担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

DOI： 10.2208/jscejj.23-16101

DOI： 10.2208/jscejj.23-16101

担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This study was conducted to clarify the relationship between fish species composition and environmental factors at various scales in river estuaries in the Japanese archipelago. The estuaries harbor diverse fish species composition due to their complex topography, varied climatic zones, and ocean currents. Non-hierarchical cluster analysis classified the fish species composition of 100 river estuaries (58 families, 152 species, and 486,356 individuals) into five groups. The highest number of species was confirmed in the group of river estuaries located in southwestern Japan and flowing into the inner bay (55.1 ± 9.6 species), characterized by an abundance of the number of Gobiidae species. In contrast, the species number was the lowest in the groups consisting of river estuaries that primarily belong to the northern Japanese archipelago (15.3 ± 3.3 species) that were characterized by an abundance of the number of cold-water fishes such as Salmonidae, Pleuronectidae, and Osmeridae. The highest fish species diversity was confirmed in the groups consisting of river estuaries flowing into the inner bays of southwestern Japan, which had a large tidal range (344 ± 132 cm), suggesting that the large tidal differences create a diverse tidal flat environment that supports fish species diversity. These results indicate that regional species diversity and geographical factors influence the classification of fish fauna. In northeastern Japan, the classification was influenced by geographic area and associated water temperature changes, whereas in southwestern Japan, tidal differences and wave effects could be more important. Understanding the factors that influence the fish species composition of a target river is fundamental to estuarine conservation, and the findings of this study provide basic knowledge for conservation.

DOI： 10.1007/s12237-023-01248-0

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Intense anthropogenic impacts in tidal rivers can cause habitat loss and ecosystem degradation. In addition, changes in water temperature associated with climate change are significantly impacting the distribution area of fish fauna within tidal rivers. In the present study, we used long-term fish fauna data to determine the relationship between climate change-induced increases in water temperature and changes in the distribution of fish species in tidal rivers in the Japanese archipelago. The distribution ranges of many subtropical and tropical fish species were found to move northward in areas affected by warm currents, suggesting further possible distributional dispersal in future. This study is the first to examine the nationwide distributional changes and future projections of fish fauna in tidal rivers. The results suggest that many subtropical and tropical fishes are expanding their distribution areas in tidal rivers and in coastal and estuarine areas.

DOI： 10.1007/s10113-023-02098-z

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Dams have contributed to population growth and technological innovation by reducing the risk of flooding and allowing humans to cultivate productive alluvial soils on river floodplains. However, in countries where many dams have already been constructed, many problems have been observed, such as river environment degradation, aging of the embankments, and inadequate dam performance. As the social and natural environment surrounding dams is becoming more complex and diverse, it is necessary to understand the current overall status of dams and the history of their construction such that we may consider how social capital and dams are related to human society and the natural environment. In this study, the relationship of basic information of dams and the social background in which the dams exist was examined for Japan, where dam construction began in earnest in the late 1800s and became a driving force for economic development. The situations surrounding dams are drastically changing, as maintenance and management costs increase due to the aging of dams and water demand varies due to changes in the industrial structure of a region. Simultaneously, there are instances where dams are expected to reduce damage, such as in the presence of more severe and frequent droughts and floods caused by climate change. It is therefore necessary to remove or restructure dams while considering numerous complex and diverse factors, such as the local social conditions, potential future changes, and environmental impact of rivers.

DOI： 10.1002/rra.4129

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This study investigated the fish fauna diversity of the Shimokita and Tsugaru peninsulas in the northernmost part of the main island of Japan. Since ocean currents influence brackish and saltwater fish distribution and dispersion, it is assumed that in the target area where ocean currents are complex, the ichthyofaunal diversity of river estuaries may vary significantly between rivers. In addition, the target area is located on a peninsula with complex topography, and topographical factors are also considered major factors influencing the fish fauna. During the field survey, 6879 individuals of fish from 34 species were collected from 25 river estuarine areas. Furthermore, the cluster analysis results indicated that the Tsugaru Warm Current, which flows from the warm current (Tsushima Current) on the Sea of Japan side to the Pacific Ocean side, strongly influences the presence of fish fauna in the regional river estuarine areas. Moreover, the wave exposure was marginal in rivers flowing into the Tsugaru Strait (7.4 ± 5.8), and saltwater fishes were absent, whereas fishes that depend on the gravel bed were observed. The bed slope of the estuarine river area of this group was large (1.65 ± 0.99%). The riverbed comprised stone and gravel, suggesting that in addition to biogeography, environmental factors strongly influence the presence of fish fauna. Furthermore, compared with previous studies conducted in the Shimokita Peninsula, the distribution area of the southern Gymnogobius species expanded, possibly due to the increase in seawater temperature caused by climate change. In the target area, where currents and topography are complex, it became clear that the area into which the river flows and topographical factors determine the fish fauna of river estuaries, suggesting that elucidating the relationship between complex environmental factors and biota is important for riverine environmental management and conservation ecology.

DOI： 10.1007/s12237-022-01097-3

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記述言語：英語   掲載種別：研究論文（学術雑誌）

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

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Headstream areas, which are located in the uppermost reaches of mountain streams, are important sections for investigating the geomorphology of stream channels and their generative mechanisms, because they are close to sediment supply sources and generally suffer little anthropogenic impacts. In this study, the occurrences and characteristics of bed morphologies in a sandstone-dominated headstream area are explored at two scales—reach and unit—which are often overlooked. As a result of field investigations, cascades and step–pools were found to occupy the majority of the stream channel laterally at the reach scale. However, most of the elevation differences were accounted for by fall–pools, cascades, and step–pools, suggesting the importance of bed morphologies with large elevation losses in the headstream area. In addition, the characteristics of the bed morphologies at the reach scale were closely related to the longitudinal profiles of each stream. The mean gradients of the reach-scale bed morphologies were 46.9% for fall–pools, 23.9% for cascades, 16.8% for step–pools, and 5.9% for pool–riffles. At the unit scale, pools occupied the majority of the stream laterally, and > 80% of the elevation differences in all the studied rivers were occupied by falls, bedrock cascades, cascades, and steps. Although there have been no studies on the elevation loss functions and characteristics of falls, this study revealed the importance of fall–pool reaches and fall units in a sandstone-dominated headwater area in the Kantō Range of Japan.

DOI： 10.1007/s10201-021-00690-y

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Pools play an important role among stream bed morphologies in mountain streams. They provide habitat and contribute to energy dissipation. However, they have received only marginal attention compared with step structures, and their forms and driving factors, such as stream-channel characteristics and structural characteristics of upstream morphologies, remain unclear. Therefore, the purpose of this study was to determine the structural characteristics of pools, including morphology, size, and deposit conditions, and the factors controlling them. Based on the results of a field survey for a channel length of 9524 m, with 428 reaches and 1302 pools, the correlations between the pool spacing, morphology, size, and deposit conditions of the pool, and controlling factors were investigated for three rock types (granite, rhyolite, and sandstone). The average pool spacing calculated by dividing the interval length of the pool by the channel width was 8.80, 12.87, 4.56, and 16.14 for fall-pool, cascade, step-pool and pool-riffle respectively. This is due to the fact that the target streams are first-order streams with small widths as well as their regional characteristics, that is, few log jams and forced pools. In addition, the depositional depth of the pools varies depending on the geology. The maximum percentage of sediment deposition in the pool was 78%, 33%, and 34% for granite, rhyolite, and sandstone, respectively. Thus, the sedimentation in granite is significantly greater than in the rhyolite and sandstone headstream areas. This is probably due to the discontinuous weathering of granite during which it is broken down into large-sized core stones and fine grains. The difference in the depositional environment of the pools depending on the geology indicates that the biota that use those pools as a habitat may also differ. However, research on the microhabitats of pools is lacked, and research regarding the future perspectives of ecosystems is required.

DOI： 10.1016/j.catena.2021.105760

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

To mitigate urban flooding, conserving pervious areas and securing the infiltration capacity are important. The infiltration capacity of an area can be significantly reduced by compaction; thus, we attempted to build a runoff reduction technology that can ensure the infiltration capacity even after compaction to mitigate urban flooding. Herein, we revealed the relationship between the degree of compaction and infiltration capacity of amended soils using humus and bamboo chips. We performed a watering infiltration experiment, which initially demonstrated the nonoccurrence of surface runoff in all experimental materials for rainfall intensities of 60 and 120 mm hr−1, without compaction. However, as the degree of compaction increased, humus mixed with soil exhibited behaviour similar to that of unimproved soil and the surface runoff exceeded seepage drainage. In contrast, in the case of bamboo chips mixed with soil, the surface runoff remained small even at high degrees of compaction. Consequently, when the rainfall intensity was 120 mm hr−1 and compaction was 3 kg cm−2, the surface runoff per unit time for bamboo chips mixed with soil was 2.4 times less than that for humus mixed with soil and 2.2 times less than that for unimproved soil. Moreover, such differences were observed in the infiltration capacity with respect to compaction because of the void structure owing to soil improvement. Thus, we conclude that soil improvement using bamboo chips can be considered an effective technology to mitigate urban flooding.

DOI： 10.1111/sum.12705

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Background Urbanisation has facilitated changes in the hydrological cycle, sediment dynamics and habitat loss and it has had a tremendous impact on river ecosystems. Moreover, the invasion of non-native species reduces the number of native species with the progress of urbanisation, thereby resulting in the homogenisation of fish fauna and significant decrease in diversity. However, the effects of urbanisation on fish fauna vary depending on the region, degree of urbanisation and number of years since the construction of the city. Hence, it is necessary to collect information on how fish fauna changes due to urbanisation in different regions. The target site of the present study is the Tsurumi River, of which approximately 85% of the basin is urbanised and many of the river channels have been affected by straightening and concrete channelling. Monitoring of biota has been conducted mainly in downstream areas; however, data on fish fauna in upstream areas and tributaries of the river, which have been substantially affected by urbanisation, are lacking. New information Surveys were conducted at 71 sites in the Tsurumi River Basin during summers and winters, focusing on river channels that have been straightened or converted to concrete channels due to urbanisation. As a result of this investigation, 10 families, 28 species and 9,335 individuals were collected. Some of the fish collected included rare species, such as Tanakia lanceolata, Lefua echigonia and Pseudobagrus tokiensis, indicating that, even in rivers that have been severely impacted by human activities, there are still rare indigenous species living there, albeit in limited numbers. In addition, Misgurnus sp. (clade B2), Micropterus salmoides, Lepomis macrochirus and Poecilia reticulata were confirmed to be non-native species. Misgurnus sp. (clade B2) was widespread; however, populations of carnivorous non-native alien species were small. The data are all accessible from the document “database_fish_urban_tsurumi” (https://ipt.pensoft.net/manage/resource?r=database_fish_urban_tsurumi).

DOI： 10.3897/BDJ.10.e83527

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

The headstream area is an important channel segment for investigating the self-organization mechanism of a stream channel or the occurrence characteristics of stream bed morphology owing to its sediment source and low anthropogenic impact such as that from check dams or channel modifications. However, less work has been conducted on the transition of stream bed morphology in channels with very high gradients, unlike in step–pool channels. This study describes the field observation results of the stream bed morphological characteristics and the relationship between the step–pool structure and stream channel characteristics in the headstream areas of rhyolitic mountains. The transition of the stream bed morphology associated with different bed slopes was confirmed through field observations. The dominant stream bed morphology changed from a fall to a cascade to a step, from upstream to downstream. Furthermore, the relationship was different between the step formation processes (hydraulic control and keystone types) and the jamming state, which was caused either by the supply process of the step constituent boulder or the external force of the step. Mountainous streams are strongly affected by geology, and this tendency is likely to be more pronounced in headstream areas. Further, the factors influencing stream bed morphology or stream channel characteristics include the formation age of mountains and the climate, geology, and the absence of fault zones. Therefore, knowledge of the stream bed morphology of headstream areas under various geological and meteorological conditions is required.

DOI： 10.1016/j.catena.2021.105427

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（学術雑誌）

Floods cause severe damage in terms of human and economic loss on a global scale. Moreover, the risk of flooding is increasing owing to a hydrological cycle intensified by climate change and by the concentration of population in cities vulnerable to flooding. Although conventional river-engineering structures, including continuous levees, flood-control dams, and drainage pump stations, have been installed in many countries to prevent flood damage, these measures are vulnerable to the large-scale floods that exceed the design level of the flood-control infrastructure. In contrast, traditional strategies and flood-control technology that has been used since ancient times allow inundation and instead strive to minimize flood damage in floodplains. Nevertheless, the onslaught of modern river-engineering methods means that traditional flood-control systems have been rapidly disappearing, with the concomitant decrease in floodplain inundation frequency. This paper reviews the current knowledge about traditional flood-control systems that are sustainable and provide effective flood countermeasures against future uncertainties. Furthermore, we describe the problems and solutions associated with the integration of traditional flood-control systems and conventional river-engineering methods to decrease flood damage in floodplains.

DOI： 10.1007/s10113-021-01820-z

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Increasing water demand due to population growth, economic development, and changes in rainfall patterns due to climate change are likely to alter the duration and magnitude of droughts. Understanding the relationship between low-flow conditions and controlling factors relative to the magnitude of a drought is important for establishing sustainable water resource management based on changes in future drought risk. This study demonstrates the relationship between low-flow and controlling factors under different severities of drought. I calculated the drought runoff coefficient for six types of occurrence probability, using past observation data of annual total discharge and precipitation in the Japanese archipelago, where multiple climate zones exist. Furthermore, I investigated the pattern of change in the drought runoff coefficient in accordance with the probability of occurrence of drought, and relationships among the coefficient and geological, land use, and topographical factors. The drought runoff coefficient for multiple drought magnitudes exhibited three behaviors, corresponding to the pattern of precipitation. Results from a generalized linear model (GLM) revealed that the controlling factors differed depending on the magnitude of the drought. During high-frequency droughts, the drought runoff coefficient was influenced by geological and vegetation factors, whereas land use and topographical factors influenced the drought runoff coefficient during low-frequency droughts. These differences were caused by differences in runoff, which dominated stream discharge, depending on the magnitude of the drought. Therefore, for effective water resource management, estimation of the volume of drought runoff needs to consider the pattern of precipitation, geology, land use, and topography.

DOI： 10.3390/w13091259

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

The alteration of hydrologic systems due to urbanization causes many problems including urban flood inundation, water quality degradation, and stream ecosystem damage related to river channel modifications such as stream burial. The purpose of this study was, therefore, to clarify the factors affecting the process of stream burial by performing a time series investigation of the changes in six river systems flowing through the Tokyo Metropolitan Area from 1909 to 2020 using historical topographic maps. The observed changes revealed that the stream burial process consists of: (1) river improvements such as meander cutoff and integration of flow channels by branch abolishment, (2) stream burial of relatively small tributaries, and (3) stream burial of large tributaries and part of the mainstream. Stream burial was remarkable in the center of the Tokyo Metropolitan Area, where the river channels and condition of stream burial were nearly the same in 2020 as they were in 1945. However, meandering channels partly remained in the tributaries of relatively large stream systems. Straight channels constituted about 10% of all channels in 1909, but constituted greater than 40% in 2020, suggesting that the remaining open channels were considerably influenced by river improvements such as meander cutoff. Furthermore, the degree of stream burial was observed to be strongly related to the proportion of urbanization and the scale of the target river system. Stream burial was found to be advanced not only by changes in land use, but also by social factors including earthquake and war damage reconstruction projects as well as measures to counter flooding and improve water quality. The findings of this study advance research into evaluating measures and goals for urban river restoration projects.

DOI： 10.1007/s12665-021-09524-7

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

The conservation and restoration of freshwater ecosystems require the understanding of potential biota of the target area. My ultimate study goal was to clarify the potential fauna of the watershed unit of the Japanese archipelago, a hotspot of biodiversity. Here, I attempted to classify the macroinvertebrate community of the major rivers within the Japanese archipelago, thereby elucidating its biogeography, and to investigate the extent to which environmental factors drive the watershed's macroinvertebrate community. I classified the rivers located in the northern region of the Japanese archipelago geographically, but did not group the geographically adjacent rivers in the western region together. Differences in watershed size, geological history (including river conflict), and paleo-drainage systems seem to affect the classification results. Moreover, Indicator Species Analysis results suggest that river groups in the northern part of the Japanese archipelago had highly endemic species, whereas, the river groups in the western part of the Japanese archipelago had few highly endemic species. The result of the canonical correspondence analysis indicated that topographic factors, the flow regime, geology, water quality, and anthropogenic factors were significantly correlated with macroinvertebrate classification and distribution. The results of the decision tree model indicated that water temperature and maximum specific discharge were explanatory factors in the classification of the macroinvertebrate community. Further, my results also suggest that environmental factors at a smaller scale than that of the watershed were needed to explain further subdivisions in classification of the macroinvertebrate community.

DOI： 10.1016/j.limno.2020.125844

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Background River estuaries provide various ecosystem services, such as nutrient circulation, climate change mitigation, habitats and coastal defence. Information on the various taxonomic groups is collected from large-scale estuaries; however, few studies have focused on river estuaries of small and medium-sized rivers. In particular, information on river estuaries in peninsulas and islands with complex marine environments is lacking. New information This paper provides basic information on summer fish fauna in the southern part of the Boso Peninsula, Japan. The Boso Peninsula is located at the northernmost point of where the warm current (Kuroshio) reaches and is considered to have highly endemic fish fauna. In total, 28 families, 51 species and 2,908 individuals were collected from the 27 river estuaries. The data are all accessible from the document “database_fish_estuary_boso (http://ipt.pensoft.net/manage/resource.do?r=database_fish_estuary_boso)”. Further, Sicyopterus japonicus and Microphis brachyurus, which appear in estuaries that are influenced by the Kuroshio, were confirmed. However, these species were confirmed in few of the rivers studied, highlighting the importance of habitat conservation.

DOI： 10.3897/BDJ.9.e67168

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>　本研究は，山地源頭部の河床形態の出現特性を調べ，山地の地形的特徴量及び縦断形状との関係を明らかにしたものである．リーチスケールの河床形態の河床勾配は，fall-pool，cascade，step-pool及びpool-riffleの順に大きく，地質間で大きな差異はみられなかった．また，対象河川の縦断形状は直線型と凹型の2つに大別でき，直線型では河床形態の勾配が上下流で変化していないのに対し，凹型では同一の河床形態であっても上流側に勾配が増加する傾向がみられた．源頭部における河床の縦断形状や河床形態の出現特性に影響を及ぼす山地の特性量として，起伏量や開析度に関する指標が選択された．これらは，土砂生産や河床の比高差に関連する指標であることから，河床形態の分布を支配する重要な要因と考えられる．</p>

DOI： 10.2208/jscejhe.77.2_i_1009

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The purpose of this research is to describe and evaluate an example of the impact of large-scale disasters on a fish fauna of rivers. In the northern part of Kyushu from July 5th to 6th, 2017, a heavy rain fell steeply into a specific area Especially in Asakura city, Fukuoka, Japan there was a recordable heavy rain which resulted in major damage to roads, buildings and rivers. From July to December 2017, we conducted capture survey at eight sites and environmental DNA (eDNA) metabarcoding at 18 sites in the middle reach tributaries of right bank of Chikugo River system in Kyushu, Japan. In the capture survey, four species 470 individuals were found from eight sites, although fish were not captured at three of those sites. In an eDNA analysis, 21 species were detected from 18 sites, however fish eDNA was not amplified at seven of those sites. The fish fauna of capture survey and eDNA analysis coincided at seven out of eight sites, which showed the high accuracy of fish fauna detection by eDNA analysis in this study. Our result confirmed that this heavy rainfall devastated blow to the fish fauna of the rivers.

DOI： 10.3825/ECE.23.161

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Adopting a comprehensive, basin-wide method for preventing flood disasters would be effective to deflect the climate-change-induced intensified water-related disasters. This study considers the land use and settlement patterns based on microtopography and flood risks. The influence of the microtopography and alluvial lowland characteristics on the location and development of residential areas in the Kuji River basin, Japan, is a fundamental aspect of historical knowledge. Investigating the relation between the microtopography and the location of antiquities shows that most of the relics dating to or before the third century were situated in the terraces near the lowlands. The development of lowlands near the mainstream of the Kuji River began around the third century. Furthermore, the relation between the microtopography and development of residential areas is investigated using building density as the development indicator. The results confirm the increase in building density in the alluvial surface, proving a history of flood damage and delayed development compared to other regions. This investigation reveals land development in areas, including the former river bed on the mouth of the Kuji River and the flood plain on the margins of the Hitachiota urban distinct, with no confirmed inhabitation before modern times because of elevated flooding risk.

DOI： 10.3390/SU12010065

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Step–pool structures are among the most important structures in riverbed morphology that can contribute to the stabilization of riverbeds and riverbanks, energy dissipation during floods, and head reduction function. Two concepts have been suggested regarding step–pool formation: the development of antidunes (antidune concept) and keystone concept. The latter suggests that a large boulder (keystone) incidentally left in a river channel can trap pebbles and build a step–pool structure. The ultimate goal of this study is to reveal the step–pool formation process and establish a design method based on the keystone concept. This paper describes the experimental results of the effects of the keystone arrangement on sediment deposition. Step–pool formation based on the keystone concept has previously been focused on the process of sediment deposition a short distance from a keystone. However, this study reveals that the obstruction of sediment supply due to the decreased flow velocity in the main river course is an important factor. When the arrangement interval of keystones is small, the amount of sediment supply downstream decreases because the flow velocity at the main flow channel between the keystones does not increase. In contrast, the flow velocity at the main river course increases between the keystones, and supplied sediment is transported to the most downstream section if the keystone arrangement interval is large enough to join the flow from the bank side of the keystones.

DOI： 10.1002/rra.3524

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Dam removal is typically intended for river restoration or as a countermeasure for aging dams. The influence of dam removal has mainly been studied in large rivers. This study is intended to investigate the influence of the sediment supplied after opening a check dam drain in a small steep stream to contribute to the establishment of sediment release technology form check dam by accumulating the basic knowledge about the influence of sediment release. Deposited sediment in the impoundment was rapidly discharged immediately after opening the drain outlet, and a moderate sediment discharge followed. The water course of the sediments deposited by repeated channel widening and riverbed degradation tended to stop longitudinal topographic changes from downstream. In addition, the turbidity during a flood was high in the first year and tended to decrease in the second year. As for the ecosystem response, changes in the benthic macroinvertebrate community were confirmed in downstream sites, and net-spinning species especially deceased immediately after the sediment supply began. Our monitoring results suggest that the increasing turbidity was suppressed during the flood because sediment release was conducted from the small-scale facility. As a result, a negative impact on the aquatic ecosystem seemed to be reduced.

DOI： 10.3390/w11040716

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

River estuaries are critical aquatic environments characterized by large environmental gradients in their water quality, riverbed material, and microtopography in the longitudinal and transverse directions. Molluscan fauna are sensitive to changes in water quality or bottom sediment conditions, and include species that inhabit unique environments or have a high capacity to thrive in different habitats. The interrelations between ecology and whole physical environment of molluscan fauna have rarely been studied, especially in medium and small sized river estuaries. This study was conducted to investigate the relationship between molluscan fauna and multiple hierarchical physical factors in river estuaries, and develop a prediction model for each of the molluscan species under study. The study focused on molluscan fauna in river estuaries in medium and small size rivers, where knowledge is particularly limited. Results obtained from quadrats were classified into three groups related to physical factors, including wave and river energy and habitat scale factors. Prediction models for molluscan species indicated that physical factors affected different species at varied scales. There were species influenced by watershed scale, habitat scale, or both. Because the physical factors influenced species at different scales, prediction of potential molluscan fauna on a site is also critical, in addition to the conservation or restoration of habitats.

DOI： 10.1016/j.ecss.2019.01.001

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

An evaluation of ecological integrity is required for ecosystem conservation and restoration. The ecological region, or “ecoregion”, has been adopted as a unit of geological area to enable a comparison of the ecological integrity of different regions. The delineation of an ecological region is difficult in countries in East Asia, including Japan because of complex topographies (i.e., several peninsulas and islands) and fauna that are very finely delineated based on climate or geology. Therefore, it is important to appropriately determine the ecoregions when determining their biological integrity and comparing it among that of other ecoregions. I attempted to delineate an ecological region of the Japanese archipelago based on the similarities among fish fauna by integrating the information on fish fauna that was collected by the researchers and the national government and local governments. In addition, quantitative analyses to investigate the relationship between fish fauna classification and meteorological and geographical factors were conducted to discuss the factors that influence fish fauna classifications. The archipelago was classified into 15 fish fauna groups, and the results of these grouped classifications were closely related to the process by which the Japanese archipelago was formed, the ocean current in its coastal waters, and the connection of the water system to the glacial age. Our findings suggest that rivers within geographical areas that are different from those within the Japanese archipelago might have different fish fauna classifications based on our results and potential fish fauna depending on the characteristics of the watershed, such as the scale of the floodplain, river conflicts, or river formation process. By applying the results of our fish fauna classification, we are able to make a comparison of the biological integrity of fish fauna among different watersheds for managing the river environments or establishing conservation policies.

DOI： 10.1016/j.ecolind.2018.08.057

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記述言語：日本語   掲載種別：研究論文（学術雑誌）

CiNii Article

CiNii Research

その他リンク： https://ndlsearch.ndl.go.jp/books/R000000004-I029383004

担当区分：筆頭著者,　最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Study region: The Kinu River basin receiving serious damage in September 2015 because of the heavy rainfall disaster that hit the districts of Kanto and Tohoku in Japan. Study focus: This paper provides future flood risk management for floods that exceed design levels (FEDL) based on past flood control systems and land use considering the natural topography in the area that was inundated by flood water from the Kinu River. New hydrological insights for the region: The results of the literature research reveal flood management methods for preventing inundation of the city of Mitsukaido, such as drainage using a discontinuous embankment and a low-lying backswamp. In addition, the areas inundated by this flood were mainly those around a high-altitude natural levee, and residential land in the backland lowland area was developed after the Meiji period (1868–1912). Furthermore, a field survey revealed that many of these flood management systems are not functioning completely because of artificial modification. Identifying locations of potential flooding in areas of low population density is necessary as a countermeasure against FEDL. It is also important to recognize microtopography such as natural levees or backswamps, to induce land use based on the different flood risks of these topographies, and to utilize historical flood control systems as countermeasures against FEDL.

DOI： 10.1016/j.ejrh.2018.10.001

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記述言語：日本語   掲載種別：研究論文（大学，研究機関等紀要）

application/pdf

DOI： 10.14945/00025035

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その他リンク： https://shizuoka.repo.nii.ac.jp/records/10049

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

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

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Background Many studies have evaluated the ecological integrity of large-scale estuaries of continental rivers using biotic indicators such as fish, phytoplankton and benthic communities. However, few studies have focused on the river estuaries of small and medium rivers. Molluscan fauna data in large estuaries or in the estuaries of large rivers have been collected by the The National Census on River Environments (conducted by the Ministry of Land, Infrastructure, Transport and Tourism) or National Survey on the Natural Environment (conducted by the Ministry of Environment). On the other hand, molluscan fauna of small and medium rivers are managed by local governments and have rarely been investigated. New information This paper provides basic information on the molluscan fauna of 70 rivers in Kyushu, Japan, collected with the aim of conserving estuaries of small and medium rivers. In total, 37 families, 82 species and 21,827 individuals were collected. The data are all accessible from the document "A dataset of shellfish fauna sampled in estuaries of medium and small rivers in Kyushu, Japan (http://ipt.pensoft.net/resource.do?r=shellfishes_in_kyushu)". According to the Red Data Book published by the Japanese Ministry of Environment in 2018, 3 species were determined as Critically endangered and Endangered, 6 species were determined as Vulnerable and 13 species were determined as Near Threatened. The proportions of individuals classified as Critically endangered and Endangered from the total number of individuals were extremely low, but the proportions of Near Threatened individuals were high. Our results indicate that the risk of molluscan extinction in small- and medium-sized river estuaries in Kyushu is high and that immediate conservation is necessary.

DOI： 10.3897/BDJ.6.e26101

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

Kyutacar

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CiNii Research

その他リンク： https://ndlsearch.ndl.go.jp/books/R000000004-I029396361

記述言語：日本語   掲載種別：研究論文（学術雑誌）

急勾配河川では洪水時の河床洗堀や河岸浸食が著しいため，環境に配慮した河道設計技術が確立されていない．本研究では長崎市に位置する急流都市河川である大井手川の環境に配慮した河道の設計のため, 移動河床での模型実験を行った．実験の結果，急勾配河川で川幅に制約がある都市河川でも石積水制によって河岸，河床の防御が可能であり，水制の配置を考慮することで，河道内に複雑な環境構造を形成しうることが示された．また今回の水制の最適構造と既往知見を比較し，水制間隔と水制長や川幅との関係や，水制間隔が相対水制高と洗堀深に与える影響について考察を行った．

DOI： 10.2208/jscejhe.74.i_1141

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その他リンク： https://www.jstage.jst.go.jp/article/jscejhe/74/4/74_I_1141/_pdf

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

Kyutacar

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CiNii Research

その他リンク： https://ndlsearch.ndl.go.jp/books/R000000004-I028905522

記述言語：日本語   掲載種別：研究論文（学術雑誌）

河川汽水域の保全，修復のためには，対象とする場の潜在的なハビタットを把握することが重要である．本研究は，河口域保全のための基礎的な情報として流域スケールの指標により河川汽水域を分類し，分類群毎に河道特性とハビタット構造の関係を調べたものである．流域指標による分類の結果，河川汽水域は潮汐，波浪及び河川のエネルギーによって波浪・河川卓越型，弱波浪型，潮汐卓越型の3つに区分された．分類群毎にハビタット構造に影響を及ぼす河道特性は異なっており，波浪・河川卓越型は蛇行度，弱波浪型は比高差，潮汐卓越型は川幅水深比がハビタット構造に影響を及ぼす要因であることが明らかとなった．

DOI： 10.2208/jscejhe.74.i_601

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CiNii Article

CiNii Research

その他リンク： https://www.jstage.jst.go.jp/article/jscejhe/74/4/74_I_601/_pdf

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>　本研究は，花崗岩山地河川源頭部に出現する河床形態と河床勾配の関係及び階段状河床形態を構成するstep構造とその支配要因の関係を調べたものである．源頭部では，河床勾配に応じた河床形態の遷移が確認され，勾配が急な上流から下流に向けて，滝，cascade，step及び早瀬と優占する河床形態が変化した．また，階段状河床形態は，河床勾配やstep間隔とstep高の比によってstep-pool，step-早瀬，step-pool-早瀬の3形態に変化することを示した．step高とstep構成礫の最大径の関係は，反砂堆型とkeystone型で異なり，反砂堆型ではstep構成礫の最大径と摩擦速度が正の関係にあり，keystone型では，河床勾配及びstep幅と正の関係があることが明らかとなった．</p>

DOI： 10.2208/jscejhe.74.5_i_1255

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その他リンク： https://www.jstage.jst.go.jp/article/jscejhe/74/5/74_I_1255/_pdf

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

砂防えん堤の排水ゲートからの土砂排出による中小河川への土砂還元施策（福岡県・加茂川）を対象に，旧湛水池からの土砂排出特性ならびに下流急流区間（概ね1/5-10）における堆砂状況について現地観測により明らかにした．花崗岩帯を背後に持つ旧湛水池には29年分の堆積土砂（約13,700m³）が砂と粘性土との互層を成して堆積していた．排水ゲート開放後，直後に堆砂量の約12.1%，その後の出水でさらに6.6％が流出した．出水期を経て堆積域には階段状の地形が形成され安定的な河床に達している．排水ゲート開放後の出水時における濁水のSS濃度は約1200mg/Lと推定され，既往のダム撤去の事例と比べると小さい部類に含まれるが，排出された土砂は下流のStep-Pool構造が発達する急流部にも堆積し，えん堤に近い一部のPoolを埋没させている．これより，急流河川においても土砂還元による顕著な地形や底質の変化が生じうることが示唆された．

DOI： 10.2208/jscejhe.74.i_913

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CiNii Article

CiNii Research

その他リンク： https://www.jstage.jst.go.jp/article/jscejhe/74/4/74_I_913/_pdf

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

River estuaries are important aquatic environments characterized by large environmental gradients in their water quality, riverbed material, and microtopography in the longitudinal and transverse directions. The geography or habitats in river estuaries differ depending on the energy from the tide, waves, and river; therefore, the biota inhabiting river estuaries vary depending on the river estuary type. In view of this, for effective conservation in river estuaries, there is a need for information about potential habitats and biota based on objective data about the river estuary type. The objective of this study thus was to classify river estuaries by their molluscan fauna and physical indicators to reveal the relationship between molluscan fauna and the physical environment. The classification results using physical indicators indicated three types of river estuaries (wave energy-dominated group, tide energy-dominated group, and low tide and wave energy group). This classification result was similar to the classification of molluscan fauna. Therefore, it was suggested that molluscan fauna is extremely useful as a variable representing the river estuary environment. From the comparison between molluscan fauna and the physical environment, some rivers were not classified into the same group in the classification of molluscan fauna, despite them having similar physical environments. Some of these rivers with a molluscan fauna that diverged from expectations had undergone channel modification, which is expected to have caused a shift in this fauna group. These results suggest that this approach could be used to identify rivers that have been degraded by human activities.

DOI： 10.3390/w9050356

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Scopus

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

本稿では，山地河道において特徴的な step-pool 構造に関する既往の知見を基本的な特徴，形成・破壊過程，物理的特性及び生息場としての機能を中心に整理し，河川技術への応用可能性について示した． 第 1 に基本的な特徴について，step-pool の形成要因や発生領域を河床勾配に着目して整理した．第 2 に形成・破壊過程について形成条件を流れや土砂の状態に着目して説明し，形成・破壊流量について既往の知見を整理した．形成過程については反砂堆理論と keystone 理論があり，両者の過程が混在しており，技術的観点から両者の成因を活用した自然再生，河川改修技術の構築の必要性を指摘した．第 3 に step-pool 構造と河道特性の関係を step 間隔と河床勾配の関係を中心にまとめた．これらは気候・土砂供給条件などによって地域的な差異が大きく，普遍的な知見の構築には更なる研究が必要であることを指摘した．第 4 に step-pool に関連する物理的特性について整理を行い，現在提案されている山地河道を対象とした流速公式，抵抗則をまとめた．最後に生物生息場としての機能や自然再生の事例を紹介した．これらを通じ，step-pool 構造のエネルギー減勢及び落差緩和機能が河道改修技術として応用可能性が高いことを指摘し，今後必要となる研究を示した.

DOI： 10.3825/ece.19.165

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その他リンク： https://ndlsearch.ndl.go.jp/books/R000000004-I028049704

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

CiNii Research

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

河口域の保全，修復のためには，対象とする場の潜在的な生物相やハビタットを把握する必要がある．本研究は，河口域保全のための基礎的な情報として，全国一級河川の河口域を対象に，底生動物の生物地理に基づくEcoregionを設定し，同一Ecoregion内で物理指標による河口域の類型化を行った．底生動物相の類似度から日本の河口域は，日本海，太平洋，西南海の3つのEcoregionに区分された．また，各Ecoregionの指標種と関係の強い物理環境要因として，波浪，潮汐，河川のエネルギーを代表する指標が選択された．これらの指標を用い日本の河口域を9つの河口タイプに分類した．同一分類に属する河口域は潜在的な生物相とハビタットが相同とみなせるため，分類結果は河川生態系保全の基礎単位となりうる．

DOI： 10.2208/jscejhe.73.i_1171

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その他リンク： https://ndlsearch.ndl.go.jp/books/R000000004-I028112916

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>Estuaries are distinctive environment which fluctuates continually by mixing fresh water and sea water due to the influence of the tide and waves. However, disappearance of habitats is a serious problem in estuaries since river improvement technology in consideration of the environment has not been established. In this study, we investigated the relation between shellfish fauna and physical factors of watershed scale and river course characteristics. As a result of single correlation analysis, sinuosity, river bed complexity, comparable height difference in low flow channel, depth ratio, bed slope and number of types of habitat had significant positive correlation to abundance of shellfish fauna. These results suggest that the securement or creation of high attitude area in low flow channel should be considered when conducting the river bed excavation, or diversity of shellfish fauna can be secured by increasing the depth ratio when conducting river improvement.</p>

DOI： 10.11532/river.23.0_657

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その他リンク： https://kyutech.repo.nii.ac.jp/records/2000523

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Selecting sites for river restoration projects or performing ex post evaluation must be done in ecoregions with comparable biological integrity. Moreover, to evaluate the integrity of a river ecosystem that varies from the headwater to downstream regions, adjustments of the ecoregion according to the longitudinal change in biota must be made. We defined regions where biota are identical according to the direction of change along the stream path as “segment-based ecoregions.” We delineated segment-based ecoregions using fish fauna data for two ecoregions in Japan: the northeast Kyushu, and south Kyushu. The northeast Kyushu ecoregion was divided into three segment-based ecoregions, and south Kyushu ecoregion into five segment-based ecoregions. Classifying fish fauna within the same ecoregion enables classification by differences in the longitudinal change in the stream path rather than by differences in watersheds. Specific topographic regions such as the amphitheater areas of the south Kyushu ecoregion was classified as independent segment-based ecoregions. We further defined indicator fish species for each segment-based ecoregion. Indicator fish species reflected the fish fauna of each ecoregion in the midstream area, such as migratory Gobiidae of the south Kyushu ecoregion. Applying the segment-based ecoregion concept helps compare the biological integrity of fish fauna depending on a common environmental type between watersheds.

DOI： 10.1016/j.ecoleng.2016.10.024

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担当区分：筆頭著者,　最終著者,　責任著者   記述言語：日本語   掲載種別：記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）

CiNii Article

CiNii Research

その他リンク： https://ndlsearch.ndl.go.jp/books/R000000004-I027471535

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Water intake structure is an important element technology for small hydroelectric generation. Currently, intake structures with bar screens have been broadly introduced; however, these require constant maintenance to avoid the clogging of bars by dust or gravel. This study considers the optimal structure of bottom intakes by focusing on two criteria: efficient water intake and prevention of clogs by trapping trash. Grating was selected as the intake structure because it is convenient to construct, widely available, and cheaper than other materials. A flume experiment was conducted to examine the relation between the grating structure and the intake efficiency and trash-trapping rate. Results indicate a clear linear relation between the installation angle and water intake capacity. Furthermore, the trash-trapping rate is low for gratings that have high opening area ratios because their surface areas are small and friction resistance is low.

DOI： 10.1063/1.4948918

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：記事・総説・解説・論説等（学術雑誌）

Here, we review existing knowledge about step-pool structures in mountain rivers with reference to their morphology, process of formation, destruction, hydraulic function, restoration, and ecological function. First, we present the constructive factors of steppool structures and their appearance, focusing on channel bed profile. Second, we summarize the processes driving the formation and destruction of step-pools, concentrating on current and sedimentation. The untidune and keystone theories are discussed as the key concepts of step-pool formation in relation to the installation of artificial step-pool structures. Third, with reference to previous studies, we discuss the relationship between step-pool structures and river course characteristics. Fourth, we describe the law of resistance and velocity in a mountain river. Finally, with reference to their ecological function, we discuss the use of step-pool structures in restoration projects. Based on earlier studies of step-pool structures, we discuss future issues and propose studies to technologize and standardize step-pool structures for river improvement and restoration.

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記述言語：英語   掲載種別：研究論文（学術雑誌）

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

都市流域における各戸貯留及び土壌改良による流出抑制効果を調べるため，東京都善福寺川上流部のマンホール集水域を対象とし，流出モデルにより年超過確率1/100の4つの降雨波形を用いて対策前後のマンホール溢水量を計算した．その結果，(1)短時間集中型降雨では流域の広範囲で溢水がみられ溢水量も長時間継続降雨と比して大きいこと，(2)各戸貯留及び土壌改良によるマンホール集水域の流出抑制効果は対策箇所毎に差異が見られるものの，長時間継続降雨では対策効果が高いこと，(3)流出抑制技術の導入は上流及び下流にも一定の効果をもたらし，背水によって溢水が生じている箇所では，上流域の溢水の削減効果も高いこと，(4)溢水量が大きい複数箇所を集中的に対策することで，効果的に下流の溢水を抑制可能であることを明らかにした．

DOI： 10.2208/jscejhe.72.49

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その他リンク： https://www.jstage.jst.go.jp/article/jscejhe/72/2/72_49/_pdf

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

 We examined relationship among specific discharge of flood and rainfall, geomorphology, land use and geology to reveal the influence of watershed characteristics on flood discharge. As a result of a correlation analysis, hourly rainfall depth was the most major factor to determine the flood discharge. Among the geomorphological factors, form factor and topographical gradient were major factors of increasing flood discharge. However, the effects of these factors differed by flood scale. In the land use factor, there was no clear relationship between broadleaf forest and flood discharge for each flood scale. Whereas, coniferous forest was factor to increase flood discharge at low frequency event.

DOI： 10.2208/jscejhe.72.i_1255

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CiNii Article

CiNii Research

その他リンク： https://ndlsearch.ndl.go.jp/books/R000000004-I027187547

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

急流都市河川に自然再生の事例は少なく，環境に配慮した改修技術は確立されていない．本研究では，長崎市大井手川を対象に，①環境に配慮した親水性の高い河道設計，②エネルギー減勢効果及び河床変動の観点から，Step-Pool構造による最適な落差緩和構造を明らかにすることを目的として，縮尺1/33の移動床水理模型実験を行った．その結果，適切に水制工，護床工を設置し，断面の急縮を避け下流部と接続することで，急流河川においても護岸を用いずに河床の静的平衡を保てること，Step-Pool構造は落差緩和，エネルギー減勢に有効であり，本研究対象区間においてはStep高0.55m，Pool深0.55mのStep-Pool構造を4段配置することで河床変動が抑制され，高いエネルギー減勢効果が得られることが確認された．

DOI： 10.2208/jscejer.71.ii_397

Kyutacar

CiNii Article

CiNii Research

その他リンク： https://www.jstage.jst.go.jp/article/jscejer/71/6/71_II_397/_pdf

記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>Combined Sewer Overflow(CSO) cause severe effect to river environment. In Japan, 200 Urban areas adopt the Combined Sewer and CSO is the nationwide problem.</p><p>In this study, We investigated the relationship between intensity of rainfall and number of occurrence of CSO in the Zenpukuji River. And, we developed the outflow simulation model of CSO by using Inforworks ICM. Then, we carried out the simulation on the assumption that infiltration facilities are set in the basins.</p><p>As a result, we reveal that over 1.1mm/5min or 2.0mm/10min, 4.3mm/30min, 6.4mm/hr rainfall caused the CSO at the upper reach of the Zenpukuji River. The simulation results indicated that the infiltration facilities can reduce the CSO peak flow when the peak discharge was under 12m3/s at the observation point.</p>

DOI： 10.11532/river.21.0_455

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CiNii Research

その他リンク： https://kyutech.repo.nii.ac.jp/records/2000528

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

River flow regime is important role in determining the river morphology, water use and biotic composition. In Japan, however, river management based on the concept of variation of flow regime is not taken. Because the knowledge of potential hydrological regime is lacking. In this study, we proposed the flow regime indicators which can explain seasonal change of stream flow at 52 watersheds in the Kyushu region. And, we investigated the relationship between flow regime indicators and factors that affect the hydrology (physiographic factors, geological factors and vegetation factors). Result of multiple regression analysis, flow regime indicators were well explained by the factors of physiography, geological and vegetation. The results indicated that geology of volcanic ejecta tends to stabilize the flow fluctuation, and urbanization and plantation tend to increase frequency of disturbance and drought.

DOI： 10.2208/jscejhe.71.i_1213

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CiNii Article

CiNii Research

その他リンク： https://ndlsearch.ndl.go.jp/books/R000000004-I026355296

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Throughout Japan, numerous restoration projects and efforts to conserve the river environment are underway. However, in spite of such efforts, effective measures to conserve the river ecosystem or post-evaluation of restoration projects remain insufficient due to a lack of environmental indicators. In many European countries and the United States, a number of biological indicators have been developed and adapted. However, it appears to be difficult to directly apply these indicators to Japan, because its biota is finely classified according to its many islands and peninsulas. The ultimate goal of this study is to comprehensively evaluate indicators of aquatic biodiversity from both physical and biological aspects. We divided the Kyushu region in Japan into several ecoregions as a preliminary step to establish an indicator. We delineated the ecoregions of the Kyushu region using the fish fauna data of 21 rivers within the Kyushu region. Presence-absence (0/1) data for each fish species were used to run a two-way indicator species analysis (TWINSPAN analysis). As a result, the Kyushu region was divided into four ecoregions (A: northwest Kyushu, B1: northeast Kyushu, B2: south Kyushu, and C: Amami-Oshima Island). Each ecoregion was characterized by the following fish species: (A) Cyprinidae, in particular Acheilognathinae, is abundant; (B1) Gobiidae is abundant, while Cyprinidae such as Tanakia limbata (not confirmed in B2) are also present; (B2) Gobiidae is abundant, while Rhingobius sp. DA and Rhingobius sp. CO (not confirmed in B1) are present. These results indicate that the fish fauna of the Kyushu region is finely delineated, and that an assessment standard for biological integrity should be established, based on differences in fish fauna. © 2011 International Consortium of Landscape and Ecological Engineering and Springer.

DOI： 10.1007/s11355-011-0171-2

Scopus

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

Kyutacar

CiNii Article

CiNii Research

その他リンク： https://ndlsearch.ndl.go.jp/books/R000000004-I024918739

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

In Japan, many restoration projects and efforts to conserve the river environment were carried out across the country. In spite of these efforts, effective measures to conserve the river ecosystem or post-evaluation of the restoration project were insufficient due to a lack of environmental indicators. We established biological indicators using fish fauna in the midstream segment-based ecoregions of the northwest ecoregions based on the concept that quality of biota can be compared in the same segment-based ecoregion. Furthermore, multiple regression analysis was carried out to explain the relationship between the index value and the physical characteristic of a habitat. As a result of the multiple regression analysis, it was found that embayment increased the number of fish species. On the other hand, weir and ponding decreased it. Establishing biological indicators using the ecoregion concept enabled to compare the integrity of fish fauna between watersheds, which had been previously difficult to examine.

DOI： 10.2208/jscejhe.69.i_1249

Kyutacar

CiNii Article

CiNii Research

その他リンク： https://kyutech.repo.nii.ac.jp/records/2000549

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

CiNii Article

CiNii Research

記述言語：日本語   掲載種別：研究論文（学術雑誌）

<p>The restoration of river ecosystems is of worldwide interest. Although various techniques have been designed, an effective method for environmental evaluation is necessary. We report a new method for the evaluation of the riverine environment on the basis of simple fish ecological data. The 16 indexes studied were (1) native species, (2) alien species, (3) red list species, (4) genuine freshwater fish species, (5) amphidromous or brackish water fish species, (6) swimming species, (7) benthonic species, (8) flowing water species, (9) still water species, (10) permanent water species, (11) temporary water (flood plain) species, (12) spawning in vegetation area species, (13) spawning in muddy bottom species, (14) spawning in sandy-gravely bottom species, (15) spawning under rocks species, and (16) spawning in mussel species. The reference data is the maximum number of potential species . First, the fish fauna data of the evaluated point was obtained. Next, a radar chart was prepared with regard to the 16 indexes. Although this assessment method can be applied in the same ecoregion, it provided a good evaluation.</p>

DOI： 10.11532/river.16.0_449

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CiNii Article

CiNii Research

その他リンク： https://kyutech.repo.nii.ac.jp/records/2000539

担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

The biological indicator should be developed in the ecoregion where biota is relatively identical. Furthermore, as stream biota widely varies from headwater to downstream, it is necessary to define segment based ecoregions where biota is longitudinally identical. In this study, we delineated segment based ecoregions for ten rivers belonging to the northwest Kyushu ecoregion based on the degree of similarity of the fish fauna. The northwest Kyushu ecoregion was divided into five segment based ecoregions. As a result, fish fauna was more clearly characterized by the differences in community structure between segment based ecoregions than those between watersheds. Moreover, distinguishing segment based ecoregions, enabled us to compare the integrity of fish fauna between watersheds, which had been previously difficult to examine.

Kyutacar

CiNii Article

CiNii Research

その他リンク： https://kyutech.repo.nii.ac.jp/records/2000542

記述言語：日本語   掲載種別：記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）

CiNii Article

CiNii Research

その他リンク： https://ndlsearch.ndl.go.jp/books/R000000004-I10381323

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

A large number of studies have been made on longitudinal changes of fish fauna, however, the relationship with the engineered viewpoint is little known. The purpose of this paper is to investigate relationship between longitudinal changes of fish fauna and segment classification defined from the viewpoint of flood control.<BR>We focused on 15 rivers in Kyushu and run TWINSPAN analysis to divide the fish fauna longitudinally and compared segment classification.<BR>The result of analysis showed that segment classification is largely corresponded with longitudinal changes of fish fauna and the values of longitudinal gradient which is the boundary of longitudinal fish fauna classification are 1/2000, 1/1000 and 1/100.

DOI： 10.2208/prohe.52.1147

Kyutacar

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その他リンク： https://kyutech.repo.nii.ac.jp/records/2000543