scholarly journals Reactivation of Floodplains in River Restorations: Long‐Term Implications on the Mobility of Floodplain Sediment Deposits

2019 ◽  
Vol 55 (10) ◽  
pp. 8178-8196 ◽  
Author(s):  
A.‐L. Maaß ◽  
H. Schüttrumpf
Keyword(s):  
Sediment Deposits ◽  
Floodplain Sediment

Investigating sediments and rock structures beneath a river using underwater ERT

2012 ◽  
Vol 4 (1) ◽  
Author(s):  
Jannis Epting ◽  
Andreas Wüest ◽  
Peter Huggenberger
Keyword(s):  
Basic Knowledge ◽  
Subsurface Water ◽  
Observation System ◽  
Resistivity Tomography ◽  
Sediment Deposits ◽  
River Bed ◽  
Rock Water Interaction ◽  
Set Up ◽  
Hydrogeological Information

AbstractThis article presents hydrogeophysical investigations performed in a well-developed, long-term hydrogeological gypsum karst research site where subsurface evaporite dissolution has led to the subsidence of a river dam and an adjacent highway; both constructed on gypsum-containing rock, southeast of Basel, Switzerland. An observation system was set up to improve the protection of surface and subsurface water resources during remedial construction measures of the highway and in order to understand the processes, as well as the temporal evolution, of rock water interaction (flow and dissolution).However, no detailed hydrogeological information beneath the river could be derived from the previous investigations. To supplement the basic knowledge on this area, underwater Electrical Resistivity Tomography (ERT) measurements were conducted in the river bed upstream of the dam. The ERT-data are interpreted together with drill-core information and a conceptual 3D-Model of the area behind the dam and beneath the river. Results help to delineate weathered zones, associated faults and the thickness of sediment deposits behind the dam, as well as to locate voids within the local karst system. The combination of the ERT and modeling allows the optimization of future site-specific remedial construction measures.

Complementary experiments for hydraulic modeling of multi-box culverts

2013 ◽  
Vol 40 (4) ◽  
pp. 324-333 ◽  
Author(s):  
H.-C. Ho ◽  
M. Muste ◽  
S. Plenner ◽  
A.R. Firoozfar
Keyword(s):  
Hydraulic Modeling ◽  
Design Flow ◽  
Dynamic Changes ◽  
Term Operation ◽  
Sediment Deposits ◽  
Box Culverts ◽  
Transport Condition ◽  
High Flows ◽  
Box Culvert

Culvert design must account for a large range of flow rates but most of the time culverts convey flows that are smaller than the design flow. Repeated high flows passing through the culverts lead to a gradual increase of the sediment deposits in the culvert vicinity, eventually resulting in reduced flow and sediment capacity. Sedimentation at culverts is quite an involved process due to the combined effect of flow non-uniformity and unsteadiness, as well as of the flow–sediment interaction. This paper reports results from a series of laboratory experiments aimed at understanding the hydro and morpho-dynamic changes occurring in the vicinity of a three-box culvert. For this purpose, velocity and turbulence characteristics upstream of the culvert were mapped globally and locally during the transition from an original flatbed to equilibrium sediment transport condition using contemporary acoustics, light detection and ranging, and image-based technologies. The experimental results reveal flow complexities not currently accounted for in the design of the multi-barrel culverts, but which can be detrimental for their long-term operation. Considerations on practical approaches to efficiently model the complexities were formulated.

scholarly journals Toward an operational approach for the characterization and modelling of fine sediments dynamics in reservoirs

2018 ◽  
Vol 40 ◽  
pp. 03028
Author(s):  
Christophe Peteuil ◽  
Magali Jodeau ◽  
Matthieu De Linares ◽  
Eric Valette ◽  
Damien Alliau ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Management Strategies ◽  
Field Method ◽  
Sediment Dynamics ◽  
Essential Requirement ◽  
Fine Sediments ◽  
Lab Experiments ◽  
Sediment Deposits ◽  
Dynamics Modelling

Achieving a sustainable management of sediment fluxes in existing or proposed reservoirs is a challenging but essential requirement for dam operators. Such objective is of utmost importance to avoid sedimentation-related consequences. Numerical modelling is of great interest to understand the flow and sediment dynamics in a reservoir, to simulate the long-term evolution of sediment deposits and to evaluate the efficiency of various management strategies. This paper presents recent case studies, which validate the feasibility and relevancy of such technical option. The progresses obtained on essential stages of the numerical modelling of sediments dynamics in reservoirs are particularly emphasized. Concerning the distribution of deposits, a promising field method based on an optimum combination of direct samplings with acoustic measurements and video auscultations is detailed. Feedbacks are then provided concerning an innovative device deployed in the field for a direct measurement of the settling velocity. Issues about the assessment of calibration parameters are also addressed in this communication. Lab experiments performed on deposits sampled in several reservoirs provide practical guidance to evaluate the erosion parameters of sediments. Finally, several examples of sediment dynamics modelling in reservoirs including both cohesive and non-cohesive sediment are presented.

Estimation of uncertainty in long term combined sewer sediment behaviour predictions, a UK case study

2008 ◽  
Vol 57 (9) ◽  
pp. 1405-1411 ◽  
Author(s):  
A. N. A. Schellart ◽  
F. A. Buijs ◽  
S. J. Tait ◽  
R. M. Ashley
Keyword(s):  
Risk Assessment ◽  
Monte Carlo ◽  
Current Knowledge ◽  
Sediment Deposits ◽  
Combined Sewer ◽  
Water Companies ◽  
Estimation Of Uncertainty ◽  
Sediment Deposit

There are regulatory driven requirements for UK water companies to reduce the number of properties at risk of sewer flooding. One of the potential causes of sewer flooding is the presence of persistent sediment deposits in sewers. This is a common problem in many combined sewers. Although the regulation is risk based, there is a gap in current knowledge on how risk assessment is affected by the uncertainty in sewer solids behaviour prediction. This paper describes a UK case study exploring the possibility of estimating uncertainty in sewer sediment deposit level predictions, using Monte Carlo simulations combined with a response database.

scholarly journals DEVELOPMENT OF A FINITE-AMPLITUDE MORPHODYNAMIC MODEL FOR TIDAL SAND WAVES BASED ON SWASH

2012 ◽  
Vol 1 (33) ◽  
pp. 18
Author(s):  
Tomas Van Oyen ◽  
T. Suzuki ◽  
M. Zijlema ◽  
P. Rauwoens ◽  
P. Troch
Keyword(s):  
Finite Amplitude ◽  
Cohesive Sediment ◽  
Coastal Structures ◽  
Sand Waves ◽  
Sediment Deposits ◽  
Bed Forms ◽  
Tidal Sand ◽  
Hydrodynamic Code ◽  
Term Management

Tidal sand waves are prominent bed forms occurring in coastal seas characterized by non-cohesive sediment deposits and relatively strong tidal currents (0.3 - 1.0 m/s). These bed features have a crest-to-crest distance between 100 and 500 m and are oriented approximately orthogonal to the main direction of the tidal current. Typical amplitudes are of the order of 1 to 10 m. Due to the ability of the bed forms to migrate, tidal sand waves pose serious hazards to many coastal structures such as pipe lines, monopiles and shipping lanes. Insight in the dynamics of these bed forms therefore is crucial for the long-term management of the coastal zone. In this work, we describe the development of a new generic numerical morphodynamic model to simulate the finite amplitude of tidal sand waves based on the hydrodynamic code SWASH.

Managing sewer solids for the reduction of foul flush effects – Forfar WTP

2002 ◽  
Vol 45 (3) ◽  
pp. 265-272
Author(s):  
A.G. Fraser ◽  
R. Sakrabani ◽  
R.M. Ashley ◽  
F.M. Johnstone
Keyword(s):  
Sediment Quality ◽  
Treatment Plant ◽  
Sediment Traps ◽  
Bulk Water ◽  
The Body ◽  
Flow Conditions ◽  
Sediment Deposits ◽  
Hydraulic Regime ◽  
High Degree

In times of high sewer flow, conditions can exist which enable previously deposited material to be re-entrained back into the body of the flow column. Pulses of this highly polluted flow have been recorded in many instances at the recently constructed wastewater treatment plant (WTP) in Forfar, Scotland. Investigations have been undertaken to characterise the incoming flows and to suggest remedial measures to manage the quality fluctuations. Initial visits to the works and incoming pipes indicated a high degree of sediment deposition in the two inlet pipes. Analyses were carried out and consequently, changes to the hydraulic regime were made. Measurements of sediment level, sediment quality, wall slime and bulk water quality were monitored in the period following the remedial works to observe any improvements. Dramatic alterations in each of the determinands measured were recorded. Analyses were then undertaken to determine long term sediment behaviour and to assess the future usefulness of existing upstream sediment traps. It was concluded that with proper maintenance of the traps, the new hydraulic regime is sufficient to prevent further significant build up of sediment deposits and reduce impacts on the WTP. Further investigations made by North of Scotland Water Authority highlighted trade inputs to the system which may also have contributed to the now managed foul flush problem.

Therapy and prevention for mental health: What if mental diseases are mostly not brain disorders?

2019 ◽  
Vol 42 ◽  
Author(s):  
John P. A. Ioannidis
Keyword(s):  
Mental Health ◽  
Mental Disease ◽  
Brain Disorders ◽  
Social Stressors ◽  
Labor Education ◽  
Mental Diseases ◽  
Long Term Follow Up ◽  
Political Decisions

AbstractNeurobiology-based interventions for mental diseases and searches for useful biomarkers of treatment response have largely failed. Clinical trials should assess interventions related to environmental and social stressors, with long-term follow-up; social rather than biological endpoints; personalized outcomes; and suitable cluster, adaptive, and n-of-1 designs. Labor, education, financial, and other social/political decisions should be evaluated for their impacts on mental disease.

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Brief summary of Kleť photographic search programme for minor planets

1999 ◽  
Vol 173 ◽  
pp. 189-192
Author(s):  
J. Tichá ◽  
M. Tichý ◽  
Z. Moravec
Keyword(s):  
Ccd Camera ◽  
Minor Planet ◽  
Minor Planets ◽  
Main Belt

AbstractA long-term photographic search programme for minor planets was begun at the Kleť Observatory at the end of seventies using a 0.63-m Maksutov telescope, but with insufficient respect for long-arc follow-up astrometry. More than two thousand provisional designations were given to new Kleť discoveries. Since 1993 targeted follow-up astrometry of Kleť candidates has been performed with a 0.57-m reflector equipped with a CCD camera, and reliable orbits for many previous Kleť discoveries have been determined. The photographic programme results in more than 350 numbered minor planets credited to Kleť, one of the world's most prolific discovery sites. Nearly 50 per cent of them were numbered as a consequence of CCD follow-up observations since 1994.This brief summary describes the results of this Kleť photographic minor planet survey between 1977 and 1996. The majority of the Kleť photographic discoveries are main belt asteroids, but two Amor type asteroids and one Trojan have been found.

Sign in / Sign up

Export Citation Format

Share Document