scholarly journals A multi-level strategy for anticipating future glacier lake formation and associated hazard potentials

2010 ◽  
Vol 10 (2) ◽  
pp. 339-352 ◽  
Author(s):  
H. Frey ◽  
W. Haeberli ◽  
A. Linsbauer ◽  
C. Huggel ◽  
F. Paul
Keyword(s):  
Swiss Alps ◽  
Bed Topography ◽  
Aster Gdem ◽  
Digital Elevation ◽  
Lake Formation ◽  
Level 3 ◽  
Multi Level ◽  
Four Levels ◽  
Elevation Model

Abstract. In the course of glacier retreat, new glacier lakes can develop. As such lakes can be a source of natural hazards, strategies for predicting future glacier lake formation are important for an early planning of safety measures. In this article, a multi-level strategy for the identification of overdeepened parts of the glacier beds and, hence, sites with potential future lake formation, is presented. At the first two of the four levels of this strategy, glacier bed overdeepenings are estimated qualitatively and over large regions based on a digital elevation model (DEM) and digital glacier outlines. On level 3, more detailed and laborious models are applied for modeling the glacier bed topography over smaller regions; and on level 4, special situations must be investigated in-situ with detailed measurements such as geophysical soundings. The approaches of the strategy are validated using historical data from Trift Glacier, where a lake formed over the past decade. Scenarios of future glacier lakes are shown for the two test regions Aletsch and Bernina in the Swiss Alps. In the Bernina region, potential future lake outbursts are modeled, using a GIS-based hydrological flow routing model. As shown by a corresponding test, the ASTER GDEM and the SRTM DEM are both suitable to be used within the proposed strategy. Application of this strategy in other mountain regions of the world is therefore possible as well.

scholarly journals The 1513 Monte Crenone rock avalanche: numerical model and geomorphological analysis

2022 ◽  
Vol 77 (1) ◽  
pp. 21-37
Author(s):  
Alessandro De Pedrini ◽  
Christian Ambrosi ◽  
Cristian Scapozza
Keyword(s):  
Numerical Modelling ◽  
Rock Avalanche ◽  
Historical Reconstruction ◽  
Field Mapping ◽  
Digital Elevation ◽  
Lake Formation ◽  
Detachment Zone ◽  
Elevation Model ◽  
Geomorphological Analysis

Abstract. As a contribution to the knowledge of historical rockslides, this research focuses on the historical reconstruction, field mapping, and simulation of the expansion, through numerical modelling, of the 30 September 1513 Monte Crenone rock avalanche. Earth observation in 2-D and 3-D, as well as direct in situ field mapping, allowed the detachment zone and the perimeter and volume of the accumulation to be determined. Thanks to the reconstruction of the post-event digital elevation model based on historical topographic maps and the numerical modelling with the RAMMS::DEBRISFLOW software, the dynamics and runout of the rock avalanche were calibrated and reconstructed. The reconstruction of the runout model allowed confirmation of the historical data concerning this event, particularly the damming of the valley floor and the lake formation up to an elevation of 390 m a.s.l., which generated an enormous flood by dam breaching on 20 May 1515, known as the “Buzza di Biasca”.

Quality Assessment of Globally Available Digital Elevation Model (DEM) for Mountainous Region

2021 ◽  
Vol 5 (1) ◽  
pp. 11-21
Author(s):  
Sangay Gyeltshen ◽  
Krisha Kumar Subedi ◽  
Laylo Zaridinova Kamoliddinovna ◽  
Jigme Tenzin
Keyword(s):  
Digital Elevation Model ◽  
Vertical Displacement ◽  
Satellite System ◽  
Topographic Map ◽  
Alos Palsar ◽  
Aster Gdem ◽  
Digital Elevation ◽  
The Government ◽  
Elevation Model ◽  
The Individual

The study assessed the accuracies of globally available Digital Elevation Models (DEM’s) i.e., SRTM v3, ASTER GDEM v2 and ALOS PALSAR DEM with respect to Topo-DEM derived from topographic map of 5m contour interval. 100 ground control points of the elevation data were collected with the help of kinematic hand held GNSS (Global Navigation Satellite System), randomly distributed over the study area. The widely used RMSE statistic, NCC correlation and sub-pixel-based approach were applied to evaluate the erroneous, correlation, horizontal and vertical displacement in terms of pixels for the individual Digital Elevation Model. Following these evaluations, SRTM DEM was found to be highly accurate in terms of RMSE and displacement compared to other DEMs. This study is intended to provide the researchers, GIS specialists and the government agencies dealing with remote sensing and GIS, a basic clue on accuracy of the DEMs so that the best model can be selected for application on various purposes of the similar region.

scholarly journals Soil Moisture Estimation Using Citizen Observatory Data, Microwave Satellite Imagery, and Environmental Covariates

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2160
Author(s):  
Daniel Kibirige ◽  
Endre Dobos
Keyword(s):  
Soil Moisture ◽  
Expert Knowledge ◽  
Coefficient Of Determination ◽  
Landsat 8 ◽  
Regression Kriging ◽  
Environmental Covariates ◽  
Observatory Data ◽  
Digital Elevation ◽  
Elevation Model

Soil moisture (SM) is a key variable in the climate system and a key parameter in earth surface processes. This study aimed to test the citizen observatory (CO) data to develop a method to estimate surface SM distribution using Sentinel-1B C-band Synthetic Aperture Radar (SAR) and Landsat 8 data; acquired between January 2019 and June 2019. An agricultural region of Tard in western Hungary was chosen as the study area. In situ soil moisture measurements in the uppermost 10 cm were carried out in 36 test fields simultaneously with SAR data acquisition. The effects of environmental covariates and the backscattering coefficient on SM were analyzed to perform SM estimation procedures. Three approaches were developed and compared for a continuous four-month period, using multiple regression analysis, regression-kriging and cokriging with the digital elevation model (DEM), and Sentinel-1B C-band and Landsat 8 images. CO data were evaluated over the landscape by expert knowledge and found to be representative of the major SM distribution processes but also presenting some indifferent short-range variability that was difficult to explain at this scale. The proposed models were evaluated using statistical metrics: The coefficient of determination (R2) and root mean square error (RMSE). Multiple linear regression provides more realistic spatial patterns over the landscape, even in a data-poor environment. Regression kriging was found to be a potential tool to refine the results, while ordinary cokriging was found to be less effective. The obtained results showed that CO data complemented with Sentinel-1B SAR, Landsat 8, and terrain data has the potential to estimate and map soil moisture content.

scholarly journals A new 100-m Digital Elevation Model of the Antarctic Peninsula derived from ASTER Global DEM: methods and accuracy assessment

2012 ◽  
Vol 4 (1) ◽  
pp. 129-142 ◽  
Author(s):  
A. J. Cook ◽  
T. Murray ◽  
A. Luckman ◽  
D. G. Vaughan ◽  
N. E. Barrand
Keyword(s):  
Digital Elevation Model ◽  
Antarctic Peninsula ◽  
Accuracy Assessment ◽  
Correction Method ◽  
Pixel Size ◽  
Aster Gdem ◽  
Digital Elevation ◽  
Vertical Accuracy ◽  
Elevation Model ◽  
The Antarctic

Abstract. A high resolution surface topography Digital Elevation Model (DEM) is required to underpin studies of the complex glacier system on the Antarctic Peninsula. A complete DEM with better than 200 m pixel size and high positional and vertical accuracy would enable mapping of all significant glacial basins and provide a dataset for glacier morphology analyses. No currently available DEM meets these specifications. We present a new 100-m DEM of the Antarctic Peninsula (63–70° S), based on ASTER Global Digital Elevation Model (GDEM) data. The raw GDEM products are of high-quality on the rugged terrain and coastal-regions of the Antarctic Peninsula and have good geospatial accuracy, but they also contain large errors on ice-covered terrain and we seek to minimise these artefacts. Conventional data correction techniques do not work so we have developed a method that significantly improves the dataset, smoothing the erroneous regions and hence creating a DEM with a pixel size of 100 m that will be suitable for many glaciological applications. We evaluate the new DEM using ICESat-derived elevations, and perform horizontal and vertical accuracy assessments based on GPS positions, SPOT-5 DEMs and the Landsat Image Mosaic of Antarctica (LIMA) imagery. The new DEM has a mean elevation difference of −4 m (± 25 m RMSE) from ICESat (compared to −13 m mean and ±97 m RMSE for the original ASTER GDEM), and a horizontal error of less than 2 pixels, although elevation accuracies are lower on mountain peaks and steep-sided slopes. The correction method significantly reduces errors on low relief slopes and therefore the DEM can be regarded as suitable for topographical studies such as measuring the geometry and ice flow properties of glaciers on the Antarctic Peninsula. The DEM is available for download from the NSIDC website: http://nsidc.org/data/nsidc-0516.html (doi:10.5060/D47P8W9D).

scholarly journals Geophysical constraints on the properties of a subglacial lake in northwest Greenland

2021 ◽  
Vol 15 (7) ◽  
pp. 3279-3291
Author(s):  
Ross Maguire ◽  
Nicholas Schmerr ◽  
Erin Pettit ◽  
Kiya Riverman ◽  
Christyna Gardner ◽  
...  
Keyword(s):  
Glacial Ice ◽  
Bed Topography ◽  
Subglacial Lake ◽  
Impedance Contrast ◽  
Lake Formation ◽  
Lake Bottom ◽  
Lake Bottom Sediments ◽  
A Site ◽  
Ground Penetrating

Abstract. In this study, we report the results of an active-source seismology and ground-penetrating radar survey performed in northwestern Greenland at a site where the presence of a subglacial lake beneath the accumulation area has previously been proposed. Both seismic and radar results show a flat reflector approximately 830–845 m below the surface, with a seismic reflection coefficient of −0.43 ± 0.17, which is consistent with the acoustic impedance contrast between a layer of water and glacial ice. Additionally, in the seismic data we observe an intermittent lake bottom reflection arriving between 14–20 ms after the lake top reflection, corresponding to a lake depth of approximately 10–15 m. A strong coda following the lake top and lake bottom reflections is consistent with a package of lake bottom sediments although its thickness and material properties are uncertain. Finally, we use these results to conduct a first-order assessment of the lake origins using a one-dimensional thermal model and hydropotential modeling based on published surface and bed topography. Using these analyses, we narrow the lake origin hypotheses to either anomalously high geothermal flux or hypersalinity due to local ancient evaporite. Because the origins are still unclear, this site provides an intriguing opportunity for the first in situ sampling of a subglacial lake in Greenland, which could better constrain mechanisms of subglacial lake formation, evolution, and relative importance to glacial hydrology.

scholarly journals Quaternary formations mapping in the region of Volta Grande do Rio Uruguai (Brazil)

2021 ◽  
Vol 41 ◽  
pp. e174174
Author(s):  
Sandra Cristina Deodoro ◽  
William Zanete Bertolini ◽  
Plinio da Costa Temba
Keyword(s):  
Particle Size Analysis ◽  
Size Analysis ◽  
Valley Bottom ◽  
Model Soil ◽  
Fluvial Dynamics ◽  
Digital Elevation ◽  
Topographic Attributes ◽  
History Of ◽  
Elevation Model

Quaternary formations (detrital and weathered materials) are an important natural resource for different areas of scientific investigation, from understanding their relation to erosive processes and morphodynamic processes that create landforms or to understanding the history of the first human settlements (geoarcheology). Quaternary coverings can be formed in situ or be transported by external geologic agents. Regarding soils, Quaternary formations are related to landscape topography and are transformed according to the characteristics of this topography. Hence, classifying and mapping these soils is not always easy. The present article aims to map the Quaternary formations along a stretch of the Uruguay River basin  known as Volta Grande (SC/RS-Brazil), by using  topographic attributes derived from the SRTM GL1-Up Sampled digital elevation model, soil particle-size analysis, and a generated Multiresolution Index of Valley Bottom Flatness (MRVBF) index . The results of the analysis show that: (i) colluvium is the predominant Quaternary formation in the study area; (ii) there is a predominance of clay, corroborating previous studies of the region; (iii) the spatial distribution of the study area’s  Quaternary formations reflect local slope dynamics based on morphology and topographic position; and, (iv) the existence of colluvium-alluvium on the Uruguay River’s banks indicates that slope attributes contributed to the pedogeomorphological dynamics of the study area and not only fluvial dynamics. Based on the results, the methodology applied in this study might be useful for pedogeomorphological studies, notably in the analysis and mapping of Quaternary formations, despite some of its limitations.

scholarly journals Assessment of erosion risk of relief based on the digital modeling

2021 ◽  
Vol 27 (2) ◽  
pp. 241-252
Author(s):  
Mariya Kondrateva ◽  
Aleksey Chashchin
Keyword(s):  
Morphometric Analysis ◽  
Average Density ◽  
Erosion Risk ◽  
Temporary Streams ◽  
Erosion Hazard ◽  
Average Value ◽  
Aster Gdem ◽  
Digital Modeling ◽  
Digital Elevation ◽  
Elevation Model

On the basis of a digital elevation model (DEM) based on generalized data from USGS STRM DEM and ASTER GDEM with a resolution of 3″ with the help of GIS technologies, a morphometric analysis of the territory of the perm Territory at a scale of 1:2.5 million was carried out and a series of morphometric maps was created, as well as an assessment map of the erosion hazard of the relief. According to the results of morphometric analysis, the values of the index of vertical dissection of the relief in the region vary within the range of 0–623 m with an average value of 44 m. The steepness of slopes varies from 0 to 40° with average values of 3°. The horizontal dissection, determined on the basis of the thalweg network of permanent and temporary streams, varies in the range of 0.145–1.202 km/km2. Comparison of morphometric indicators in key areas with the data obtained by traditional methods of morphometric analysis revealed their coincidence at the level of gradations. The following geomorphological factions curtains: wide development of slope surfaces with elevation differences over 50 m and slopes exceeding 3°. According to the results of cartometric analysis, such conditions characterize 35 % of the region’s area. More than half of the region’s area (60 %) has an average density of erosional dissection of 0.5–0.8 km/km2, another 36 % of the area is characterized by moderate values of 0.2–0.5 km/km2. The calculated relief energy index has a value of 3–13 points; on its basis, 4 categories of relief erosion hazard were identified. In accordance with the results obtained, most of the perm Territory (63.0 %) is characterized by a low erosion hazardous relief, 36.6 % by a medium and highly erosion hazardous. The share of land, the relief of which is characterized by zero erosion potential, is 0.4 % of the region’s area.

scholarly journals Comparison of Vertical Accuracy of Open-Source Global Digital Elevation Models: A Case Study of Adama City, Ethiopia

2021 ◽  
Vol 12 (4) ◽  
pp. 1731-1744
Author(s):  
Hailu Zewde Abili
Keyword(s):  
Open Source ◽  
Thermal Emission ◽  
Accuracy Assessment ◽  
Shuttle Radar Topography Mission ◽  
Surface Model ◽  
Aster Gdem ◽  
Digital Elevation ◽  
Wide Range ◽  
Vertical Accuracy ◽  
Elevation Model

DEM can be generated from a wide range of sources including land surveys, Photogrammetry, and Remote sensing satellites. SRTM 30m DEM by The Shuttle Radar Topography Mission (SRTM), the Global Digital Elevation Model by Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER GDEM) and a global surface model called ALOS Worldview 3D 30 meter (AW3D30) by Advanced Land Observing Satellite (ALOS) are satellite-based global DEMs open-source DEM datasets. This study aims to assess the vertical accuracy of ASTER GDEM2, SRTM 30m, and ALOS (AW3D30) global DEMs over Ethiopia in the study area-Adama by using DGPS points and available accurate reference DEM data. The method used to evaluate the vertical accuracy of those DEMs ranges from simple visual comparison to relative and absolute comparisons providing quantitative assessment (Statistical) that used the elevation differences between DEM datasets and reference datasets. The result of this assessment showed better accuracy of SRTM 30m DEM (having RMSE of ± 4.63 m) and closely followed by ALOS (AW3D30) DEM which scored RMSE of ± 5.25 m respectively. ASTER GDEM 2 showed the least accuracy by scoring RMSE of ± 11.18 m in the study area. The second accuracy assessment was done by the analysis of derived products such as slope and drainage networks. This also resulted in a better quality of DEM derived products for SRTM than ALOS DEM and ASTER GDEM.

scholarly journals PENENTUAN TINGKAT BAHAYA EROSI DI WILAYAH DAS BEDADUNG KABUPATEN JEMBER

2020 ◽  
Vol 8 (1) ◽  
pp. 1-11
Author(s):  
Idah Andriyani ◽  
Sri Wahyuningsih ◽  
Rosalina Sekar Arumsari
Keyword(s):  
Digital Elevation Model ◽  
Soil Loss ◽  
Universal Soil Loss Equation ◽  
Data Input ◽  
Aster Gdem ◽  
Digital Elevation ◽  
Elevation Model ◽  
Soil Loss Equation

Kondisi perkembangan Daerah Aliran Sungai (DAS) di wilayah Kabupaten Jember untuk saat ini perlu dievaluasi karena kondisinya sudah rusak mulai dari tahun 1999. Hal ini dapat menimbulkan bencana alam di kawasan DAS seperti tanah longsor, erosi dan banjir yang memakan korban jiwa. Tujuan dari penelitian ini adalah mengetahui besarnya tingkat bahaya erosi yang dipengaruhi oleh beberapa nilai parameter erosi menggunakan metode Revised Universal Soil Loss Equation (RUSLE) di DAS Bedadung. Data input yang digunakan pada penelitian ini yaitu curah hujan tahun 2004 - 2014, peta jenis tanah, peta penggunaan lahan RBI tahun 2014, dan data Digital Elevation Model (DEM) dari ASTER-GDEM. Hasil penelitian menunjukkan bahwa nilai parameter erosivitas hujan (R) DAS Bedadung rata-rata 1708,70 MJ.cm/tahun. Parameter erodibilitas tanah (K) didominasi jenis tanah latosol dengan nilai K sebesar 0,26. Parameter panjang dan kemiringan lereng (LS) didominasi kelas datar yaitu dengan besar kemiringan 0-8%. Parameter vegetasi penutupan lahan dan pengelolaan tanah (CP) didominasi sawah irigasi dengan nilai CP sebesar 0,02. Laju erosi DAS Bedadung sebesar 160,57 ton/ha.tahun, laju erosi ini termasuk pada kondisi sedang. Tingkat bahaya erosi pada DAS Bedadung didominasi pada tingkat sangat rendah yaitu besar erosi berkisar 0-15 (ton/ha.tahun) atau 62,20% dari luas wilayahnya.

scholarly journals Constructing a Comprehensive Tool for Deriving Drainage Network using Semi-Open Source Tools and Comparision on Different DEM Data Sources

2014 ◽  
Vol XL-8 ◽  
pp. 1129-1132
Author(s):  
P. K. Gupta ◽  
P. Yadav
Keyword(s):  
Human Error ◽  
Input Parameter ◽  
Data Sources ◽  
Drainage Network ◽  
Drainage Pattern ◽  
Primary Input ◽  
Aster Gdem ◽  
Digital Elevation ◽  
Cartosat Dem ◽  
Elevation Model

Digital elevation model (DEM) provides elevation information in raster format for an area which help in analysis as these phenomena are gravity depended. Hydrological study requires creation of drainage network map. DEM is the primary input for this process. Generally 6 or more processes are required to be completed to get the drainage network. These are available in form of hydrology tools in the ArcGIS software. These processes are manual and time consuming which increases the chances of human error. An automated process is constructed in this paper which aims to create a tool that can handle multiple files in an intelligent manner. <br><br> The input DEM plays a significant role in hydrological studies. This study attempts to do a comparative study to analyse the variation in the drainage network and the intermediate products with the change in the input DEM. <br><br> A tool is created using ArcPy site package in Python programming language to integrate all required hydrology tools. The script is then used to create a tool in ArcGIS 10 which takes location as an input parameter and perform the process on all the DEM files inside the directory. The tool creates separate directory for every DEM file and thus reduces the chances of file mismanagement. The proposed tool is tested on two different datasets namely ASTER GDEM and Cartosat DEM. The tool runs efficiently on both the datasets and thus provides results to compare the drainage pattern produced by these different data sources.

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