Wave Set-Up Height and Salinity Intrusion in Yoneshiro River Mouth in Winter

It is known that in the coastal area facing the Sea of Japan, winter storm is very severe due to strong wind from Siberia and the wave height attains to 6-7m during this period. Hence water level rise in a river entrance due to wave set-up may exceed 1m, which is considerably higher than average tidal amplitude in this region, 0.2-0.5m. However, due to much influence of complicated geographical processes on wave set-up height in a river mouth, quantitative investigations have hardly been done until now. In addition, the water level in a river mouth is complicatedly interacted among tidal motion, river discharge, ocean waves and so on, and hence it is difficult to make highly precise estimation. In this study, water level rise in the mouth of the Yoneshiro River in Akita Prefecture, Japan is investigated. Geographical features of the river mouth are greatly dependent on seasonal variation of major physical forces. Therefore, the characteristic of wave set-up is assumed to be different according to the season, and hence monthly variation of wave set-up is quantified. It is found in winter, the water level rise by wave set-up becomes approximately 10% of the deep water wave height, whereas this ratio decreases rapidly in summer due to flushing of sediment around the river mouth caused by frequent occurrence of floods.

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Response of salinity intrusion to the hydrodynamic conditions and river mouth morphological changes induced by the 2011 tsunami

Journal of Science and Technology in Civil Engineering (STCE) - NUCE ◽

10.31814/stce.nuce2020-14(2)-01 ◽

2020 ◽

Vol 14 (2) ◽

pp. 1-16

Author(s):

Nguyen Xuan Tinh ◽

Jin Wang ◽

Hitoshi Tanaka ◽

Kinuko Ito

Keyword(s):

Morphological Changes ◽

Salt Water ◽

Water Discharge ◽

River Mouth ◽

River Channel ◽

Salt Transport ◽

Ground Subsidence ◽

Fishing Ground ◽

Estuarine System ◽

Salinity Intrusion

The 2011 Tohoku Earthquake and tsunami were one of the most devastating natural disasters in history. It caused significant ground subsidence and erosion along the Japan coastline. The Natori river mouth which is a habitat for both fishes and bivalves, as an important fishing ground, has been damaged by the tsunami because of the change of the process of salt transport in an estuarine system. In general, salinity intrusion into the river mouth can be affected by many factors such as river water discharge and tidal level, as well as estuarine morphology. In this study, the response of salinity intrusion to the river mouth morphological changes induced by the 2011 Tsunami is investigated. The topographical changes caused by the tsunami are mainly divided into two stages. The first is the direct action of the tsunami, which caused the severe scouring of the coast and the widening of the river. The results have clearly indicated that after tsunami the salt water can intrude much further upstream compare to the condition before the tsunami event. Another changes occurred during the restoration process after the tsunami. The sediment accumulation in the river channel prevented the salt water from entering the river channel, which reduced the salt intrusion degree. However, the effect of the morphology change caused directly by the tsunami is far greater than the sedimentation of the river. Keywords: salinity intrusion; river morphology; tsunami impact; numerical simulation; EFDC model.

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Simulation of Salinity Intrusion Into Nanakita River, Japan, Taking Into Account Effects of Morphological Changes And Wave Set-Up

Advances in Water Resources and Hydraulic Engineering ◽

10.1007/978-3-540-89465-0_245 ◽

2009 ◽

pp. 1401-1406

Author(s):

Nguyen Trung Viet ◽

Hitoshi Tanaka

Keyword(s):

Morphological Changes ◽

Salinity Intrusion ◽

Set Up

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EFFECT OF MORPHOLOGICAL CHANGES AND WAVES ON SALINITY INTRUSION IN THE NANAKITA RIVER MOUTH

PROCEEDINGS OF HYDRAULIC ENGINEERING ◽

10.2208/prohe.50.139 ◽

2006 ◽

Vol 50 ◽

pp. 139-144 ◽

Cited By ~ 1

Author(s):

Nguyen Trung VIET ◽

Hitoshi TANAKA ◽

Daisuke NAKAYAMA ◽

Hiroto YAMAJI

Keyword(s):

Morphological Changes ◽

River Mouth ◽

Salinity Intrusion

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Propagation of tides along a river with a sloping bed

Journal of Fluid Mechanics ◽

10.1017/jfm.2019.331 ◽

2019 ◽

Vol 872 ◽

pp. 39-73 ◽

Cited By ~ 5

Author(s):

K. Kästner ◽

A. J. F. Hoitink ◽

P. J. J. F. Torfs ◽

E. Deleersnijder ◽

N. S. Ningsih

Keyword(s):

Sea Level ◽

River Discharge ◽

River Flow ◽

River Mouth ◽

Tidal River ◽

Tidal Range ◽

Narrow Channels ◽

Tidal Waves ◽

Frictional Damping ◽

Set Up

Conceptually, tidal rivers are seen as narrow channels along which the cross-section geometry remains constant and the bed is horizontal. As tidal waves propagate along such a channel, they decrease exponentially in height. The more rapid the decrease, the stronger the river flow. Near the coast, the tidally averaged width and depth change little throughout the year, even if the river discharge varies strongly between the seasons. However, further upstream, the water depth varies considerably with the river discharge. Recent observations from the Kapuas River, Indonesia, show that the water surface forms a backwater profile when the river flow is low. In this case, the depth converges, i.e. it gradually decreases between the river mouth and the point where the bed reaches sea level. This effect distinctly influences how tidal waves propagate up river so that their wave height does not decrease exponentially any more. We present a theoretical analysis of this phenomenon, which reveals several so far overlooked aspects of river tides. These aspects are particularly relevant to low river flow. Along the downstream part of the tidal river, depth convergence counteracts frictional damping so that the tidal range is higher than expected. Along the upstream parts of the tidal river, the low depth increases the damping so that the tide more rapidly attenuates. The point where the bed reaches sea level effectively limits the tidal intrusion, which carries over to the overtide and the subtidal water level set-up.

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Influence of Jetty Construction on Morphology and Wave Set-Up at a River Mouth

Coastal Engineering Journal ◽

10.1142/s0578563403000956 ◽

2003 ◽

Vol 45 (4) ◽

pp. 659-683 ◽

Cited By ~ 5

Author(s):

Hitoshi Tanaka ◽

Hyun-Seok Lee

Keyword(s):

River Mouth ◽

Set Up

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The Effects of Drying Techniques on Clay-Rich Soil Texture

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052341 ◽

1974 ◽

Vol 32 ◽

pp. 466-467

Author(s):

T. G. Naymik

Keyword(s):

Critical Point ◽

Liquid Nitrogen ◽

Liquid Nitrogen Temperature ◽

Drying Methods ◽

Air Drying ◽

Freeze Dried ◽

Critical Point Drying ◽

Set Up ◽

The Relationship ◽

Quartz Grains

Three techniques were incorporated for drying clay-rich specimens: air-drying, freeze-drying and critical point drying. In air-drying, the specimens were set out for several days to dry or were placed in an oven (80°F) for several hours. The freeze-dried specimens were frozen by immersion in liquid nitrogen or in isopentane at near liquid nitrogen temperature and then were immediately placed in the freeze-dry vacuum chamber. The critical point specimens were molded in agar immediately after sampling. When the agar had set up the dehydration series, water-alcohol-amyl acetate-CO2 was carried out. The objectives were to compare the fabric plasmas (clays and precipitates), fabricskeletons (quartz grains) and the relationship between them for each drying technique. The three drying methods are not only applicable to the study of treated soils, but can be incorporated into all SEM clay soil studies.

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