scholarly journals Assessment of a numerical model to reproduce event-scale erosion and deposition distributions in a braided river

2016 ◽  
Vol 52 (8) ◽  
pp. 6621-6642 ◽  
Author(s):  
R. D. Williams ◽  
R. Measures ◽  
D. M. Hicks ◽  
J. Brasington
Keyword(s):  
Numerical Model ◽  
Braided River ◽  
Erosion And Deposition ◽  
Event Scale

Physical and numerical modelling of sediment guiding walls in an alpine river

2021 ◽  
Author(s):  
Jakob Siedersleben ◽  
Marco Schuster ◽  
Dennis Ties ◽  
Benjamin Zwick ◽  
Markus Aufleger ◽  
...  
Keyword(s):  
Numerical Model ◽  
Numerical Modelling ◽  
Power Plants ◽  
Sediment Management ◽  
Design Flow ◽  
Scale Model ◽  
Surface Measurement ◽  
Management Options ◽  
Erosion And Deposition ◽  
Alpine River

<p>The presented work is part of the optimization of the sediment management at the hydroelectric powerplants in Reutte/Höfen in Austria. The weirs of the two powerplants are situated at the alpine river Lech, located about 3 km upstream of the Lechaschau gauge (A=1012.2 km²). Totally five sluice gates and a fixed overflow weir are controlling the upstream reservoir, being subjected to high rates of coarse bed load material. In frame of a coupled approach of physical and numerical modelling, different options to (i) avoid/minimize sediment deposition and (ii) allow improved sediment flushing were tested and optimized. Besides a lowering of energy losses (reduced spilling times) the reduction of depositions downstream close to the turbine outlet were considered.</p><p>The physical model covers the hydropower and weir system of both power plants within a stretch of 400m / 150m using a model scale of 1:25. Investigated situations covered periods of reservoir sedimentation, flushing of the reservoir and typical flood flow situations (e.g. HQ1 and an unsteady HQ5 event). For model parametrization, sediment samples to quantify size distribution were taken in the field. Sediment inputs to the model were realized dynamically and were required (due to scaling effects) to exclude cohesive fractions having a minimum particle size of 0.5 mm. The full-area surface measurement of the river bed was made by means of airborne laser bathymetry and echo sounding.</p><p>As part of an optimization of the overall sediment management strategy, the focus of the presented research is on the western located runoff power plant Höfen. Via a lateral water intake, a maximum design flow of 15 m³/s is withdrawn causing that the intake structure is subjected to sediment depositions. Within the described scale model (1:25) and a partial scale model (1:15) covering the western side, several management options and configurations of sediment guiding walls were tested. Erosion and deposition as well as the transported material are assessed by 3D laser scanning and permanent monitoring of transported sediment load entering and leaving the scale model.</p><p>Complementary, a 2D hydro numerical model using a layer based multi fraction approach for sediment transport is set up for an extended area to simulate the morpho-dynamic behavior. The numerical model covers the whole weir system and 750 m of the upstream part of the Lech. The simulations made were realized at nature scale and allowed to mimic the erosion and deposition pattern obtained within the physical modelling for different tested options. Regardless of a chosen guiding wall setup, the results showed that each one is compromise between sediment defense and the effectiveness of the subsequent flushing processes.</p>

Bathymetric mapping in turbid braided mountain streams using SfM-MVS photogrammetry and statistical approaches

2020 ◽  
Author(s):  
Davide Mancini ◽  
Gilles Antoniazza ◽  
Stuart Lane
Keyword(s):  
Braided River ◽  
Differential Gps ◽  
Erosion And Deposition ◽  
Survey Techniques ◽  
Bathymetric Data ◽  
River Bed ◽  
Braided Stream ◽  
Suspended Sediment Concentrations ◽  
Statistical Relationships ◽  
Derived Data

<p>River bathymetric investigation has a long tradition as river-bed morphology is a crucial geomorphological variable that also has implications for river ecology and sediment management. In one sense, this is becoming more straightforward with the development of UAV platforms and SfM-MVS photogrammetry. Mapping inundated and exposed areas simultaneously has proved possible either by adopting two media refraction correction or by using some form of the Beer-Lambert Law. However, both of these approaches rely upon the bed being visible which becomes restricted to progressively shallower zones as stream turbidity increases. Traditional survey techniques to collect bathymetric data for inundated zones (e.g. total station or differential GPS systems) are time consuming and require a trade-off between point density and the spatial extent of survey. In this study we test a simple hypothesis: it is possible to generalize the likely depth of water in a shallow braided stream from basic planimetric information and use such statistical relationships to reconstruct the bathymetry of inundated zones. This is based upon the principle that a suite of planimetric variables (e.g. distance from stream banks, river channel width, local curvature magnitude and direction, streamline convergence and divergence) can be used to model the spatial distribution of water depths. We attempt to do this for a shallow braided river with high suspended sediment concentrations using orthoimages and DEMs derived from application of SfM-MVS photogrammetry to UAV-based imagery. We develop separate calibration and validation relationships to train and to assess the statistical models developed. These are then applied to the stream to produce bathymetric maps of flow depth for integration with SfM-MVS derived data from exposed areas. The method produces a point specific measure of uncertainty and tests suggest that the associated uncertainties are sufficiently low that after propagation into DEMs of difference reliable data on braided river dynamics and erosion and deposition volumes can be obtained.</p>

Modifikation der IES-R zur Diagnostik posttraumatischer Belastung bei Traumatisierung durch die Diagnose Krebs

Diagnostica ◽  
2011 ◽  
Vol 57 (2) ◽  
pp. 84-98 ◽  
Author(s):  
Annette F. Bölter ◽  
Julia Lange ◽  
Bernd Anger ◽  
Christian Geiser ◽  
Heinz-Martin Süß ◽  
...  
Keyword(s):  
Posttraumatische Belastungsstörung ◽  
Impact Of Event Scale ◽  
Event Scale ◽  
Dsm Iv

Zusammenfassung. Nach DSM-IV können lebensbedrohliche Erkrankungen wie Krebs eine Posttraumatische Belastungsstörung (PTSD) auslösen. Der Erfassung mit üblichen PTSD-Diagnoseinstrumenten wie der Impact-of-Event-Scale (IES-R) mangelt es jedoch an Validität. Methodik: Ein krebsspezifisches PTSD-Konzept wurde theoriebasiert entwickelt und über die IES-R sowie neu formulierte Items erfasst. 400 Rehabilitationspatienten mit heterogenen Tumordiagnosen und Diagnosestellung vor max. einem Jahr wurden untersucht. Faktorenanalytisch (CFA) wurde ein Screeninginstrument, der Fragebogen zur krebsspezifischen posttraumatischen Belastung (PTB-KS), entwickelt. Der Reliabilitätsanalyse folgte eine Konstruktvalidierung. Ergebnis: Die statistischen Analysen unterstützen die Modellannahmen (χ2/df = 2.28; CFI = .960; RMSEA = .057). Der PTB-KS umfasst auf vier Skalen Intrusionen und Vermeidung (IES-R), krebsspezifische Belastung sowie Fehlanpassung. Reliabilität und konvergente Validität sind zufriedenstellend, die diskriminante Validität ist nicht hinreichend gesichert. Diskussion: Das erweiterte diagnostische Modell verbessert die Erfassung von posttraumatischer Belastung bei Krebspatienten. Aus klinischer Sicht eignet es sich trotz methodischer Einschränkungen als Screeninginstrument.

Childbirth and Posttraumatic Stress Responses

2006 ◽  
Vol 22 (4) ◽  
pp. 259-267 ◽  
Author(s):  
Eelco Olde ◽  
Rolf J. Kleber ◽  
Onno van der Hart ◽  
Victor J.M. Pop
Keyword(s):  
Posttraumatic Stress Disorder ◽  
Posttraumatic Stress ◽  
Stress Responses ◽  
Rating Scales ◽  
Rating Scale ◽  
Stress Disorder ◽  
Traumatic Experience ◽  
Event Scale ◽  
Self Rating ◽  
The Impact

Childbirth has been identified as a possible traumatic experience, leading to traumatic stress responses and even to the development of posttraumatic stress disorder (PTSD). The current study investigated the psychometric properties of the Dutch version of the Impact of Event Scale-Revised (IES-R) in a group of women who recently gave birth (N = 435). In addition, a comparison was made between the original IES and the IES-R. The scale showed high internal consistency (α = 0.88). Using confirmatory factor analysis no support was found for a three-factor structure of an intrusion, an avoidance, and a hyperarousal factor. Goodness of fit was only reasonable, even after fitting one intrusion item on the hyperarousal scale. The IES-R correlated significantly with scores on depression and anxiety self-rating scales, as well as with scores on a self-rating scale of posttraumatic stress disorder. Although the IES-R can be used for studying posttraumatic stress reactions in women who recently gave birth, the original IES proved to be a better instrument compared to the IES-R. It is concluded that adding the hyperarousal scale to the IES-R did not make the scale stronger.

Confirmatory Factor Analysis of the Impact of Event Scale - Revised

2007 ◽  
Author(s):  
Robert Orazem ◽  
Claire Hebenstreit ◽  
Daniel King ◽  
Lynda King ◽  
Arieh Shalev ◽  
...  
Keyword(s):  
Factor Analysis ◽  
Confirmatory Factor Analysis ◽  
Impact Of Event Scale ◽  
Event Scale ◽  
Confirmatory Factor ◽  
The Impact
Sign in / Sign up

Export Citation Format

Share Document