scholarly journals Climate-induced landslide reactivation at the edge of the Most Basin (Czech Republic) – progress towards better landslide prediction

2013 ◽  
Vol 13 (2) ◽  
pp. 361-374 ◽  
Author(s):  
J. Burda ◽  
F. Hartvich ◽  
J. Valenta ◽  
V. Smítka ◽  
J. Rybář
Keyword(s):  
Water Table ◽  
Laser Scanning ◽  
Shear Plane ◽  
Morphological Development ◽  
Climatic Data ◽  
Landslide Activity ◽  
Geomorphological Mapping ◽  
Reactivated Landslide ◽  
Dramatic Rise ◽  
Landslide Reactivation

Abstract. The catastrophic landslide at Eisenberg in North Bohemia was reactivated during January 2011. This study integrates a range of geoscientific evidence in order to constrain the spatial and temporal development of this reactivation. It has investigated long-term geodetic measurements to assess the morphological development of the site over the last two decades. There is evidence to suggest that, over this period, the site had been subjected to progressive deformation caused by the collapse of an old mine gallery. However, climatic data show that the reactivation itself was triggered by a dramatic rise in the water table induced by rapid snowmelt during a period of winter warming. Furthermore, geomorphological mapping has been used to characterise the morphology of the reactivated landslide and geophysical profiling has been used to analyse its internal structure. The results show that fissures are continuing to develop above the reactivated landslide scarp while highly saturated stiff-fissured claystones provide an incipient slide plane. The application of laser scanning has shown minimal evidence for ongoing landslide activity. It is, however, clear that future landslide events will occur here due to the favourable lithological, structural, and geotechnical conditions. Finally, we propose that future landslide activity at the site may be predicted by the height of water table as this defines theoretical pore pressure at the depth of the shear plane.

scholarly journals Geomorphological mapping based on DEMs and GIS: A review

2019 ◽  
Vol 1 ◽  
pp. 1-1
Author(s):  
Takashi Oguchi
Keyword(s):  
Remote Sensing ◽  
Laser Scanning ◽  
Aerial Photographs ◽  
Topographic Maps ◽  
Formation Processes ◽  
Geomorphological Mapping ◽  
Topographic Data ◽  
Aerial Photogrammetry ◽  
Landform Classification ◽  
Shape Characteristics

<p><strong>Abstract.</strong> Geomorphology is a scientific discipline dealing with the characteristics, origin, and evolution of landforms. It utilizes topographic data such as spot height information, contour lines on topographic maps, and DEMs (Digital Elevation Models). Topographic data were traditionally obtained by ground surveying, but introduction of aerial photogrammetry in the early 20th century enabled more efficient data acquisition based on remote sensing. In recent years, active remote sensing methods including airborne and terrestrial laser scanning and applications of satellite radar have also been employed, and aerial photogrammetry has become easier and popular thanks to drones and a new photogrammetric method, SfM (Structure from Motion). The resultant topographic data especially raster DEMs are combined with GIS (Geographic Information Systems) to obtain derivatives such as slope and aspect as well as to conduct efficient geomorphological mapping. Resultant maps can depict various topographic characteristics based on surface height and DEM derivatives, and applications of advanced algorithms and some heuristic reasoning permit semi-automated landform classification. This quantitative approach differs from traditional and more qualitative methods to produce landform classification maps using visual interpretation of analogue aerial photographs and topographic maps as well as field observations.</p><p>For scientific purposes, landforms need to be classified based on not only shape characteristics but also formation processes and ages. Among them, DEMs only represent shape characteristics, and understanding formation processes and ages usually require other data such as properties of surficial deposits observed in the field. However, numerous geomorphological studies indicate relationships between shapes and forming-processes of landforms, and even ages of landforms affect shapes such as a wider distribution of dissected elements within older landforms. Recent introduction of artificial intelligence in geomorphology including machine learning and deep learning may permit us to better understand the relationships of shapes with processes and ages. Establishing such relationships, however, is still highly challenging, and at this moment most geomorphologists think landform classification maps based on the traditional methods are more usable than those from the DEM-based methods. Nevertheless, researchers of some other fields such as civil engineering more appreciate the DEM-based methods because they can be conducted without deep geomorphological knowledge. Therefore, the methods should be developed for interdisciplinary understanding. This paper reviews and discusses such complex situations of geomorphological mapping today in relation to historical development of methodology.</p>

scholarly journals Assessment of Genes Associated with Streptococcus mutans Biofilm Morphology

2006 ◽  
Vol 72 (9) ◽  
pp. 6277-6287 ◽  
Author(s):  
Mizuho Motegi ◽  
Yuzo Takagi ◽  
Hideo Yonezawa ◽  
Nobuhiro Hanada ◽  
Jun Terajima ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Biofilm Formation ◽  
Laser Scanning ◽  
Protein Gene ◽  
Laser Scanning Microscopy ◽  
Live Cells ◽  
Confocal Laser ◽  
Morphological Development ◽  
Phosphotransferase System ◽  
Whole Saliva

ABSTRACT Streptococcus mutans, the major pathogen responsible for dental caries in humans, is a biofilm-forming bacterium. In the present study, 17 different pulsed-field gel electrophoresis patterns of genomic DNA were identified in S. mutans organisms isolated clinically from whole saliva. The S. mutans isolates showed different abilities to form biofilms on polystyrene surfaces in semidefined minimal medium cultures. Following cultivation in a flow cell system in tryptic soy broth with 0.25% sucrose and staining using a BacLight LIVE/DEAD system, two strains, designated FSC-3 and FSC-4, showed the greatest and least, respectively, levels of biofilm formation when examined with confocal laser scanning microscopy. Further, image analyses of spatial distribution and architecture were performed to quantify the merged green (live cells) and red (dead cells) light. The light intensity of the FSC-3 biofilm was greater than that of the FSC-4 biofilm in the bottom area but not in the top area. S. mutans whole-genome array results showed that approximately 3.8% of the genes were differentially expressed in the two strains, of which approximately 2.2%, including bacitracin transport ATP-binding protein gene glrA and a BLpL-like putative immunity protein gene, were activated in FSC-3. In addition, about 1.6% of the genes, including those associated with phosphotransferase system genes, were repressed. Analyses of the glrA-deficient strains and reverse transcription-PCR confirmed the role of the gene in biofilm formation. Differential assessment of biofilm-associated genes in clinical strains may provide useful information for understanding the morphological development of streptococcal biofilm, as well as for colonization of S. mutans.

scholarly journals Microtopography is a fundamental organizing structure in black ash wetlands

2019 ◽  
Author(s):  
Jacob S. Diamond ◽  
Daniel L. McLaughlin ◽  
Robert A. Slesak ◽  
Atticus Stovall
Keyword(s):  
Water Table ◽  
Laser Scanning ◽  
Binary Classification ◽  
Base Cations ◽  
Basal Area ◽  
Forested Wetlands ◽  
Primary Control ◽  
Structural Element ◽  
Soil Elevation ◽  
Black Ash

Abstract. All wetland ecosystems are controlled by water table and soil saturation dynamics, so any local scale deviation in soil elevation represents variability in this primary control. Wetland microtopography is the structured variability in soil elevation, and is typically categorized into a binary classification of local high points (hummocks) and local low points (hollows). Although the influence of microtopography on vegetation composition and biogeochemical processes has received attention in wetlands around the globe, its role in forested wetlands is still poorly understood. We studied relationships among microtopography on understory vegetation communities, tree biomass, and soil chemistry in 10 black ash (Fraxinus nigra Marshall) wetlands in northern Minnesota, U.S.A. To do so, we combined a 1-cm resolution surface elevation model generated from terrestrial laser scanning (TLS) with co-located water table, vegetation, and soil measurements. We observed that microtopography was an important structural element across sites, where hummocks were loci of greater species richness, greater midstory and canopy basal area, and higher soil concentrations of chloride, phosphorus, and base cations. In contrast, hollows were associated with higher soil nitrate and sulfate concentrations. We also found that the effect of microtopography on vegetation and soils was greater at wetter sites than at drier sites, suggesting that distance to mean water table is a primary determinant of wetland biogeochemistry. These findings highlight clear controls of mictopography on vegetation and soil distributions, while also supporting the notion that microtopography arises from feedbacks that concentrate biomass, soil nutrients, and productivity on microsite highs, especially in otherwise wet conditions. We therefore conclude that microtopography is a fundamental organizing structure in black ash wetlands.

scholarly journals Morphometry and kinematics of landslides inferred from precise DTMs in West Belgium

2005 ◽  
Vol 5 (2) ◽  
pp. 259-265 ◽  
Author(s):  
O. Dewitte ◽  
A. Demoulin
Keyword(s):  
Vertical Displacement ◽  
3D Models ◽  
Temporal Variations ◽  
Aerial Photographs ◽  
Precise Information ◽  
Landslide Activity ◽  
Landslide Reactivation ◽  
Better Than

Abstract. The Flemish Ardennes (W Belgium) are known to be affected by deep-seated landslides. The assessment of the landslide reactivation hazard requires understanding the driving processes and delimiting precisely not only the landslide boundaries but especially that of their most active parts. Precise 3D models of 13 landslides were produced by digital stereophotogrammetry using aerial photographs of different dates. Dealing with photographs at the scale 1:25000 or larger, we obtained for each model an accuracy better than 0.5m. As a first result, the main size parameters of the landslides (width, length, depth, volume, ...) are easily computed. Moreover, the obtained DTMs may be subtracted from each other in order to determine the apparent vertical displacement of each pixel during the interval of time considered. Provided that more than 2 epochs are documented, such DTMs not only supply precise information about distribution and style of the landslide activity but may also point to temporal variations in this activity. The subtraction of DTMs allows us to give an estimation of the volume of the "uplifted" and "collapsed" terrains between two epochs.

scholarly journals Methods for detecting channel bed surface changes in a mountain torrent – experiences from the Dorfbach torrent

2015 ◽  
Vol 70 (4) ◽  
pp. 265-279 ◽  
Author(s):  
C. Willi ◽  
C. Graf ◽  
Y. Deubelbeiss ◽  
M. Keiler
Keyword(s):  
Debris Flow ◽  
Spatial Resolution ◽  
Cross Sections ◽  
Laser Scanning ◽  
Small Scale ◽  
Sources Of Information ◽  
Field Methods ◽  
Geomorphological Mapping ◽  
Flow Monitoring ◽  
Advantages And Disadvantages

Abstract. The erosion of and depositions on channel bed surfaces are instrumental to understanding debris flow processes. We present an overview of existing field methods and highlight their respective advantages and disadvantages. Terrestrial laser scanning (TLS), airborne laser scanning (ALS), erosion sensors, cross sections (CS) and geomorphological mapping are compared. Additionally, two of these approaches (i.e. TLS and CS) are tested and applied in the channel reaches of the torrent catchments. The results of the comparison indicate that the methods are associated with variable temporal and spatial resolution as well as data quality and invested effort. TLS data were able to quantify small-scale variations of erosion and deposition volumes. While the same changes could be detected with CS and geomorphological mapping, it was only possible with lower precision and coarser spatial resolution. The study presents a range of potential methods that can be applied accordingly to address the objectives and to support the analyses of specific applications. The availability of erosion data, acquired mainly by TLS and ALS, in combination with debris-flow monitoring data, provides promising sources of information to further support torrent risk management.

scholarly journals Landslide reactivation susceptibility modeling in Iași Municipality

2017 ◽  
Vol 19 (1) ◽  
pp. 101-117 ◽  
Author(s):  
NECULA Nicușor ◽  
NICULIȚĂ Mihai
Keyword(s):  
Urban Areas ◽  
Landslide Inventory ◽  
Geomorphological Mapping ◽  
Susceptibility Modeling ◽  
Main Scarp ◽  
Landslide Body ◽  
History Of ◽  
Landslide Reactivation ◽  
Slow Evolution ◽  
Future Work

Iași Municipality as other urban areas around the world has a long history of landslide activity which needs to be studied considering the urban sprawl. We performed a first landslide susceptibility modeling for Iași Municipality based on the AHP method using weights given by expert judgements regarding the influence of preparatory and conditional landslides factors (slope, ruggedness, lithology, historic landslide density and hydrogeology) and weights given by the historic landslide density over the factors. The landslide inventory was performed based on LiDAR data and aerial imagery using the geomorphological mapping of landslide elements. Using the landslide probability density function we have shown that the landslide inventory is valid and we have selected 411 landslides considered recent to be used for the validation. The resulted susceptibility show that the most susceptible to landslide reactivations are the hillslopes of cuesta hills with relict and old landslides, especially at the main scarp. Recent landslides are mainly scarp slumps or landslide body translational reactivations. The validation showed that almost 70% of recent landslides are located on high susceptibility areas. Future work to improve the susceptibility and extend it to hazard modeling is needed considering the long history of landslide reactivations from Iași Municipality and the slow evolution of old landslides like in Țicău neighborhoods.

scholarly journals GEOMORPHOLOGICAL MAPPING WITH TERRESTRIAL LASER SCANNING AND UAV-BASED IMAGING

2016 ◽  
Vol XLI-B5 ◽  
pp. 591-597 ◽  
Author(s):  
N. Tilly ◽  
D. Kelterbaum ◽  
R. Zeese
Keyword(s):  
High Resolution ◽  
Laser Scanning ◽  
Low Cost ◽  
Terrestrial Laser Scanning ◽  
Small Scale ◽  
Data Sets ◽  
Geomorphological Mapping ◽  
3D Data ◽  
Multi Temporal ◽  
Mean Differences

High-resolution digital elevation models (DEMs) are useful for the detailed mapping of geomorphological features. Nowadays various sensors and platforms are available to collect 3D data. The presented study compares terrestrial laser scanning (TLS) and low-cost unmanned aerial vehicles (UAV)-based imaging in terms of their usability for capturing small-scale surface structures. In October 2014 and June 2015 measurements with both systems were carried out in an episodically water-filled karst depression under pasture farming in the region of Hohenlohe (Southwest Germany). The overall aims were to establish high-resolution DEMs and monitor changes of the relief caused by dissolution and compare the advantages and drawbacks of both systems for such studies. Due to the short time between the campaigns the clear detection of temporal changes was hardly possible. However, the multi-temporal campaigns allowed an extensive investigation of the usability of both sensors under different environmental conditions. In addition to the remote sensing measurements, the coordinates of several positions in the study area were measured with a RTK-DGPS system as independent reference data sets in both campaigns. The TLS- and UAV-derived DEM heights at these positions were validated against the DGPS-derived heights. The accuracy of the TLS-derived values is supported by low mean differences between TLS and DGPS measurements while the UAV-derived models show a weaker performance. In the future years additional simultaneous measurements with both approaches under more similar vegetation conditions are necessary to detect surface movements. Moreover, by investigating the subsurface the interaction of above and below ground processes might be detected.

scholarly journals Microtopography is a fundamental organizing structure of vegetation and soil chemistry in black ash wetlands

2020 ◽  
Vol 17 (4) ◽  
pp. 901-915 ◽  
Author(s):  
Jacob S. Diamond ◽  
Daniel L. McLaughlin ◽  
Robert A. Slesak ◽  
Atticus Stovall
Keyword(s):  
Water Table ◽  
Soil Chemistry ◽  
Laser Scanning ◽  
Binary Classification ◽  
Base Cations ◽  
Basal Area ◽  
Primary Control ◽  
Structural Element ◽  
Soil Elevation ◽  
Black Ash

Abstract. All wetland ecosystems are controlled by water table and soil saturation dynamics, so any local-scale deviation in soil elevation and thus water table position represents variability in this primary control. Wetland microtopography is the structured variability in soil elevation and is typically categorized into a binary classification of local high points (hummocks) and local low points (hollows). Although the influence of microtopography on vegetation composition and biogeochemical processes in wetlands has received attention around the globe, its role in forested wetlands is still less understood. We studied relationships among microtopography and understory vegetation communities, tree biomass, and soil chemistry in 10 black ash (Fraxinus nigra Marshall) wetlands in northern Minnesota, USA. To do so, we combined a 1 cm resolution surface elevation model generated from terrestrial laser scanning (TLS) with colocated water table, vegetation, and soil measurements. We observed that microtopography was an important structural element across sites, where hummocks were loci of greater species richness; greater midstory and canopy basal area; and higher soil concentrations of chloride, phosphorus, and base cations. In contrast, hollows were associated with higher soil nitrate and sulfate concentrations. We also found that the effect of microtopography on vegetation and soils was greater at wetter sites than at drier sites, suggesting that the distance-to-mean water table is a primary determinant of wetland biogeochemistry. These findings highlight clear controls of microtopography on vegetation and soil distributions while also supporting the notion that microtopography arises from feedbacks that concentrate biomass, soil nutrients, and productivity on microsite highs, especially in otherwise wet conditions. We therefore conclude that microtopography is a fundamental organizing structure in black ash wetlands.

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