scholarly journals Rationality in pier geometry of Kintaikyo Bridge from viewpoint of river engineering

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Hirokazu Sato
Keyword(s):  
Water Level ◽  
Hydraulic Model ◽  
Regular Hexagon ◽  
River Engineering ◽  
Model Experiments ◽  
Landscape Element ◽  
Water Level Rise ◽  
Engineering Characteristics ◽  
Statistical Dispersion ◽  
First Time

AbstractThe Kintaikyo Bridge, with its elegant wooden arches, has a unique pier shape and continues to be loved by residents and visitors alike. Although this bridge is an active footbridge and an important landscape element along with the Nishikigawa River and its river beach, the rationality or irrationality of the shape of its piers remains unknown. This paper is intended to clarify the river engineering characteristics of the piers for the first time by conducting 1/129 scale hydraulic model experiments. The shapes tested were a perfect spindle shape (which has been adopted as a common theory for many years) and a reconstructed current shape based on the spindle shape, and for comparison, an oval and a non-regular hexagon shape with the same width and area. The current shape, along with the spindle shape, suppressed the water level rise around the pier more than the others. As for the riverbed fluctuation, the current shape slightly increased the scour more than the others, but it also maximized the sedimentation around the scoured part. In other words, the current shape has the potential to facilitate the procurement of sediment for post-flood restoration. In addition, the current shape overwhelmingly reduced the statistical dispersion associated with the experiment, suggesting that it stabilizes the trend of riverbed fluctuation even during actual floods. Based on the results, the future conservation of the Kintaikyo Bridge was also discussed.

HYDROLOGICAL REGIME AND FREEZING OF HUMMOCKY BOGS ON THE EUROPEAN NORTH OF RUSSIA

2019 ◽  
Vol 12 (9-10) ◽  
pp. 38-48
Author(s):  
V. I. Batuev ◽  
I. L. Kalyuzhny
Keyword(s):  
Water Level ◽  
Hydrological Regime ◽  
Average Intensity ◽  
Water Level Rise ◽  
Northern European ◽  
European North ◽  
Bog Waters ◽  
Northern European Russia ◽  
Seasonal Thawing ◽  
First Time

The development of the European North of Russia, where flat and high-hummocky bog complexes are spread, requires information on the processes of formation of their hydrological regime and freezing of this territory. For the first time, based on observational data, for the period from 1993 to 2013, characteristics of the hydrological regime and freezing of hummocky bogs in Northern European Russia are presented, the case study of the Lovozerskoye bog. The observations were carried out in accordance with the unified methods, approved for the specialized network of Roshydromet bog stations. The regularities of the formation of the hydrological regime of hummocky bogs have been revealed: bog water level drops dramatically from the beginning of freezing to the end of March, rises during snow melt period, slightly drops in summer and rises in autumn. The main feature of hummocky bogs is permafrost, which determines their specific structure. It has been discovered that gravitation snowmelt and liquid precipitation waters relatively quickly run down the hummocks over the frozen layer into hollows between them. Levels of bog waters on the hummocks are absent for a longer period of time. In spring, the amplitude of water level rise in swamplands is on average 60–80 cm. Air temperature and insulation properties of snow are the main factors that influence the bog freezing. Hummocks freeze out as deep as 63–65 cm, which corresponds to the depth of their seasonal thawing in the warm period of the year, and adjoin the permafrost. The greatest depth of freezing of the swamplands is 82 – 87 cm, with an average of 68 cm. The frozen layer at swamplands thaws out from both its upper and bottom sides. The melting of the frozen layer at hummocks occurs only from the bog surface with an average intensity of 0,51 cm/day.

HYDRAULIC MODEL EXPERIMENTS TO UNDERSTAND INFLUENCE OF UPCOAST STRUCTURES ON MEASURES AGAINST CLOGGING OF THE MOTOFUJI CALVERT

2019 ◽  
Vol 75 (2) ◽  
pp. I_541-I_546
Author(s):  
Masaki IKEDA ◽  
Hiroshige MATSUMOTO ◽  
Fumiaki ITO ◽  
Satoshi HENMI ◽  
Go ASANO
Keyword(s):  
Hydraulic Model ◽  
Model Experiments

scholarly journals WAVE REDUCTION EFFECT OF HYDROPLANE TSUNAMI BARRIER IN TERMS OF HYDRAULIC MODEL EXPERIMENTS

2015 ◽  
Vol 71 (2) ◽  
pp. I_1081-I_1086
Author(s):  
Ryoukei AZUMA ◽  
Tadao ITO ◽  
Hideaki HANDA ◽  
Tetsuya HIRAISHI ◽  
Takahiro SUGANO
Keyword(s):  
Hydraulic Model ◽  
Model Experiments ◽  
Reduction Effect ◽  
Wave Reduction

scholarly journals Range extension for Lacantunia enigmatica Rodiles-Hernández, Hendrickson & Lundberg, 2005 (Siluriformes, Lacantuniidae) in the Usumacinta river basin, Guatemala

Check List ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 161-167 ◽  
Author(s):  
Yasmín Quintana ◽  
Christian Barrientos ◽  
Rocio Rodiles-Hernández
Keyword(s):  
Water Level ◽  
River Basin ◽  
New Records ◽  
Range Extension ◽  
Rio Negro ◽  
First Time

The Lacantun Catfish, Lacantunia enigmatica, is reported for the first time in the Usumacinta river basin in Guatemala. Two specimens were collected in the Usumacinta tributaries Río La Pasión and Río Negro, which are characterized by seasonally fast-flowing deep channels and high fluctuations in water-level. We present a map with new records, and a brief description, and images of the specimens collected.

Topological Properties of Circumcoronenes

1998 ◽  
Vol 53 (8) ◽  
pp. 699-703 ◽  
Author(s):  
Ivan Gutman ◽  
Sven J. Cyvina ◽  
Vesna Ivanov-Petrović
Keyword(s):  
Regular Hexagon ◽  
Topological Properties ◽  
Benzenoid Hydrocarbons ◽  
Spectral Moments ◽  
Energy Effect ◽  
Cyclic Conjugation ◽  
Clar Structures ◽  
First Time ◽  
Structural Invariants

Abstract The regular-hexagon-shaped benzenoid hydrocarbons: B1 = benzene (C6H6), B2 = coronene (C24H12), B3 = circumcoronene (C54H18), B4 = circumcircumcoronene (C150H30), etc. possess unique topological properties. General expressions for the most important of such properties (number of fun-damental structural invariants, number of Kekule and Clar structures, number of aromatic sextets, Wiener and Szeged indices, spectral moments) are given, including a number of results that are communicated here for the first time. Cyclic conjugation in circumcoronenes is analyzed by means of its energy-effect, and found to agree with the predictions of Clar's aromatic sextet theory only in the case of B1 and B2.

scholarly journals Modeling Tsunami-Induced Erosion of Bridge-Abutment Backfill

2020 ◽  
Vol 8 (11) ◽  
pp. 922
Author(s):  
Tomoaki Nakamura ◽  
Yuto Nakai ◽  
Yong-Hwan Cho ◽  
Norimi Mizutani
Keyword(s):  
Numerical Simulation ◽  
Soil Cover ◽  
Coastal Areas ◽  
Hydraulic Model ◽  
Numerical Analyses ◽  
Conical Part ◽  
Model Experiments ◽  
Cover Depth ◽  
Bridge Abutment

Tsunamis can seriously damage bridges in coastal areas. Studies of such damage have elucidated the action of tsunami-induced forces on girders. However, tsunami-induced erosion of bridge-abutment backfill has been largely neglected. This article investigates this little-studied topic using hydraulic model experiments and numerical analyses. The results show that a tsunami erodes the backfill close to the abutment; the scale of the erosion increases with the duration of the tsunami. By contrast, the backfill on the far side of the abutment remains relatively intact. This suggests that the presence of the abutment accelerates the erosion of the backfill in its vicinity. A numerical simulation shows that the tsunami erodes the oval conical part of the backfill on the landward side of the onshore wing. When the erosion reaches the lower end of the wing the backfill begins to flow out from underneath. Thus, an increase in the soil-cover depth of the onshore wing might help slow down the erosion.

From pristine to present state: hydrology evolution of Lake Saint-François, St. Lawrence River

1998 ◽  
Vol 25 (5) ◽  
pp. 864-879 ◽  
Author(s):  
Jean Morin ◽  
Michel Leclerc
Keyword(s):  
Water Level ◽  
Plant Biomass ◽  
Seasonal Pattern ◽  
Water Levels ◽  
Ship Traffic ◽  
Water Level Rise ◽  
Hydropower Production ◽  
Discharge Regulation ◽  
The Impact ◽  
St Lawrence River

Lake Saint-François is a relatively shallow fluvial lake of the St. Lawrence River with numerous deep channels. This complex system has been considerably altered from its pristine state 150 years ago. Currently, the water level is stabilized and the flow is regulated; important areas have been dredged and the major part of its outflow is diverted through the Beauharnois canal. The evolution of water levels shows a trend towards stabilization as required for ship traffic in the St. Lawrence Seaway and for hydropower production. With the construction of the Moses-Saunders dam in 1960, the flow of the river could be regulated; changes occur in the seasonal pattern of the flow. Ancient stage-discharge relationships were recreated to describe the impact of the 1849 damming and of the present level stabilization. Stabilization of the water level has favored the growth of submerged plants. Manning's friction coefficient was used to show that plant biomass has doubled since 1920; the onset of biomass increases corresponds to a water level stabilization event. The distribution of wetlands in the Lake Saint-François area was drastically modified by the water level rise caused by the 1849 damming. New wetlands were created and pre-1849 wetlands, located on what are currently shoals in the central part of the lake, have totally disappeared.Key words: Lake Saint-François, St. Lawrence River, impact of civil works, flow discharge regulation, water level regulation, wetland flooding cycle, submerged macrophyte, ecosystem reaction, civil work history.

Sign in / Sign up

Export Citation Format

Share Document