Gascoin ◽  
Manuel Grizonnet ◽  
Marine Bouchet ◽  
Germain Salgues ◽  
Olivier Hagolle
Keyword(s):  
High Resolution ◽  
Snow Cover ◽  
Snow Depth ◽  
Western Europe ◽  
Landsat 8 ◽  
Mountain Regions ◽  
Snow Cover Area ◽  
Level 2 ◽  
Sentinel 2

Abstract. The Theia Snow collection routinely provides high resolution maps of the snow cover area from Sentinel-2 and Landsat-8 observations. The collection covers selected areas worldwide including the main mountain regions in Western Europe (e.g. Alps, Pyrenees) and the High Atlas in Morocco. Each product of the Snow collection contains four classes: snow, no-snow, cloud and no-data. We present the algorithm to generate the snow products and provide an evaluation of their accuracy using in situ snow depth measurements, higher resolution snow maps, and visual control. The results suggest that the snow is accurately detected in the Theia snow collection, and that the snow detection is more accurate than the sen2cor outputs (ESA level 2 product). An issue that should be addressed in a future release is the occurrence of false snow detection in some large clouds. The snow maps are currently produced and freely distributed in average 5 days after the image acquisition as raster and vector files via the Theia portal (http://doi.org/10.24400/329360/F7Q52MNK).

scholarly journals Topographic and geometric controls on glacier changes in the central Tien Shan, China, since the Little Ice Age

2014 ◽  
Vol 55 (66) ◽  
pp. 177-186 ◽  
Author(s):  
Yanan Li ◽  
Yingkui Li
Keyword(s):  
Little Ice Age ◽  
Climatic Factors ◽  
Google Earth ◽  
Tien Shan ◽  
Ice Age ◽  
Slope Aspect ◽  
Glacier Area ◽  
Equilibrium Line Altitude ◽  
Local Factors ◽  
Glacier Changes

AbstractThis paper examines the topographic and geometric controls on glacier changes in area and equilibrium-line altitude (ELA) in the central Tien Shan, China, since the Little Ice Age (LIA). We delineate the extents of 487 modern glaciers and their corresponding maximum LIA glacial advances using satellite imagery in Google Earth, and analyze the relationships between the magnitude of glacier changes and a set of local topographic/geometric factors including glacier area, slope, aspect, shape, hypsometry and mean elevation. Our results show that: (1) glacier area decreased from 460.2 km2 during the LIA to 265.6 km2 in the 2000s (a loss of 42.3%), with an average ELA increase of ~100m; (2) relative area changes of glaciers are strongly affected by two of these local factors (glacier area and mean elevation); and (3) ELA change does not show a strong relationship with local factors, suggesting that it may be controlled mainly by climatic factors. This study provides important insights into the local controls on glacier changes at the centennial timescale, which are of critical importance to assess future glacier changes in this arid and semi-arid region.

scholarly journals Analysis of the Snow Cover Area of the Gangotri and Surrounding Glaciers using Remote Sensing and GIS

2021 ◽  
Vol 9 (8) ◽  
pp. 2761-2776
Author(s):  
Vikram Nath
Keyword(s):  
Remote Sensing ◽  
Snow Cover ◽  
Large Range ◽  
Remote Sensing And Gis ◽  
Landsat 8 ◽  
Snow Cover Area ◽  
Snow Covered Area ◽  
Covered Area ◽  
Drastic Increase ◽  
Freshwater Reservoir

Abstract: Himalayas has one in every of the biggest resources of snow and ice, which act as a freshwater reservoir for all of the rivers originating from it. Monitoring of these sources is vital for the assessment of availability of water within the Himalayan Rivers. The mapping of Glaciers could be very tough undertaking due to the inaccessibility and remoteness of the terrain. Faraway sensing techniques are regularly the simplest way to research glaciers in remote mountains and to monitor a large range of glaciers in multitemporal manner. This paper presents the results obtained from the analysis of 5 set of Landsat 8 Band 3 - Green and Band 6 - SWIR 1 images from year 2017 to 2021 for the monitoring and analysis of approx 76% of Gangotri and Surrounding Glaciers (GSG) main snow covered area. It is seen in the analysis that there has been a down fall around 85 sq km of the Snow Cover of the Gangotri and Surrounding Glacier and Surrounding Glaciers (GSG) Area in the years of 2018 and 2019 respectively from the year 2017. In 2020 huge recovery has occurred with a drastic increase in snow cover area by approximately the same amount which has been previously depleted. After 2020, it seems that a gradual drop of 27 sq km occurred in 2021. Calculation shows a dip of 14.91% of snow cover area from 2017 to 2018 of the Gangotri and Surrounding Glaciers (GSG) which was recovered to original level in 2020. Slight dip of around 4.88% occurred in the current year 2021.

scholarly journals Assessment of Glacier Area Change in the Tekes River Basin, Central Tien Shan, Kazakhstan Between 1976 and 2013 Using Landsat and KH-9 Imagery

2016 ◽  
Author(s):  
Zamira Usmanova ◽  
Maria Shahgedanova ◽  
Igor Severskiy ◽  
Gennady Nosenko ◽  
Vassiliy Kapitsa
Keyword(s):  
River Basin ◽  
Tien Shan ◽  
Relative Reduction ◽  
Glacier Area ◽  
Uncertainty Of Measurement ◽  
Area Reduction ◽  
Glacier Recession ◽  
Significant Difference ◽  
Recession Rates ◽  
Northern Tien Shan

Abstract. Changes in glacierized area in the Kazakhstani sector of the Tekes River basin were assessed using Landsat and KH-9 imagery from 2013, 1992 and 1976. Between 1992 and 2013, the combined area of 118 glaciers declined from 121.4 ± 9.2 km2 to 105.0 ± 5.5 km2. The total area loss was 16.4 ± 5.9 km2 or 13.5 ± 7.5 %. The rate of area reduction was 0.78 km2 a-1 or 0.64 % a-1. This rate is lower than in other regions of northern Tien Shan because of the presence of several large glaciers in the sample. The combined glacier area in 2013 exceeds the combined glacier area reported by the RGI5.0/GAMDAM inventories for 1999–2003 by 24 % because the latter did not include glacierized areas on slopes exceeding 40° and a number of small glaciers. Changes in the recession rates between 1976, 1992 and 2013 were examined using a sub-sample of 28 glaciers which occupied 61% of the total glacierized area in 1992 and 64 % in 2013. These glaciers lost 8.3 ± 5.6 % in the 1976–1992 period, 8.4 ± 5.9 % in the 1992–2013 period and 16.0 ± 5.8 % between 1976 and 2013. The recession rates were 0.52 ± 0.35 % a-1 in 1976–1992 and 0.40 ± 0.28 % a-1 in 1992–2013 and although they appear to indicate a slow down in the glacier recession, the change in the retreat rates is within the uncertainty of measurement. The relative reduction in glacier area in the sub-sample is lower than for the basin as a whole because of a larger size of glaciers. Temperature increase was observed in all seasons reaching 0.18 °C per 10 years in summer and 0.39 °C per 10 years in autumn in the 1947–2015 period. Precipitation exhibited strong variability declining between 1952 and 1977 and then increasing until 2000s with a number of dry years in the 2010s. There was no statistically significant difference between the means of annual precipitation in the 1952–1977 and 1977–2015 periods. Combined with the nearly steady recession rates, this suggests that it is an increase in summer, late spring and early autumn temperature that drives glacier retreat.

scholarly journals Evaluating the Effect of Heat Waves on Early Melting of Snow Covers of Karkheh Catchment in Iran

2021 ◽  
Author(s):  
Ghasem Keikhosravi
Keyword(s):  
High Pressure ◽  
Snow Cover ◽  
Heat Waves ◽  
Ground Level ◽  
Google Earth ◽  
Maximum Temperature ◽  
Synoptic Pattern ◽  
Snow Cover Area ◽  
Synoptic Patterns ◽  
Pressure Ridge

Abstract The present study aims to evaluate the effect of heat waves on the early melting of snow cover in the Karkheh catchment of Iran. After collecting daily data on the maximum temperature of meteorological stations in the catchment during the statistical period (2000-2019), three indices of WSDI, Baldi, and ocular method were used to determine the threshold of days with heat wave. By extracting the hot waves and applying programming, the snow cover maps were drawn in the Google Earth Engine system and the area of ​​snow cover zones was calculated in the Model Builder environment. Finally, the atmospheric data were received from the NCEP/NCAR site and their generating patterns were examined after drawing in Grads software environment after determining the atmospheric synoptic patterns. The results indicated that the slope trend of hot waves is increasing at the catchment level. The average annual frequency of heat waves extracted for the snow cover growth period (November to May) was equal to 24 days of hot waves during the year. Regarding the ground pressure conditions and synoptic conditions of high atmospheric levels, two dominant synoptic patterns of heat waves were identified in the region as follows: 1) The Siberian high-pressure synoptic pattern at the ground level and the Saudi-African high-pressure ridge at high atmospheric levels. This synoptic pattern reduces snow cover area by an average of 40% in the Karkheh catchment and the highest frequency of the occurrence of this synoptic pattern is in February and March. 2) Pakistan-Africa low-pressure synoptic pattern at ground level and Saudi-African high-pressure ridge at high atmospheric levels, the frequency of the occurrence of which is higher in April and May months and reduces the snow cover area in the Karkheh catchment by an average of more than 55%.

Application of GIS, Hydraulic and Hydrologic Modelling to Investigate the Changes of Flood Inundation Characteristics due to the Construction of Dams for different scenarios

2018 ◽  
Vol 1 (2) ◽  
pp. 61-77
Author(s):  
Hossameldin M. Elhanafy
Keyword(s):  
Fluid Mechanics ◽  
Flood Control ◽  
Reduction Rate ◽  
Hydraulic Modeling ◽  
Direct Result ◽  
Flood Inundation ◽  
High Ability ◽  
The West ◽  
Hydrologic Modelling ◽  
New Location

The novelty of the research project reported in this paper is the coupling of hydrological and hydraulic modeling which are based on the first principal of fluid mechanics for the simulation of flash floods at Wadi Elarish watershed to optimize the a new location of another dam rather than Elrawfa dam which already exist. Results show that, the optimum scenario is obtained by the construction of the west dam. As a direct result of this dam, the downstream inundated area can be reduced up to 15.7 % as function of reservoir available storage behind the dam. Furthermore, calculations showed that the reduction rate of inundated area for 50-year floods is largely more than 100-year floods, implies the high ability of west dam on flood control especially for floods with shorter return period.

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