Papers by Tetsunori Inoue
Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2011
Three approaches; eddy-correlation (EC), turbulent kinetic energy (TKE), and inertial dissipation... more Three approaches; eddy-correlation (EC), turbulent kinetic energy (TKE), and inertial dissipation (ID) methods were compared to evaluate their potential for estimation of shear velocity in a protected coastal region. As an independent assessment parameter we used simultaneous oxygen recordings in the vicinity of the sediment-water interface that were compared with theoretical distribution as derived from the respective shear velocity estimates. Overall differences from measured oxygen concentration were 0.2% for EC method, 9.8% for TKE method, and 0.7% and 4.6% for ID method using vertical and longitudinal velocity components, respectively. The results revealed that the EC method appeared to be the best approach though not significantly different from the ID method using vertical velocity component at the study site.
Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research), 2021
Journal of Advanced Marine Science and Technology Society, 2017
Although most fatalities in tsunami-related disasters are conjectured to be a result of drowning,... more Although most fatalities in tsunami-related disasters are conjectured to be a result of drowning, injury risk owing to collision with other floating debris or fixed buildings has not been studied sufficiently. In this study, the impact force corresponding to the collision of a concrete block and drifting test body in a tsunami wave was experimentally investigated, and the injury risk was evaluated in terms of different biomechanical indexes; specifically, maximum acceleration, head injury criterion, and impact force. The injury risk indicated by the considered indexes was reasonably low. It was noted that if a healthy adult collided with a concrete wall under a velocity of 2.5 m s-1 and wave height of 0.59 m, the adult would likely not be critically injured. However, a similar collision impact poses considerable risk to infants and children, as well as the more sensitive regions of the adult body. Moreover, in the case of large tsunamis, such as that in the 2011 Great East Japan Ear...
Coastal Engineering Journal, 2020
WRF simulations were conducted for Ise Bay, Japan for January and July 2016 to evaluate sensitivi... more WRF simulations were conducted for Ise Bay, Japan for January and July 2016 to evaluate sensitivity of model input and output above sea surface to the replacement of three default input datasets with region-specific input datasets. For atmospheric input data, a final analysis created by the National Centers for Environmental Prediction (NCEP-FNL) was replaced with a mesoscale analysis created by the Japan Meteorological Agency (JMA). Topography and land use dataset released by the US Geological Survey were replaced with dataset released by the GeoSpatial Information authority of Japan. For sea surface temperature (SST) data, NCEP-FNL was replaced with an analysis created by JMA. Of the three region-specific datasets, replacement of atmospheric data results in the largest improvements in the accuracy of simulated wind speeds in January and July and of temperature in July 2016. Improvements in model output accuracy over sea surface can be seen near the coastline by replacing topography and land use data. Replacement of SST data results in the largest improvements in simulated temperature accuracy in January 2016. Replacing all three default input datasets results in the largest improvement, and expands on results from previous studies that focused on the effects of replacing only one input data.
Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering), 2012
Advances in Fluid Modeling and Turbulence Measurements, 2002
Continuous field observations of water temperature, conductivity, turbidity and flow velocity wer... more Continuous field observations of water temperature, conductivity, turbidity and flow velocity were performed at a central point of Lake Shinji, a shallow lagoon in Japan, in summer for a month. Observational results revealed that turbidity in the overlying water showed a distinct diel variation, independent on the existence of the stratification. As wind-induced wave diurnally developed when the atmosphere became unstable in the afternoon, and as wind-induced wave propagated to the bottom layer even under the stratified condition in the water column, diurnal fluctuation of resuspension was possible under stratified conditions. Furthermore, experimental results showed that sediment resuspension enhanced phosphate release rate from the sediment under anoxic condition. As anoxic water often develops under stratified conditions, these results strongly indicate that the anoxic resuspension caused by the wind-induced wave enhances phosphate release from the sediment.
Journal of Soils and Sediments, 2012
Purpose The purpose of this study was to investigate the responses of the benthic soluble reactiv... more Purpose The purpose of this study was to investigate the responses of the benthic soluble reactive phosphorus (SRP) transfer rate to step changes in the flow velocity of the overlying water using laboratory experiments and a nonsteady-state numerical model. Materials and methods Laboratory experiments were conducted using a rectangular recirculating flume. After preincubation of sediments in a cavity of the experimental flume for 2 days, the step responses of the SRP transfer rate to sudden increases in the flow velocity were examined under anaerobic conditions. The benthic SRP transfer rates were obtained from the rate of increase in the SRP concentration of the overlying water. We also analysed the response using a newly constructed numerical model that consists of a one-dimensional diffusion model of the diffusive boundary layer (DBL) and a biochemical model of the sediment, in which oxygen, SRP, ferrous iron and nitrate were model variables. The non-steady-state calculation was performed to reproduce the experiments after the step change in the flow velocity. The experiments revealed a rapid increase in the SRP concentration in the overlying water that continued for approximately 5 min after the step change in flow velocity and was followed by a lower, steady increase in the SRP concentration. The model analyses also demonstrated that a step increase in flow velocity leads to a drastic enhancement of the SRP transfer rate within a few minutes. The abrupt increase in the transfer rate was due to the rapid transport of SRP that had accumulated in the DBL and to enhanced diffusion caused by a temporal increase in the SRP concentration gradient in the DBL. The modelled results for the SRP transfer rate were in agreement with the experimental results. Conclusions The temporal increase in SRP transfer was due to rapid SRP transport caused by intensified diffusion following a decrease in DBL thickness. The model-based results for the response of the SRP transfer rate were in agreement with the experimental results. Therefore, our model can simulate the response of the SRP concentration profile near the sediment-water interface to temporal variations in flow velocity.
European Journal of Phycology, 2008
A new species of the green algal genus Pseudocodium is described on the basis of specimens collec... more A new species of the green algal genus Pseudocodium is described on the basis of specimens collected from Okinawa, southern Japan. It differs from the generitype species P. de-vriesii Weber-van Bosse from South Africa, P. australasicum Womersley from Australia and P. floridanum C. J. Dawes & A. C. Mathieson from Florida in its smaller size (1-2 cm in height, axes 0.5-1.0 mm in width) and infrequent branching. Unlike P. de-vriesii and P. australasicum also is its total lack of constricted or articulated axes. Molecular-phylogenetic analyses based on plastid encoded rbcL gene sequences show the Okinawan plants to group with Atlantic P. floridanum but to be specifically distinct owing to substantial base pair differences (88 bp, 11.876%). Remarkable differences in morphometric data, ecological preferences and geographic distribution were also found between them. We thus describe the Okinawan entity as Pseudocodium okinawense E. J. Faye, M. Uchimura et S. Shimada sp. nov. In addition, on the basis of laboratory culture experiments, a diminutive, entirely tubular growth form showing great morphological dissimilarity with field materials is newly observed in the genus, thus adding further details to our understanding of the plants vegetative phenology at early developmental stages.
Japanese Journal of Limnology (Rikusuigaku Zasshi), 2001
Environmental Engineering Research, 2000
Field observations have been made with respect to the diel vertical migration of dinoflagellate, ... more Field observations have been made with respect to the diel vertical migration of dinoflagellate, Peridinium bipes and nutrient concentration profiles in a thermal stratified reservoir. Results showed that P. bipes could take nutrients and photosynthesize by migration in a calm thermal stratified mesotrophic reservoir. Faster migration from surface layer to middle layer was advantageous to take nutrients, and the possibility of active migration of P. bipes was suggested from the estimation of setting velocity . Furthermore, observational results suggested that P. bipes migration played an important role in nutrient cycling in a stratified reservoir. KEYWORDS;Peridinium bipes, vertical migration, nutrient cycling, thermal stratified reser voir 1. はじめに 近年、ダム湖 ・貯水池等の閉鎖水域において、特定の植物プランク トンの異常増殖に伴 うアオコや 淡水赤潮の発生が問題 となっている。例えば、児島湖では水田で発生 したEuglena spp.が 用水路を介 して流入 し、淡水赤潮を引き起こした例が報告されている1)。 アオコや淡水赤潮に関する問題を考える上では、どの植物プランク トン種が優 占す るのかが問題 と なるが、一般的には水温、栄養塩濃度、日射量、動物プランク トン等による捕食圧等の項 目について 検討がなされ...
Halophila japonica sp. nov. is described from Japan. Although this entity has long been referred ... more Halophila japonica sp. nov. is described from Japan. Although this entity has long been referred to as H. ovalis, data obtained from detailed morphological examination of field collections and herbarium specimens, geographical distribution records and ITS sequence analyses demonstrate that it is distinguishable from all other members of this genus and can be recognized as a new species. H. japonica is presently reported to occur from Ibusuki (Kagoshima Prefecture, Kyushu region, Japan) in the south, to Mutsu Bay (Aomori Prefecture, Honshu region, Japan) in the north. In order to better characterize H. ovalis materials from Japan, some observations on this species were also provided. As an outcome of this study, there are now four species of Halophila known from Japan: H. ovalis, H. euphlebia, H. decipiens and H. japonica.
Water
The Ohashi River is a narrow water stream that connects two brackish lakes in Japan. Intermittent... more The Ohashi River is a narrow water stream that connects two brackish lakes in Japan. Intermittent saline water intrusion often occurs in Lake Shinji from Lake Nakaumi through Ohashi River. In this study, two approaches were discussed to reproduce the hydrodynamic conditions of a morphologically complex river. In the first approach, the river sinuosity was straightened. The straightening of the river resulted in a higher flow velocity and water flux coefficient due to the reduction in the flow path and the resistance, and this approach was found to be appropriate for the reproduction of the flow velocity. However, the river shape was visually quite different from the actual river morphology. In the second approach, the prime focus was given to the shape and bathymetry to quantitively reproduce the flowrate of the saline water intrusion. This approach resulted in an underestimation of the flow velocity, which was compensated by increasing the cross-sectional area of the river. A slowe...
Science of The Total Environment
The Proceedings of the Symposium on sports and human dynamics
PLOS ONE
We investigated a method for surviving tsunamis that involved the use of personal flotation devic... more We investigated a method for surviving tsunamis that involved the use of personal flotation devices (PFDs). In our work, we succeeded in numerically demonstrating that the heads of all the dummies wearing PFDs remained on the surface and were not dragged underwater after the artificial tsunami wave hit them. In contrast, the heads of all the dummies not wearing PFDs were drawn underwater immediately; these dummies were subsequently entrapped in a vortex. The results of our series of experiments are important as a first step to preventing the tragedies caused by tsunamis.
The Proceedings of The Computational Mechanics Conference
Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering)
The age of bottom water which indicates the period in which oceanic water stays at the bottom of ... more The age of bottom water which indicates the period in which oceanic water stays at the bottom of the inner bay basin after intrusion from the bay mouth was calculated to verify whether the age is a good index for the development of bottom water hypoxia. The spatially distributed water quality data was utilized in this study for three consecutive year in 2012,2013 and 2014. The data was observed monthly on sixteen monitoring stations by Suzuka fisheries laboratory of Mie prefectural government. To calculate the age of bottom water, a temperature-based age index model was used, the model based on the assumption that bottom water in the Ise Bay originates from the bay mouth (Lower strait water) in the predominate stratified period, i.e., summer season and age of the bottom water is the elapsed time from the beginning of intrusion from the bay mouth. From the analysis of age index model, it was found that the age of bottom water was higher in the center of the bay and water can be of 60 days old whereas near the bay mouth it was much younger and its age varied from 0 to 10 days. In September 2014, the entire basin accounted for younger water mass with a maximum age of 10 days at the center as compared to other years. Overall bottom water age in Ise Bay has also been calculated by taking an average of all stations, and it was found that the maximum average age occurred in June 2013 while the minimum one occurred in September 2014. The bottom water oxygen concentration indicated a high average correlation coefficient (R 2 >0•70) with bottom water age in June, July, and August, whereas low average correlation coefficient (R 2 <0•30) in September.
Journal of Water and Environment Technology
Effect of water disturbance on grazing by the sea urchin with the refuge habitat was estimated. W... more Effect of water disturbance on grazing by the sea urchin with the refuge habitat was estimated. We tested the hypothesis that sea urchins ceased feeding and remained in refuge habitat for protection against disturbance even though water flows were not high to inhibit their grazing. Fecal density from sea urchins was positively related to their residence time under the undisturbed condition. This result suggested that the fecal density is a useful criterion for understanding the residence time of sea urchins in the calm condition. Five types of structure (L-shaped, cave shaped, crack-shaped, smaller and larger rectangular structure) as refuge habitats were deployed in the undisturbed tank with sea urchins and the fecal densities at each structure were measured to examine the habitat forms which sea urchins prefer. This experiment indicated that the crack-shaped form was used for sea urchins as the refuge habitat. Feeding rate of sea urchins inversely corresponded to water flow. Feeding rates with the refuge habitat were lower than in the absence of habitat, although water disturbances were almost the same. The presence of refuge habitat seemed to be a factor responsible for the reduction of their grazing, because sea urchins sheltered to avoid water disturbances.
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Papers by Tetsunori Inoue