scholarly journals Preliminary assessment of rockslide and rockfall hazards using a DEM (Oppstadhornet, Norway)

2005 ◽  
Vol 5 (2) ◽  
pp. 285-292 ◽  
Author(s):  
M.-H. Derron ◽  
M. Jaboyedoff ◽  
L. H. Blikra
Keyword(s):  
Field Measurements ◽  
High Energy ◽  
Rock Falls ◽  
Digital Elevation ◽  
Prone Area ◽  
Slow Moving ◽  
Elevation Model ◽  
Few Data ◽  
Good Agreement

Abstract. The increasing availability and precision of digital elevation model (DEM) helps in the assessment of landslide prone areas where only few data are available. This approach is performed in 6 main steps which include: DEM creation; identification of geomorphologic features; determination of the main sets of discontinuities; mapping of the most likely dangerous structures; preliminary rock-fall assessment; estimation of the large instabilities volumes. The method is applied to two the cases studies in the Oppstadhornet mountain (730m alt): (1) a 10 millions m3 slow-moving rockslide and (2) a potential high-energy rock falling prone area. The orientations of the foliation and of the major discontinuities have been determined directly from the DEM. These results are in very good agreement with field measurements. Spatial arrangements of discontinuities and foliation with the topography revealed hazardous structures. Maps of potential occurrence of these hazardous structures show highly probable sliding areas at the foot of the main landslide and potential rock falls in the eastern part of the mountain.

scholarly journals A new glacier inventory for the Jostedalsbreen region, Norway, from Landsat TM scenes of 2006 and changes since 1966

2011 ◽  
Vol 52 (59) ◽  
pp. 153-162 ◽  
Author(s):  
Frank Paul ◽  
Liss M. Andreassen ◽  
Solveig H. Winsvold
Keyword(s):  
Field Measurements ◽  
Glacier Inventory ◽  
Digital Elevation ◽  
Cumulative Length ◽  
Length Changes ◽  
Snow Conditions ◽  
The 1960S ◽  
Elevation Model ◽  
Good Agreement ◽  
Area Determination

AbstractPronounced changes in glacier mass and length were observed for the monitored glaciers in the Jostedalsbreen region, Norway, since the last glacier inventories were compiled in the 1960s and 1980s. However, the current overall extent of the glaciers in the region is not well known. To obtain this information, we have compiled a new inventory from two mosaicked Landsat Thematic Mapper (TM) scenes acquired in 2006 that have excellent snow conditions for glacier mapping, the first suitable scenes for this purpose after 22 years of imaging with TM. Drainage divides and topographic inventory parameters were derived from a 25 m national digital elevation model for 1450 glaciers. By digitizing glacier outlines from 1 : 50 000 scale topographic maps of 1966, we calculated changes in glacier area for ~300 glaciers. Cumulative length changes for the 1997–2006 period were derived from an additional TM scene and compared with field measurements for nine glaciers. Overall, we find a 9% area loss since 1966, with a clear dependence on glacier size; however, seasonal snow in 1966 in some regions made area determination challenging. The satellite-derived length changes confirmed the observed high spatial variability and were in good agreement with field data (±1 pixel), apart from glacier tongues in cast shadow. The new inventory will be freely available from the Global Land Ice Measurements from Space (GLIMS) glacier database.

scholarly journals Influência de lineamentos estruturais no desencadeamento dos movimentos de massa no maciço de Uruburetama, Ceará

2020 ◽  
Vol 13 (3) ◽  
pp. 1294
Author(s):  
Eduardo Viana Freires ◽  
Cláudio Ângelo da Silva Neto ◽  
Cynthia Romariz Duarte ◽  
César Ulisses Vieira Veríssimo ◽  
Daniel Dantas Moreira Gomes ◽  
...  
Keyword(s):  
High Energy ◽  
Automatic Extraction ◽  
Mass Movements ◽  
Alos Palsar ◽  
Geological Structures ◽  
Physical Conditions ◽  
Directional Filters ◽  
Digital Elevation ◽  
Predominant Orientation ◽  
Elevation Model

A disposição de estruturas geológicas em áreas planálticas é elemento importante na compreensão da dinâmica que ocorre na superfície de suas encostas e que é responsável pela esculturação do relevo. Neste contexto destacam-se os movimentos gravitacionais, que podem gerar perdas econômicas, ambientais e humanas em eventos de alta energia e/ou com grande extensão. Esta pesquisa analisou a influência de lineamentos estruturais no desencadeamento dos movimentos gravitacionais no maciço de Uruburetama, localizado no estado do Ceará. A metodologia consistiu na extração automática de lineamentos a partir do Modelo Digital de Elevação (MDE) fornecido pelo sensor orbital ALOS PALSAR. A partir da média de filtros direcionais aplicados a 0°, 45°, 90° e 135° de iluminação foi possível realçar as feições lineares da imagem original, facilitando sua extração. Posteriormente, foram elaborados mapas de distribuição espacial e densidade de lineamentos, além de diagrama de roseta. Tais produtos subsidiaram a análise da disposição dos principais trends estruturais da área, destacando que a maior densidade e a orientação predominante de lineamentos podem ser indicativas do grau de susceptibilidade à ocorrência de movimentos de massa no maciço de Uruburetama, desde que também sejam consideradas as características físicas dominantes e o grau de intervenção humana nas encostas. Os resultados demonstraram que os lineamentos estruturais obtidos de forma automática, quando analisados em conjunto com as características ambientais podem ser aplicados na análise de susceptibilidade à ocorrência de movimentos de massa.  Influence of structural lineaments as a trigger of mass movements in the Uruburetama massif, Ceará state, Brazil A B S T R A C TThe geological structures arrangement in plateau areas is an important element in understanding the dynamics that occur on the surface of their slopes and which is responsible for relief sculpting. In this context, gravitational movements stand out, which can generate economic, environmental and human losses in high energy events and / or with large extension. This research analyzed the influence of structural lineaments in the gravitational movements triggering in the Uruburetama massif, located in the state of Ceará. The methodology consisted of automatic extraction of lineaments from the Digital Elevation Model (DEM) provided by the ALOS PALSAR orbital sensor. From the average of directional filters applied at 0°, 45°, 90° and 135° of illumination it was possible to enhance the linear features of the original image, facilitating their extraction. Subsequently, maps of spatial distribution and lineaments density were developed, as well as a rosette diagram. Such products subsidized the analysis of the disposition of the main structural trends of the area, emphasizing that the higher density and the predominant orientation of lineaments may be indicative of the degree of susceptibility to the occurrence of mass movements in the Uruburetama massif, if the dominant physical conditions and the degree of human intervention on the slopes are also considered. The results showed that the structural lineaments obtained automatically, when analyzed together with the environmental characteristics can be applied in the susceptibility analysis to the occurrence of mass movements.Keywords: ALOS PALSAR, directional filters, image fusion, lineaments extraction

scholarly journals Compartimentação dos elementos do relevo da bacia hidrográfica do arroio Pantanoso – Canguçu/RS, através da proposta dos geomorphons

2020 ◽  
Vol 13 (2) ◽  
pp. 713
Author(s):  
Danilo Da Silva Dutra ◽  
André Ricardo Furlan ◽  
Luís Eduardo De Souza Robaina
Keyword(s):  
Digital Elevation Model ◽  
River Basin ◽  
Spatial Resolution ◽  
Advantages And Disadvantages ◽  
Digital Elevation ◽  
Relief Elements ◽  
Gis Environment ◽  
Elevation Model

O relevo é a base onde todas as populações vivem e desenvolvem suas atividades, derivando dessa relação vantagens e desvantagens, daí a importância de conhecê-lo através do estudo de suas diferentes formas e elementos. Nesse contexto insere-se a importância de metodologias para o seu estudo, sendo que atualmente vivencia-se a expressividade de dados disponíveis para aplicação de geoprocessamento. A partir das geotecnologias pode-se empreender diversas análises sobre o relevo, destacando-se nesse contexto, a proposta dos geomorphons a qual foi aplicada na bacia hidrográfica do arroio Pantanoso. O objetivo da pesquisa é a identificação e análise dos elementos do relevo definido por geomorphons, quais sejam: 1) Planos, 2) Picos, 3) Cristas, 4) Ressaltos, 5) Crista secundária, 6) Encostas, 7) Escavado, 8) Base de encosta, 9) Vales e 10) Fosso. A determinação dos geomorphons foi a partir do processamento em ambiente SIG do Modelo Digital de Elevação (MDE) do Shuttle Radar Topograph Mission (SRTM) com resolução espacial 3 arcsec (90 metros), “L” Lookup (distância em metros) definiu-se como de 20 pixels (1800 metros) e o “T” Theresholdt (nivelamento em graus) definiu-se em 2º. Para visualização do comportamento dos elementos do relevo na área de estudo realizaram-se trabalhos de campo, o que contribuiu para evidenciar a padronização desses elementos. Os quatro elementos geomorphons mais representativos são encostas, vales, cristas e planos. Subdivision of relief elements through the proposal of geomorphons: river basin of arroio Pantanoso - Canguçu/RS A B S T R A C TRelief is the basis where all populations live and develop their activities, deriving from this relation advantages and disadvantages, hence the importance of knowing it through the study of its different forms and elements. In this context, the importance of methodologies for its study is inserted and geoprocessing application for data available for is currently experienced. From the geotechnologies one can undertake several analyzes on the relief, highlighting in this context, the proposal of the geomorphons which was applied in Pantanoso stream basin. The objective of the research is to identify and analyze the elements of the relief defined by geomorphons, namely: 1) Flats, 2) Peaks, 3) Ridges, 4) Shoulders, 5) Spurs, 6)Slopes, 7) Hollows, 8) Footslope, 9) Valley and 10) Pits. The determination of the geomorphons was based on the GIS environment of the Shuttle Radar Topograph Mission (SRTM) Digital Elevation Model (DEM) with spatial resolution 3 arcsec (90 meters), "L" Lookup (distance in meters) was defined as of 20 pixels (1800 meters) and the "T" Theresholdt (leveling in degrees) was defined in 2º. In order to visualize the behavior of the relief elements in the study area, fieldwork was carried out, which contributed to the standardization of these elements. The four most representative geomorphons, which are: Slopes, Valleys, Ridges and Flat.Keywords: SIG, Geomorphons; Canguçu/RS; relief

scholarly journals Mapping glaciers in Jotunheimen, South-Norway, during the "Little Ice Age" maximum

2009 ◽  
Vol 3 (2) ◽  
pp. 231-243 ◽  
Author(s):  
S. Baumann ◽  
S. Winkler ◽  
L. M. Andreassen
Keyword(s):  
Little Ice Age ◽  
18Th Century ◽  
Field Measurements ◽  
Geographical Information ◽  
Ice Age ◽  
Inventory Data ◽  
Digital Elevation ◽  
Remote Sensing Techniques ◽  
Southern Norway ◽  
Elevation Model

Abstract. The maximum glacier extent during the "Little Ice Age" (mid 18th century AD) in Jotunheimen, southern Norway, was mapped using remote sensing techniques. Interpretation of existing glaciochronological studies, analysis of geomorphological maps, and own GPS-field measurements were applied for validation of the mapping. The length of glacier centrelines and other inventory data were determined using a Geographical Information System (GIS) and a Digital Elevation Model. "Little Ice Age" maximum extent for a total of 233 glaciers comprising an overall glacier area of about 290 km2 was mapped. Mean length of the centreline was calculated to 1.6 km. Until AD 2003, the area and length shrank by 35% and 34%, respectively, compared with the maximum "Little Ice Age" extent.

scholarly journals A computationally efficient depression-filling algorithm for digital elevation models applied to proglacial lake drainage

2016 ◽  
Author(s):  
Constantijn J. Berends ◽  
Roderik S. W. van de Wal
Keyword(s):  
Geographical Area ◽  
Computation Time ◽  
Equation Model ◽  
Limiting Factor ◽  
Computationally Efficient ◽  
Digital Elevation ◽  
Lake Drainage ◽  
Elevation Model ◽  
Flood Fill

Abstract. We present and evaluate several optimizations to a standard flood-fill algorithm in terms of computational efficiency. As an example, we determine the land/ocean-mask for a 1 km resolution digital elevation model (DEM) of North America and Greenland, a geographical area of roughly 7000 by 5000 km (roughly 35 million elements), about half of which is covered by ocean. Determining the land/ocean-mask with our improved flood-fill algorithm reduces computation time by 90 % relative to using a standard stack-based flood-fill algorithm. In another experiment, we use the bedrock elevation, ice thickness and geoid perturbation fields from the output of a coupled ice-sheet–sea-level equation model at 30,000 years before present and determine the extent of Lake Agassiz, using both the standard and improved versions of the flood-fill algorithm. We show that several optimizations to the flood-fill algorithm used for filling a depression up to a water level, that is not defined at forehand, decrease the computation time by up to 99 %. The resulting reduction in computation time allows determination of the extent and volume of depressions in a DEM over large geographical grids or repeatedly over long periods of time, where computation time might otherwise be a limiting factor.

Determination of the drainage structure of a watershed using a digital elevation model and a digital river and lake network

2001 ◽  
Vol 240 (3-4) ◽  
pp. 225-242 ◽  
Author(s):  
R Turcotte ◽  
J.-P Fortin ◽  
A.N Rousseau ◽  
S Massicotte ◽  
J.-P Villeneuve
Keyword(s):  
Digital Elevation Model ◽  
Digital Elevation ◽  
Elevation Model

Filler-Elastomer Interactions. Part VI. Characterization of Carbon Blacks by Inverse Gas Chromatography at Finite Concentration

1992 ◽  
Vol 65 (5) ◽  
pp. 890-907 ◽  
Author(s):  
Meng-Jiao Wang ◽  
Siegfried Wolff
Keyword(s):  
Gas Chromatography ◽  
Energy Distribution ◽  
Inverse Gas Chromatography ◽  
General Trend ◽  
High Energy ◽  
Carbon Blacks ◽  
Finite Concentration ◽  
Good Agreement

Abstract Carbon blacks ranging from N110 to N990 were characterized by means of inverse gas chromatography at finite concentration. The isotherms, net heat, and spreading pressures for benzene and cyclohexane adsorption suggest a general trend of increasing surface activity with increases in specific surface area. This is in good agreement with surface-energy measurements reported previously. The energy-distribution function of adsorption shows that while the concentrations of low-energy sites are comparable for most of the carbon blacks, differences exist with regard to high-energy sites. These suggest that small-particle-size blacks possess a greater number of high-energy centers. The graphitization of carbon blacks results in a considerable reduction in their adsorption capacity and narrows the energy distribution of their surfaces. One can therefore conclude that high-energy sites play an important role in the determination of the surface energies and reinforcing ability of carbon blacks.

scholarly journals Determination of GT-transition Strengths in \(A=34\) Isobars Using Charge Exchange \((^3\text{He},t)\) Reaction

2012 ◽  
Vol 22 (1) ◽  
pp. 91-96
Author(s):  
Nguyen Tuan Khai ◽  
Bui Duy Linh ◽  
Tran Duc Thiep ◽  
Y. Fujita ◽  
T Adachi ◽  
...  
Keyword(s):  
Excitation Energy ◽  
Excited States ◽  
Ground State ◽  
Incident Energy ◽  
High Energy ◽  
High Energy Resolution ◽  
Good Quantum Number ◽  
Gamow Teller ◽  
Good Agreement

Under the assumption that isospin \(T\) is a good quantum number, mirror transitions \(T_{z }= +1 \to  0\) and \(T_{z }= -1  \to  0\) were studied in \(A = 34\) isobars, where \(T_{z}\) is \(z\) component of iospin \(T\) and is defined by \(T_{z} = (N-Z)/2\). With a high energy resolution of 35 keV in \(^{34}\)S\((^{3}He,t)^{34}\)Cl reaction measurement at \(0^{\circ}\) scattering angle and at an incident energy of 140 MeV/nucleon, strengths of Fermi and Gamow-Teller (GT) transitions from the \(J^{\pi } = 0^{ + }\), \(T_{z }= +1\) ground state of \(^{34}\)S to the \(J^{\pi } = 1^{+ }\), \(T_{z }= 0\) excited states in \(^{34}\)Cl were determined up to excitation energy \((E_{x})\) of \(7.08\) MeV. The corresponding isospin-symmetric transitions connecting \(T_{z }= -1\) and \(T_{z }= 0\) states can be studied in the \(^{34}\)Ar \(\beta ^{ + }\) decay. The strengths of the \((GT)_{\pm }\) transitions were compared up to the excitation energy of 3.1 MeV. A good agreement was observed for two strong transitions to \(2.580\) MeV and \(3.129\) MeV states, while a disagreement about \(45\text{%}\) was observed for a weaker transition to \(0.666\) MeV low-lying state.

scholarly journals Spatial and Temporal Variation of Net Snow Accumulation in a Small Alpine Watershed, Emerald Lake Basin, Sierra Nevada, California, U.S.A.

1989 ◽  
Vol 13 ◽  
pp. 56-63 ◽  
Author(s):  
K. Elder ◽  
J. Dozier ◽  
J. Michaelsen
Keyword(s):  
Sierra Nevada ◽  
Field Measurements ◽  
Snow Accumulation ◽  
Spatial And Temporal Variation ◽  
Lake Basin ◽  
Snow Properties ◽  
Digital Elevation ◽  
Snow Water ◽  
Elevation Model ◽  
Topographic Parameters

Distribution of snow-water equivalence (SWE) in the Emerald Lake watershed located in Sequoia National Park, California, U.S.A, was examined during the 1987 water year. Elevations at this site range from 2780 to 3416 m a.s.l., and the total watershed area is about 122 ha. A stratified sampling scheme was evaluated by identifying and mapping zones of similar snow properties, based on topographic parameters that account for variations in both accumulation and ablation of snow. Elevation, slope, and radiation values calculated from a digital elevation model were used to identify these zones. Field measurements of SWE were combined with characteristics of the sample locations and clustered to identify similar classes of SWE. The entire basin was then partitioned into zones for each set of survey data. The topographic parameters of the basin used in classification, namely slope and elevation, are constant in time and did not change between survey dates. The radiation data showed temporal variability providing a physically justified basis for changes in SWE distribution through time. Although results do not identify which of the classification attempts is superior to the others, net radiation is clearly of primary importance, and slope and elevation appear to be important to a lesser degree. The peak accumulation for the 1987 water year was 598 mm SWE, which is about half the 50 year mean.

Sign in / Sign up

Export Citation Format

Share Document