As one of the methods to evaluate groundwater flow and geological structures that represent obstacles to the flow, a method using thermography images of the soil surface temperature was tested. A laboratory experiment was conducted using a flow tank filled with glass beads. Obstacle blocks were arranged in the bottom of the flow tank. The obstacle block layer (5 cm) was covered with the homogeneous glass beads layer. Tap water was heated to 60 °C and colored with food dye was used as a tracer. The experimental results showed that the distribution of the obstacles had an influence on the surface temperature difference. When there was a thinner cover, it was easier to determine the distribution of the obstacles and the groundwater flow path.

View full abstract

 A region with tropical wet and dry climate is characterised by two major seasons of wet and dry. Baseflow could be a good predictor of drought by representing the low flow conditions in this region. Hence, having knowledge regarding baseflow is important for the drought preparedness. Based on this aspect, the study aims to separate the baseflow of Baitarani River, India in a tropical wet and dry climate region using the Eckhardt filter and to compare that with Lyne and Hollick (L&H) filter. The baseflow separated using two filters were further used for the estimation of Baseflow Index (BFI) values for the wet and dry seasons. Throughout both the seasons, Eckhardt filter generates almost same BFI values and shows a high level of agreement with each other, whereas the L&H filter generates a wide range of BFI values. Further, sensitivity analyses performed to analyse the relative importance of Eckhardt filter parameters exhibited that recession parameter is having a significant effect on baseflow only during the dry season, but the BFI has a notable effect on baseflow throughout the season. Hence, being a two parameter filter, Eckhardt filter gives good estimates of baseflow compared to the L&H filter.

View full abstract

 Groundwater plays a key role in public water supplies around the world. A consideration of social dimension is a key issue in the sustainable groundwater management, and making sure a safe and affordable drinking water for all is one of the main targets of 17 United Nations Development Goals. Recently in Hanoi, Vietnam, the groundwater overexploitation and contamination have been reported, which are life-threatening to the sustainable development of the community. This study is an attempt to assess the sustainability of groundwater from a social perspective. An outstanding multi-criteria decision-making approach, Analytical Hierarchy Process (AHP) is utilized here because it is suitable for sustainability assessment. In the AHP application for sustainability assessment, defining appropriate aspects and their indicators in each aspect is one of the most difficult tasks. This study proposes for the first time three main aspects including quantity, quality and management and their twelve sustainability indicators from a social point of view, based on the specific consideration of groundwater current problems in Hanoi. Hence, this study defines the index-based definitions of those sustainability indicators to clarify the way of their sustainability evaluations. Results show that the aspects and indicators are appropriate to cover Hanoi groundwater situation from a social point of view. The sustainability indices of Hanoi groundwater quantity and quality are assessed as socially good and acceptable, respectively. The sustainability index of the management aspect is assessed as socially acceptable. So that generally, Hanoi groundwater is assessed as socially acceptable.

View full abstract

 The Afghan government has planned the project of Kabul New City (KNC) in order to deal with the rapid growth of existing capital city, Kabul. The area of KNC is 1.5 times of existing Kabul City. The location of this new city is on a desert area beside the existing Kabul, and it is also surrounded by some watersheds with steep slope topography. Due to these topographical reasons, KNC will suffer a water scarcity problem. This study investigates the feasibility of a rooftop rainwater harvesting system in KNC to relieve the water scarcity problem. The volume of water which could be harvested by the system is estimated with using 10 years rainfall data. The volume of non-potable water consumption is also estimated from the current water use in Kabul city. As a case study, the efficiency of the rooftop rainwater harvesting system is cleared for a primary school, some types of houses and commercial buildings. An appropriate size of the water harvesting tank is also discussed based on the balance between harvested water volume and non-potable water demand.

View full abstract

 Groundwater is one of good quality and abundant water resources, which uses for living, agricultural and industrial water. However excessive pumping caused ground subsidence and groundwater salinization, it was actualized as a social problem. Kurobe River alluvial fan had confirmed the increasing trend of chloride ion concentration. This study clarifies factor of groundwater salinization and analysis effect by pumping restriction in “Sho-zu of Shimizu-an”. Factor of groundwater salinization is groundwater level lowering than sea level rise. “Sho-zu of Shimizu-an” supposed executing pumping restriction after 2011. As a result, “Sho-zu of Shimizu-an” stop groundwater salinization when it reduce 60 to 70%. “Sho-zu of Shimizu-an” exempt groundwater salinization when it reduce over 80 %.

View full abstract

 Water demand depends on various factors such as global climate change, population decline, household composition change, increasing awareness about efficient water use and improvement on water-saving appliances. Even though it is important to evaluate the influence of each factor, there is a little research on that of household composition change on the future water demand. In this paper, we evaluate the impact of population decline and the change of household composition on the water demand in Matsuyama City, Ehime, Japan and water held by an upstream dam in a drought period. We also compare the influence with the impact of the global climate change. We use the 188 samples of domestic water use that was collected by meter reading every 2 months and distribute that into daily use by a temporal disaggregation method. While the population decline decreases total domestic water demand of the city by 7.0 %, the change of the household composition increases the total demand by 2.2 % because the number of people per household decreases. The minimum volume of water held by the dam decreases by 3.0 % to 5.61 x10⁶m³ by the less water inflow due to the climate change, although that is covered by the population decline and the change of the household composition.

View full abstract

 In recent years torrential downpour occurrs frequently due to the effect of climate change. Because of this, excess of high turbidity in reservoirs and long term persistence of turbidity has recently been regarded as a serious problem. Behavior of turbidity in reservoirs is greatly influenced by the condition of thermal stratification and grainsize patterns of suspended sediment. In this study, we applied a vertical 1-dimension hydraulic model for future prediction of turbidity in reservoirs under climate change.
 As a result, we revealed that turbidity in reservoirs can become higher due to the increase of inflow turbidity caused by increased rainfall in the future. We also found that changes of weather conditions of temperature and solar radiation will influence on turbidity in reservoirs, and hydraulic turnover rate of a reservoir can be a determining factor on duration of high turbidity discharge from reservoirs.

View full abstract

 In order to identify the factors related to runoff of woody debris, we analyzed the relationship between woody debris volume and some parameters which are basin area and inflow discharge by using the data of woody debris volume deposited annually into 1103 dam reservoir across Japan. After quality check of these data, we applied single regression analysis. The results showed that woody debris volume increased logarithmically with inflow discharge. To find further relationship between woody debris volume and other parameters, we applied multiple regression analysis. It showed that woody debris volume is related to forest area, inflow discharge and 5 year daily rainfall.

View full abstract

 Four sequential typhoons caused severe floods over many river basins in Hokkaido during the middle to latter half of August in 2016. This study investigated spatial and temporal rainfall distribution at a upper reach of Sorachi river basin where a flood occurred due to the typhoon 10th (Lionrock). Furthermore, Uncertainty of rainfall amount over 235 catchments in whole Japan was investigated. Eventually, uncertainty of river discharge associated with spatial distributions of rainfall observation and its of ensemble members from 2 days were quantified. As a result, its associated with spatial distributions of rainfall observation is larger than its of ensemble member.

View full abstract

 1km-resolution terrestrial model over Japan is developped to build a high quality river discharge forecasting system. Effects of model resolution and soil type dataset are investigated by a sensitivity experiment concerning resolution and soil type dataset. The experiment period is 2 years of 2014, 2015 and analysis is conducted for 6 river basins in Japan. The terrestrial model is consists of MATSIRO, a land surface model and CaMa-Flood, a river routing model. Peak discharge and low discharge representation are improved by using a more detailed soil type dataset. In 9 of 12 experiments, ratios of model discharge to observation are improved by 1-14% and in all experiments, RMSE are decreased . Also, using high resolution experiment settings showed lower RMSE in 10 of 12 experiments.

View full abstract

 We consider a heat supply system that employs felled timber and driftwood, which accumulate at nearby dam, as a source of wood fuel. Because it is known that the calorific value of driftwood differs from that of conventional firewood, drying and burning experiments were conducted, to determine the exact value. Variations in the output of the currently operating boilers were measured at one-minute intervals, and the proper output for the wood fuel boiler that should be attained was calculated. Two types of boilers—firewood and chip—were used for this study. Construction, operation, and fuel expenses were calculated by considering nine scenarios, including a case in which a boiler is installed in each hotel and a case of district heat supply, to determine the most cost effective scenario. To eliminate any bias, unit costs were derived from various sources, such as case studies, and catalog representative values (approximation / mean). From this, the case in which a chip boiler is installed in each hotel was found to be least expensive. The study also revealed that hotels could recover the initial cost of installing these boilers in four years, which would be more economical compared to the case in which they continued to use heavy oil boilers.

View full abstract

 The purpose of this study is to evaluate an efficiency of ground source heat pump systems (GSHPs) in a standard residensial on a regional scale by the numerical simulation with the three-dimensional database of the effective thermal conductivity. The database was constructed through the indicator-kriging procedure based on the available borehole and water-well data to cover the depths beyond about 100 m for installation of borehole heat exchangers (BHEs). This study also proposed the methodology to determine required lengths of BHEs for a target value of seasonally averaged coefficients of performance (tCOP) in the GSHPs. The GSHPs simulation was demonstrated by using the Ground Club algorithm in a regular grid of 10 km over the northern area (the latitude > 36°) of Japan. First, this study showed that the COP values were calculated at about 4.0 in the Hokkaido area and about 4.4 in the Tohoku and northern Kanto areas when the BHE was assumed to be a standard length of 100 m. Next, the required median length of BHE for tCOP = 4.25 was estimated at about 80 m in the Tohoku and the northern Kanto areas. The smaller BHE length means that the intial costs for GSHPs could be efficiently reduced. On the other hand, the required median length was about 130 m in the Hokkaido area because the heating loads were relatively high in the cold region. The reduction ratio of CO₂ emissions was estimated at about 45-60 % when the ground source heat pump systems were utilized over the area instead of the conventional electric, oil and gas boiler systems. The reduction ratio was relatively large in the Tohoku and northern Kanto areas, indicating the potential increase of GSHPs in the future.

View full abstract

 Defining successful community bioenergy development is often difficult due to diverging interpretation on what the most important aspect on bioenergy development. Sustainable bioenergy is one that equitable, habitable, and feasible based on economy, social, and environment aspect of bioenergy production and these three aspects ideally should be in balance to achieve sustainability. This study is to develop a model using Engel Coefficient (ECF) to explain links among communities' incentive, increasing community's willingness to participate; and communitoes' welfare improvement, and apply it for the Community based Bioenergy Program in Bangkalan, Indonesia to survey its sustainability.
 In Bangkalan case, sustainability of community bioenergy project is affected by incentive ratio. Decreasing incentive ratio did not significantly decrease overall participation level due to steady income from selling biomass material. It did affect new participation from poor community and led to lower poor household decrease rate. However, decreasing incentive ratio would increase project's Benefit/Cost ratio.

View full abstract

 Due to the recent changes in social and economic circumstances, the design of energy systems has been recognized as a regional issue. In this study, we modeled the design process of a distributed energy system in the perspective of mathematical optimization problems. In a case of energy supply to basic facilities (hot bath facilities) in a hilly and mountainous area of Japan, this study evaluated the impacts of regional conditions, social system, business-based behavioral norms, etc., on the indicators such as costs, CO₂ emissions, and resource consumption through optimized selection of energy system. Results indicate that in current situations, it is possible to popularize the distributed energy system utilizing local woody biomass, while additional social burden is likely to occur. Therefore, sequential effect verification and response in institutional operation are required. Furthermore, we also discussed the standards for system installation based on a sensitivity analysis on demand scale and fuel price changes.

View full abstract

 In this paper, we analyze the possibility of achieving CO₂ resuction target in household sector. Considering regional energy consumption characteristics due to differencesin climate and residence etc, we estimate energy consumption and CO₂ emission by 2050 for each of 5 scenarios using the latest data related with household energy consumption. As a result, it is found that the reduction target of CO₂ emissions in 2030 can be sufficiently attained if the emission coefficient of power decreased to 0.37 kgCO₂/kWh, which is the taeget of the Federation of Electric Power Companies.
 Regarding 2050, in addition to all the means necessary for reducing CO₂ emissions, such as improving efficiency of equipment, progress of electrification, progress of energy-saving lifestyle, and the emission coefficient of electricity does not decrease to 0.104 kgCO₂/kWh, 2013 It was found that it is difficult to reduce 80% of the year.

View full abstract

 U-city is one of the local cities which are planning to conduct environmental policy to conserve favorable and sustainable environment. For this purpose, U-city preformed questionnaire to understand current thought of local residents. In this study, by the use of self-organizing map (SOM) based on the results of the questionnaire, the consciousness of local residents were analyzed. As a results of this study, environmental issues of high interest, approach to environmental problems, and satisfaction/ importance of environmental policy were clearly investigated. We confirmed that the SOM is one of the useful tools to classify the results of questionnaire.

View full abstract

 Demands for seawater desalination facilities are increasing all over the world with population increase and economic development. It is important to evaluate the effectiveness of the facilities with respect to water supply and social benefit according to the reduction of drought damages by considering changes in population and water use per capita in the future as well as the facilities' operation cost. This study analyzes cost benefit of a desalination facility in Fukuoka Prefecture namely Mamizu Pia. In particular it compared its social benefit in reducing drought risk in Fukuoka metropolitan area and total cost including the operation cost. The estimated net present value is 48.73 billion yen and cost benefit ratio is 1.66 if we assume 30,000 m³/day of water production by Mamizu Pia. Moreover, with the desalination facility, the most severe water supply restriction in 1978 could be mitigated by 80 % in the daily water supply and almost the same reduction in the drought economic damage.

View full abstract

 This study proposed a new methodology of largest scale hydrographs using the following three cases; 1) historical recorded daily rainfall of JMA, 2) Niigata-Fukushima heavy rainfall disaster in 2011, 3) ex-isting design rainfall. Those rainfall data were multiplied each catchment area of upstream.
 Above mentioned three hydrograph as boundary condition, the Jinzu and Joganji Rivers were assumed to overflow at the same time, 2-D unsteady flow analysis was carried out. As a result of numerical simulations, Case 2 was calculated maximum flooding area, 15.3 % of city area. Moreover, maximum 13,944 people (4.3 % of city population) lost public shelters.

View full abstract

 In order to encourage conservation and rehabilitation of the coral reef ecosystem in Yaeyama district in crisis, it is necessary to improve suitable environmental conditions in the sea for coral habitats. The application of environmental certification to encourage improvement of business activities such as agriculture, fishery, and tourism industry to reduce the impacts for coral reef ecosystems was focused. In this paper, the correlation structure of stakeholders and the applicability of environmental certification to encourage improvement of business activities were analyzed by the interviews with stakeholders related to coral reef ecosystem in Yaeyama district. As a result, applicability was found in meat cattle stock raising, sugar cane cultivation, pineapple cultivation, fishery, tourism industry, etc.

View full abstract

 Water scarcity and water conflict between rice farming and shrimp farming are major concerns in the coastal area of Vietnam. Developing an appropriate water allocation scheme may be a solution in this situation. To provide information on water use efficiency for water allocation problems, in this study, we assessed the value of water use for irrigation and shrimp farming using the Residual Value Method. Face-to-face interviews were conducted with 144 households in the target area to collect data relating to farming activities, such as average yield, input cost, and output benefit. In combination with estimates of water volumes to irrigate rice paddies and to supply shrimp farming, the water value was evaluated.
 The average economic values of irrigation water in Bac Lieu and Soc Trang provinces were 0.054 and 0.060 USD/m³, respectively. The water value in intensive shrimp farming was 0.58 USD/m³ in Bac Lieu province, and 0.67 USD/m³ in Soc Trang province, whereas in extensive/improved extensive shrimp farming, the values were 0.027 and 0.034 USD/m³ in Bac Lieu and Soc Trang provinces, respectively. Although these results show that the net return benefit from intensive shrimp farming was higher than that from rice farming, a multi-objective approach including social equity and environment protection as well as economic benefit should be considered for the sustainable development of river basins. Assigning economic values to water resources can encourage farmers to adopt sparing and efficient water uses.

View full abstract

 We design a model to examine the relationship between the evaluation of value connected to others and the motivation for environmental conservation activities by using structural equation modeling with questionnaire data from residents living in the area around Hayasaki-naiko. The proposed model shows that residents who are attaching to the community and having high ties with others outside the area are evaluating the value as a place of connection to others for Hayasaki-naiko, and that residents who are evaluating the value of connecting to residents within the community and visitors / tourists are strongly motivated to pursue their environmental conservation activities, and that it is better to encourage the motivation for supporting event such as environmental education by aiming for connecting to residents within the community rather than connecting with visitors / tourists.

View full abstract

 In this paper, a dynamic model of mobile sources of air pollution is used to predict emission levels from a vehicle population within a monitoring system over time. This model is also used to assess the effectiveness of applying a new gas exhaust standard. Regarding the results in relation to vehicle type, HDVs (heavy duty vehicles) were the main sources of NO_x and PM, accounting for 57% of NO_x and 70.1% of PM emissions in Ulaanbaatar, Mongolia. The HDVs and other vehicles more than 10 years old, accounted for a significant proportion of the total pollution. In comparing 2015 with 2040, the total vehicle population was increased 3.9 times, the total vehicle emission level was increased 4.3 times. The emission level of NO_x, PM and CO₂ was increased about 4.2 times, and CO was increased 2.8 times. We made an emission estimate to apply the Euro 4 and 5 standards in Ulaanbaatar by 2 scenario. The result of scenario 1, by con- verting to the Euro standard, the emission level in the real situation shows that NO_x was 1/3, PM was 1/7-1/37, and CO was 1/3-1/5. As a result for the scenario 2, the emission level in the real situation reduced that NO_x 0.8-22%, PM 10-38%, and CO 4-27%.

View full abstract

 Countermeasures against sand beach erosion are carried out by combining various construction methods. These are measures against outflow of sand by artificial structures and waves, but not necessarily assuming global warming. This study aims to provide information necessary for considering adaptation policy to global warming, and we have calculated cost-effectiveness of the policy by using new data concerning impact on sand beach erosion and new estimation model on recreational value of sand beach. Here, some previous public works on sand beach preservation in each prefecture were investigated. The damage cost on recreational value due to sand beach erosion in each prefecture was estimated under the climate model MIROC and the scenarios RCP 2.6 and RCP 8.5. And the cost-effectiveness of adaptation policy was examined.

View full abstract

 The aim of this research was to estimate waste amount and determine distinctive features and household waste flow in the city of Ulaanbaatar, Mongolia based on site and questionnaire surveys. Recyclables amount to be sold, daily burnt waste, illegal waste, and municipal waste flow were estimated via public surveys and interviews with citizens.
 The research was conducted based on identification of waste amounts and types in 18 households and two survey methods such as written questionnaire and oral interviews with residents, industries, and companies. The questionnaire was completed by 404 residents. Current waste management situation in the city and the key issues such as recycling management, environmental pollution and distinctive features of generated waste depending on the season were identified. The data retrieved from each participating household were further analyzed and the features of waste products were determined.
 The findings of this study show that although there are six-fold more households in ger areas than in apartment areas, they pay the same fee for monthly waste service. Coal ash is generated by each ger household per day during the six months of winter, which occupies 84.71% of the total waste amount. 2.63 tons of toxic waste is produced every day, and air emissions from backyard burning in ger households are released directly to the atmosphere without being treated. The maximum illegal waste amount (152 tons) occurs in winter, because of the coal ash (122 tons) generated by ger households in the season. This has led to severe environmental pollution.

View full abstract

 This paper attempts to clarify a cognitive and evaluation structure of the general public in terms of policies for making city resilient by analyzing the data of web-based questionnaire in nine cities in Japan. Major findings are as follows; i) The most respondents recognize risk of earthquake, most respondents regard “high percentage of elderly population/depopulation” as vulnerability, most respondents regard “suspension of administrative activities” as situation to be avoided in general. However, the scores of most indices of risk and velnerability are different among cities. ii) The cognitive and evaluation structure in which external force risk, vulnerability, situation to be avoided are assumued to determine the attitude to resilient policies was proven to be supported basically but naturaly it is different among cities in detail.

View full abstract

 A physically based model for assessment of shallow landslides triggered by heavy rainfall was analysed, applied, and validated to a case in the Khao Phnom, Krabi, Thailand. This model is based on the coupling of the hydrological model with an infinite slope stability model. Modified Green-Ampt model and steady groundwater flow model were used in the hydrological model. The distributions of rainfall intensity were obtained from eighteen rain gauges around the landslides. The model prediction capability was evaluated by using the receiver operating characteristic (ROC) curve. Considering to the analysis results, it was found that the model can predict the unstable areas (FS<1) where occur the hillslopes surrounding the peak of the mountain. The accuracy of the model was 0.737 for the Khao Phnom landslide.

View full abstract

 This study is development of slope failure risk information output to support regional government using adaptation conter measure due to climate change. As study aim, we tried to pursue the sophistication of traditional approach slope failure probablility model (pay attend: spatial resolution, geological condition). And we terid to develop slope failure risk information output to make overlap slope failure probability datas and sediment disaster caution zone datas. We were able to prepare sediment disaster caution zone probability map respond to rainfall variation in Nagano prefecture. And we developed to probability respondence line in sediment disaster caution zones. Leading sediment disaster adaptation tool was planned as support regional government in this study

View full abstract

 Mountainous area in North Vietnam is considered as one of the most prone region to landslide in Vietnam. Landslides in this area often occurs under the influences of heavy rainfall or tropical storms, steep slopes on mountainous sides and human activities such as road or house constructions. This paper applied Landsat satellite images and calculated Normalized Difference Indexes (NDIs) to evaluate the condition of vegetation, soil and water and detected 43 landslide points in Bac Kan, Ha Giang, Thai Nguyen and Tuyen Quang provinces in North Vietnam in 2015. In this paper, historical landslide data in 2013 was also used to analyse causative factors. Historical landslides often occur in a slope range from 10° to 40° on the elevation from 100 m – 300 m (48.23%) and on forests and crop sites. With regard to triggering factor and slope condition, three typical types of landslides are classified as i) landslide caused by rainfall on construction sites, ii) landslide caused by rainfall on natural slopes, and iii) landslide caused by rainfall and water drawdown on banks of reservoirs or streams. Considering the Landsat result type 2 and type 3 consist larger proportions (58.14 % and 25.58 %) compared to those in historical data (11.7 % and 1.53 %). This means that many landslide would occur in mountainous areas that far from residential or road areas (type 1). This paper thus would provide initial assessment for further studies on landslide problems on the bank of water sites such as reservoirs or streams.

View full abstract

 Radar rainfall estimates are widely used for real-time flood forecasting. An effective and accurate early warning system, with the assistance of radar rainfall estimates and hydrological modelling, is vital for reducing the effects of flood related-hazards. Detailed spatial and temporal data on the distribution of rainfall over a wide range area can be provided by weather radar. However, rainfall data captured at a single point location remains inaccurate. The combination of two datasets, radar and ground gauges, therefore constitutes the optimal method to estimate rainfall in a river basin.
 This study evaluated the rainfall data-combining technique of conditional merging (CM) in the Jinzu River Basin. This was then applied as the rainfall input for flood forecasting. A distributed hydrological model, developed by the International Center for Water Hazard and Risk Management (ICHARM) known as the Integrated Flood Analysis System (IFAS), was established and applied to evaluate the performance of the CM method for flood forecasting relative to the original radar simulations. Numerous cases with two sets of input data (radar and conditional methods) were tested during the period of 2011-2014. Here, the CM method was evaluated, and the applicability of a distributed model to flood forecasting in the Jinzu River Basin was quantitatively examined.

View full abstract

 Torrential rainfall is one of the important hydrologic event having a direct impact on urban hydrology. It is im-portant to have knowledge regarding the spatiotemporal patterns of torrential rainfall in order to prevent its ad-verse effects. Hence this study aims to present the spatiotemporal correlation characteristics of torrential rainfall events by the comparison of X-band MP radar data with 1-minute ground observation rainfall data in the upper basin of Kanda river in Tokyo. During typhoon, the meshed area of X-band MP radar data shows higher corre-lation with each ground observation rainfall data and this high correlation area having a spatiotemporal move-ment associated with the movement of the rainfall area. Even though the high correlation area having a spatio-temporal movement with the typhoon, the maximum correlation mesh is adjacently located with the overlap-ping mesh even in lag times of a few minutes. This can be attributed to the wide area coverage of typhoon and the small watershed under study. In cases of atmospheric instability, we can understand that the spatiotemporal correlation distribution is changing by every single rainfall peak by separating the duration of a multiple peak event by considering rainfall cell caused by torrential rainfall peak. The results shows the separation of multi peak rainfall event can cause the high correlation mesh area more widespread in case of particularly localized torrential rainfall. This can be interpreted as the effect of wind, upward air current, and the small area coverage of atmospheric instability.

View full abstract

 It is possible to discuss three dimensional fields of atmosphere by using multi-doppler and variational principle. This study adopted two X-band multi-parametric radars and analyzed meteorological fields for a heavy snowfall event which was associated with a small low pressure system over Ishikari Bay. The variational method used in this study has been developed for airborne-type and adjusted to apply for ground-based radars. Results showed that horizontal wind convergence was detected in lower troposphere over a coastal zone of Ishikari Bay which is northwesterly located from Sapporo area. In addition, stronger reflectivity propagates to southeasterly direction including Sapporo area. Obtained wind vectors in the variational method was validated with those in a numerical model and radiosonde observation, respectively.

View full abstract

 In recent years, social interest in climate change such as global warming has been increasing due to the report of an increase in extreme events. However, prediction such as heavy rain, which is one of extreme phenomena, is difficult to predict since the phenomenon itself occurs on a very local spatial scale. On the other hand, the water isotopic ratio is a physical quantity sensitive to phase change of water, which is advantageous for exploring details of the local precipitation process. In this study, we analyzed the isotope ratio fluctuation during heavy rainfall observed in Mase, Tsukuba city, Ibaraki prefecture during the Kanto and Tohoku heavy rains in September 2015. As a result, it became clear that water vapor from different sea areas reached in a short period of time, and the behavior that the water vapor isotopic ratio (δ¹⁸O) by IsoGSM increases and decreases from September 8 to 10 is due to the difference in the origin of water vapor. The Amount Effect usually refers to the apparent statistical relationship between the precipitation isotopic ratio and the precipitation amount, but the short-term fluctuation of the water vapor isotope ratio is sensitive to the amount of precipitation which was made along the transport pathway of the mass before reaching to the observation site.

View full abstract

 The development of the city occurs not only above ground but also underground. Underground infrastructure is especially vulnerable to flood damage, caused by extreme events and natural disasters, as it forms the lowest layer un the hierarchy of urban structure. However, despite the increasing importance of urban inundation analysis, the lack of availability of data regarding underground space restricted analysis in previous studies. In this study, we established three-dimensional GIS data of subways using records and drawings of construction, which can be used for underground infrastructure inundation analysis in urban areas. Utilizing this established three-dimensional subway GIS data, we modeled and analyzed the areas of subway stations and train lines to be inundated by the projected Nankai Trough Earthquake. 82% of Nagoya city's Meiko Line close to the coastal area is expected to be submerged by an over 1m-deep flooding, and tsunami run-up through the train line is estimated to occur.

View full abstract

 The Shibuya River originates close to Shibuya Station and passes through Shibuya Ward for 2.6 km. Its name changes to Furu River at Tengenji Bridge in Minato Ward and then flows for another 4.4 km into Tokyo Bay near Shiba Park. It is classified as a Class B river by the government. The Shibuya and Furu River basins cover 14.0 km² and 8.8 km² respectively.
 The 1964 Tokyo Olympic Games and the urbanization of the area was an opportunity for the upstream portion of the Shibuya River to be diverted through culverts. In 2005, the area around Shibuya Station was designated as an urgent maintenance area by the Urban Revitalization Special Measures Law. As a result, several corporations have been working closely together on projects around Shibuya Station, and redevelopment plans for the area include the prospect of a more accessible Shibuya River with new landscaping and a sloped embankment.
 Previous studies of Shibuya River have not been conducted focussing on the downstream section of Shibuya River or its improvement and sewerage planning. Therefore, this study concentrates on downstream Shibuya River and summarizes the history and progress of the improvements to the river environment. As a result, some new findings are presented in this study.

View full abstract

 In this study, we propose a method to monitor vegetation in Japanese rivers using a synthetic aperture radar (SAR) satellite. The proposed method was applied to the Sabagawa River in Yamaguchi Prefecture, Japan. We compared a combined X and L band SAR image with a survey result obtained by drone aerial shooting. While we observed shadow areas behind a bamboo grove in the river on the line-of-sight of the satellite in the X band SAR image, any distinctive shadow area of the bamboo grove was not observed in the L band SAR image. Extracting shadow areas that appeared only in X band SAR image, we found that the extracted area were observed behind the bamboo grove area. Based on the observation principle of SAR satellite, we proposed an equation to estimate a bamboo height from a shadow area on a combined X and L band SAR image. The proposed equation reproduced the bamboo heights from the shadow areas on the SAR image accurately. The mean and standard deviation of relative errors were -15.6% and 17.0%, respectively.

View full abstract

 In this research, we first show the actual flow rate differences due to the difference in observation method in real observation about the observed flow velocity. Based on the results, we classified the flow velocities for each observation method and derived a new theory about these relationships. Numerical calculations were carried out to verify the theory and quantitatively evaluate.
 In the past, the standard high-water level river discharge measurement method in Japan had been the float method. However, recently measurement methods using doppler radar or image processing had been seriously studied and been applied to practical river discharge measurement. Until now a lot of studies had been done on the accuracy of these measurement methods, but few focus on what kind of velocity (the discharge are usually calculated by the velocity and cross-section area) has been measured. Because there is more than one definition of velocity to describe river flow. The result can be quite different when measuring the different kind of velocity
 In the present study, we will firstly show that the discharge which been measured by different measurement method are actually different. Based on the result, we will study which kind of velocity and discharge have been measured by the popular measurement methods. We had also studied the relation between different kinds of velocity both theoretically and numerically. As the result, the numerical experiment agree with the theory very well. The observation based on Euler's definition of velocity shows a bigger value than the observation based on lagrange's definition of velocity.

View full abstract

 In this study, we aimed to elucidate the detailed hydraulic mechanism of long term persistance of turbidity in reservoirs, since the phenomeman cause water quality problem in the downstream river of the dams. For that purpose, we made field measurements on velocity disribusion characteristic under a thermally stratified condition and grain size of suspended sediment after a flood event in Isawa Dam Reservoir in Japan. A current meter with high temporal resolution was used in order to measure the velocity distribution that could influence on long term suspension of fine grained sediment in the reservoir. The device was moored during the measurement in the reservoir at intended depths by using the apparatus that was assembled with rope, angle bars, submerged floats, and self-jamming pulleies. From the obtained data, velocity distribution was analyzed as well as the swaying condition of the current meter during the measurement. The grain size of the suspended sediment sampled in this study showed almost homogenious distribution from the upper layer to the middle layer and concentrated around 10μm. The velocity distribution was rather uniform regardless of the depth. Therefore, we presumed that such velocity distribution and fluctuation could effect on keeping suspended sediment from falling, and cause active diffusion in epilimnion in the reservoir.

View full abstract

 Long term fluctuations of fine particulate organic carbon (FPOC) and nitrogen (FPON) were analyzed in two mountain streams located in the northern part of Gunma prefecture. Then transport yields were estimated by rating curve (L_LQ) and the product of the concentration of FPOC or FPON and discharge (L_CQ). Both transport yields of the FPOC and the FPON have about 12 ~ 20% difference between by L_LQ and L_CQ. L_LQ underestimates the transport rate at low flow rates, on the other hand, L_CQ underestimates the transport rate at no sampling during flood. Applying an appropriate monitoring method is important to estimate the transport yield of particulate organic matter. The influence of discharge on the transport yield of FPOC and FPON is large in both methods. In addition, CN ratio representing the quality of organic matter had no difference. Therefore, forest type difference has a subtle influence on the transport of particulate organic matter.

View full abstract

 One of the problems in flood control is the backwater in upstream direction which occurs when the river channel suddenly contracts. It is very important to understand the water surface profile in such river channels under the maximum possible flow considered the effect of climate change. In the present study, the following two works had been accomplished: 1, Using numerical simulation technics to quantitatively evaluate the water surface profile in river channel which including sudden contraction. 2, Using Yamada's theory to study the backwater-curve transitions considering the changing of cross-section area of the river channel. An example of the result of the present study indicates that a discontinuous water surface profile is formed at the contraction part of the channel. The flow at the downstream side of the contraction part is supercritical flow and the water level at the upstream side has been dam-up about 3m. The regime diagram of the water surface profile in the river channel which has sudden contraction suggested by Yamada showed that the result of numerical simulation agrees with this regime diagram very well. In addition, the storage effect of the unsteady and non-uniform flow caused by the non-uniformity of the river channel had also been studied. Using numerical simulation, we can calculate that how much quantity had been stored in the dam-up part at the upstream side and evaluate the effect of lowering the water level at downstream side.

View full abstract

 In this study, an hourly evapotranspiration model that can express the amount of evapotranspiration accounting for differences in soil moisture and infiltration characteristics of individual land-surface features is developed. The model is composed of two components; the pervious area model based on SMPT model to represent the permeation process of the surface soil, and the impervious area model considering depression storage in impervious areas. Furthermore, the pervious area model takes into account the state of the soil moisture and differences in land use of the land-surface features, and estimates the latent and sensible heat using a heat balance equation based on the bulk formula. The model was applied to the highly urbanized upper Kanda River watershed, and the impacts of differences in land use on the spatial distribution of evapotranspiration and land-surface temperature was analyzed.

View full abstract

 The effect of rainfall on spatio-temporal variability of water quality and flow dynamics in the Shakujii and Sumida river estuaries was studied. The water level, salinity, turbidity, and flow velocity were observed for 12.5 hours after the occurrence of heavy rain on Nov. 11, 2016. Suspended sediment concentration (SSC) was analyzed. The results of the study showed mesotidal river estuaries having stratified to partially well mixed water columns. Rainfall brought a large freshwater discharge which caused the estuaries to be stratified, diminishing mixing and circulation in some stations. The saline water influx from Tokyo Bay was evident in the bottom layer of Sumida and Shakujii rivers while the buoyant freshwater flows in the upper layer. Comparing the different stations, Shakujii and upstream Sumida were largely affected by freshwater while downstream Sumida has a brackish water nature. Through the analysis of salinity and SSC, the phenomena of bottom sediment uplift, flocculation and erosion from local turbulent eddies were observed. Particulate organic matter and SSC relationship was also studied, which showed linear trend in the upstream while inorganic matter dominated the downstream. Other than rainfall, topography was identified to cause stratification. In Sumida river, deeper bottom depth decreased vertical mixing while in Shakujii river, salinity was retained due to bathymetry irregularities.

View full abstract

 In the tidal area of urban river, Sludge will accumulate on river bed caused by the inflow of untreated sewage water. Dissolved oxygen decrease to a low level and elution of nutrient occurred at the river bed. This study found this problem in Nihonbashi River. The author using 4 types of improving sediment materials for improving an effect of dissolved oxygen consumption and nutrient elution. Dissolved oxygen consumption and nutrient elution rate were calculated and compared by lab batch experiments with the acrylic cylindrical column. The result of the experiment are granulated coal ash and sand covered were suppressed on dissolved oxygen consumption and nutrient elution. Iron charcoal was most suppressed on nutrient elution about DTP. However, it was not suppress on dissolved oxygen consumption.

View full abstract

 It is predicted that the storm surge damage due to climate change may be more serious in the world. The objective of this study is to verify the estimation method for economic damage of storm surge, focusing on the case of Isewan typhoon. This study compares the two estimation methods of storm surge damage using the case of Isewan Typhoon. Specifically, the economic damage was estimated by two methods: 1) the method based on flood control and the economic research manual and 2) the method based on macro socio-economic indicators such as GDP and affected population. It was found that the former estimated the damage 10 times as large as observed one and the latter estimated the damage smaller than the observed one.

View full abstract

 The objective of this study was to assess global impact of sea level rise based on RCP/SSP scenarios. Global areas of inundation due to seal level rise and astronomical high tide were identified. Combining the results of inundated areas based on RCP scenarios with SSP scenarios, the populations affected and the economic damages caused by inundation due to future climate change were also estimated. Consequently, potential inundated areas vary 370 thousand km² (RCP2.6) to 420 thousand km² (RCP8.5) and affected population vary 55.3 million (RCP2.6, SSP1) to 106 million (RCP8.5, SSP3) in 2100. This quantitative information is expected to be valuable in implementing desirable adaptations according to the regional conditions.

View full abstract

 In northeast Thailand, the ratio of irrigated agricultural land was only 7.6% and others were rain-fed so that climate change makes agricultural production more unstable and also makes crucial damage to the societies and economics in rural area. To mitigate these issues, it is desirable to develop and disseminate enhanced adaptation systems. In this study, we focused on weather-index insurance for climate change adaptation measure. Firstly, we evaluated how affect the rainfall amount and patterns on rice production through regression analysis by using the meteorological and agricultural statistic data from 1985 until 2004. The production of wet season rice had positive relationship(R>0.2, Slope>0.2) with 3 month accumulated rainfall (Jun-Aug) in 11 province. As a result, employed rainfall index was suitable for accurate estimation of rice production in wet season. Secondly, household survey was conducted to grasp farmer's conditions of water use, cultivation, income balance. And then, economic loss by weather induced agricultural damage was estimated and impact on farmer's household income was evaluated by using the agricultural statistic and rice price data from 1981 until 2013. Recently, agricultural economic loss of around 600 million Baht was often occurred in northeast Thailand. However farmers household income was mostly rely on non-agricultural sector so that agricultural economic loss was less than 10% of their annual income. Current weather index was designed by 5-10 years return periods in many province and that also might be the one reason of obstacles of insurance sales.

View full abstract

 We, using 7 years of panel data of 41 municipalities in Hyogo, Japan, analyzed the relationship between rice productivity and climate and economic factors, and assessed the impact of future temperature increase on rice productivity. The findings of this study are as follows. (1) The relationships between rice productivity and temperature were an inverted U-shaped before a heading time and a negative linear after it. (2) The changes in rice yield by future temperature increase scenarios using results of MIROC5 were estimated to be from decrease of 2.00% to increase of 0.04% in the RCP2.6, from decrease of 0.28% to 3.22% in the RCP4.5, and from decreases of 1.90% to 7.10% in the RCP8.5, respectively. (3) As most municipalities in Hyogo were unable to cope with future temperature increase, they need adaptation strategies for rice productivity.

View full abstract

 Changes in crop yield due to future climate change will affect land use, agricultural production volume, and prices in the agriculture sector, as well as macroeconomics. While there has been much research into food prices and food security using economic models, there is little research on macroeconomic effects. Therefore, this study clarifies the macroeconomic impacts of crop yield changes using the CYGMA model, which is one of the most advanced global yield models, the AIM / CGE economic model, and the AIM / PLUM land use distribution model. In doing so, we dealt with factors and uncertainty that affect macroeconomics as much as possible, such as adaptation measures due to land use change, socioeconomic conditions, CO2 fertilization effects, and the uncertainty of climate models. This showed that the CO2 fertilization effect and the land use adaptation measures did not necessarily produce distinct differences in macroeconomic effects, and were smaller (0.02-0.06%) than the economic impacts of climate change in other commonly known sectors. However, socioeconomic conditions changed their values greatly and there was a large influence (0.6%) that can be compared with other sectors based on a pessimistic world scenario, such as a large population increase and low incomes.

View full abstract

 This study focused on precipitation outputs from regional climate models and compared the properties of precipitation products which were obtained by using several bias correction methods. Result indicated future change of variance and continued heavy rainfall (i.e. 5 days total rain) could largely vary according to the choice of bias correction methods and regional climate models.
 This study also suggests a bias correction method which aims to correct temporal variation of daily precipitation obtained from the climate models. The proposed method showed relatively better performance in reproducing maximum 5 days total precipitation, which statistics would be important in evaluating the potential for water disasters. Result also indicated although spatial distribution of daily precipitation is improved by bias correction methods, the frequencies of each precipitation pattern are different according to regional climate models and employed bias correction methods.

View full abstract