Observation and Modeling of Seawater Exchange in a Strait-Basin System in the          Seto Inland Sea, Japan

Kobayashi, Shiho; Nakada, Satoshi; Futamura, Akira; Nagamoto, Kazuhisa; Fujiwara, Tateki

doi:10.2965/jwet.18-042

Cited by 5 publications

(2 citation statements)

References 19 publications

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“…In addition, considering the early creation of tidal flats, artificial sediment injection is considered to be more effective than natural Fig. 13 Model results of longitudinal distribution of salinity near the river banks at high tide and low tide. The dotted lines refer to the right bankside, and the solid lines refer to the left bankside.…”

Section: B) Proposed Improvementsmentioning

confidence: 99%

Physical Environmental Characteristics of the Otogo Tidal Flat in the Yoshii River and Proposal of New Tidal Flat Creation Sites

2022

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Although tidal flats with good natural environment spread on both banksides in the lower reach of the Yoshii River, the tidal flat area considerably decreased owing to the river bank and dam construction works. The Otogo tidal flat is the remaining tidal area in the Yoshii river estuary. This study proposes a candidate site for tidal flat creation in an estuary depending on numerical analysis results. First, physical environment of the Otogo tidal flat was clarified by examining the observed salinity data and numerically obtained salinity and hydraulic data. Second, a promising site for creating a new tidal flat, which has a physical environment similar to that of the Otogo tidal flat was investigated and proposed on the left bank side of 4-4.6 km from the river mouth, which is approximately 2 km upstream of the Otogo tidal flat. Finally, some numerical experiments were conducted assuming the sediment replenishment and construction of new groynes. The results show that the extracted site has a similar sustainability with the Otogo tidal flat against the flood flow with several years return period.

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Section: B) Proposed Improvementsmentioning

confidence: 99%

Physical Environmental Characteristics of the Otogo Tidal Flat in the Yoshii River and Proposal of New Tidal Flat Creation Sites

2022

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“…Much research has been performed in the entire Seto Inland Sea [7][8][9][15][16][17][18][19][20], Harima Nada [10][11][12][13][14][21][22][23][24][25][26], and its surrounding areas like Osaka Bay [14,27,28], and different numerical and simulation models and monitoring observations have been proposed, applied, and conducted to describe and study the characteristics of these regions. Until this date, all the reported ocean dynamic models for the area used offline atmospherical forcing, which means that the input of atmospheric variables was either previously calculated using an atmospheric model, belonged to reanalysis datasets, or consisted of a time series of observed data.…”

Section: Introductionmentioning

confidence: 99%

Seasonal Study of the Kako River Discharge Dynamics into Harima Nada Using a Coupled Atmospheric–Marine Model

Pintos Andreoli,

Shimadera,

Yasuga

et al. 2024

Water

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This study developed a coupled atmospheric–marine model using the COAWST model system for the Harima Nada area between spring 2010 and winter 2011 to evaluate the seasonal influence of the Kako River’s discharge in the sea. The Kako River is one of the largest rivers in southwest Japan, contributing almost half of the freshwater discharged in the Harima Nada region in the Seto Inland Sea. Validation was conducted for the entire period, showing a good performance for the atmospheric and marine variables selected. Multiple experiments injecting an inert tracer in the Kako River estuary were performed to simulate the seasonal river water distribution from the estuary into the sea and to analyze the seasonal differences in concentration patterns and mean residence times in Harima Nada. Because the study area is shallow, the results were evaluated at the surface and 10 m depth layers and showed significant seasonal differences in tracer distribution, circulation patterns, and mean residence times for the region. On the other hand, differences seemed to not be significant during the same season at different depths. The obtained results also agreed with the area’s natural water circulation, showing that the Kako River waters tend to distribute towards the west coast of Harima Nada in the warmer seasons but shift towards the east in winter. The influence of the Kako River in the center of the study area is seasonal and strongly dependent on the direction of the horizontal velocities more than their magnitude. The mean residence times varied seasonally from approximately 30 days in spring to 12 days in fall. The magnitude of the horizontal velocity was found to be maximum during summer when circulation patterns at the surface and 10 m depth in the central part of Harima Nada also seem to promote the strongest horizontal and vertical mixes.

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Numerical Assessment of Total Nitrogen (Tn) Load Discharged from Rivers into Harima-Nada, the Seto Inland Sea, Using A Numerical Coupled Hydrological-Water Quality Model

Andreoli

Mori

Koga

et al. 2021

IOP Conf. Ser.: Earth Environ. Sci.

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Harima-Nada region, located in the east of Seto Inland Sea, is a semi-enclosed sea-area next to Osaka Bay that has been suffering a sustained oligotrophication process during the past 25 years. A hydrogeological model, coupled with a water quality model, was applied to assess the numerical discharge of freshwater and total nitrogen (TN) load from rivers into the sea. The model was validated for the main rivers from the northern and southern regions (the Kako River and the Yoshino River, respectively). The obtained results showed that the main contribution of freshwater and TN load to the sea comes from Hyogo Prefecture Rivers. The type of activities developed on each watershed showed to be substantially more relevant on TN load contribution than the size itself of the considered watershed. For the eight years considered in this study (2009 - 2016), the annual average of TN discharged into Harima-Nada was almost constant, while the volume of discharged freshwater showed more variations. Additionally, the sustained decrement in nitrogen concentration in Harima-Nada seemed not to be directly bonded with riverine TN load, suggesting that nitrogen availability is closely related to sea nutrients mechanisms more than to TN inland contribution.

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Observation and Modeling of Seawater Exchange in a Strait-Basin System in the Seto Inland Sea, Japan

Cited by 5 publications

References 19 publications

Physical Environmental Characteristics of the Otogo Tidal Flat in the Yoshii River and Proposal of New Tidal Flat Creation Sites

Physical Environmental Characteristics of the Otogo Tidal Flat in the Yoshii River and Proposal of New Tidal Flat Creation Sites

Seasonal Study of the Kako River Discharge Dynamics into Harima Nada Using a Coupled Atmospheric–Marine Model

Numerical Assessment of Total Nitrogen (Tn) Load Discharged from Rivers into Harima-Nada, the Seto Inland Sea, Using A Numerical Coupled Hydrological-Water Quality Model

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