Humidity variation for Baiu rainy season for around the Kyoho period (1716-1735) in central Japan was reconstructed using intra-ring measurements of tree-ring oxygen isotope ratio. Cellulose oxygen isotope ratios for two hinoki cypress trees collected from Mt. Tanakami, central Japan, were measured at a resolution of 1/12 (partly, 1/24, 1/6 and 1/2, depending on ring width) of annual growth ring for the period of 1704-1757 and 1968-1994. As results, interannual variation of oxygen isotope ratio for the early half of growth ring was found highly synchronous with averaged relative humidity for May 1 through July 20, early summer and Baiu rainy season in Japan. Also, it was found that amplitude of interannual variation of oxygen isotope ratio for early half of growth ring is substantially large for around 1720-1730 and dry Baiu rainy season occurred once in several years in this period.

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Previous studies have employed deterministic equations to project global economic losses by tropical cyclones. However, the relations between Tropical Cyclone (TC) risk and its explanatory variables (i.e. hazard, exposure, and vulnerability) would be stochastic rather than deterministic, suggesting possible advantage of using probability based method for global TC risk projection. In this study, we developed regression models which are based on Bayesian modeling and estimated global TC economic losses with taking account of stochastic fluctuations of losses. Furthermore, we suggest hierarchical Bayesian models considering TC intensity and geographical characteristics. The hierarchical Bayesian models yielded to improved performance in estimating TC losses in historical period.

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Climate information and services for Impacts, Adaptation and Vulnerability (IAV) Assessments are of great concern. In order to develop probabilistic regional climate information that represents the uncertainty in climate scenario experiments in East Asia (CORDEX-EA), the probability distribution of 2m air temperature was estimated by using developed regression model. The method can be easily applicable to other regions and other physical quantities, and also to downscale to finer-scale dependent on availability of observation dataset. Probabilistic climate information in present (1969-1998) and future (2069-2098) climate was developed using CMIP3 SRES A1b scenarios 21 models and the observation data (CRU_TS3.22 & University of Delaware in CORDEX-EA, NIAES AMeDAS mesh data in Japan). The prototype of probabilistic information in CORDEX-EA and Japan represent the quantified structural uncertainties of multi-model ensemble experiments of climate change scenarios.

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We identify climate analogues for 17 Australian cities using the non-parametric approach of climate analogue after multi-ensemble future climate projections with a global cimate model under SRES A1B with a horizontal resolution of about 60 km. We identify 10 climate analogue cities out of 17 within Australia in the global search, while we identify the other 7 outside Australia. By limiting a search area within Australia, we identify the 7 climate analogues within Australia but with low scores of an index for climate analogue.

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The H08 global water resources model enables us to simulate global water availability and use at high spatial and temporal resolution. H08 has been used to assess the impact of climate change and estimation of water footprint, and others. To express human water use more realistically, water abstraction schemes were substantially enhanced, and global water availability and use in circa 2000 were reconstructed.

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Regional atmospheric models coupled with land surface models are capable to characterize more precisely the land-atmosphere interactions and feedbacks. The role of land surface conditions on the land surface-atmosphere interactions, and their relations to the water and energy cycles can be of considerable importance for characterizing the behaviour of regional weather. Paraguay, a landlocked country in South America has suffered dramatic forest cover losses as a consequence of the expansion of the agricultural frontier, resulting in a fragmented landscape with highly altered surface conditions that could hinder the effectiveness of climate models to accurately simulate precipitation and temperature in the region. Thus, This study has the main objective of comparing simulated precipitation and temperature obtained with the CReSiBUC model in order to find the most suitable model settings that would lead to an improvement of the simulated precipitation and temperature over Paraguay.

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In this study, we assess environmental impact of debris flow hazards in Imgi Mine, located at northern part of Busan Metropolitan City in South Korea and very close to water supply plant of Busan. From field surveys in the last decade, surface erosion has become more and more severely, and have transported a great volume of sediments in and contaminated the mountain stream. Besides, during 1973-2005, annual precipitation in Busan area had a significant positively-increasing trend. Presumably, under the geological and climatological conditions, Imgi Mine is prone to happen large volume of mass movements, which may seriously threat human life and property as well as clear source of water supply. Therefore, to assess the possible future hazards, we conducted numerical simulation of debris flow to analyze the possible affected area and environmental influence at Imgi Mine under different scenarios, which include present and extreme conditions. 

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In snowy regions, basins facing the Sea of Japan, water
from snowmelt can be used as irrigation water. Due to climate change, reduction of snowfall
amount, reduction of snow cover and change in snowmelt timing are of increasing
concern. Assessment of time and spatial distribution of snow-related water
resources are required. Various kinds of GCM output are provided in the SOUSEI
program. d4PDF (database for Policy Decision making for Future climate change) were
published in 2015. 100-member ensemble of 60kmGCM can evaluate the uncertainty
in the future projection with high precision. Method for utilizing ensemble
member of d4PDF for assessing the impact of climate change on snow-related
water resources is investigated. To combine probability density distribution of
winter’s temperature obtained from d4PDF and that of winter’s precipitation can
be evaluate the uncertainty of annual maximum SWE in the future projection.

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We
have developed a statistical downscaling method for estimating probabilistic
regional climate projection using multi general circulation models (GCMs). A
regression model was established so that the combination of weight of GCMs reflects
the characteristics of the variation of observation at each grid point. Cross
validation was conducted to validate the stochastic model.

We
applied this method to the monthly surface air temperature and precipitation for
the present climate and future projection using CMIP5 dataset. Temperature
increase was remarkable in the northern part of Japan and cold season in the
end of 21^st century. The probability of temperature increase
exceeding 4 K around Kanto-region was over 60 % for RCP8.5, which was
approximately 30 % for RCP4.5. Winter precipitation decrease was notable in the
Japan-Sea side, that may crucially affect the snow amount and water resources
in this region. As for summer precipitation, precipitation increase in the
Pacific side of the southern Japan was projected with relatively high
probability. In order to adapt the warmer climate, this stochastic model plays
an important role in estimating various risks associated with the climate
change.

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   In recent years, there have been the flood damages caused by torrential heavy rainfall, which is called ‘Guerrilla-Heavy rainfall’ in urban areas in Japan. It has been pointed out that increasing rainfall events today can be due to global warming. Therefore, it is required to project the future change of the
frequency of such kind of rainfall events. In this study, we implemented some fundamental analysis in August in the Kinki Region, from the view point of both the rainfall distribution and the unstable atmospheric condition. First, we picked up localized heavy rainfall events by visual judgement. Then, we analyzed the atmospheric stability of the events we picked up, using SSI (ShowalterStability Index). As a result, the trend of future change in the number oflocalized heavy rainfall events is similar to that of the number of unstable events.

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Recent studies have argued that the extreme precipitation intensities are increasing in many regions across the globe due to atmospheric warming, which may cause the natural disasters such as floods, coastal erosion, landslides, water hazards etc. more frequently. In our study, we analyzed multi-model experiment results to investigate the individual model behavior as well as the model uncertainty in reproducing the extreme precipitations and their relationship with temperature. We found that the 90^th and higher percentile precipitations are ~10mm/h over Japan and occurrence of short duration (up to 2 hours) rainfall is more compared to longer duration. Simulated relationship of extreme precipitations with temperature from ensemble experiments agrees well with the observation that a peak occurs around 19-22°C for all percentiles of extreme precipitation. Extreme precipitation intensities are projected to increase by 5 mm/d in a future climate for temperatures above 21°C.

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Future changes in the proportions of global precipitation by different weather systems (tropical cyclones, centers and fronts of extratropical cyclones, and others) are quantified based on objective weather system detection method and the climate model realizations (1980-1999 and 2080-2099) from the Coupled Model Intercomparison Project Phase 5 (CMIP5). It was found that the subtropics, particularly in the Pacific and North Atlantic, are the regions where the weather system-wise proportions of annual and extreme precipitation display notable changes, indicating distinct shifts in climate regimes. All of these regions have a common feature: they are substantially influenced by, and are in reach of, many weather systems in the present climate.

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Indian Monsoon Rainfall (IMR) which impacts on a large number of people is significantly important in terms of prediction. Identification of attributing climate factors of Indian monsoon rainfall is extremely important to achieve this target. The inverse relationship between winter Eurasian snow cover and the subsequent IMR is a famous hypothesis which has been studied for over century in order to facilitate better prediction capabilities for the Asian monsoon rainfall. This study was conducted to investigate the above inverse relationship which affirms in Bamzai and Shukla (1999), and to extend the results for using extensive observational data. The present study further analyses the relation of IMR and winter Eurasian snow cover using a 100 ensemble of historical climate experiment, named 'database for Policy Decision making for Future climate change' (d4PDF). The study especially focuses the Western Eurasian winter snow cover (WESN) where a high correlation have been recorded.

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"Convection genesis"i.e. air motion of thermal without precipitation particles,  is a trigger of generating baby-cell. In this study, genesis of cumulus cloud is simulated using our developed meteorological model based on large-eddy simulation (LES). A pair of positive and negative vortex tube was simulated. 

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Guerrilla-Heavy rainfall are very difficult to forecast with its rapid development, thus it is very necessary to detect potentially hazardous convective cells at earlier stage. Nakakita et. al. developed the risk prediction system with the vertical vorticity information in a convective cell at its first stage. However, it is unclear why the cell with high vorticity value develops to heavy rainfall. In this study, we challenged to understand how a cell develops to heavy rainfall with the structural analysis of vorticity inside a cell. We analyzed on relationship between vortex tubes and updraft using Z_DR and Triple Doppler method. In conclusion, we found the region of vorticity was associated with updraft.

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Occurrence detection of snowstorm is important to countermeasure the snow-related disaster.
The goal of this study is to detect snowstorm using X-band MP radar data.
In this presentation, we show the comparison results of ground observation data vs. X-band MP radar data.

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We carried out the ground-based direct intensive observation of precipitation particles by Ground-based Particle Image and Mass Measurement System at Mt. Zao during 2014-2015 winter season, and at Mt. Daisen during 2015-2016 winter season, targeting the melting layer. G-PIMMS can capture particle images by CCD cameras and measure particle weight by the electronic balance. We often experienced sleet or wet snow on the ground in early/late winter season, and succeeded in observation of the melting layer. Rain and snow, including sleet, were discriminated at 0.9-2.1ºC in wet-bulb temperature. It was also found the density of precipitation changing with temperature between 0ºC and 2ºC. It seems to be able to express the density as a function of the temperature, although we need additional observations. To clarify the temperature dependency of particle densities will give us important information on the improvement of precipitation estimation in the bright band.

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For the improvement of accuracy in satellite-observation oriented precipitation products, such as GSMaP, it is essential to utilize globally covered geostationary satellite observations (GEO). Initially, we developed precipitation provability map (PPM) estimated by look-up-table (LUT) of which based on same-overpass observations of TRMM/PR, GPM/DPR and GEO’s IR1 and WV channels Tbb. In addition, we have been tried to estimate precipitation-related-variables from HIMAWARI-8’s multi-band information by random forest method. Utilized GEO would directly contribute for improvement of GSMaP as a 1^st guess value. Furthermore, time series of PPM can contributes rain gauge based gridded product such as APHRODITE, for more fine time resolution (less than 1 day) or date check (local time to same as UTC).

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Land surface emissivity plays a central role in passive microwave remote sensing and data assimilation. we try to evaluate the characterictics of microwave land surface emissivities using AMSR-E around Japan area.

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Recently,implementation of drones (UAVs; Unmanned Aerial Vehicles), represented by radio-controlled
helicopters, has rapidly increased in fields such as inspection of disaster areas and maintenance management of bridges in off-limits areas. In this study, assuming the implementation of UAVs in observing the temperature and wind in the upper air, we investigated the posture stability of a UAV in strong wind conditions. In addition, the relationship between wind speed and pitch angle of the UAV was clarified and the feasibility of the upper-air observation method was determined using the posture stability data of the UAV. In this study, the maximum safe wind speed for observation via the UAV was approximately 15 m/s. Moreover, an analysis of the pitch and yaw angle of the UAV shows that the estimation of wind speed and wind direction in upper air is possible.

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In recent years, the dissolved oxygen at the bottom of the Lake Biwa has been decreasing. It is considered that the decrease in precipitation (about 100 mm), the rise in temperature (about 1 or 2 Celsius degree), and the decrease in wind speed (about 5 %) during the past 20 years leads to this phenomena. In particular, the rise in air temperature and the decrease in wind speed weakens the vertical mixing, and it may cause the reason of low oxygenation at the bottom layer.
In our present study, we show that we can reproduce the seasonal and inter-annual change of the structure of water stratification with developing the 3-dimensional hydrodynamic model. This model can reproduce the observed vertical water distribution in order to elucidate how the change of the stratification due to global warming will influence the low dissolved oxygen in Lake Biwa in the future.

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In recent years, an innovative analytical technique for oxygen stable isotope ratio of phosphate (δ¹⁸O_P) has been developed to identify sources of river phosphate. This study aimed to characterize the values of δ¹⁸O_P in rivers by comparing them between two watersheds with different land-use and geological compositions in central Japan.

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The diffusion of the radioactive substance occurred by the accident of the nuclear power plant in Fukushima Prefecture in March, 2011. As for the radioactive substance deposited on the ground, it was thought that the radioactive substance would move with water movement.  Then, the movement of the radioactive substance that diffuses around Fukushima Prefecture in the water system investigates, and has been researched aggressively in many universities and research laboratories immediately after struck.  In this report, the result from 2012 to 2013 would be introduced among the surveillance studies in the Abukuma river water system Hirose river.

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After the accident at the FDNPP (Fukushima Dai-ichi Nuclear Power Plant), a large amount of radiocesium was widely deposited on the land surface and strongly adsorbed to the soil particles, especially the fine particles such as clay and silt. To evaluate the environmental fate, for example deposition on riverbeds and discharge to the Pacific Ocean, of radiocesium, it is necessary to predict size-dependent transport of soil particles in rainfall-runoff process. In this study, the behaviors of radiocesium adsorbed to eroded soil particles in the Abukuma river basin, located 30-100 km west of the FDNPP, were analyzed by a water quality model. Results showed that 78.4 TBq of radiocesium were transported to the ocean from May 2011 to December 2012.

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For the planning of decontamination measure at forestry area, we have to analyze the factors affecting the variations in the air dose rate, especially, at forestry edge. This is because 1) cesium containing biomass could be a important source of the poullution at receiving waters and 2) forestry area is a place for humane activities. Air dose rate is a standard deciding the necessity of forestry decontamimation. Our monitoring at the Hippo area at Marumori in Miyagi revealed the inportance of hydrological runoff process as a factor affecting the vatiarions in the air dose rate.

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To establish effective countermeasures toward nitrate polluted groundwater, it is important to investigate its pollution sources. Main pollution sources are known to be chemical fertilizer, livestock waste, and domestic wastewater. As a method to identify source of the pollution, a new method to use Coprostanol was proposed. The Coprostanol has been used as a fecal contamination indicator. The method was applied to the case of nitrate pollution in Shimabara, Nagasaki, Japan. The results showed that the Coprostanol availability for the source identification was suggested.

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In order to assess the sustainability of groundwater resources in Hanoi by applying Analytical Hierarchy Process (AHP) approach, this study develops a sustainability framework including the series of foremost components contributing to the sustainability goal. In order to cope with the limited data availability of groundwater sustainability assessment, this study focuses on the framework from the social point of view since social aspect is one of three bottom-line sustainability concepts. Hanoi’s groundwater quantity, quality and management are defined as three main criteria, the components at highest level, respectively consisting five, four and three core indicators which are referred as the components at the lowest level of the social sustainability assessment framework. These core indicators and criteria cover mainly the local groundwater problems and the situation from the social point of view.  The framework defined is the basic step for the further sustainability assessment of the groundwater resources.

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In order to predict fate and transport of nitrogen and carbon in a soil with pH buffering as a result of decomposition of soil organic matters (SOMs), we modified a coupled nitrogen and carbon cycling model based on the LEACHM code (Hutson, 2005) to include dissolution of NH₃ and CO₂ as well as proton reactions in nitrification using the PHREEQC program. The pH buffering was described with the variable charge model. The SOM decay model were linked with water flow, solute transport, and gas diffusion in HYDRUS-1D using the HP1 code. Various nitrogen and carbon scenarios as a result of application of organic matters to variable-saturated Andisol and Sand under a nonisothermal condition were demonstrated.

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For a numerical simulation of water flow in soils with evapotranspiration and root water uptake, it is necessary to give evaporation rates as a surface boundary condition and transpiration rates as a sink term in the Richards’ equation, respectively. The purpose of this study is to evaluate ratio of potential transpiration to potential evapotranspiration (SCF) in a soybean growing process based on observed transpiration rate. Field measurements of soil water contents, meteorological dataset, and crop data (crop height, LAI, and fraction of vegetation cover) were conducted in a soybean field with covering the soil
surface by plastic mulch. Transpiration rates, T_a, were estimated based on observed soil water content in 0-60 cm depth using the water balance equation, and potential evapotranspiration rates, ET_p, were
estimated using the Penman-Monteith equation. The ratio T_p/ ET_p  was determined assuming T_a as potential transpiration rate, T_p in relatively high soil water content conditions.  

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To reduce uncertainty in hydrological simulations, appropriate initial condition of soil moisture and water table depth (WTD) is an important factor. The evaluation criteria using annual change ratio is widely used to judge whether soil moisture has reached equilibrium. However, how is equilibrium soil moisture determined by climate conditions? We try to discuss this issue by using LSM with representation of water table dynamics (MAT-GW). First, we estimated equilibrium soil moisture within the threshold. At arid regions, it took about a thousand spin-up years to reach equilibrium soil moisture. Therefore, we made a function from the persentage change in soil moisture which may reduce spin-up periods. Next, we examined WTD and found a lump at specific WTD related to soil type. We revealed that the negative recharge and continuous base runoff caused the deepening of WTD. These result indicate that we need to reassess the hydraulic conductivity and base runoff of MAT-GW.

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This report demonstrates our activities in this year. Our young researchers group had two main activities. First one was the field tour and workshop held before the JSHWR annual conference, second one was the workshop for hydrology and water resource studies. The purpose of the first workshop and the field tour were to interact over university and other study field, and the second workshop was to discuss specific research topics in sufficient time and studies which should be made progress toward future.

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In academic field relevant to hydrology and
water resources, there are large numbers of studies using or dealing with
numerical analysis of surface water flow. In case of surface water flow
dominated by one dimensional flow or horizontal two dimensional flows, the
shallow water equations (Saint-Venant equations) or their simplified forms
which describe the space-time variation of water depth and flow rate are
commonly used. However, the approaches to overcome their non-linearity and ease
of numerically oscillation are thought to depend on the research field and vary
a great deal.
This research group was established aiming
to share the commonly used techniques in each academic discipline, ideas on
calculation and valuable information such as failure experiences and to seek
seeds of new collaboration research among young researchers, students and
construction consulting experiencers familiar with numerical analysis
technology of surface water flow.

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In 2011, our research group proposed some important suggestions regarding to groundwater resources based on the preliminary investigations on the devastated area with other groups organized by related academic associations soon after hitting the Tohoku Earthquake. Several research projects supported by academic funding and relevant academic association have conducted researches and accumulated the knowledge of the mechanism of groundwater pollution and its recovering processes for a solution of groundwater resource management issues in the last 5 years. Now we think it is the time to spread our knowledge to the all of the citizen for prevention of shortage of water resources when next disaster happened. Here we report outreach efforts by our research group did in 2015.

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Associated with global warming, the effects of sea level rise are linked to frequency and intensity of storms and other weather events. Previous researches argue that sea spray affects the development of typhoons. This study reports a marine observation on Tanabe bay near Wakayama Prefecture utilizing a measurement instrument called parsivel. Parsivel can detect the diameter of a droplet and the distribution of velocity. In our observation point, we reveal the presence of spray droplets with 1.5mm ~ 5.510mm diameter when typhoon events occurs in 2015. We discuss the relationship between sea spray and wind velocity when storm events occurs.

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Numerical Flood Prediction is a method to predict future state of rivers by using numerical models and forecast values as input. This enables predictions to have a much longer lead time. However, due to uncertainty caused by input values and model parameterization, ensemble simulation is suggested.
 In this study, a regional ensemble flood prediction system considering precipitation input uncertainty was built and hindcasted a real flood event. The spatial and temporal reslutions are 0.05 degrees and 1 hour, respectively.   Verification experiment forced by Radar precipitation reproduced annual discharge and each peaks well. In the hindcast for Kinu-River flood due to Kanto-Tohoku heavy rain, the system simulated the occurrence of a flood 35 hours before. The number of members which predicted the flood increases with initial forecast time, where 43 out of 51 members predicted floods 11 hours before the actual flood while only 17 did so 35 hours before.

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In this study, effect of sandbag and estimated overflow amount the Kanto-Tohoku Haevy Rainfall Disaster in Ibaraki Prefecture Joso City.Hydraulic analysis model is to use the Nays2DH of the river simulation software iRIC. Target section is 16.4km from Mitsukaido water level observation to Kamaniwa water level observation. Hydraulic analysis model, compares the calculated water level and flood traces of water level, the average value of the error is 0.3m or less, the overflow time of the natural levee is substantially equal to the investigation report documents of the Ministry of Land, Infrastructure and Transport, the validity We were able to show.
As a result, the peak on the upstream side of 25.35k Wakamiyado land destination 102m3/s, the peak on the downstream side 24.75k 380m3/s, was estimated to be as a whole 481m3/s.
Since the flood water of Joso has been estimated to be about 34 million m3, roughly one-third is considered to be due to flooding from the Wakamiyado land destination.
On the other hand, large sandbags are installed in 25.35k by river administrator is Imatsugi disaster, in order to understand the effect, on the assumption that there is no large sandbags, it was recalculated. As a result, flooding is started from 9/10 4:50 If there is no large sandbags, flooding is started from 9/10 5:50 in the case where there is a large sandbags, delaying the difference one hour flooded start time It is considered that an effect.

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Water release from irrigation ponds is introduced to conduct comprehensive flood control in Hyogo prefecture. Water stage of irrigation ponds is kept low in September and October of non-irrigation season and typhoon season and water storage for irrigation in nest year is recovered by inflow from November through March. In this study, a water release method based on probable inflow volume in winter season estimated by long-term rainfall-runoff simulation is applied and the stormwater storage capacity by water release from all irrigation ponds in Tamba-Sasayama area and Awaji area is estimated. Moreover, the relationship between size of irrigation ponds and stormwater storage capacity by water release is investigated and the result shows that the water release from selected large ponds is efficient for securement of stormwater storage capacity in study areas.

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With more and more regions in the world are facing water scarcity due to the climate change and human activities, various technologies to increase the water supply such as seawater desalination have been promptly developed by the projects with huge investment cost, thus it is crucially necessary to assess their costs and benefits to determine whether or not the projects are financially feasible. In this study, it chooses to develop an empirical methodology to assess the cost and benefit of seawater desalination within three socioeconomics scenarios, i.e. SSP1, SSP2 and SPP3 and furtherly estimate the optimal time to apply (OTA) of such technology basing on their different income levels of those scenarios countries.

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This paper shows the best performance in designing a basic triangle of gravity dam using the artificial swarm intelligence (ASI) approach of the bee colony optimization (BCO) scheme. The obstacle to design a basic triangle is to optimize the parameters to be decided subject to the minimized the triangle area because the shape of the fillet makes the vertical forces of the static water and sediment pressures with bilinear processes in cases that a sediment height gets greater than a fillet one. In this research, two steps of mathematical approaches are conducted. The first step is to employ the 0-extension approach to lump two-cased equations together. The second one is to use the BCO approach to optimize the dam parameters in bilinear processes. It can be concluded that the proposed approach is most useful in optimally designing the parameters of gravity dam with a fillet in all ASI approaches.

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This study analyzes flood runoff at the upper Kinu River Basin during Kanto-Tohoku torrential rainfall in September 2015. After 140 mm of initial rainfall, 20 mm/h of rainfall continued for more than 10 hours. Since the time of concentration of this catchment is estimated around 5 to 6 hours, we hypothesize that the rainfall-runoff process over the catchment (= 102 km²) reached a steady state condition during the stom. In fact, the observed record showed nearly constant discharge for about 6 hours. However, the runoff was approximately 5 mm/h smaller than the input rainfall (i.e. 20 mm/h). Our simulation result with a distributed rainfall-runoff model shows the necessity for representing a flowpath to loose a considerble amount of water from a dominant flow path. Also the model coupled with Time-Space Accounting Scheme (T-SAS) was employed to evaluate the spatial and temporal sources of water during the flood.

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Torrential rainfall frequently occurred resulted in flood disaster in recent years. To prevent flood disaster, we are developing flood forecasting system with leadtime of more than 12 hours. We utilize regional ensemble prediction system to account for uncertainty of prediction. The obtained precipitation is given to a hydrological model, Rainfall-Runoff-Inundation model, to simulate river discharge. We applied this system to the 2015 Kinugawa flood event and examined their forecast skill. We examined four different initial times, in forecast time (FT) of 30h, 24h, 18h, and 12h. The discharge forecast results showed better forecast skill as decreasing leadtime. Also, at least some ensemble members predicted observed discharge peak in every point, except for FT=24h. We examined flood forecasts using rainfall forecasts from JMA operational MSM. They failed to forecast in most of the cases, however. We confirmed that the ensemble flood forecasting system could provide useful probability information of the flood.

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We developed the real-time river
stage prediction model, using the hybrid neural network and physically based
distributed model.

As the basic model, 4 layer
feed-forward artificial neural network (ANN) was used. As a network training
method, the deep learning technique was applied. Input of the ANN model is
hourly change of water level and hourly rainfall, output data is water level of
downstream station.

The prediction procedure of the hybrid model
is as follows; first, downstream discharge was calculated by the distributed
model, then estimates the hourly change of catchment storage form rainfall and
calculated discharge as the input of the ANN model, and finally the ANN model
was calculated.

The developed model was applied
to the one catchment of the OOYODO River. The result of the hybrid model
outperforms the basic ANN model and distributed model, especially improved the
performance at the biggest flood event.

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This Study developed a water management module (WMM) to be coupled with hydrological models for discharge simulation. A case study was applied in the Kamo River Basin to evaluate the performance of WMM by comparing the observed basin outlet discharge and simulated data. Four indices were used including RMSE, MAE, MRE and NSE. The resulst show WMM has a good performance coupled with the hydrological predictions for the environment (HYPE) model in the Kamo River Basin. However, the transferability of WMM requires more demonstration in other basins using different hydrological models.

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Intensity and frequency of heavy rains due to the effects of global warming will rise, therefore, it is predicted that the disasters such as floodwaters violently occur in the future. Thus, in the future of river management, it is considered to be important to grasp the situation of the future of the river flow rate that affected the climate change. This study was aimed to calculate the impact human activities such as dam and agriculture, domestic, industrial water to the primary river and to estimate the river flow in the future with regional climate change prediction data of the Ministry of the Environment, which was based on the climate scenario.

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This study aims to estimate discharge over floodplain in the Lower
Mekong Basin. Rainfall-Runoff-Inundation model (RRI model) is used in this
study. The remarkable point of the model is that the model treats both waters
in river channel and over floodplain simultaneously considering interaction of
the waters. Furthermore, water level distribution over floodplain is estimated
with MODIS data and DSM following estimation of inundation extent. Then,
velocity distribution over floodplain is estimated with the Manning’s equation
assuming equivalent roughness is 0.4 m-1/3s. Estimated discharges over
floodplain by the RRI model and by the MODIS showed reasonable agreement at
three cross-sections out of four cross-sections. The other cross-section which
is located close to the Tonle Touch River showed a difference. This might be
caused by the RRI model does not consider the river. The Tonle Touch River will
be incorporated in the RRI model for more precise simulation in future.

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Each effect of a green dam and a dam on the stormflow mitigation was addressed, and subjects necessary for the evaluation were specified ,in this presentation. Interdisciplinary discussions were highly encouraged in our hydrological society.

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Dependences of runoff characteristics on the magnitudes of storms were analyzed from a data set of rainfall and runoff observed for 15 years in a small forested catchment located in a sedimentary rock mountain in Shiga Prefecture.

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Catchment coevolution is a theoretical framework that seeks to formulate hypotheses about the mechanisms and conditions that determine the historical development of catchments and how such evolution affects their hydrological response. To test the hypotheses and attempt to understand why such simple and predictable relations have emerged across a climate gradient, we used a process-based hydrological model that was independently calibrated for eight catchments underlain by volcanic rock of different ages and conducted a numerical experiment to decouple the effects of internal and external properties of the catchments. We investigated the causality of this relationship and found from several simulated time scales and model fluxes that younger catchments on average (1) require longer for the transmission zone storage to fill and empty, (2) take longer to release water from deep aquifers, and (3) have greater recharge to deep aquifers. These findings corroborate the hypothesis of coevolution of volcanic catchments.

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