Language：Japanese   Publishing type：Research paper (scientific journal)  

Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)  

researchmap

Language：Others   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

An open levee system is a traditional flood mitigation system for reducing the expansion of inland flooding and decreasing the peak flow. However, there have been few quantitative studies on its feasibility. Furthermore, the differences in applicability depending on the topography and the construction of continuous levees have not been fully examined. We studied its feasibility based on simulations in the Kuji River area, where the vast Typhoon Hagibis occurred. Morphological models representing the past (the 1940s) and the present (2019), obtained by modifying the highly accurate digital elevation models (DEM) via the tracing of aerial photos, were applied to a 2D unsteady flow simulation model to reveal the effects of the levee system on river hydrography and overland flood behavior. The results indicated that inundation flow through an open area decreased both inundation duration and depth, while the reduction of peak discharge is relatively insignificant at approximately 10%. The sub levees are not adequate under the current conditions and floodwater volume, and their effectiveness depends on the surrounding conditions, such as the development of continuous levees.

DOI： 10.3390/w14091343

Scopus

researchmap

Language：English   Publishing type：Research paper (other academic)   Publisher：IOP Publishing  

Abstract

The diverse socio-cultural conditions in Indonesia can make it difficult to develop sustainable micro-hydro power (MHP) generation in rural areas. However, the existing framework of sustainable development indicators to assess MHP sustainability does not include indicators for locations with traditional characteristics. This study aimed to develop indicators related to the specific cultural features for evaluating the sustainability of MHP generation. The identification of indicators was accomplished through field investigations and literature studies. Thirty-one experts in the Delphi method validated the indicators. The results revealed three indicators related to specific traditional characteristics and importance to the sustainability of MHP generation, i.e., electricity-supported cultural activities, customary rules of environmental protection, and directive of a traditional leader. These indicators can be elaborated with the existing framework and expected to increase sustainability assessment efforts for MHP generation in remote locations.

DOI： 10.1088/1755-1315/994/1/012003

Scopus

researchmap

Other Link： https://iopscience.iop.org/article/10.1088/1755-1315/994/1/012003/pdf

Language：Japanese   Publisher：Japan Society of Civil Engineers  

DOI： 10.11532/river.28.0_43

CiNii Research

Language：Japanese   Publisher：Japan Society of Civil Engineers  

DOI： 10.11532/river.28.0_19

CiNii Research

Language：English  

DOI： https://doi.org/10.3390/en14206727

Language：Others   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/en14206456

Language：Others   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s10113-021-01820-z

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/en14113349

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.egyr.2020.11.230

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Although many significant policies and legislation have been put forth by the Chinese government aiming toward “ecological civilization” for the aquatic environment, in practice, the situation is still undesirable. A pioneering multi-year study has since been conducted on the East Tiaoxi River (a major tributary of the renowned Yangtze River), focusing on fish distribution, influencing factors and habitat requirements, and river health as well. This revealed certain key species, hotspot protection areas, negative impacts of local anthropogenic activities, and inappropriate perceptions and practices of conservation and restoration. We found that not all fish species were equally conserved and that the supposedly ecological engineering measures were initiated without regard for ecological integrity. Our exemplary study appreciates scientific basis and truly ecological notion, and urgently advocates comprehensive and continuous basin-scale scientific investigation of fish biodiversity, and “ecological river”-oriented conservation and restoration action for the Yangtze River Basin and broader areas of China.

DOI： 10.3390/w12113043

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

<p> インドネシアでは小水力発電等の再生可能エネルギーによって遠隔地域における村落の電化が進められてきた．しかし，そのような村落に設置された小水力発電所（MHPP）の導入後の維持管理については追跡調査が行われておらず，MHPPの運営実態については十分にわかっていない．本研究では西ジャワ州の遠隔農村であるCiptagelar（チプタゲラ）集落を対象に，住民主体で管理されているMHPPの運営実態の詳細を明らかにすることを目的として，小水力発電事業の歴史，MHPPの概要，およびその運営状況を調査した．チプタゲラ集落にある4つのMHPPはこれまで，人為的な操作ミスや災害等により度々故障し，長期的に稼働停止する場合があった．MHPPの維持管理・運営コストと電気料金の帳簿データを精査した結果，住民からの電気料金によってMHPPの最低限の維持管理はできるが，災害復旧費等は確保できない状況にあることがわかった．取水河川の流況から推定したMHPPの発電出力から，使用可能電力の偏在が確認され，余剰電力の有効活用や災害へのレジリエンスを高めるマイクログリッドが有効であると考えられた．</p>

DOI： 10.3178/jjshwr.33.212

Language：Japanese  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jhydrol.2020.124936

Language：English  

Language：Others  

Socio-economic Development of Local Community through SHP Development: A Case Study of Oohito 50kW SHP in Hinokage town, Miyazaki Prefecture, Japan

Language：English   Publishing type：Research paper (scientific journal)  

Influence of Microtopography and Alluvial Lowland Characteristics on Location and Development of Residential Areas in the Kuji River Basin of Japan

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1080/24705357.2019.1663713

Language：Others   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/w11040716

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Others  

Combined Small Hydropower Technologies in Asia: Indonesian Turbine, Japanese Electrical Control and Indian Calculating Model
Edited by: Japan council for Renewable Energy

Language：Others   Publishing type：Research paper (scientific journal)  

Investigating the influence of various stormwater runoff control facilities on runoff control efficiency in a small catchment area
© 2018 by the authors. Licensee MDPI, Basel, Switzerland. Urbanization causes an increase in the flood discharge because of the infiltration capacity. Furthermore, extreme precipitation events have been an increasing concern for many regions worldwide. This study aimed to investigate the influence of different outflow control facilities on runoff reduction in a small watershed. We focused on the soil-improvement technology and rainwater tanks as outflow control facilities and conducted a runoff calculation using a rainfall event of a magnitude that is likely to occur once in a hundred years. The calculation showed that the soil-improvement technology reduced runoff during long-term continuous rainfall, whereas in a concentrated short-term rainfall event, a significant difference in the runoff reduction effect between rainfall tanks of various volumes was observed. Since effective countermeasures for runoff reduction differ depending on the rainfall distribution pattern, we suggested both facilities for storing initial rainfall and initiating countermeasures for penetration improvement over the long term.

DOI： 10.3390/su10020407

Language：Japanese  

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.2208/jscejhe.74.5_I_1255

Language：Japanese  

DOI： https://doi.org/10.3178/jjshwr.31.262

DOI： https://doi.org/10.3825/ece.19.165

Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： https://doi.org/10.1016/j.egypro.2017.11.044

Language：Japanese  

DOI： https://doi.org/10.2208/jscejhe.72.49

Language：English  

Language：English  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Others   Publishing type：Research paper (scientific journal)  

Effect of waterfalls on fluvial fish distribution and landlocked Rhinogobius brunneus populations on Yakushima Island, Japan
© 2014, The Ichthyological Society of Japan. The distribution of fluvial fish was surveyed at 55 sites on Yakushima Island, Japan, which has precipitous mountains and waterfalls (below- or no-waterfall sites: 31; above-waterfall sites: 24). Eleven diadromous and one river resident (introduced Oncorhynchus masou masou) species were found, but absolutely no fish were detected at the 18 above-waterfall sites. Statistical analyses revealed that the presence of waterfalls (> 5 m in height) below the sites had a significant negative effect on fish distribution, suggesting that waterfalls prevent migration of diadromous fishes. We found Rhinogobius brunneus populations above high waterfalls such as Nunobiki Falls (50 m) and Ohko Falls (88 m). Otolith Sr:Ca ratios and mitochondrial DNA (cyt-b region) were examined to determine the migratory history and genetic properties of these populations; the Sr:Ca ratios indicated that the populations had a landlocked life cycle, whereas the genetic endemism/isolation of landlocked populations was unexpectedly absent. There is no clear explanation for this phenomenon, but fairly infrequent individuals of nonlandlocked type might have migrated beyond the waterfalls with their sucker-like organ and mated with landlocked populations, disrupting the genetic isolation of landlocked populations.

DOI： 10.1007/s10228-014-0400-4

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.4236/oje.2014.47031

Language：Others   Publishing type：Research paper (scientific journal)  

Language：Others   Publishing type：Research paper (scientific journal)  

Navigation disturbance and its impact on fish assemblage in the East Tiaoxi River, China
We provide the first evidence for navigation impact on resident river fish in China. The survey was conducted in the East Tiaoxi River that discharges into Lake Taihu near Shanghai, on which cargo ship traffic has dramatically increased in the recent economic development period. Water turbidity, ship traffic and other environmental factors were evaluated at 29 sites on the river. In a multiple regression model with the stepwise method, turbidity was significantly correlated with ship traffic (R 2 = 0.53). Another survey was conducted at 46 sites in the same area of the river, in which environmental factors were evaluated and fish individuals were electrofished. A generalised linear model with the stepwise method was applied to predict ecological indicators of the fish assemblage (species richness, individual density and Shannon's diversity index) based on environmental factors. The results showed that the indicators were negatively correlated with turbidity and presence of artificial shore embankment structures. Another analysis further showed that the negative effect of turbid water was especially considerable for fish of smaller size. In conclusion, cargo ship traffic has a negative impact on fish assemblage, especially on smaller individuals, in the East Tiaoxi River. A higher profile for conservation actions and consideration of environmental impacts of such traffic should be given increasing focus for this and other similar East Asian water courses. © 2011 International Consortium of Landscape and Ecological Engineering and Springer.

DOI： 10.1007/s11355-011-0181-0

Language：Others   Publishing type：Research paper (scientific journal)  

Distribution pattern, threats and conservation of fish biodiversity in the East Tiaoxi, China
East Tiaoxi River is one of the largest inflowing rivers into Taihu Lake, and the fish fauna in the river is poorly understood. In the present study, an extensive survey of fish was conducted in October and November 2009, May and September 2010 and May 2011 covering a total of 55 sites along the whole river. A total of 84 freshwater fish species belonging to 8 orders, 18 families and 52 genera have been recorded. Among these are 35 species endemic to China, and 3 newly recorded exotic species. The fish composition varies greatly from headwaters to downstream. Based on cluster analysis with presence-absence data, the East Tiaoxi River is divided into four regions, specifically, the upper reach, middle-up reach, middle reach and lower reach. It is observed that species richness and the proportion of omnivorous species increased from upstream to downstream while the proportion of invertivorous species decreased consequently. Habitat alteration, overfishing, pollution and inland navigation adversely affect the fish diversity and ecosystem functioning in the East Tiaoxi River. To protect fish diversity more effectively in the area, the conservation of fish biodiversity in the North Tiaoxi River and Middle Tiaoxi River should be considered as a priority. Meanwhile, shallow zones or backwater areas should be created in the middle-lower reaches. Furthermore, river restoration, in terms of habitat creation, should be considered to protect the structure and diversity of fish communities, halt the progressive deterioration of freshwater ecosystems and sustain a valuable ecological resource for humans. © 2012 Springer Science+Business Media B.V.

DOI： 10.1007/s10641-012-0036-z

Language：Others   Publishing type：Research paper (scientific journal)  

Fishes of the east Tiaoxi river in Zhejiang Province, China
We conducted fish sampling at 90 sites in the East Tiaoxi River, Yangtze River basin, China. Seventy-seven species belonging to 19 families were recorded, and photographs of live specimens are provided for all species. Three exotic species were recorded: Cirrhinus cirrhosus, C. molitorella, Gambusia affinis. The top 3 species-rich families were Cyprinidae (46 &#37;), Cobitidae (5 &#37;) and Gobiidae (5 &#37;). The species composition in the East Tiaoxi River is similar to that of the Yangtze River Basin; however, the East Tiaoxi River has quite a diverse fish fauna for a small river system. © 2013 by Verlag Dr. Friedrich Pfeil, München, Germany.

Language：Japanese  

Language：Others   Publishing type：Research paper (scientific journal)  

Spatial and temporal variation of fish assemblages and their associations to habitat variables in a mountain stream of north Tiaoxi River, China
The spatial and temporal variations of the fish assemblages in mountain streams of China are poorly understood. The relationships between the fish assemblage and selected habitat features were examined in the North Tiaoxi River, one of headwaters of Taihu Lake. A total of 3,348 individuals belonging to 5 orders, 11 families, 25 genera and 34 species were collected including 33 native species and one invasive species. Among those, about 20 species were endemic to China. Non-metric Multidimensional Scaling (NMDS) was applied to compare fish assemblage structures from upstream to downstream during four seasons. Species assemblages differed along the stream continuum, but there was little apparent change associated with the seasons. Species richness and Shannon-Weaver index (H′) tended to increase along the stream continuum from the upstream to downstream and the proportion of invertivorous fish tended to significantly decrease along the continuum with a parallel significant increase in the percentage of omnivores. Fish assemblages were significantly related to both water quality and habitat structure variables. Canonical Correspondence Analysis ordinations (CCA) revealed that 6 of the 14 selected environmental variables had significant relationships with the fish assemblage such as distance to source, stream width, altitude, pH, water depth, and water velocity and different sampling sites were associated with different environmental variables in different seasons. The main differences in fish assemblage structure and diversity within the whole watercourse are probably related to large-scale factors such distance to source, altitude and stream width. Differences of instream characteristics are likely to be caused by natural variability of the ecosystems but also, in some case, by anthropogenic influence like human settlements, agriculture and river embankment and pollution from small factory. © 2011 Springer Science+Business Media B.V.

DOI： 10.1007/s10641-011-9928-6

Language：Japanese  

Language：Others   Publishing type：Research paper (scientific journal)  

Distribution pattern of loaches (teleostei: Cobitoidea) in the river east Tiaoxi, China
The distribution patterns of loaches (Teleostei: Cobitoidea) were revealed in the River East Tiaoxi in China. Eight loach species (Cobitis sinensis, C. dolichorhynchus, C. laterimaculata, Misgurnus anguillicaudatus, Paramisgurnus dabryanus, Leptobotia tchangi, Vanmanenia pingchowensis and V. stenosoma) were found in field surveys at 90 sites. A macroscale analysis of the geographical distribution showed that related species were segregated in accordance with longitudinal alterations along the river course. M. anguillicaudatus was widely distributed from the middle reaches to upstream of the river whereas the related species, P. dabryanus, was distributed only downstream. Three spined loaches, namely C. dolichorhynchus, C. sinensis, and C. laterimaculata, were distributed in the middle reaches, the middle to upstream reaches, and the upstream section of the river, respectively. The distribution of V. pingchowensis was further upper stream than that of V. stenosoma in the upstream section. More detailed microscale analysis revealed that L. tchangi and the two Vanmanenia species, V. stenosoma and V. pingchowensis were mostly found in the 'Riffle' (lotic) habitats, whereas the two spined loaches, C. laterimaculata and C. sinensis preferred the 'Pool' (lentic) habitats. These results demonstrated that related loach species preferred similar habitat units in the River East Tiaoxi system.

Language：Japanese  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Language：Japanese  

In Taihu Lake Basin in China, due to the rapid development of economy and society, degradation of aquatic environment has been one of the most urgent issues. On the other hand, the region still holds a lot of rivers and lakes with good environmental condition, which Japan and other advanced countries have already lost. For the first step to conserve such remaining environments, the past and present environmental status of the East Tiaoxi River (one of the most significant rivers in Taihu Lake Basin) was surveyed using GPS-logger, Google Earth and Landsat images. At first, NDBI, NDVI, BA was calculated from the multi-temporal Landsat images. The past Landsat images showed that, since 2000, urban areas and open-cast mining have been drastically expanded in the region. Classification of bank type was conducted using high resolution satellite images of Google Earth and digital photographs taken at main stream of East Tiaoxi; As a result, it was suggested that the carrying vessels for mineral substance considerably disturb the river environment.

researchmap

researchmap