Tama River Basin Research Articles

Impact of Urbanization on the Vegetation Dynamic in Tama River Basin

Impact of Urbanization on the Vegetation Dynamic in Tama River Basin

River bank role as wildlife habitats : implication for combining hydrospheric disaster prevention and ecosystem conservation at Tama River basin

哺乳類のハビタットネットワークの形成を行う場合，各種や生態系の生態学的な現状を把握する必要がある。日本では，キツネVulpes vulpesやニホンイタチMustela itatsiは環境に合わせて餌食物を変化させるジェネラリストであるため，都市化の進行した環境や，開発の進んだモザイク環境でも生息可能となっていると考えられる。都市の河川においては，河川敷が生息地やコリドーとしての機能を担っているが，一方で，水害防除のための河川敷の改変や構造物設置はやむをえない面がある。災害防除と生態系保全を両立する河川敷のあり方について検討するため，多摩川中流域において，消波根固ブロックの野生食肉目による利用を調査した。その結果，在来種ではタヌキNyctereutes procyonoidesとニホンイタチによる利用が確認された。

有吉堤竣工100年，アミガサ事件の背景を考察する（その2）

有吉堤竣工100年，アミガサ事件の背景を考察する（その2）

The Analysis of Regional Burden on Rubble Treatment at Flood—Case Study on Flood in the Tama River Basin—

The Analysis of Regional Burden on Rubble Treatment at Flood—Case Study on Flood in the Tama River Basin—

What is the quantity of consumer goods stocked in a Japanese household? Estimating potential disaster waste generation during floods

This study aims to estimate micro material stock derived from consumer goods using fundamental data such as possession and expenditure of consumer goods in housing, considering the type of housing and class of total floor area of housing. A questionnaire survey of residents living in the eight cities of the Tama river basin was conducted to clarify the possession and expenditure of consumer goods in units of items/housing and JPY/housing. Identified consumer goods were 14 types and 97 items. The questionnaire also asked the storeys on which the consumer goods are installed. Material intensity coefficients (MIC) regarding the weight of consumer goods were calculated based on web–based and statistical surveys in units of kg/item and kg/USD. Micro material stock derived from consumer goods in housing totalled 5.84 t (t) in detached housing and 5.71 t in complex housing. Amount of the micro material stock derived from consumer goods corresponds to 10.9% of the macro material stock derived from detached housing. Reliability and validity of questionnaire results and the MIC were confirmed through two types of sensitivity analysis. As a case study, the total weight of all consumer goods in Kawasaki City was calculated as 3,667,000 t. The disaster waste derived from consumer goods considering the flood damage was estimated based on the total weight of all consumer goods in the city. The resulting estimation was 229,000 t. This estimation is 0.72 times bigger than the above-mentioned result that considered the storeys on which the consumer goods are installed.

Tributary effects on fluvial terrace development since the last interglacial in the upper Tama River valley, central Japan

To understand the sediment routing system from mountains to lowlands in the Quaternary Period, it is necessary to evaluate the interactions of fluvial processes and their response to climate changes. We reconstructed the development of fluvial landforms along the upper Tama River valley of central Japan since the last interglacial, focusing on distinguishing toe-cut terraces (remnants of tributary fans) from trunk-river terraces by combining analyses of the sediments and geomorphology of terrace deposits with age dating of tephra and organic matter in these deposits. Our results show that late in MIS 5, the tributaries supplied sediment to the trunk valley that, together with sediment in the trunk river, elevated the bed of the trunk river. In MIS 4 and 3, tributary deposits built small fan surfaces around the tributary junctions, while trunk river sediment was transported downstream and did not contribute to filling of the trunk valley. After the last glacial maximum, lateral erosion by the Tama River transformed the tributary fans into toe-cut terraces, and the reworked tributary deposits contributed to the formation of fill-cut terraces while helping the trunk river maintain an equilibrium state. In the Tama River basin, the contribution of tributaries to the sediment routing system systematically increased upstream, where steeper tributaries, with catchment basins of higher relief, join the trunk valley more frequently. Our findings suggest that cutting and filling of tributary sediment around stream junctions contributed buffering effects that have stabilized the bed of the Tama River against Quaternary climatic changes.

Estimation of flood waste amounts from housing and other buildings in the anticipated inundation area of the Tama River basin

Estimation of flood waste amounts from housing and other buildings in the anticipated inundation area of the Tama River basin

Occurrence and behavior of the chiral anti-inflammatory drug naproxen in an aquatic environment.

The present study reports on the occurrence and chiral behavior of the anti-inflammatory drug (S)-naproxen (NAP)-(S)-2-(6-methoxynaphthalen-2-yl)propionic acid-in an aquatic environment under both field and laboratory conditions. In influents and effluents of sewage treatment plants (STPs) in the Tama River basin (Tokyo), (S)-NAP was detected at concentrations of 0.03 µg L(-1) to 0.43 µg L(-1) and 0.01 µg L(-1) to 0.11 µg L(-1), respectively. The concentrations of a major metabolite, 6-O-desmethyl NAP (DM-NAP) were up to 0.47 µg L(-1) and 0.56 µg L(-1) in influents and effluents, respectively. (R)-naproxen was not detected in STP influents, although it was present in effluents, and the enantiomeric faction (= S/[S + R]) of NAP ranged from 0.88 to 0.91. Under laboratory conditions with activated sludge from STPs, rapid degradation of (S)-NAP to DM-NAP and chiral inversion of (S)-NAP to (R)-NAP were observed. During river die-away experiments, degradation and chiral inversion of NAP were extremely slow. In addition, chiral inversion of (S)-NAP to (R)-NAP was not observed during photodegradation experiments. In the river receiving STP discharge, NAP and DM-NAP concentrations reached 0.08 µg L(-1) and 0.16 µg L(-1) , respectively. The enantiomeric faction of NAP in the river ranged from 0.84 to 0.98 and remained almost unchanged with the increasing contribution of rainfall to the river water. These results suggest that the absence and decrease of (R)-NAP in river waters could indicate the inflow of untreated sewage. E

Influence of the domestic alien fish Rhynchocypris oxycephalus invasion on the distribution of the closely related native fish R. lagowskii in the Tama River Basin, Japan

In Japan, domestic freshwater fish are accidentally introduced into non-native freshwater habitats by human activity, such as the planting of fish. Introduction of the domestic alien fish may have a detrimental effect on native fish inhabitants. However, investigations on the distribution and establishment of such domestic alien fish in non-native river basins and their influence on native fish remains limited. Therefore, we investigated the distribution and establishment of the domestic alien fish Rhynchocypris oxycephalus and its influence on native fish in the Tama River Basin, Japan. Specifically, we used mitochondrial DNA and morphological analyses to clarify the influence of the invasion of this species on the distribution of the closely related fish R. lagowskii, which is native to the river basin. Fish sampled from the upstream section of the main river were mostly R. oxycephalus. This indicates that R. oxycephalus has replaced R. lagowskii in the upstream region. Fish sampled from the downstream section of the main river were mostly R. lagowskii. R. oxycephalus was also captured from agricultural canals linked to the Tama River, and in streams connected to the river via the canals. These observations indicate that the agricultural canal water networks facilitate the invasion of R. oxycephalus to peripheral habitats, such as canals and streams. In contrast, R. lagowskii was found in streams that flowed into the upstream section of the Tama River, with these streams having many large drop structures, indicating that drop structures prevent R. oxycephalus from invading aquatic habitats in these streams.

Development of gravitational rock deformation and its related landforms on the Hounose-dendeiro Ridge, the upper Tama River Basin

Development of gravitational rock deformation and its related landforms on the Hounose-dendeiro Ridge, the upper Tama River Basin

Structural Features of the Networks among Civic Groups in Tama River Basin

Structural Features of the Networks among Civic Groups in Tama River Basin

訂正：多摩川流域における外用医薬品の実態調査と塩素処理性の評価［水環境学会誌 Vol.33 No.10 (2010) pp.151-157］

上記論文について、以下の4箇所を訂正いたします。

Distribution of antibiotic resistance in urban watershed in Japan

Antibiotic-resistant E. coli concentrations showed large spatial and temporal variations, with greater concentrations observed in tributaries and downstream than in the upstream and midstream. Twenty percent of the geometric mean concentrations of antibiotic-resistant E. coli in the Tama River basin (Japan) exceeded the maximum acceptable concentration of indicator E. coli established by the USEPA. The indicator E. coli concentrations were positively correlated with those of antibiotic-resistant E. coli and multiple-antibiotic-resistant E. coli (resistance to more than two kinds of antibiotics), respectively, but not the detection rate of antibiotic-resistant E. coli, implying that use of antibiotic-resistant E. coli concentration rather than the detection rate can be a better approach for water quality assessment. Multiple-antibiotic-resistant E. coli is a useful indicator for estimating the resistance diffusion, water quality degradation and public health risk potential. This assessment provides beneficial information for setting national regulatory or environmental standards and managing integrated watershed areas.

多摩川流域における外用医薬品の実態調査と塩素処理性の評価

In recent years, pharmaceuticals and their metabolites have been detected in aquatic environments, and their risk management has become an emergent concern about the environment, water supply and sewerage. In particular, pharmaceuticals for external use may be discharged in large amounts into aquatic environments. In this study, we monitored three pharmaceuticals for external use, namely, crotamiton, lidocaine and diethyltoluamide (DEET), in water samples (i.e., river water, effluent of wastewater treatment plants (WWTPs), and groundwater) from the Tama river basin in Japan. The calculated loads of the target compounds in effluent samples from WWTPs in the Tama river basin were comparable to those in the river water samples, indicating that the major source of the compounds is wastewater effluent. The loads in the WWTP effluent samples varied seasonally depending on their application. The removal efficiency of groundwater recharge varied among the target compounds. Lidocaine and DEET were removed more efficiently than crotamiton. The removal efficiency of chlorination also varied among the target compounds. Although negligible amounts of crotamiton and DEET were removed, lidocaine was almost completely removed within 1 hour.

Occurrence and Distribution of Perfluorooctane Sulfonate and Perfluorooctanoic Acid in the Rivers of Tokyo

Comprehensive survey of major rivers in the Tokyo metropolitan area was conducted for clarifying the emission sources of perfluorooctane sulfonate (PFOS) in Tokyo. PFOS was found at all sampling sites at concentrations ranging from 0.5 to 58 ng L−1; in addition to this, it was also indicated that unknown PFOS emission sources are present in the midstream of the Tama River basin. The relationship between PFOS and perfluorooctanoic acid (PFOA) was constant at a ratio of 10:3 (PFOS/PFOA) throughout the Tama River basin. The sum of daily load amounts of PFOS from Tokyo’s major rivers to Tokyo Bay reached 215 g day−1. This value corresponds to 12.8 μg day−1 per person using the sum of wastewater treatment district populations. In contrast, an estimation of PFOS contribution of domestic wastewater was also attempted, and the contribution was 1.6 μg day−1 per person. We took samples up trunk sewers in the Tama River and finally found at the highest PFOS concentration (58,000 ng L−1) from one of the wastewater of the electronic parts manufacturing facilities.

Effects of combined sewer overflow and stormwater on indicator bacteria concentrations in the Tama River due to the high population density of Tokyo Metropolitan area

The indicator bacteria (standard plate count, total coliform, and fecal coliform bacteria) concentrations have been investigated using six ambient habitats (population density, percent sewer penetration, stream flow rate (m(3)/sec), percent residential area, percent forest area and percent agricultural area) in the Tama River basin in Tokyo, Japan during June 2003 to January 2005. The downstream and tributary Tama River showed higher concentrations of TC and FC bacteria than the upstream waters, which exceeded an environmental quality standard for rivers and a bathing water quality criterion. It was estimated that combined sewer overflow (CSO) and stormwater effluents contributed -4-23% to the indicator bacteria concentrations of the Tama River. The results of multiple regression analyses show that the indicator bacteria concentrations of Tama River basin are significantly affected by population density. It is concluded that the Tama River received a significant bacterial contamination load originating from the anthropogenic source.

Potential Changes in Extreme Events Under Global Climate Change

Climate-related disasters are a serious problem in Asia. Advances in the understanding of meteorology and in the development of monitoring and forecasting systems have enhanced early warning systems, contributing immensely to reducing fatalities resulting from typhoons, cyclones, and floods. The frequency of extreme events causing water-related disasters has increased, however, over the last decade and may grow in the future due to anthropogenic activity. The sections that follow introduce two recent efforts in hydrologic projection in Asia. Time-slice ensemble experiments using a high-resolution (T106) atmospheric general circulation model (AGCM) on the earth simulator revealed changes in the South Asian summer monsoon resulting from climate change. Model results under global warming conditions suggest increases in mean and extreme precipitation during the Asian summer monsoon. increases generally attributed to greater atmospheric moisture content. a thermodynamic change. Dynamic changes limit the intensification of mean precipitation. Enhanced extreme precipitation over land in South Asia arises from dynamic rather than thermodynamic changes. The impact of global warming on heavy precipitation features and flood risks in the Tama River basin in Japan is addressed using 12 atmosphere-ocean coupled general circulation models (AOGCMs). Multi-model ensemble average 200-year quantiles in Tokyo from 2050 to 2300 under Intergovernmental Panel on Climate Changes (IPCC) Special Reports on Emissions Scenarios (SRES) A1B scenario climate conditions were 1.07-1.20 times greater than that under present climate conditions. A 200-year quantile extreme event in the present occurs in much shorter return periods in the A1B scenario. High-water discharge in the basin rose by 10%-26% and flood volume increased by 46%-131% for precipitation in a 200-year return period. The risk of flooding in the basin is thus, even though the increase of extreme precipitation is not substantial, projected to be much higher than that presently estimated.

都内河川における１，４‐ジオキサンの動態

To clarify the behavior of 1,4-dioxane in a water environment, concentrations and loads of 1,4-dioxane in water in the Tama River and its inflow rivers were investigated. Contamination of 1,4-dioxane was observed at every sampling point. The level of 1,4-dioxane in the river increased because of the inflow of the branches and especially inflows of those carrying effluent from sewage treatment plants. The cumulative load of 1,4-dioxane from catchments along the river stream from Nagata Bridge, as the uppermost point in this study, closely resembled the measured load at each sampling point in the Tama River. These results indicate that 1,4-dioxane was scarcely degraded, volatilized, or absorbed during flow down the river. The respective contribution rates of the loads of the branches and the sewage were estimated as 25 % and 75 %. Furthermore, the measured load of inflow was 30 times higher than the estimated loads based on Pollutant Release and Transfer Register system (PRTR) in the Tama River Basin. These findings suggest that the present PRTR has never covered the 1,4-dioxane emission sources completely.

山岳地の渓流水質形成に及ぼす流域平均傾斜の影響

The relationship between the stream water quality and mean basin slope was examined in the mountainous region of the Azusa River and Tama River basin. The ionic compositions of stream water are of Ca-HCO3 type and of Ca · Na-HCO3 type. The HCO3-, Ca2+ and Na+ concentrations in stream water exhibit a negative correlation with the mean slope angle in the mountainous watersheds of the Tama River. In contrast, the HCO3- and Ca2+ concentrations in stream water are correlated to the mean slope angle in the mountainous watersheds of the Azusa River, and the Na+ concentrations are not correlated with the mean slope angle. The Na+/Ca2+ ratio in stream water has a negative correlation with the mean slope in the mountainous watersheds of both the Azusa River and Tama River. It is proposed that the depth of groundwater flow coupled with the basin slope is one of the factors influencing the stream water quality.

IMPACTS OF GLOBAL WARMING ON HEAVY PRECIPITATION FREQUENCY AND FLOOD RISK

We describe impacts of global warming on heavy precipitation characteristics and flood risk using the 2-day precipitation of the 12 General Circulation Models. The frequency analysis based on partial duration series was carried out. The model ensemble average 200-year quantiles in Tokyo during 2050-2300 under the climate condition of IPCC SRES-A1B scenario were 1.07-1.20 times as large as the one under the present climate condition. Those influences on runoff discharge and flood risk in the Tama river basin were investigated using the numerical simulations. The estimated high water discharge rise by 10-26%, and the flood volume increased by 46-131% if the precipitation with a 200-year return period occurred.