Temperature difference may occur between inside of fishway and downstream area of fishway, because exit of fishway are located near surface water of dams or weirs. Since Anguilla japonica is ectothermic organism, water temperature difference between fishway and downstream area have great effect on migration rate. In this study, it examined effects of change in acclimation water temperature and water temperature in fishway on migration characteristics of Anguilla japonica. The results showed that migration challenge and success rate were highest when acclimation water temperature and water temperature in fishway were 20℃ and 25℃. When acclimation water temperature and water temperature in fishway increased, Anguilla japonica became more active and migrated without much rest.

 Habitat models that predict the distribution of stream animals along environmental gradients at the catchment scale are useful in river environment management. However, past studies have not examined such prediction model along a broader gradient of riffle-pool hydraulic variables such as water depth. In this study, we developed a model for predicting distribution of stream invertebrates along gradients of rifle-pool hydraulic variables using an unsamble machine learning technique, random forest, in the Omaru River catchment, located in southern Japan. As a result, many biological and environmental variables (e.g., slope) significantly increased in riffle reaches compared with those in pool reaches. In the prediction models of 156 taxa that appeared at three or more locations, elevation and catchment area were the most important predictors, followed by hydraulic variables such as current velocity and water depth. As a result of performing 4-fold cross-validation by adding hydraulic variables to predictor variables, a predictive performance metric of presence / absence (i.e., AUC; Area Under Curve) significantly increased for the four orders (ephemeroptera, plecoptera, trichoptera and diptera) and five life types (burrowers, case-bearers, crawlers, net-spinners and swimmer) of stream invertebrates.

 Evacuation orders have not been lifted in the northwestern part of Namie Town, Fukushima Prefecture, following the 2011 nuclear power plant accident. To show the time and safety required to lift the evacuation order, observation data based on scientific knowledge is required. The terrain in the northwestern part of Namie Town is particularly steep making the investigation of mountain streams difficult. Currently, discussions the ecosystem of mountain streams is discussed by assessing the radioactive compounds accumulating in the bodies of mountain stream fish. Periphyton and moss were gaining interest from biological researchers as adsorbents at the time. Therefore, in this study, we developed a method for assessing periphyton and moss using aerial photos recorded with a drone

 Global warming is predicted to result in extreme climatic changes, such as sea-level rise, tropical cyclone activation, and increased precipitation, which could cause water-related disasters. Therefore, the risk of flood disasters in coastal countries is increasing. Consequently, it is crucial to make accurate damage predictions and implement adaptive measures. Herein, reserach has been conducted to compile global levee data and assess the damages to enhance the accuracy of imundation simulations for storm surges. During the study, it was realized that the run-up of storm surges into rivers was an important factor that had to be considered. Therefore, in this study, we created river levee data for international rivers indicating various regions globally, we also verified the effectiveness of this data.

 Conserving biodiversity is one of the great concerns for developing sustainable society. This study attempts to identify in what regions and what measures are effective to conserve the biodiversity by integrating economic, land-use and biodiversity models in a single modeling framework. More specifically, we implemented scenarios to change the dietary patterns and supply side measures such as yield improvement and efficient pasture utilizations. The results indicate that the dietary change in developing countries is effective to achieve the objective and not only large population countries like China and India, African and Latin American regions which has large area could have a significant role.

 In recent years, flood disasters have become more frequent and larger in scale due to increased precipitation caused by global warming. In order to reduce the flood damage, several flood control methods and countermeasures are being undertaken throughout the entire basins. In Toyama Prefecture rivers, vegetation is found to be thriving in the river channels, and the vegetation management of the rivers is expected to have the effect of reducing water levels during the flood event. In addition, the rice paddy field dams are expected to have a rainfall storage effect due to the high land use of rice fields in the Toyama prefecture. In this study, we evaluated the effects of vegetation management in the rivers and rice paddy dams on the future flow rate of the rivers in Toyama Prefecture. The effect of vegetation management of the rivers on the Oyabe River, where vegetation thrives, was an average reduction of 0.2 m in water level, assuming a 4°C rise in the future. The rice paddy field dam was effective in the Oyabe River, where paddy land use is high, and the water level decreased by an average of 0.93 m when the rice paddy field dam application rate was 100% and by 0.44 m when the application rate was 50%, assuming a 4°C rise in the future climate.

 The effect of reducing GHG emissions by limiting the consumption of livestock products has been reported. However, the specific impact on the food system and land use system that are the sources of GHG emissions has not been evaluated. The purpose of this paper is to clarify the impact of restricted consumption of livestock products on the environment and food system using the AIM/CGE model. Our analysis shows that restricted livestock consumption reduced GHG emissions by 960MtCO_2eq/year, increased forest area by 93Mha, increased carbon sequestration of land by 240MtCO_2eq/year, reduced irrigation water use by 200million m³ /year and reduced Nitrogen fertilizer use by 3 million tonne N in 2050. In conclusion, limiting the consumption of livestock products is expected to be effective not only for reducing GHG emissions but also for protecting the environment.

 We considered the current consciousness of elementary school students to value food and their knowledge and action not to produce food waste, and considered changes in their consciousness as elementary school students attend food and nutrition education. As a result, the current elementary school students value food on a daily basis, and the word food waste itself is recognized by elementary school students to some extent. It was confirmed that among the action not to produce food waste, many elementary school students are able to practice actions that are relatively easy to tackle, but many elementary school students are not able to practice actions that are difficult to tackle. In addition, by taking a quiz, the effect of food and nutrition education can be expected to acquire knowledge about food waste. Furthermore, it was clarified that the effects of food and nutrition education can be expected for the acquisition of knowledge about food waste, such as (1) consciousness of the amount of food waste, (2) its type, and (3) the difference in meaning between the freshness date and expired date.

 Current many climate change mitigation scenarios that meet so-called 2°C or 1.5°C target intending to keep global average temperature rise below 2 or 1.5 °C show that around 20-30% of total energy would be supplied by bioenergy. And it is said that the reduction of meat consumption will reduce land use of farmlands and pastures, which can be used for land use such as establishment of nature reserves to protect species and ecosystems and production of energy crops. Therefore, the potential amount of biomass energy potential, including economic aspects, was clarified, taking into account future changes in food content. 146 EJ/year of biomass energy potential in the baseline scenario for 2050 and 261 EJ/year of potential in the global meat restriction scenario The results obtained suggest that changes in the diet.

 This study quantified greenhouse gas (GHG) and air pollutant emissions from a rice husk gasification power generation system using a life cycle assessment method. We set three assessment scenarios: a rice husk gasification power generation scenario, a rice husk gasification-only scenario, and a conventional scenario. The functional units were 1 kg of brown rice and electricity and heat obtained from rice husks, the byproduct of brown rice. The results of the assessment showed that the introduction of a rice husk gasification power generation system or a rice husk gasification system could reduce GHG emissions by 6–7% compared to a conventional scenario. When the effects of using biochar obtained from the rice husk gasification process for soil improvement and carbon sequestration were considered, 6.5% of GHG emissions would be additionally reduced compared to a conventional scenario. In addition, scenarios with system installation can reduce air pollutant emissions by 44–45% compared to a conventional scenario. An interview survey with a farm that is using a rice husk gasification power generation system revealed that while the advantages of introducing the system were summarized as waste reduction and economic benefits from the sale of biochar, preparing storage space for rice husks would become an issue to expand the number of users.

 One of methods to estimate hydrograph in ungauged basins is to calibrate a hydrological model through setting streamflow signatures or hydrological time series data as the objective variables. To detect the streamflow signatures or hydrological time series data which have ability to reproduce hydrograph as the objective variables in the calibration, numerical experiments were conducted in 23 basins in Japan. Note that we employed Baseflow index (BFI), Flashiness index (FI), annual runoff height (Q_MEAN), and 3 indices of flow duration curve (Q₁₀, Q₅₀, Q90) for the streamflow signatures, and terrestrial water storage anomaly (∆TWS) and soil water anomaly (∆SM) for the hydrological time series data. We found that ∆TWS has ability to reproduce hydrograph as the objective variables in the calibration. The reason is that ∆TWS can relate to all parameters within the hydrological model and have enough information of the model error due to time series data.

 Understanding the situation of the potential water resources (PWR) available and their spatial distribution is essential for an efficient water management on a basin scale. Water scarcity is a complex issue that many countries in the world, including Madagascar, face. In this article, we assess the potential water resource availability and the competition of use within a basin. Here we show the importance of the water resources assessment within a large river basin scale. Three imbalance indicators were introduced to evaluate the spatial availability, distribution, and variability of the PWR available for daily life use and agriculture. The Indicator N°1 presents the total amount of PWR per capita and agriculture area in the whole basin. The Indicator N°2 indicates the distribution of water compared to the outlet if there is more or less water in the upstream area. Indicator N°3 demonstrates the water variability upstream to downstream. Results reveal the uneven spatial distribution of the water available upstream-downstream which is the core issue of the river basin management. Our results demonstrate how the three imbalance indicators provide a relevant information about the situation of water resources, helping to solve the conflicts of use and to overcome the pressures on water scarcity.

 The basic controls leading to slope failure driven by rainfall are still not well quantified. Therefore, the uncertainty input parameters are considered, such as soil properties and spatial variation of soil thickness, and different spatial resolutions of a grid cell. Those parameters are well-known essential factors controlling shallow landslides. In this paper, the physically-based model is used to evaluate the effect of spatial variation of soil thickness, the spatial distribution of rainfall, and spatial resolution at the Uchi and Gofukuya rivers basin, Marumori town on Typhoon Hagibis event. The model prediction accuracy is evaluated by ROC curve for different scenarios selected by soil thickness model, distribution rainfall, and spatial resolution. As a result of the model, the soil thickness is an important parameter and related to the slip failure plane. In addition, the distribution of rainfall, rainfall intensity and slope gradient affect landslides by increased driving force that causes different landslide characteristics in Uchi and Gofukuya river basins.

 This study presents a method for constructing confidence intervals for multivariate extreme value distributions based on probability limit method test, and multivariate extreme value analysis method that introduces such confidence intervals. The method can estimate the peak flood discharge values and their confidence limits under the rainfall of interest by introducing confidence intervals into the multivariate extreme value analysis, which is useful for the problem of the large uncertainty of various possible spatiotemporal distributions of river discharge in rainfall data that have not been accumulated for several decades. The results are shown below. Furthermore, as an application of this method, it is possible to quantitatively discuss flood risks related to rainfall and peak discharge under a future climate by using a large ensemble of data.

 The vegetation growth on the sediment deposited around the filter unit (FU) can be expected to provide ecological habitat, improve the landscape, and protect the revetment. Hydraulic experiments and numerical simulations on the vegetation around the filter units placed in a row were conducted to investigate the impact of vegetation on the river revetment. As a result, it was shown that even the vegetation lodging during the flood could reduce the surrounding flow velocity by about 40% and protect the revetment. The water level rise during floods was about 0.1 m. On the other hand, the riverbed scouring increased due to the impact of vegetation. The range of sediment outflow from the FU base was less than half the width of the FU, and the FU itself would not incline and sink. The vegetation growing around the FUs is effective in protecting the revetment at the water-colliding front in small-to-medium-sized rivers.

 In Brazil, the slope disasters caused by heavy rainfall are frequent due to a combination of factors such as the climate change, development of suburban slopes due to the urban expansion, delay construction of the disaster prevention facilities, and less software for the disaster prevention measures. This paper reviews the actual situation of landslide disasters in Brazil and its disaster prevention measures, and summarizes the trends of slope monitoring methods implemented in Brazil. Then, analysis of their applicability to slope hazards was conducted including the slope failure detection sensors using tilt sensors. As a result, it was found that the slope failure detection sensor is almost applicable to the monitoring of the slope surface failures and the tailings dam failures. It is also expected to improve the evacuation behavior of residents.

 In this study, a method for extracting fronts from weather maps treated as weather information was developed and applied to 34 years of weather maps. The front can now be treated as grid data, and it is shown that rainfall within 100 km around the front accounts for more than 30% of the rainfall in the Kyushu region in June and July. Furthermore, it was found that the spatial mean rainfall over the area passed by the front as it moved meridionally over the Kyushu region reached a maximum when the front moved about 300 kilometers. The weather patterns suggest that the north-south movement of the front is affected by moving depression with fronts, the approach of a typhoon or tropical cyclone, and an enhancement of an anticyclone.

 In recent years, record-breaking rainfall has been occurring frequently due to climate change, causing extensive damage in many areas. It is important to properly assess future changes and take adaptive measures to cope with such heavy rainfall. In Japan, the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) has been promoting flood control planning using large ensemble climate prediction data. The data can be used for flood risk assessment based on the spatiotemporal distribution of rainfall. In this study, future changes in rainfall waveforms, which are important for flood risk assessment, were analyzed. It was shown that the proportion of backward-concentrated rainfall increases as the rainfall duration increases, and that there is a tendency for future events with rainfall intensity of 15 to 20 mm/h to continue falling for a long time. In comparison with the actual measurements, the rainfall waveforms of the future experiment generally agreed with the actual measurements, and the peak rainfall intensity tended to increase compared to the actual measurements.

 The Kain-Fritsch (KF) is one of the most-used cumulus schemes in weather prediction models. An improved and scale-aware version of this scheme, called Multi-scale KF (MSKF), brings improvement to the simulated precipitation values which are often overestimated by KF. However, the applicability and performance of MSKF over the Philippines in simulating precipitation are yet to be verified. Herein, we examined these by simulating five typhoon-induced heavy precipitation events in the Weather Research and Forecasting (WRF) Model. The results were compared with the results of three other cumulus schemes – KF, Grell-Freitas (GF), and Tiedtke. Based on the results, the MSKF is applicable for use in simulating heavy precipitations over the Philippines with performance comparable to other schemes. Additionally, MSKF has generally lower precipitation values than KF but does not always perform better. It is suggested to use MSKF like other cumulus schemes – as part of an ensemble forecast. Further research is called upon for the improvement of cumulus schemes.

 Drop size distribution of sea spray generated from wave breakings can be a confounding factor for rainfall observations at sea, and has significance as a sea-salt particle that causes salt damage and rainfall inland. In this study, field observations of sea spray were conducted using a disdrometer, and drop size distribution equation as a function of wind speed was proposed. The proposed equation enables the estimation of the amount of sea spray that can be mixed during rainfall observations and the estimation of the amount of sea spray that are the source of sea salt particles that cause salt damage and cause rainfall.

 The purpose of this study is to evaluate the long-term efficiency of a ground-source heat pump system through a simulation for 100-yrs from 2001 to 2100 at an office building in cold Sapporo and warm Tokyo under three different scenarios of climate change. Hourly meteorological conditions were estimated from originally monthly data, and the calculation of thermal demands in a building followed. Underground temperatures were predicted considering thermal and water budgets on the surface. As a result, 20yrs-averaged seasonal performance factors were expected to be kept for both cooling and heating and by both vertical and horizontal heat exchangers. However, the performance will become lower in a specific case for heating in Tokyo because of constant electricity consumption for circulation pumps. The difference in the seasonal performance factors among the three scenarios was less than 0.1-0.2 in Sapporo. The value was about 0.7 for heating in Tokyo, indicating the uncertainty in the system efficiency under climate change.

 This study determined the resistance of sediment discharge buffering effect using case study of mass movment along a river channel in the Gofukuya River (Marumori, Miyagi Prefecture) during the East Japan Typhoon 2019. The case of the Gofukuya River was verified using spatial numerical information acquired with LP(Laser profilers) and UAV, as the aim of quantifying examples of mitigation effects against compounding phenomena that may promote severe disasters. Despite being an area of concentrated sediment and flood inundation, 25/54 (46%) tree sediment runoff buffer cases were extracted in the Gofukuya River. In the area that showed a particularly large buffer effect, the results resulted in a resistance of 43.73 kN/tree (Japanese cedar). However, the age-tree height equation indicates that the amount of tree growth in the area is significant.

 The flood damage caused by a typhoon and the heavy rain was frequent in Japan. River management became important in such situation. The particle size distribution of the riverbed materials in the river channel was an important index from the viewpoint of sediment management. However, many considerations for particle size were related to the surface layer of the river bed.The examination about the riverbed materials at the deeper point was not carried out. These information was very important parameters to affect the precision of the numerical simulation.

 In this study, the change of the particle size distribution in the horizontal and vertical direction gathered riverbed materials and considered from multiple points at the Babamegawa River. In addition, the numerical computation was performed using a got particle size distribution. Then it was compared the mixed-sized particle with the uniform grain diameter. As a result, a calculation in the mixed-sized particle was the highest in precision. The case of using the peak value of the occupancy rate became highest in precision by the numerical computation of uniform grain diameter.

 A steel pipe open Sabo dam has been constructed as a countermeasure structure against debris flow. In the event of debris flow, boulder and driftwood block the permable part of the open Sabo dam, trapping the following sediment. This is because the boulder and driftwood are concentrated at the front part of debris flow. However, the mechanism of this occurrence is still unclear in many points, and there is still little research on driftwood, which has been a trend in recent disasters. This study investigates the conditions for the occurrence of classification phenomena in mixture of water and sand, water and driftwoods, sesiment and driftwoods including water using a ball mill device. The results is shown that driftwood generates classification phenomena by water and sand circulation.

 We are developing technology to explore the internal structure of river embankments with greater exploration depth and spacial resolution than conventional method. The geometric shape of the embankment was reconstructed by the observation data from the sluiceway. The density distribution inside the embankment was estimated with a resolution of 1 m × 1 m using tomographic inversion. In addition, we developed two small semiconductor detectors to save space and labor, and considered the observation accuracy for their applicability to river embankments. We confirmed that two observations were equivalent when the detector-housing temperature difference was kept within ±1°C except for a sudden change of the detector housing temperature.

 Using observations and the Ensemble Climate Prediction Database (d4PDF), we analyzed the occurrence characteristics of linear and stagnant precipitation bands. In recent years, heavy rainfall disasters involving LRB have been frequent all over Japan, and the Japan Meteorological Agency defines a linear precipitation bands from the shape and stagnation time of precipitation zones of 80 mm/3h or more from the aspect of disaster prevention. In Hokkaido, however, several floods and landslides have occurred even with much lower precipitation than that. In this study, LRB are redefined for the Hokkaido region, and the frequency of occurrence, regional distribution, and model characteristics in past and present climates are shown through observations and application to the d4PDF.

 The Tamagawa acidic water originates from the Tamagawa hot springs in eastern Akita Prefecture. Currently, the pH of Lake Tazawa has increased from 4.6 to about 5.8 due to the operation of a neutralization treatment facility. However, it has not recovered to 6.8, and the water environment and ecosystem have not yet recovered. In this study, a neutralizer was prepared using fly ash to improve Tamagawa acidic water and to expand the use of coal ash. Neutralization experiments were conducted to evaluate the effectiveness of the neutralizer by analyzing pH changes, the neutralizer, and treated water. The results showed that the neutralizer did not disintegrate or leach heavy metal ions in the weakly acidic range, suggesting that the neutralizer could be used stably.

 Climate change mitigation is generally associated with several co-benefits, such as reducing health impacts due to air pollution. The number of excess mortality due to PM_2.5 has been calculated using a function called IER (Integrated Exposure-Response model). Recently, the GEMM (Global Exposure Mortality Model), an improved function of IER, has been developed and existing studies reported that there are considerable differences among their estimates. This study attempts to clarify the differences in the estimates of health impacts and co-benefits between these two functions using future scenarios of air pollutant emissions with different greenhouse gases emission pathways . The results indicated that the estimated number of PM_2.5-derived deaths from GEMM was about 1.7 times higher than that from IER regardless of the scenarios. Also, the estimated co-benefits, avoidable premature mortality, using GEMM exceeded IER in most regions, with a combined global increase of about 34%. The choice of function would have a significant impact on health estimates in future scenarios.

 In recent years, a large amount of attention has been paid to the health effects of PM_2.5 and the agricultural effects of tropospheric ozone as effects of air pollution. However, the effects of differences in the horizontal resolution of the chemical transport models used for the above effects have not yet been clarified. Therefore, this study calculates ozone and PM_2.5 concentrations for fine-resolution regional scale and coarse-resolution global scale simulations using a chemical transport model (CTM). Furthermore, the model evaluates the compatibility of the observed concentrations and the impact on estimates of the agricultural and health impacts. The results showed slight variation in future global impact analysis with the acceptable resolution. However, depending on the region, the variation in the yield loss with the satisfactory resolution was considerable. Therefore, we conclude that a higher resolution of CTM could change the agricultural impact analysis for some regions but have little effect on others, and therefore, the change in the overall impact analysis is limited.

 Turbidity observation in a river is important for understanding sediment dynamics and the river environment. However, turbid water often occurs during flood events, which have risks such as damage to observation equipment and the safety of observers. If a non-contact method for observing turbidity can be developed, these risks can be avoided. In this study, we examined the possibility of estimating turbidity using artificial neural network (ANN) with color information obtained from images taken continuously in a river using time-lapse camera. The results showed that it is difficult to estimate turbidity based on color information alone. On the other hand, the addition of water level data to ANN improves the turbidity estimation over the conventional method based on the L-Q equation. Furthermore, the ANN with color information, water level, and light conditions suggests the possibility of accounting for hysteresis loops that cause differences between the rise in water level and the rise in turbidity during flood.

 The farming conditions in the large-scale dairy area of eastern Hokkaido are changing due to the implementation of an environmental conservation-type irrigation and drainage project and crop conversion following climate changes. Changes in the outflow routes of water pollutants and subsequent changes in nitrogen cycle are consequently predicted, and it is necessary to quantify the impact on the water quality environment in the entire basin scale. In this study, we applied SWAT, a semi-distributed model, to small-scale watershed, and analyzed river water quality assuming farming conditions in three periods, namely, the past, present, and near future. The results showed an increased nitrogen load of the surface flow due to the conversion from pasture to silage corn, but surface, lateral and groundwater flow could all be reduced by arranging project facilities in and around the converted farmland.

 The new coronavirus (COVID-19) reduces consumers' consumption such as accesses to natural environmental qualities, leading to decrease benefit values of being used for bases of natural environmental managements. The purpose of this study is to develop a simple benefit valuation model that adjusts the consumption suppression by summing up the amounts of observed and reduced consumptions. The empirical estimation by the repeated discrete choice model is shown by using data on the number of visits and canceling visits on tourism activities during 2021, and the sites' attractions as alternative variables on environmental qualities. The results show that the benefit values by canceling are about 84% of benefit values by observed tourism demand.

 In recent years, the number of localized heavy rainfall events has been on the increase, resulting in many water-related accidents. In this study, the accuracy of short-time precipitation forecasts and high-resolution precipitation nowcasts published by the Japan Meteorological Agency were verified, and an analysis was conducted regarding the safety assurance of sewer construction. Furthermore, since the depth of water in sewer pipelines is also greatly related to safety, we analyzed the effect of different amounts of rainfall in a short period of time on the depth of water in sewer pipelines. It was found that the prediction accuracy decreased as the prediction time became longer, and that the difference in rainfall affected the depth of water in the sewer pipe, which in turn affected whether it was possible to walk in the pipe or not.

 To date few studies have tackled evaluation of flow alterations involved with changing climates at a watershed scale. Here we evaluated changes in climate in the past 40 years in the Omaru River catchment in south-west Japan, and resulted flow alterations as well as their spatial patterns using a distributed hydro-logical model and indicators of hydrologic alteration (IHA). We divided the study period into base and impact periods and the extents of the alterations were quantified by the ratio of IHA between them. Results show that the monthly median flow during winter season increased although the flow during spring season decreased. This attributes to the decline of snowfall in winter due to temperature rise in the impact period. We also found significant positive alteration in the annual maximum daily streamflow over middle to upstream. This may cause negative impacts on the ecosystem especially in the upper streams through promoting hydraulic erosion and passive drifts of benthic animals.

 To discuss future water supply system development in developing countries, it is important to quantitatively understand stakeholders' evaluations and demands. In this study, we conducted a questionnaire survey targeting university students in Vietnam to clarify actual use and evaluation of tap water by university students in the country. The answers obtained in the survey were analyzed using Fisher's exact test and T-test in order to examine if its use and evaluation are different between urban and rural areas. As a result, no significant differences between the two areas were found in the evaluation of tap water through five physical senses, satisfaction of tap water, demand for improvement of water supply system, evaluation of tap water charges, perception of risks associated with tap water, and trust in water supply administrator. Despite the differences in availability of tap water and its actual use between urban and rural areas, high evaluation of tap water and demand for its improvement were commonly found. The high evaluation of tap water could be attributed to the fact that the water supply has released them from the water-drawing work and reduced their health risks. On the other hand, the demand for improvement of tap water was still high owing to new problems such as the amount of water supplied, insufficient water pressure, and deterioration of water quality in the rainy season.

 Economic losses and water crises due to climate-related disasters are expected to further increase worldwide in the future. The purpose of this study is to clarify the interrelationship between water resource policies and climate change adaptation measures through the differences in socioeconomic characteristics between Japan and Thailand. The research methods included a qualitative evaluation of water resource policies in the context of socioeconomic background and a quantitative comparative evaluation using hydrological and climatic data. The comparison revealed that Japan and Thailand had similar water resource policy transitions, and that there were differences in the clarity of the positioning of water resource-related laws in Japan and Thailand. Quantitative comparisons revealed that Japan's adaptation to extreme climate events and Thailand's economic and agricultural sectors' vulnerability to hydrological and climatic events were identified as challenges for water resource policies.

 Since preparing for anticipated sea-level rises resulting from climate change is a critical issue in coastal areas, this study investigates the costs of protective measures against increasing sea levels using coastal structures, which are assumed to be the construction costs of several coastal revetment types. Specifically, three coastal revetment types were investigated (sloped, upright, and composite), and their relative construction costs were calculated based on cross-sectional views provided in Shibata et al. We also estimated the cost of raising the crown height by replacing some parts. Herein, representative concentration pathway (RCP) 8.5 and RCP 2.6, as promulgated in the 2014 Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), were used as climate change and sea-level rise scenarios. Our investigation showed that the costs for adapting to anticipated sea level rises would be between 668 billion and 2.96 trillion yen (depending on the revetment type, without existing revetment). This result, which assumes that such revetments would be constructed and raised on all Japanese coasts, is expected to provide helpful information that will assist planners in formulating and implementing practical and effective adaptation measures.

 To measure economic effects of climate change and socioeconomic change, we estimate the loss of recreation value for sandy beach due to future beach erosion and population change and evaluate the economic effectiveness of hypothetical adaptation measures to restore sandy beach. The main findings of our study are presented as follows. (1) Damage costs due to climate change and socioeconomic change in 2081-2100 were estimated respectively as 257.7 billion yen/year for SSP1-2.6, 290.0 billion yen/year for SSP2-4.5, and 267.8 billion yen/year for SSP5-8.5. (2) For all combinations of RCP scenarios and SSP scenarios, adaptation measures were economically efficient in 31 to 35 prefectures, while they are inefficient in 6 prefectures (Hokkaido, Aomori, Tokushima, Kochi, Miyazaki, and Kagoshima).

 This study evaluated the impact of sea level rise (SLR) and astronomical tides in coastal Japanese prefectures, and assessed outcomes such as the potentially inundated area, affected population, and economic damage. The latest climate scenarios, tidal data, and shared socioeconomic pathways (SSPs) were used to evaluate SLR and inundation effects in the coastal areas of Japan at a resolution of 1 km. Economic assessment was incorporated by including SSP population and land use scenarios, also gridded at 1 km. This study evaluated economic damage based on the “Manual for economic evaluation of flood control investment (draft), ” whereas our previous study used the econometric relationship between past hydrological disasters. The uncertainty between high and low emission scenarios (SSP5-8.5 and SSP1-2.6) was also analysed. The potentially inundated area of Japan was determined to be about 2,111-2,127 km² in 2050 and 2,261-2,598 km² in 2100. The affected population was estimated to be 4.45-4.70 million in 2050 and 3.76-4.92 million in 2100, depending on the SSP. Finally, the economic damage was estimated to vary within about 143-170 trillion yen in 2050 and about 229-430 trillion yen in 2100. All impacts (inundated area, affected population, and economic damage) under SSP1-2.6 were smaller than those under SSP5-8.5, suggesting the importance of mitigation efforts. Economic damage using this “manual” estimation method was more than 20 times as large as when using the previous estimation method. The manual method also indicated more impacts around three major bays, mainly due to damage to buildings and the size of the affected population.

 This study proposes a method for estimating the cost of residential relocation, one of the adaptive measures being considered in response to expected sea level rise due to climate change. A reliable and valid cost estimation method was developed by following the conventional scheme of the “Project for promoting community relocation for disaster prevention” and by using the abundant existing empirical data on the costs of civil engineering works. Using SSP1-2.6(SSP1-RCP2.6) and SSP5-8.5(SSP5-RCP8.5) as typical combination of climate and socioeconomic scenarios, this study estimated the costs required to relocate the inundation-affected population under each scenario. As a result, the total cost of residential relocation under SSP1-2.6 was estimated to be approximately 92-183 trillion yen in 2050 and 121-274 trillion yen in 2100. Similarly, the total cost under SSP5-8.5 was estimated to be approximately 105-215 trillion yen in 2050 and 210-501 trillion yen in 2100. Tokyo accounted for the majority of the cost. The relocation cost of this study was higher than the protection cost of the previous study.

 In this study, using the past 25 years of inundation records, we identified frequent inland water inundation areas in Nagoya City where inland water inundations have occurred more than five times in the past.

 As a result of the time-series analysis of frequent inland water inundation areas, it showed that the frequent inland water inundation areas formed between 1993 and 2005 were caused by the land-use change from rice paddies to residential areas in or around frequent inland water inundation areas. This land-use change was affected as the topographical factors of inland water inundation.

 On the other hand, the influence of land-use change was small in the frequent inland water inundation areas formed between 2006 and 2017. This suggests that the increase in probable precipitation caused the drainage channels to become insufficient in their discharge capacity designed in the 1950s, resulting in frequent inland water inundation in areas where inundation had not previously occurred.

 In addition, the frequent inland water inundation areas in Nagoya City were formed in areas with almost no slope and regardless of the direction of overflow, the mere presence of structures in the vicinity was related to the formation of frequent inland water inundation areas.

 The purpose of this study is to clarify the characteristics of inland water inundation in Wakayama City, Wakayama Prefecture, based on past inundation records. We created a GIS database of flood-damaged area maps that recorded historical inland water inundation records for the past 25 years and extracted frequent inland water inundation areas where inland water inundations have occurred more than three times in the past. As a result of the time-series analysis of frequent inland water inundation areas, it was found that the number of frequent inland water inundation areas has been increasing. The results of the analysis of the causes of inland water inundation show that the influence of Anthropogenic and meteorological causes has increased in recent years. In the increase of the Anthropogenic factors, there are two land-use changes cases: (1) the number of paddy fields in the vicinity of frequent inland water inundation areas has decreased, resulting in a decrease in the retarding capacity of rainfall at paddy fields, and thus the direct flow of rainfall (inland water) into the frequent inland water inundation area, and (2) the overall decrease in the number of paddy fields around frequent inland water inundation area has caused a flow of inland water that exceeds the retarding capacity of the paddies in the vicinity of the frequent inland water inundation area.

 This study evaluated the effect of climate change and land-use change on flood damage using climate scenario data by shared socioeconomic pathways (SSPs) throughout Japan. The inundation depth caused by flooding was calculated using a two-dimensional unsteady flow model. The flood damage cost was calculated by multiplying the asset value of the inundated land by the damage rate based on the inundation depth. Extreme rainfall in future climates was estimated from the output values of five general circulation models. The increase rate of the expected annual damage cost (EADC) in the near-future climate (2031–2050) was estimated to be 2% under the SSP1-2.6 and 7% under the SSP5-8.5 compared to the baseline climate (1981–2000). The EADC decrease rate in the late 21st-century climate (2081–2100) was estimated to be 33% under the SSP1-2.6 and 11% under the SSP5-8.5 compared to the baseline climate.

 The Ino map was created by Japan's first modern surveying technology in the latter half of the Edo period (1603-1867). It has a wealth of geographical information centered on coastal areas and major highways nation-wide. In this study, spatial information analysis was used to link the geographic information found in the Ino map with the current hazard information, and to examine the manifestation of the inundation risk. As a result, it became clear that the disappearance of place names due to urbanization may have reduced the rate of inundation risk.

 According to the Paris Agreement, the parties are required to update their national emission reduction targets (NDCs) every five years. Emissions trading can be an economically efficient option to realize the condition of updated NDCs. This study made the economic assessment of implementing updated NDCs and quantified the effects of emissions trading using a global computable general equilibrium model. The results showed that updates of NDCs brought an increase in GDP loss mainly in developed countries relative to outdated NDCs. The introduction of emissions trading mitigates GDP losses across the world, but increased those in some developing countries where the level of emission reduction targets is relatively lower. While emissions trading can promote emissions reductions in the global level cost-effectively, it imposes a heavy economic burden on some developing countries. Thus, it simultaneously implied the importance of considering emission allocation schemes and providing additional financial supports to developing countries.

 With the growing interest in emission reductions and technology developments, the direct air capture (DAC) is focused as an attractive mitigation options. This study modeled DAC in an economic model that considers multiple sectors and goods, and estimated economic and energy system impacts of DAC. The model developed in this research estimated that DAC increases to 4.9 Gt-CO₂ of carbon dioxide in 2050 under an emission reduction scenario that limits the global average temperature increase below 1.5 degrees Celsius. Then, DAC shows the effect of reducing the consumption of biomass and curbing food price increse. DAC also reduced the GDP losses associated with emission reductions by 21.7% and the loss calculated by the equivalent variation by 4.6%. The results of this study shows that DAC is an effective emission reduction technology for household consumption.

 This study explored key strategies and associated costs of several options to remove residual emissions in the context of Japan’s net-zero greenhouse gases emissions by 2050 on top of carbon dioxide removal technologies which have been taken into consideration in the existing literatures. As scenarios depending on the domestic mitigation options, upscaling of hydrogen-based alternative fuels and energy demand reduction can contribute to avoiding negative emission for achieving net-zero emission goals. While this study explored the possibilities of imports of hydrogen-based energy carriers and emission allowances from the international carbon markets as effective options, these scenarios involve increases in energy and emission allowance imports by 2050, exceeding their import costs in 2010. The results highlighted the importance of developing the long-term low emissions strategies considering progresses on technology development and international policy frameworks, as the scenarios suggested several technological and economic challenges of the net-zero emission goals as well as multiple possible pathways to accomplish them.

 This study identified an energy system that will significantly reduce CO₂ emissions by 2050 in Maniwa City, Okayama Prefecture, through the use of an energy technology selection model. The results of the scenario analysis showed that a 58% reduction from 2015 emission levels would be achievable, even under a no-mitigation scenario, by 2050, and an 85% reduction from 2015 levels would be feasible with the implementation of mitigation measures. The primary mitigation measures selected included the use of local biomass resources in the power generation and industrial sectors, achieving 100% electricity self-sufficiency through solar and biomass power generation and the widespread use of electric vehicles. The study also indicated that CO₂ emissions would remain in the industrial sector if extreme measures, such as converting all fossil fuels in the industrial sector into biomass, were not implemented. To compensate for these residual emissions and achieve regional decarbonization, additional measures, including afforestation and the use of synthetic fuels, should be considered.

 In order to achieve net zero CO₂ emissions in 2050 corresponding to the 1.5 degree target of the Paris Agreement, it is needed to remove CO₂ emissions in sectors where electrification is difficult. Diffusion of synthetic fuels can be an effective option to accomplish decarbonization in these sectors. This study aimed to quantitatively assess a role of synthetic fuels in the global netzero emission scenarios using an energy system model. The results show that synthetic fuels can be an important low-carbon energy carriers in the scenarios that meet the 1.5 degrees target, especially in the transportation sector owing to their demands for liquid fuels. The introduction of synthetic fuels also contributes to reducing electrification rate and avoiding rapid increase of hydrogen energy share, revealing their effectiveness in mitigating disruptive changes in the energy system.

 It has been reported that emission reductions in the agricultural and livestock sectors, which produce non-carbon dioxide emissions, will play an important role in achieving net-zero global greenhouse gas (GHG) emissions. In this study, we estimated the potential GHG emission reductions and costs associated with GHG reductions in the agricultural and livestock sectors worldwide, considering not only production-side measures but also consumption-side measures, such as limiting the consumption of livestock products. The results show that the global GHG emission reduction rate in the agriculture and livestock sector in 2050 is 50.2% in the scenario considering only the production side (compared to the scenario without measures), and 69.9% in the scenario considering both production and consumption sides (compared to the scenario with measures). This suggests that efforts on the consumption side of agriculture and livestock products will result in additional emission reductions of 20% (relative to the No Action Scenario) and play an important role in achieving net-zero emissions.