Nagaoka City Research Articles

新潟県見附市・長岡市栃尾地区及び五泉市・新潟市新津周辺域におけるエチゴモグラMogera etigoの分布，2011年の現状

新潟県見附市・長岡市栃尾地区及び五泉市・新潟市新津周辺域におけるエチゴモグラMogera etigoの分布，2011年の現状

SVD Inversion of Zero-Offset Profiling Data Obtained in the Vadose Zone Using Cross-Borehole Radar

An artificial groundwater infiltration experiment was conducted in Nagaoka city in Japan, and time-lapse cross-borehole ground-penetrating radar (GPR) data were collected to monitor the infiltration process in the vadose zone using zero-offset profiling (ZOP) mode. The downward migration of induced water was observed as a variation of GPR travel times, which can be transformed into dielectric constant and further converted to volumetric water content. In this paper, we present an effective approach to extract accurate information about the hydrogeologic process in the vadose zone from ZOP data. This approach is based on a least squares inversion method using singular-value decomposition, in which a finite-difference time-domain forward modeling is used for computing electromagnetic wave fields on 2-D cylindrical coordinates. The inversion approach is validated using a synthetic example and applied to the field data. We can successfully estimate the variation of soil water content during infiltration in the Nagaoka site from the reconstructed dielectric constant models. The inversion results show that the saturation information is useful to assess hydrogeologic properties of the test soil zone.

Study on Dip Slope Failure at Higashi Takezawa Induced by 2004 Niigata-Ken Chuetsu Earthquake

ABSTRACT An extensive number of slopes failed in the 2004 Niigata-ken Chuetsu Earthquake. Among them, a dip slope containing a weak layer in Yamakoshi Village (currently Nagaoka City) was investigated intensively. Regarding its morphological characteristics, it is argued that the earthquake reactivated a pre-existing failure plane which then formed most of the present sliding plane. In order to reveal the strength properties of the weak layer that formed the sliding plane, including the behavior against cyclic loading, a series of triaxial compression tests and simple shear tests was performed on undisturbed specimens that were retrieved by block sampling from the site. Based on the test results, a stability analysis and the calculation of the earthquake-induced displacement were performed. By extending Newmark's sliding block analysis, while considering the effects of the irregular geometry of the sliding plane and its strain-softening properties, a reasonable simulation of the process of this slope failure could be provided.

Research on analysis of water quality change of combined sewer overflow (CSO) and the CSO control for pollution load from CSO in Nagaoka City

Research on analysis of water quality change of combined sewer overflow (CSO) and the CSO control for pollution load from CSO in Nagaoka City

LCA for the Sludge Disposal and Beneficial Use of Biogas in Nagaoka City

LCA for the Sludge Disposal and Beneficial Use of Biogas in Nagaoka City

A DEM-based evaluation of potential flood risk to enhance decision support system for safe evacuation

A practical, DEM-based practical method is proposed to enhance flood risk management in fluvial areas by quantifying relative risk as a function of vulnerability to inland and evacuation difficulty. Both measures are based mainly on the topography of the region, so the method does not require detailed data on the physical characteristics of the land. First, we use the deterministic 8-node method on a digital elevation map (DEM) to trace storm waterways. Second, we repeat the process on a reversed DEM to trace evacuation routes that avoid the waterways and zones dangerously close to the rivers. Finally, on the basis of such two flow lines of evacuee and storm water, we proposed the protocol to evaluate the flood risk at every point on the map taking into account both the minimum time required for floodwater to arrive and duration of an evacuation from that location. The time that must be allocated for safe evacuation is defined as the potential flood risk of evacuation (PFRE). The method is demonstrated on a fluvial area of the Kaki River in Nagaoka city, Japan. In addition, we illustrated the application of the PFRE map to divide the region into areas of greater or lesser evacuation urgency.

EVALUATION OF SCENARIOS FOR URBAN COMPACTIZATION BY QUANTITY OF CO2 EMISSION

We establish the standard emissions of CO2 from the work of construction, demolition/scraping and renewal /maintenance and get these following results.1. We establish the standard emissions of CO2 per area from the work of construction, demolition/scraping and renewal/maintenance of the urban facilities as well as buildings by calculating 5 years construction work in Nagaoka city to facilitate comparison of scenarios for the urban restructuring.2. We create 3 scenarios for compactization for the urban image of Nagaoka in the year of 2050. They are Market Scenario, Monocentric Scenario and Polycentric Scenario.3. By evaluating long-term CO2 emissions which includes both the reconfiguration period and the following operation period, we conclude the polycentric Scenario is the most desirable toward compact city among three sceinarois.

Characteristics of Oxygen Stable Isotopic Ratio in Precipitations in Niigata Prefecture, Japan

Time-course of oxygen stable isotopic ratios(i.e., δ18O)as well as annual or seasonal variation of δ18O has been examined to investigate the sources, the passing route and characteristics of precipitations in Niigata Prefecture. The precipitation samples have been mainly collected with a filtrating bulk sampler at the rooftop of Niigata University from 1999 to 2008. Furthermore, backward trajectories analyses have been also conducted for these samples taken sequentially for a short period.Consequently, the following features have been mainly clarified for the precipitations in Niigata Prefecture. (1)The δ18O values varied between −25.14‰ and −1.60‰, while the mean value of δ18O in each year was from −8.37‰(in 2006)to −7.33‰(in 2001). (2)As for the comparison among sampling points, the mean value of δ18O at seaside spots(i.e., Niigata City and Joetsu City)or marine spots(i.e., Sado City)is larger than that of inland spots(Shitada Village and Nagaoka City). (3)δ18O value was generally small in the rainy season, and relatively large in summer, and small in winter. (4)Decreasing δ18O content with time, as predicted by Rayleigh models of atmospheric vapor condensation, is a predominant feature of sequentially sampled rainfalls, particularly for precipitations taken during passage of typhoons.

合流式下水道越流水の長期観測と流出解析による汚濁負荷の定量的評価

To reduce the pollution load caused by Combined Sewer Overflow (CSO), which significantly affects the properties of water for public use in the event of rain, effective measures are adopted after the outflow behavior and pollution load are carefully studied. In this research, an area of about 127 ha around the confluence zone located in Nagaoka City, Niigata was targeted, the outflow rate, the water quality of CSO and the amount of rainfall were continuously monitored for 1200 days. The observation was started in June 2004 at two points where chamber has been equipped. As a next step, a simulation model with high reproducibility was designed on the basis of the data obtained by continuous observation using MOUSE. Since the water quality was predicted using the model in the case when it could not be measured, the pollution load of CSO was accurately estimated. It was found that the pollution loads of SS and of BOD for eight months (from April to November) were 50×103 kg and 28×103 kg, respectively. In addition, we found that the pollution load basic units of SS and BOD were 59×103 kg km-2 year-1 and 33×103 kg km-2 year-1, respectively.

DEVELOPMENT OF BURIED TYPE SNOW-MELTING TANK FOR REMOVING SNOW PILED BY PLOW MACHINE IN FRONT OF RESIDENTIAL HOUSE

In this research, a buried type snow-melting tank with low cost and maintenance was developed. By the questionnaire survey conducted in new town areas in Nagaoka and Akita, it is clarified that there is the necessity of an individual snow removal method for residential houses. The new snow-melting tank developed here consists of a reinforced concrete box, an electric snow-melting mat and draining pumps. The prototype model was installed to the residential house in Nagaoka City and its performance was examined. As a result, the snow supplied to this equipment was melt and drained certainly and the effectiveness was validated.

RECONSTRUCTION OF HOUSING AFTER THE MID-NIIGATA PREFECTURAL EARTHQUAKE

The purpose of this study is to grasp the factors to continue to live in intermediate and mountainous area through the case of Yamakoshi, Nagaoka City after the mid-niigata prefectural earthquake. From the results of questionnaire survey and case studies, it became clear following 2 aspects.1. The factors of difficulty to continue to live in Yamakoshi were as followings; abolition of public transportation, inconvenient of medical or social welfare service and closing of commercial facilities.2. On the other hand, to continue to live in Yamakoshi revitalized some elderly. After they returned to Yamakosi, they had recovered because they started to farming and found their role in their attached community.

Government 2.0

PurposeResearchers have argued that social networks within a community have positive effects on people's behavior in disasters. The Japanese government is testing online SNS at the municipal level with the intention to improve community building, democratic processes, and disaster management. This paper seeks to explore the use of social networking services (SNSs) in government and disaster in Japan.Design/methodology/approachThis study is based on a literature review of social capital, social support, disaster, and social software. Two exploratory case studies of local government SNS in Yatsushiro city, Kumamoto prefecture and Nagaoka city, Niigata prefecture provide empirical evidence. Consequently, the role of local SNS for social capital development and disaster is discussed.FindingsYatsushiro's solution seems to be sustainable, Nagaoka's SNS is in decline. Both have to compete with popular SNS like Mixi and lack critical mass. There are some indications that government‐initiated SNS helps to build social capital and utilize it in times of a disaster.Research limitations/implicationsThe paper contributes to the research on eParticipation and Public Management by describing an internet‐based social software application and its embeddedness in the administrative organization. Any conclusions must be tentative, especially as a consequence of the non‐representative number of users and the lack of testing in a disaster.Practical implicationsThe paper provides practitioners with two real life case studies on the implementation and use of local SNS in government.Originality/valueThe paper offers theoretical and practical insights into the use of social software in government. Moreover, it connects current trends in government 2.0 to disaster research.

Time-lapse borehole radar monitoring of an infiltration experiment in the vadose zone

Ground-penetrating radar (GPR) is an effective tool for imaging the spatial distribution of water content. An artificial groundwater recharge test was conducted in Nagaoka City in Japan, and time-lapse crosshole GPR data were collected to monitor the infiltration process in the vadose zone. Since electromagnetic wave velocities in the vadose zone are largely controlled by variations in water content, an increase in traveltime is interpreted as an increase in saturation. In the test zone, the infiltrated water penetrated downward with an average velocity of about 2.7 m/h. A finite-difference time-domain method using two-dimensional cylindrical coordinates is applied to simulate radargrams associated with the advancing wetting front and to quantify the effects of critical refraction. Standard zero-offset profiling for which all first-arrivals are assumed to be direct waves results in an underestimation of water content in the transition zone above the wetting front. As a result, correct velocity analysis requires identification of first-arriving critically refracted waves from the traveltime profile to accurately determine a water content profile.

THE ACTUAL CONDITIONS AND TENDENCY OF LOCAL FACILITIES AS SPECIFIED REFUGE SHELTER IN THE MID NIIGATA PREFECTURE EARTHQUAKE 2004

The purpose of this study is to clarify the actual conditions and tendency of local facilities as specified refuge shelter in The Mid Niigata Prefecture Earthquake 2004 in order to improve the plan of refuge shelter. The former Nagaoka city was chosen for investigation. As the result, the followings are made clear: 1) case of school facilities, the gymnasium was mainly used for refuge shelter; 2) case of community center and nursery school, most of the rooms were used for refuge shelter; 3) a securing of privacy was the main problem in a refuge life. It is important for the refuge shelter to discuss the correspondence of problems considered characteristic of each local facilities.

長岡実証試験サイトにおける二酸化炭素挙動モニタリングへの物理検層の適用

A pilot-scale sequestration of CO2 into an onshore aquifer has been conducted by Research Institute of Innovative Technology for the Earth (RITE) in cooperation with Engineering Advancement Association of Japan (ENAA) . The CO2 injection site is located at Minami-Nagaoka gas field, Nagaoka city, Niigata prefecture, Japan. One injection well (IW-1) and three observation wells (OB-2, OB-3, OB-4) were drilled. CO2 was injected into a thin permeable zone of the reservoir at 20-40 tonnes per day. The CO2 injection started on 7 July 2003, and ended on 11 January 2005 with the total CO2 amount of 10,400 tonnes. The pilot-scale demonstration allowed an improved understanding of the CO2 movement in a porous sandstone reservoir, by conducting time-lapse geophysical well logs at the three observation wells. CO2 breakthrough was identified by induction, sonic, and neutron logs. The sonic P-wave velocity decreased up to 28% at OB-2, and 13% at OB-4. Small effects of CO2 saturation on resistivity resulted in small changes in induction logs when the reservoir was partially saturated.

長岡プロジェクトからみた二酸化炭素 地中貯留技術の現状と課題

Several key questions need to be answered when CO2 geological storage is to be undertaken worldwide. How should CO2 be stored underground? Can trapping be assumed in saline formations and can CO2 be retained for long periods safely in the subsurface? The first Japanese pilot-scale CO2 sequestration project in Nagaoka was undertaken to provide answers to these questions. The injection site is located at the Minami-Nagaoka gas field in Nagaoka City, 200km north of Tokyo. Supercritical CO2 was injected into an onshore saline aquifer at a depth of 1,100m. CO2 was injected at a rate of 20 to 40 tonnes per day over an 18-month period, with a cumulative amount of 10,400 tonnes. A series of monitoring activities, which consisted of time-lapse well logging, crosswell seismic tomography, 3D seismic survey and formation fluid sampling, was carried out successfully to monitor CO2 movement in the sandstone reservoir. This paper presents an overview of the results obtained from both field and laboratory studies to examine the spatial-time distribution of CO2 and various trapping mechanisms in the reservoir. CO2 breakthrough at two of the three observation wells was clearly identified by changes in resistivity, sonic P-wave velocity and neutron porosity from time-lapse well logging. Each velocity difference tomogram obtained by crosswell seismic tomography showed a striking anomaly area around the injection well. As the amount of injected CO2 increased, the low-velocity zone expanded preferentially along the formation up-dip direction during the first two monitoring surveys and less change around the CO2-bearing zone could be confirmed from the following surveys. Unfortunately there was no significant change in 3D seismic results due to CO2 injection. The pilot-scale project demonstrated that CO2 can be injected into a deep saline aquifer without adverse health, safety or environmental effects. The Nagaoka project also provides unique data to develop economically viable, environmentally effective options for reducing carbon emissions in Japan.

新潟県中越地震と同中越沖地震における大規模集客施設内部の非構造材（吊り天井）被害の比較

One week after the Niigata-Chuetsu-Oki earthquake, 2007, the authors investigated damage to non-structural components, especially suspended ceilings, in six large enclosures at Nagaoka City. All of the six enclosures had damage to suspended ceilings in 2004 Niigata-Chuetsu earthquake and have made certain recovery works and improvements to their ceiling systems. In this paper the authors compare the damage in these six structures in both earthquakes and try to examine the validity of the improvements that have been made between the two earthquakes.

Acoustic environmental problems at temporary shelters for victims of the Mid-Niigata Earthquake

An earthquake on 23 October 2004 inflicted heavy damage on the Mid‐Niigata district. The earthquake isolated Yamakoshi village; consequently, all the village residents were forced to evacuate to temporary shelters in neighboring Nagaoka city for 2 months. Two types of temporary shelters were used: gymnasiums, and buildings with large separated rooms similar to community centers. A questionnaire survey and interviews (N=95) were conducted to elucidate problems of the living environment at the temporary shelters. This study analyzed acoustic environmental problems there. Noise‐related problems were noted by 40 respondents (46.5%): they were the fifth most frequently cited environmental problems. Several serious complaints, e.g., general annoyance at the shelters and footsteps of refugees at night, were only indicated by respondents who had evacuated to the gymnasiums. However, some problems, e.g., the clamor of children, including crying babies and voices of other refugees, were indicated by respondents irrespective of the type of the shelters to which they had been evacuated. Therefore, buildings like community centers were more desirable for temporary shelters, at least from the perspective of noise problems.

A STUDY ON THE BENEFITS OF IMPROVING LOCAL BUS SERVICE PUNCTUALITY

In local cities, it is important to improve bus service level in order to keep the number of passengers and to maintain bus routes since there is no other public transportation system operated except bus. Our research focuses on the punctuality, which is one of the most important factors to determine the level of bus service. Improvement of the punctuality of bus service does not provide benefits only to bus users but also to bus operators. For example,improving of the bus service level will increases number of passengers and, in the meantime,decreases the expense to bus operator because of reducing the bus waiting time at terminals.Our survey was conducted in Nagaoka city, Niigata to study the behavior of passengers coming to bus stops and to analyze the operation costs of bus operator. In addition, we estimate the benefits on both bus passengers and bus operator when the punctuality of bus service has been improved.

Evaluation of Natural Slope Failures Induced by the 2004 Niigata-Ken Chuetsu Earthquake

Slope failures occurring near earthquake centres have attracted much attention since the 2004 Niigata-ken Chuetsu Earthquake. The 1995 Hyogoken-nambu Earthquake affected large modern cities and urban infrastructure, but hilly and mountainous areas suffered heavy damage from the Niigata-ken Chuetsu Earthquake. During that earthquake, numerous landslides occurred in Koshi of Nagaoka city (formerly Yamakoshi village). Social problems developed when many towns became isolated because landslides cut off traffic and public service lifelines. Soil from landslides closed river channels and formed natural dams along the Imo River, which flows north to south in Koshi. The natural dams submerged some towns and emergency measures were promptly undertaken to prevent debris flows caused by natural dam breaks. In addition, many surface slides also occurred at steep slopes. The endogenous and exogenous factors of those landslides must be clarified because of their few precedents. For that purpose, topography and geology in this region are arranged according to each failure type. In addition, triaxial tests of saturated and unsaturated soils obtained from a slope failure site were conducted to examine the soils' strength properties. This research is intended to propose estimation items that can help to judge the risk of natural slope failure.