scholarly journals Flow resistance of vegetated oblique weir-like obstacles during high water stages

2014 ◽  
Vol 18 (1) ◽  
pp. 1-14 ◽  
Author(s):  
S. Ali ◽  
W. S. J. Uijttewaal
Keyword(s):  
Flow Resistance ◽  
Research Work ◽  
High Water ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Water Levels ◽  
Sudden Expansion ◽  
Form Drag ◽  
Head Losses ◽  
The One

Abstract. At high water stages, obstacles (submerged and particularly emerged vegetation) in the flood plains of a river contribute to the flow resistance and hamper the conveyance capacity. In particular the elevated vegetated parts are expected to play an important role. The objective of this research work is to determine the form drag due to vegetated oblique weir-like obstacles. Experiments have been performed to measure the energy head losses for a range of subcritical flow conditions, varying discharges and downstream water levels. The energy head loss caused by the submerged vegetated weir-like obstacle has been modeled using an expansion loss form drag model that has been derived from the one-dimensional momentum conservation equation and accounts for the energy loss associated with a deceleration of the flow downstream of a sudden expansion. The results have been compared with the experimental data and showed an overall good agreement.

scholarly journals Flow resistance of vegetated oblique weir-like obstacles during high water stages

2013 ◽  
Vol 10 (4) ◽  
pp. 5491-5534
Author(s):  
S. Ali ◽  
W. S. J. Uijttewaal
Keyword(s):  
Flow Resistance ◽  
Research Work ◽  
High Water ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Water Levels ◽  
Sudden Expansion ◽  
Form Drag ◽  
Flood Plains ◽  
Head Losses

Abstract. At high water stages obstacles in the flood plains of a river contribute to the flow resistance and hamper the conveyance capacity. In particular the elevated vegetated parts are expected to play an important role. The objective of this research work is to determine the form drag due to vegetated oblique weir-like obstacles. The experiments have been performed to measure the energy head losses for a range of subcritical flow conditions, varying discharges and downstream water levels. The energy head loss caused by the submerged vegetated weir-like obstacle has been modeled using an expansion loss form drag model that has been derived from one dimensional momentum conservation equation and accounts for the energy loss associated with a deceleration of the flow downstream of a sudden expansion. The results have been compared with the experimental data and showed an overall good agreement.

scholarly journals Observations of Cross-Shore Chenier Dynamics in Demak, Indonesia

2020 ◽  
Vol 8 (12) ◽  
pp. 972
Author(s):  
Silke A. J. Tas ◽  
Dirk S. van Maren ◽  
Ad J. H. M. Reniers
Keyword(s):  
Sediment Transport ◽  
Monsoon Season ◽  
High Water ◽  
Water Levels ◽  
Coarse Grained ◽  
Observational Period ◽  
The Cross ◽  
The One ◽  
Velocity Moments

Cheniers are important for stabilising mud-dominated coastlines. A chenier is a body of wave-reworked, coarse-grained sediment consisting of sand and shells overlying a muddy substrate. In this paper we present and analyse a week of field observations of the dynamics of a single chenier along the coast of Demak, Indonesia. Despite relatively calm hydrodynamics during the one-week observational period, the chenier migrated surprisingly fast in the landward direction. The role of the tide and waves on the cross-shore chenier dynamics is explored using velocity moments as a proxy for the sediment transport. This approach shows that both tide and waves are capable of transporting the sediment of the chenier system. During calm conditions (representative for the south-east monsoon season), the tides generate a landward-directed sediment transport when the chenier crest is high relative to mean sea level. Waves only generate substantial sediment transport (direct, via skewness, and indirect, via stirring) when the chenier is submerged during periods with higher waves. The cross-shore chenier dynamics are very sensitive to the timing of tide and waves: most transport takes place when high water levels coincide with (relatively) high waves.

Das waldreiche obere Theresiental (Transkarpatien, Ukraine) – geografisch-ökologische und sozioökonomische Beschreibung | The forest-rich upper Theresian Valley (Transcarpathia, Ukraine): a geographic-ecological and socio-economical description

2007 ◽  
Vol 158 (1-2) ◽  
pp. 14-21
Author(s):  
Vasyl Sabadosh ◽  
Oleg Suprunenko
Keyword(s):  
Forest Management ◽  
High Water ◽  
The State ◽  
Water Levels ◽  
Private Companies ◽  
Foreign Investors ◽  
Wood Processing ◽  
Job Opportunities ◽  
Orange Revolution

The upper Theresian Valley lies along the southwest-facing ridge of the Ukrainian Carpathians. Despite expansive forestation high water levels are frequent. The forest belongs to the state and is centrally administrated. Felling is sometimes outsourced to private companies and private companies have also been founded to process the timber. Job opportunities have become fewer and illegal work is increasing. A new democratic awareness has emerged since the «Orange Revolution» in 2004. With foreign investors, however, new risks emerge. The authors recommend giving monies from forest management to the communities, the founding of new wood processing enterprises and more transparent information.

Modelling Techniques in Applied Glaciology: Numerical Modelling of Avalanches

1983 ◽  
Vol 4 ◽  
pp. 297-297
Author(s):  
G. Brugnot
Keyword(s):  
Finite Difference Method ◽  
Transverse Velocity ◽  
Longitudinal Velocity ◽  
Momentum Conservation ◽  
Dimensional Model ◽  
One Dimensional ◽  
Modelling Techniques ◽  
Reference Grid ◽  
The One ◽  
Near Future

We consider the paper by Brugnot and Pochat (1981), which describes a one-dimensional model applied to a snow avalanche. The main advance made here is the introduction of the second dimension in the runout zone. Indeed, in the channelled course, we still use the one-dimensional model, but, when the avalanche spreads before stopping, we apply a (x, y) grid on the ground and six equations have to be solved: (1) for the avalanche body, one equation for continuity and two equations for momentum conservation, and (2) at the front, one equation for continuity and two equations for momentum conservation. We suppose the front to be a mobile jump, with longitudinal velocity varying more rapidly than transverse velocity.We solve these equations by a finite difference method. This involves many topological problems, due to the actual position of the front, which is defined by its intersection with the reference grid (SI, YJ). In the near future our two directions of research will be testing the code on actual avalanches and improving it by trying to make it cheaper without impairing its accuracy.

scholarly journals Modeling of solid sediment transport in mountain rivers

2020 ◽  
Vol 175 ◽  
pp. 12002 ◽  
Author(s):  
Issam Boukhanef ◽  
Anna Khadzhidi ◽  
Lyudmila Kravchenko ◽  
Zeroual Ayoub ◽  
Kastali Abdennour
Keyword(s):  
Sediment Transport ◽  
Fine Particles ◽  
Agricultural Soils ◽  
Suspended Sediments ◽  
High Water ◽  
The Other ◽  
Concentration Data ◽  
Solid Transport ◽  
One Year ◽  
The One

In Algeria, the problems of erosion and sediment transport are critical, since they have the most dramatic consequences of the degradation of agricultural soils on the one hand and the siltation of the dam on the other .The sediment transport in the Algerian basins is very important especially during the periods of floods, It is in this sense that this study, which consists of estimating the sediment transport in suspension and determining the models of relation linking the liquid discharge and the sediment discharge in order to estimate the solid transport in the absence of suspended sediments concentration data at the Sidi Akkacha station at the outlet of the basin of Oued Allala which is subject to a high water erosion, it degrades from one year to the other under the effect of this phenomenon especially during the floods which drain high amounts of fine particles exceeding in general, the concentration of 150 g/l, the results obtained from the application of the models are very encouraging since the correlation between liquid and solid discharge exceeds 80 %.

Lake and inland dunes as interconnected Systems: The story of Lake Tresssee and an adjacent dune field (Schleswig-Holstein, North Germany)

The Holocene ◽  
2020 ◽  
pp. 095968362098168
Author(s):  
Christian Stolz ◽  
Magdalena Suchora ◽  
Irena A Pidek ◽  
Alexander Fülling
Keyword(s):  
Water Level ◽  
Bronze Age ◽  
Environmental Changes ◽  
High Water ◽  
Alluvial Fan ◽  
Water Levels ◽  
Lake Area ◽  
Dune Field ◽  
The North ◽  
Sand Drift

The specific aim of the study was to investigate how four adjacent geomorphological systems – a lake, a dune field, a small alluvial fan and a slope system – responded to the same impacts. Lake Tresssee is a shallow lake in the North of Germany (Schleswig-Holstein). During the Holocene, the lake’s water surface declined drastically, predominately as a consequence of human impact. The adjacent inland dune field shows several traces of former sand drift events. Using 30 new radiocarbon ages and the results of 16 OSL samples, this study aims to create a new timeline tracing the interaction between lake and dunes, as well, as how both the lake and the dunes reacted to environmental changes. The water level of the lake is presumed to have peaked during the period before the Younger Dryas (YD; start at 10.73 ka BC). After the Boreal period (OSL age 8050 ± 690 BC) the level must have undergone fluctuations triggered by climatic events and the first human influences. The last demonstrable high water level was during the Late Bronze Age (1003–844 cal. BC). The first to the 9th century AD saw slightly shrinking water levels, and more significant ones thereafter. In the 19th century, the lake area was artificially reduced to a minimum by the human population. In the dunes, a total of seven different phases of sand drift were demonstrated for the last 13,000 years. It is one of the most precisely dated inland-dune chronologies of Central Europe. The small alluvial fan took shape mainly between the 13th and 17th centuries AD. After 1700 cal. BC (Middle Bronze Age), and again during the sixth and seventh centuries AD, we find enhanced slope activity with the formation of Holocene colluvia.

scholarly journals Cultural Sustainability in University Students’ Flamenco Music Event Attendance: A Neural Networks Approach

2021 ◽  
Vol 13 (5) ◽  
pp. 2911
Author(s):  
Jesús Manuel De Sancha-Navarro ◽  
Juan Lara-Rubio ◽  
María Dolores Oliver-Alfonso ◽  
Luis Palma-Martos
Keyword(s):  
University Students ◽  
Cultural Capital ◽  
Research Work ◽  
Cultural Consumption ◽  
Cultural Sustainability ◽  
Intangible Heritage ◽  
Live Music ◽  
Socioeconomic Profile ◽  
The One ◽  
The Relationship

University students consume live music; however, almost 40% declare that they have never attended a flamenco show, an intangible heritage of humankind. Numerous studies have shown that cultural capital and socioeconomic profile, among other factors, are variables that influence cultural consumption, and therefore, cultural sustainability. Considering the relationship between several variables, this paper pursues a double objective. On the one hand, identifying the factors that influence attendance at flamenco shows, and on the other, proposing a predictive model that quantifies the likelihood of an individual attending a flamenco show. To this end, we analyse flamenco consumption by means of a survey conducted on 452 university students, using Multilayer Perceptrom (a non-parametric model), a methodology based on an artificial neural network. Our results confirm the importance of cultural capital, as well as personal and external factors, among other. The findings of this research work are of potential interest for management and planning of cultural events, as well as to promote cultural sustainability.

Performance of Light Coastal Structures Under Normal and High Water Conditions

1975 ◽  
Vol 2 (4) ◽  
pp. 381-391 ◽  
Author(s):  
J. W. Kamphuis
Keyword(s):  
Lake Erie ◽  
High Water ◽  
Water Levels ◽  
Coastal Protection ◽  
Coastal Structures ◽  
Water Conditions ◽  
Protection Structures

A number of lightweight coastal protection structures, built on the Lake Erie shore are discussed in this paper. There were two constraints on the design; limited funds and a very precarious downdrift beach. Thus the structures were inexpensive and the protection was low-key to prevent damage downdrift. In 1972–1974 these structures were subjected to a combination of large waves and high water levels and thus they were tested well beyond their design limits.The paper discusses the structures, their performance under normal conditions, and their performance during and after the abnormally high water levels. It is found that inexpensive, low-key structures are sufficiently strong to survive normal conditions, but fail by overtopping and flanking under conditions beyond their low design limits.

Response to Jean-Pierre Chretien

1990 ◽  
Vol 19 (1) ◽  
pp. 41-41
Author(s):  
René Lemarchand
Keyword(s):  
Research Work ◽  
The Other ◽  
Other Hand ◽  
Excellent Work ◽  
The One

My apologies to Mr. Chrétien and to your readers for “developing some simplistic formulas on Burundi” in my quest for “media success.” No such simplistic formulas enter his criticism of my Congressional testimony. On the one hand, I am taken to task for not conceding that my interpretation of the Hutu-Tutsi conflict as a recent phenomenon is the product of Chrétien’s “patient research work” over the last quarter of a century; on the other hand, “some very similar analysis” had appeared in my “excellent work of 1970,” which came out long before Mr. Chrétien embarked on his patient research! Try to figure that one out if you can.

II.—On some Recent Wells in Dorset

1908 ◽  
Vol 5 (6) ◽  
pp. 243-251
Author(s):  
W. H. Hudleston
Keyword(s):  
Water Level ◽  
Water Levels ◽  
Horizontal Distance ◽  
The One

For some years past the troops encamped at Bovington had to be content with such water as was supplied by a well a few hundred yards to the S.S.E. of the recently excavated borehole. The following particulars have been gathered respecting this well, but I cannot guarantee that in all respects they are strictly accurate. It was sunk in the Bagshot Beds about 1899, and is said to be 87 feet deep; the water-level stands at 82 feet from the surface, and the yield is 360 gallons per hour. The same Bagshot water-level was struck in the borehole. On comparing these two water-levels it is found that the one in the borehole stands at 85 feet above Ordnance Datum, whilst that in the well stands at 73 feet above O.D. This difference of 12 feet in a horizontal distance of 450 feet amounts to 1 in 37·5, showing a dip in the Bagshot Beds of 1½° to the S.S.E. This may not exactly represent the direction of maximum dip, but there are good reasons for believing that the line of maximum dip of the Bagshots hereabouts is not far from S.S.E.

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