Contribution de la photogrammetrie numerique a l'etude spatio-temporelle de versants instables; l'exemple du glissement de terrain de Super-Sauze (Alpes-de-Haute-Provence, France)

2000 ◽  
Vol 171 (6) ◽  
pp. 637-648 ◽  
Author(s):  
Dominique Weber ◽  
Agnes Herrmann
Keyword(s):  
Aerial Photography ◽  
Morphological Evolution ◽  
Historical Evolution ◽  
Complex Flow ◽  
Glissement De Terrain ◽  
Digital Elevation ◽  
Recent Developments ◽  
Unstable Slope ◽  
Morphological Processes ◽  
Spatio Temporal

Abstract Recent developments in image processing and digital photogrammetry offer to the geomorphologists increasingly accessible and effective tools for the spatio-temporal knowledge of landslides. These techniques were used to reconstitute the historical evolution of a complex flow slide occurring in the "Terres Noires" of the Barcelonnette basin. The lithological and morphological environment of the studied site is characteristic of the whole southern French Prealps where are largely present Jurassic marly formations. Six digital elevation models (D.E.M.) generated from stereoscopic couples of aerial photography, but also various ortho-images and perspective views, allow to follow the morphological evolution of the unstable slope since the years 1950's -- before the releasing of the landslide -- until our days. Besides multitemporal descriptions of the landscape and of the morphological processes occurred on this site, the implemented method appears particularly useful for the quantitative analysis of the instabilities. It appears notably as a powerful tool for the 3-D reconstruction of the landslide geometry and by the same occasion for the calculation of its volume.

Recent Developments in Spatio-Temporal EEG Source Reconstruction Techniques

2021 ◽  
Author(s):  
Chamandeep Kaur ◽  
Preeti Singh ◽  
Amandeep Bisht ◽  
Garima Joshi ◽  
Sunil Agrawal
Keyword(s):  
Source Reconstruction ◽  
Recent Developments ◽  
Spatio Temporal

Gains achieved by molecular approaches in the area of lignification

2001 ◽  
Vol 73 (3) ◽  
pp. 561-566 ◽  
Author(s):  
Alain-M. Boudet ◽  
Matthieu Chabannes
Keyword(s):  
Molecular Biology ◽  
Lignin Content ◽  
Ectopic Expression ◽  
Lignin Biosynthesis ◽  
Cell Types ◽  
Molecular Approaches ◽  
Regulatory Circuits ◽  
Recent Developments ◽  
Spatio Temporal ◽  
Different Cell Types

In this article we highlight the contribution of molecular biology and lignin genetic engineering toward a better understanding of lignin biosynthesis and spatio-temporal deposition of lignin. Specific examples from the literature and from our laboratory will serve to underline the chemical flexibility of lignins, the complexity of the regulatory circuits involved in their synthesis, and the specific behavior of different cell types within the xylem. We will also focus on strategies aiming to reduce the lignin content or to modify the lignin composition of plants and present their impact on plant development. We will show that the ectopic expression of a specific transgene may have a different impact, depending on the genetic background, and that plants with a severe reduction in lignin content may undergo normal development. Lignification is currently benefiting enormously from recent developments in molecular biology and transgenesis, and the progress made opens the way for future developments to study how the walls of lignified plant cells are built and organized.

scholarly journals Two Dimensional Model for Backwater Geomorphology: Darby Creek, PA

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2204 ◽  
Author(s):  
Hosseiny ◽  
Smith
Keyword(s):  
Urban Areas ◽  
Water Surface ◽  
Integrated Model ◽  
Shear Stresses ◽  
Two Dimensional ◽  
Morphological Alterations ◽  
Digital Elevation ◽  
Starting Point ◽  
Spatio Temporal ◽  
Elevation Model

Predicting morphological alterations in backwater zones has substantial merit as it potentially influences the life of millions of people by the change in flood dynamics and land topography. While there is no two-dimensional river model available for predicting morphological alterations in backwater zones, there is an absolute need for such models. This study presents an integrated iterative two-dimensional fluvial morphological model to quantify spatio-temporal fluvial morphological alterations in normal flow to backwater conditions. The integrated model works through the following steps iteratively to derive geomorphic change: (1) iRIC model is used to generate a 2D normal water surface; (2) a 1D water surface is developed for the backwater; (3) the normal and backwater surfaces are integrated; (4) an analytical 2D model is established to estimate shear stresses and morphological alterations in the normal, transitional, and backwater zones. The integrated model generates a new digital elevation model based on the estimated erosion and deposition. The resultant topography then serves as the starting point for the next iteration of flow, ultimately modeling geomorphic changes through time. This model was tested on Darby Creek in Metro-Philadelphia, one of the most flood-prone urban areas in the US and the largest freshwater marsh in Pennsylvania.

scholarly journals Accuracy of the UAV-Based DEM of Beach–Foredune Topography in Relation to Selected Morphometric Variables, Land Cover, and Multitemporal Sediment Budget

2020 ◽  
Vol 43 (8) ◽  
pp. 1939-1955
Author(s):  
Joanna Rotnicka ◽  
Maciej Dłużewski ◽  
Maciej Dąbski ◽  
Mirosław Rodzewicz ◽  
Wojciech Włodarski ◽  
...  
Keyword(s):  
High Resolution ◽  
Land Cover ◽  
Sediment Budget ◽  
Slope Inclination ◽  
Baltic Coast ◽  
Digital Elevation ◽  
Marram Grass ◽  
Recent Developments ◽  
Gps Rtk ◽  
Dem Accuracy

Abstract Recent developments in unmanned aerial vehicles (UAVs) have resulted in high-resolution digital elevation models (DEMs) of vulnerable coastal environments, including beach–foredune topography. If performed repetitively, they can offer an excellent tool to determine the spatial and temporal changes in the sediment budget, which may be required for proper land management. However, the quality of a UAV, slope parameters, and vegetation significantly influence DEM accuracy. The aim of this study is to compare precise GPS-RTK transects across a section of the South Baltic coast in Poland with those obtained from a DEM based on high-resolution and high-accuracy images obtained by a wind-resistant, high-quality fixed-wing UAV during beyond visual line of sight operation (BVLOS). Different land cover classes, slope inclination, and general curvature, as well as surface roughness, were taken into consideration as possible factors influencing the uncertainty. The study revealed that marram grass greatly affects the accuracy of the UAV-derived model and that the uncertainty of the UAV-derived DEM increases together with increasing slope inclination and, to a lesser degree, with increasing general slope curvature. We showed that sediment budget determinations with the use of a UAV-based DEM are correct only where grass cover is sparse, in our study, up to 20% of the area.

scholarly journals Surface kinematics of periglacial sorted circles using Structure-from-Motion technology

2013 ◽  
Vol 7 (6) ◽  
pp. 6043-6074 ◽  
Author(s):  
A. Kääb ◽  
L. Girod ◽  
I. Berthling
Keyword(s):  
Structure From Motion ◽  
Temporal Evolution ◽  
Horizontal Displacement ◽  
Radial Symmetry ◽  
Displacement Fields ◽  
Patterned Ground ◽  
Large Sets ◽  
Digital Elevation ◽  
Spatio Temporal ◽  
Changes Over Time

Abstract. Sorted soil circles are a conspicuous form of periglacial patterned ground. Numerical modelling suggests that these features develop from a convection-like circulation of material in the active layer of permafrost. The related iterative burying and resurfacing of material is believed to play an important role in the soil carbon cycle of high latitudes. The connection of sorted circles to permafrost conditions and its changes over time make these ground forms to a potential paleoclimatic indicator. In this study we apply the photogrammetric Structure-from-Motion technology (SfM) to large sets of overlapping terrestrial photos taken in Augusts 2007 and 2010 over three sorted circles at Kvadehuksletta, Western Spitsbergen. We retrieve repeat digital elevation models (DEMs) and orthoimages with millimetre-resolution and accuracy. Changes in microrelief over the three years are obtained from DEM-differencing and horizontal displacement fields from tracking features between the orthoimages. In the inner domains of the circles, consisting of fines, material moves radially outside with horizontal surface speeds of up to 2 cm yr−1. The outer circle ridges consist of coarse stones that displace towards the inner circle domain at similar rates. A number of substantial deviations from this overall radial symmetry, both in horizontal displacements and in microrelief, shed new light on the potential spatio-temporal evolution of sorted soil circles, and periglacial patterned ground in general.

scholarly journals Implementing a hydrodynamic model to complement water depth and flow velocity data for physical scale experiments of rivers and estuaries

2020 ◽  
Author(s):  
Steven A. H. Weisscher ◽  
Marcio Boechat-Albernaz ◽  
Jasper R. F. W. Leuven ◽  
Wout M. Van Dijk ◽  
Yasuyuki Shimizu ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Water Depth ◽  
Hydrodynamic Model ◽  
Tidal Flow ◽  
Measured Data ◽  
Post Processing ◽  
Model Flow ◽  
Digital Elevation ◽  
Physical Scale ◽  
Spatio Temporal

Abstract. Physical scale experiments enhance our understanding of fluvial, tidal and coastal processes. However, it has proven challenging to acquire accurate and continuous data on water depth and flow velocity due to limitations of the measuring equipment and necessary simplifications during post-processing. A novel means to augment measurements is to numerically model flow over the experimental digital elevation models. We investigated to what extent the numerical hydrodynamic model Nays2D can reproduce unsteady, nonuniform shallow flow in scale experiments and under which conditions a model is preferred to measurements. To this end, we tested Nays2D for one tidal and two fluvial scale experiments and extended Nays2D to allow for flume tilting which is necessary to steer tidal flow. The modelled water depth and flow velocity closely resembled the measured data for locations where the quality of the measured data was most reliable, and model results may be improved by applying a spatially variable roughness. The implication of the experimental data-model integration is that conducting experiments requires fewer measurements and less post-processing in a simple, affordable and labour-inexpensive manner that results in continuous spatio-temporal data of better overall quality. Also, this integration will aid experimental design.

MAPPING OF SUB-WATERSHEDS FROM DIGITAL ELEVATION MODEL: A MORPHOLOGICAL APPROACH

2003 ◽  
Vol 17 (02) ◽  
pp. 269-274 ◽  
Author(s):  
L. CHOCKALINGAM ◽  
B. S. DAYA SAGAR
Keyword(s):  
Digital Elevation Model ◽  
Short Note ◽  
Discrete Space ◽  
Hilly Terrain ◽  
Digital Elevation ◽  
Morphological Approach ◽  
Quantitative Manner ◽  
Morphological Processes ◽  
Elevation Model

This short note presents an application of an algorithm to extract two singular networks of topological interest, such as channel and ridge connectivity networks, from a contour based Digital Elevation Model (DEM) of a region with hilly terrain. From these two extracted networks, a sub-watershed map of this region has been automatically generated. This study facilitates in understanding the watershed morphological processes in a firm quantitative manner in discrete space.

scholarly journals Surface kinematics of periglacial sorted circles using structure-from-motion technology

2014 ◽  
Vol 8 (3) ◽  
pp. 1041-1056 ◽  
Author(s):  
A. Kääb ◽  
L. Girod ◽  
I. Berthling
Keyword(s):  
Structure From Motion ◽  
Field Measurements ◽  
Horizontal Displacement ◽  
Radial Symmetry ◽  
Displacement Fields ◽  
Patterned Ground ◽  
Large Sets ◽  
Digital Elevation ◽  
Spatio Temporal ◽  
Fine Domain

Abstract. Sorted soil circles are a form of periglacial patterned ground that is commonly noted for its striking geometric regularity. They consist of an inner fine domain bordered by gravel rings that rise some decimetres above the fine domain. Field measurements and numerical modelling suggest that these features develop from a convection-like circulation of soil in the active layer of permafrost. The related cyclic burial and exhumation of material is believed to play an important role in the soil carbon cycle of high latitudes. The connection of sorted circles to permafrost conditions and its changes over time make these ground forms potential palaeoclimatic indicators. In this study, we apply for the first time photogrammetric structure-from-motion technology (SfM) to large sets of overlapping terrestrial photos taken in August 2007 and 2010 over three sorted circles at Kvadehuksletta, western Spitsbergen. We retrieve repeat digital elevation models (DEMs) and orthoimages with millimetre resolution and precision. Changes in microrelief over the 3 yr are obtained from DEM differencing and horizontal displacement fields from tracking features between the orthoimages. In the fine domain, surface material moves radially outward at horizontal rates of up to ~2 cm yr−1. The coarse stones on the inner slopes of the gravel rings move radially inward at similar rates. A number of substantial deviations from this overall radial symmetry, both in horizontal displacements and in microrelief, shed new light on the spatio-temporal evolution of sorted soil circles, and potentially of periglacial patterned ground in general.

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