Hydro-debris2D model has been developed for the purpose of predicting occurrence of the debris flow throughout hydrological regime changes. The model contains three components: (1) Shallow-water based surface flow module in order to predict mountain zone torrential flow regime, (2) rapid subsurface/interflow in the weathered rock, and (3) debris flow components. The model has been applied into both Hiroshima debris flow disaster in 2014, and Izu Oshima Island debris flow event in 2013. As input data we used observed rainfall station dataset from AMeDAS. Simulated debris flow occurrence zone by the model agreed with the real debris flow event especially in specifying valley. 

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In general, there are two main triggering reasons of landslides, one is earthquake and the other is rainfall. And during rainfall, the storage change inner the slope is very difficult to measure. It depends on the soil and geomorphology features not to mention the storage change on the whole watershed. Therefore in this study, we will focus on the storage process of rainfall-induced landslides. The storage process means the rainfall infiltrating into slopes, and its volume change of the water inner the slopes during every rainfall event. In this study, rainfall-runoff (Yamada) model would be used to calculate this process and then estimate the possible storage change during rainfall. Finally the storage process inner the slope during rainfall can be evaluated and the results of this storage would apply to the analysis of slope stability and furthermore the early warning application.

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This paper aims at flood prediction by means of simple models.   For this purpose there are two serial procedures: rainfall prediction and runoff computation.   In this paper the latter is discussed for development of the methods.   Most of the runoff models are non-linear because of complicated natural phenomena.   This fact shows us the difficulty of realtime flood computation.   Many important non-linear parameters cannot be easily improved in the realtime basis.   In spite of such problem, linear model is applicable to quick dissemination of recommendation of evacuation by local governments.   This means the unit hydrograph method.   By the least square method the latest rainfall and water level can be automatically used for determing the unit hydrograph parameters, which are applied to flood prediction at the nearest future.   Such procedures can continue repeatedly as far as required. 

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Since about 2000, atmospheric temperatures have increased at a slower pace than they rose in preceding decades. Nonetheless, extremely hot temperatures over land show that the trend remains upward during the so called global warming hiatus period.  On the other hand, previous researches indicated that the frequency of river flood would increase in many regions under the warming climate and there are strong positive correlation between surface air temperature and flood frequency. Hence, the target of this research is to analyze frequency of flood in observed and modeled river discharge assuming that the frequency of river flood would show upward trend even during the global warming hiatus period after 2000. Results indicate that annual maximum daily temperature over land remain increasing as indicated by previous studies and flood frequency obtained from both observed and modeled discharge show continuous upward tends in twentieth century and twenty-first century.

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In this study, we made the inundation prediction map of Kameoka city in the Katsura-river basin based on multiple precipitation scenarios as the case study, and then tried to develop the inundation prediction map which makes citizens remember easily the inundation situation from precipitation information by linking the precipitation information to be provided at the time of heavy rain. In consideration of the characteristics between a spatial-temporal scale and a strength of precipitation, we made multiple precipitation scenario which put various patterns of the precipitation area, duration and strength. Each precipitation scenario was categorized as threshold of disaster prevention weather information related to an inundation disaster. Then, the inundation situation assumed in each disaster prevention weather information could be grasped. As a result, it was shown that the developed map could provide the disaster prevention weather information which citizens should pay their attention according to the difference in precipitation characteristics. 

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Transportation especially railway often suffers major impacts from service stops due to climatic factors such as heavy rain and heavy snow.  This study aimed at rationalizing train operation management by introducing flood predictions based on rainfall predictions whose accuracy has been improved significantly in recent years. In this study, the Sabagawa flowing in Yamaguchi Prefecture, southwest Japan is selected for a model river.  As external forces, the error equation on the rainfall prediction and the rainfall prediction released by the Japan Meteorological Agency are input to runoff analysis models. The duration and the probability of exceeding various regulation water levels involved in the service management set down on railway bridges are calculated by applying each hydrograph which corresponds to each error. In the formulas for the train operation management, the forecast over time is set to exceed the actual over time.

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In 2014-2015 winter season, we had an intensive observation of melting layer in Zao, Yamagata. This field campaign is targeting the melting layer for the GPM/DPR ground validation. Two Ka radars were installed on the mountainside of Mt. Zao. We often experienced sleet or wet snow on the ground in early/late winter season between two Ka radar sites, which means we were in the melting layer of the cloud. For the better understanding of microphysical structures in the melting layer, it is important to measure the precipitation particle s directly. We developed a new instrument to measure precipitation particle images and their weight on the ground. We can know particles are liquid or melting or not. Our goal is to know what kind of particles exist in the melting layer, and to clarify the particle abundance ratio associated with the density distributions in the melting layer.

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Correction to Non Uniform Beam Filling(NUBF) isn't be equipped with by standard algorithm of a Dual-frequency Precipitation Radar.The validity of the estimation method of important parameter σ_n of NUBF correction in PR algorithm was inspected using ground radar by this research. Moreover, σ_n using a footprint of two frequencies was inspected to presume more σ_n by DPR algorithm.

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We focus on the calculation conditions and compare the rain rate estimates by GPM/KuPR and TRMM/PR. According to the result, it is similar to PR's result in case of applying the SRT and NUBF conditions to KuPR. Therefore, it is necessary to consider about related parameters of these conditions.

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Guerilla-Heavy rainfall rapidly develops, and threatens human life, thus the risk prediction method with a good accuracy is the very important issue. Nakakita et al.(2014) developed the risk prediction system with X-MP radars, which judge the risk from the vertical vorticity in a convective cell at the first stage. For more accurate prediction, in this study, we analyzed the vertical vorticity or vortex tubes in the cells. Samples of potentially hazardous convective cells has positive both vorticity and negative vorticity, and vortex tubes were vertically growing up in every samples. It is estimated that the pair of positive and negative vorticity is associated with updraft.

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The diffusion phenomena of heat and pollutants caused by turbulent flows in the non-isothermal field is one of the important phenomena concerned with local heavy rain or high levels of air pollution. The large eddy simulation (LES) which can analyze the turbulence structures in the non-isothermal field is considered as one of the effective means for investigating those phenomena.
  The purpose of this study is to develop a computational method for the LES of the turbulent transport of heat and vapor in the micrometeorological field. The coherent-structure Smagorinsky model (Kobayashi, 2005) is applied as a subgrid-scale turbulence model.
Some numerical experiments were carried out to demonstrate the validity of this computational method. The computed results showed the good agreements compared with the physical or the other numerical experimental results, so the results suggested the validity of this method for the investigation of the turbulent transport of heat and vapor.

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Localized torrential rainfall disasters in Summer and Baiu season of Japan is called as “Guerrilla-heavy-rainfall” in Japanese media. This rainfall is produced by an isolated cumulonimbus that grew rapidly. To prevent this disasters, the approach to detection baby-cell of rainfall earlier by X-band radar has been performed. However, in order to enhance prediction of Guerrilla-heavy-rainfall, we have to analyze convection genesis of which is affected to a large degree by urban area, because it is concerned a large component of that generate baby-cell. We aim to clarify this convection genesis by development of urban meteorological model based on large-eddy simulation. 

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This study reports the first detection and analysis of a localized water vapor distribution obtained using InSAR during the Seino heavy rain episode on 2 September 2008. The InSAR data retrieved during the ALOS/PALSAR emergency observations for the event revealed a radar line-of-sight (LOS) change of up to 130 mm within 10 km² caused by water vapor. To geophysically confirm this signal, numerical weather simulations were performed using WRF model, revealing a deep convection that caused a similar delay signal in the interferogram and was initiated by orographic lift caused by the Yoro Mountains. Another simulation that did not include the Yoro Mountains did not produce a deep convection. These simulation results demonstrated the importance of realistic topography in the high-resolution numerical weather modeling. The WRF simulation also suggested that the effect of hydrometeors can account for approximately 20 % of the maximum LOS change.

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We focus on the Probable Maximum
Precipitation (PMP) and Probable Maximum Flood (PMF) over the Upper Tone River basin
using WRF model, through weather conditions change. The results are summarized
as follows: (1) In the case of typhoons, an increase of relative humidity
affects not only total rainfall but also its temporal variation. (2) Moisture
fluxes show high correlation with total and 12 to 72-hour rainfalls through WRF
model calculation in the basin, which clearly suggests they can be used as a
suitable parameter to estimate PMP. (3) PMP is calculated from the past
maximized and climate chahge predictions moisture flux in 12 , 24, and 72-hour
rainfall durations. (4) PMF is calculated by run-off model for 6 pattern of PMP,
and its exceeds current peak discharge of Tone River basic policy for river
improvement.

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Recent studies have argued that the extreme precipitation intensities are increased in almost every region across the globe due to atmospheric warming. This argument is based on the principle of Clausius-Clapeyron relationship which states that atmosphere can hold more moisture under warmer climate (~7%/°C). In our study, we have investigated the dependence of extreme precipitation intensity on temperature over Japan by using multimodel ensemble downscaling experiments of three RCMs (NHRCM, NRAMS, WRF) forced by JRA25, as well as three GCMs (CCSM4, MIROC5, MRI-CGCM3). Extreme precipitation intensity increases with temperatures up to 22°C in future climate scenarios, while the peak is 20°C for the current climate. Extreme precipitations at higher percentiles are projected to have larger rates of increase in future climate scenarios (3-5%/°C in current and 4-6%/°C in future). An insufficient water vapor supply for saturation at higher temperatures can lead to a decrease in cloud formation and extreme precipitation.

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Japan Meteorological Agency announces special alert if 10 or more gauging stations record 3-hourly precipitation higher than 50-year value. This is not applicable for a small island such as Izu-Oshima suffered from torrential rainfall in 2013. In this study,  50-year 3 hourly precipitation and 50-year 48 hourly precipitation are estimated by using GSMaP data and they are compared with estimates by JMA.

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The objective of this study is to characterize an effect of intensive thinning of Japanses cypress forest on normal and peak discharge by a sloping lysimeter. A sloping lysimeter located in the Inuyama Research Forest of the Ecohydrology Research Institute (the University of Tokyo Forests) was used for this study. An intensive thinning (62% of all trees) was conducted on 20 December 2012. We compared the relationship between normal and peak discharges during before and after intensive thinning. The normal discharge after thinning increased one-and-a-half times than that before thinning, whereas the peak discharge after thinning decreased one-half than that before thinning.

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Employing a disdrometer, three parameters solely representing throughfall drip were measured and calculated: maximum drop diameter, median volume diameter of drops, and relative volume percentage of drops. Beneath Liriodendron tulipifera L. in Maryland (USA), all of the three parameters were substantially larger when the canopy was unfoliated. In fact, the presence or absence of foliage was one of the primary factors affecting throughfall drops along with air temperature, according to the boosted regression tree analysis. Experimental results were attributed to differing physical properties of intercepted water between foliated and unfoliated periods and differential water behavior on leaves and bark.

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We considered the mechanisms for stabilization of flow condition with spatial scaling in weathered granite catchments. In smaller catchments, the contributions from shallow soil layer and deep bedrock layers are different in each catchment. In larger catchments, the contribution from these two layers became uniform, and the flow condition stabled. The soil surface topography commonly used in the modelling of rainfall-runoff mechanisms. However, our result shows the groundwater recharge/discharge between small catchments. This fact means that the soil surface topography is not a key parameter for the rainfall-runoff processes in headwater catchments.

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Land surface model (LSM) is an important tool to estimate global scale energy and water balance. In order to perform a realistic simulation, preparing high quality land surface parameters is one of necessary tasks. During a few decades, satellite observations have rapidly advanced and have exploited in the broad fields of Earth system sciences. Satellite remote sensing also has contributed to land surface simulation  providing global land cover datasets. However, in previous research, it is mentioned that those datasets have uncertainty due to different methods in different purposes and spatiotemporal heterogeneity in datasets. In this study, multiple land parameters (five leaf area index, five land cover, and three soil type datasets) are collected and examined to quantify impacts of their uncertainties on the water budget estimation using Minimal Advanced Treatments of Surface Interaction and Runoff LSM. The results show that impacts of uncertainties in global land surface parameters on total water budget are not significant though impacts on partitioning of evapotranspiration and runoff are considerable.

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Imazu Bay located in the west of Fukuoka City is biologically very important bay. However, Imazu Bay is highly enclosed, and it is comparatively easy to cause eutrophication by nutrient load. Therefore, to evaluate nutrient loading flowing into Imazu Bay is important. The purpose of this study is to evaluate the nutrient loading flowing into Imazu Bay by river and groundwater. We evaluated the amount of river and groundwater discharge by water balance computation. As the result, we got the following knowledge. First one is that the amount of groundwater discharge flowing into Imazu Bay is about 23 % of total discharge. Second one is that the sum of nitrate nitrogen and ammonium nitrogen loading through the groundwater is less than one tenth of that of through the river. We must closely observe the environment of Imazu Bay, because the treated sewage discharged from treatment plant will increase.

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After the accident of Fukushima Dai-ichi Nuclear Power Plant (FDNPP), a large amount of radiocesium were deposited in the wide area and adsorbed strongly to the soil particles, especially the fine particles. To evaluate the environmental fate of radiocesium, it is necessary to predict the behaviors of the different size soil particles by rain-runoff. In this study, the size distribution analysis of suspended solids (SS) in river water in the Abukuma river basin, located in the vicinity of FDNPP, was analyzed by a hydrological/water quality model for the three years of 2009 – 2011. The hydrological/water quality model simulated river flows and the behaviors of soil particles: clay, silt, very fine sand and fine sand.

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To elucidate the factors controlling dissolved organic carbon (DOC) dynamics in river systems, we investigated DOC concentrations and fluorescence emission-excitation matrix characteristics in three rivers draining into the Kesennuma and Moune Bays from 2012 to 2014. DOC concentrations and the relative fluorescence intensity of fulvic-acid-like substances (F) increased with agricultural areas. The relative fluorescence intensity of protein-like substances (P) and the ratio of P to F had a significant correlation with urban areas. In Moune river where small salt marsh were created after the Great East Japan Earthquake and following tsunami at the estuary, DOC concentrations and values of F and P increased significantly. These results indicate that anthropogenic landuse (agriculture and urban areas) and newly-created salt marsh can control DOC concentrations and fluorescence characteristics in the river basins.

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This study tries to link analyses on
forestry silica runoff with those on the role of silica for aquatic food web
dynamics. First of all, the effects of silica decrease on the shift of photosynthetic
to bacterial loop as energy flow within aquatic ecosystems were shown using
data of mesocoms experiments done by authors previously. Based on this
importance of silica as ecosystem tuner, we analyzed the performance of
silicate runoff from forestry area to know subsequent silica input to receiving
waters.

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We modeled time series of water quality of the tap water by using fractal theory. As a result, we think that mono-fractal model can be used for modeling the time series, especially fLm, fractional Levy motion.

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We measured snow water equivalent (SWE) and snowmelt in three Japanese cedar stands and at an opening (OP) during a snowmelt season in 2005. SWE was measured at beginning of snowmelt period (March 9) and in the midst of snowmelt period (April 12). On March 9, SWE was 1048 mm at OP, 1016 mm in the stand A (a degree of canopy openness of 17.8%), 944 mm in the stand B (5.2%), and 838 mm in the stand C (2.4%), respectively. On April 12, SWE was 825 mm in B, 785 mm in A, 639 mm in C, and 585 mm at OP, respectively. Snow disappeared on April 28 at OP, on May 8, 16 and 7 in the stand A, B and C, respectively, which means the stand B with moderate stand density, is the most suitable for water resources management.

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We developed a measurement method to observe snow depths using small temperature loggers. These loggers were attached to poles at 20cm intervals, and temperatures were recorded by each logger. The snow depths were estimated by making assessments in terms of daily temperature variations in air and snow. If the standard deviation of twelve temperature values by a temperature logger within a given day was less than 0.3, the logger was considered to be covered by snow. Although the outputs of the developed method are discrete variables, the snow depths were quite well reproduced by the method. Moreover, the method is inexpensive and robust. Then, we observed snow depths at many points in a forested catchment using the developed method. We investigated the relationships between snow characteristics and topographical information (elevation and aspect) and forest properties (canopy openness). It is found that the influences of the topographical and forest properties were changed considerably over the winter period.

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The Zaravshan river in Central Asia is trans-boundary river originating in Tajikistan mountains and flowing to Uzbekistan. Main source of the river flow is the glacier-snow melt, and 97% of runoff is generated in the upstream part (Tajikistan). This study aims to physically analyze the available water resources of the Zaravshan river basin to provide the scientific basis to the water resources development plan in this river basin. SiBUC is used for land surface process, and global products are used for land surface parameters and meteorological forcing data. To reproduce river discharge accurately, many bias methods used for SiBUC. Such as altitude dependence correction of precipitation data and downward long-wave radiation data. However, still the discharge peak is not reproduced correctly. So in this study, the short wave radiation is also modified considering direction of the slope to simulate the glacier-snow melt process more precisely.

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Time and spatial distribution of the snow water equivalent around the Hakusan mountain was estimated by the land surface model using the surface meteorological data and RAP precipitation data. Water balance of the Tedori River Dam catchment was checked with daily inflow data. Analized runoff was generally well for the period from 2010 to 2012. On the other hand, due to the underestimation of RAP precipitation, analized runoff was under estimated from 2006 to 2009.  "Reanalysis" of the RAP precipitation is strongly recommended using the all available off-line raingauge information. From the result for 2010-2011 winter, maximum snow water equivalent in the headwater area of the Tedori River dam reached more than 2000mm in early april.

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Various kinds of GCM output are provided in the
SOUSEI program. Compared with 20km GCM, 60km GCM has many number of
ensemble members. Although 60km is relatively high resolution in GCMs, complex
topography in Japan region is not well represented. In snowy regions, basins
facing the Sea of Japan, water from snowmelt can be used as irrigation water.
As the evaluation of snow water amount is crucial for assessing the impact of
climate change on water resources, effect of the resolution of GCM output on
the snow water equivalent is investigated by the land surface model’s output
driven by original (20km) resolution and up-scaled (60km) resolution. Annual
maximum SWE ratio by 60km-scale analysis and 20km-scale analysis is explained
by winter season’s precipitation, standard deviation of sub-grid scale
elevation, and precipitation weighted average winter season’s temperature from
multiple regression analysis with determination coefficient of 0.92 for 300-600m
elevation zone.

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  This report demonstrates our activities in this year. Our young researchers group had four main activities. First one was the discussion meeting and workshop held before the JSHWR annual conference, second one was the research community of associated water field established and the other was the workshop for hydrology and water resource studies. The purpose of the meeting was to interact over university and other study field, first workshop was to give master students a better understanding of the researches in the JSHWR, the research community was to establish a place for discussion about studies of different 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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Semi-mountainous area has gathered attention in recent years because of the multiple functions in the area: a variety of food supply, biodiversity conservation, providing employment opportunities, disaster mitigation etc. However, Semi-mountainous area is facing aging society, population decline based on the specific economic and social conditions in these areas. According to previous studies, if the situation continue in this area, the existence of area itself faces difficulty surviving. On these background, our study group, which consist of young researchers in the fields of hydrology, agricultural engineering and river engineering, is discussing about the vision of flood prevention in semi-mountainous area. Our past activities were 10 times study meeting and the research excursion in Sayo-town (Hyogo Prefecture): suffered a sever damage from a great flood in 2009. Based on these activities, our group started a new research theme: “Impact assessment of flood disaster on the semi-mountainous area decline -In case of Sayo town, Hyogo.-“.

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As a method to evaluate the groundwater flow and the geologic structure which becomes the obstacle to the flow, a new method using thermography images of the soil surface temperature is proposed. A flow
tank filled with glass beads was used in the laboratory experiment. The obstacles were arranged at random in the bottom of the flow tank. 6 patterns for obstacles distribution were designed, and hydraulic head
difference between upper and lower boundary was performed in case of 5 mm and 8 mm for each pattern. The tap water heated to 60 degrees centigrade was used as a tracer. During experiment, the thermal image of surface temperature was taken by the thermography camera at specified time intervals. The experimental results showed that the distribution of the obstacles is having an influence on the
temperature difference. However, the evaluation of the obstacles distribution was unclear by the proposed experiments.

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In this paper, We evaluated parameter estimation of Urban Storage Function model which is considering urban runoff process with seven parameters for river discharge data to which included errors.

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Parameters p in a storage function model has been estimated from parameteryzing overland downslope flow, but this concept has not been validated by some hillslope observations. The present stduy explained its physical background by the soil physical properties of vertical unsaturated fllow in the soil layer.   

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The aim of this study is to overcome an insufficiency of the deterministic flood forecast using ensemble outputs with 48-hr forecast time and 2km high-resolution and to explore an accuracy improvement of the flood forecasting using ensemble NWP rainfall forecast. Therefore, we assess the latest ensemble NWP outputs with 51 ensemble members, 48-hr forecast time and 2km horizontal resolution whether they can produce suitable rainfall predictions or not during the Typhoon No. 18 ‘Man-yi’ 2013 event, and we also assess the performance of ensemble flood forecasting for application of flood early warning based on the latest ensemble NWP rainfall forecast over the Katsura river basin.

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In 1980s, 'Mega Rice Project' for the expanded agricultural production was planned in Indonesia, and so many drainage canals have been constructed for irrigation and drainage of tropical swamp peatland in Kalimantan Island. But it brought the groundwater level drawdown in the drained swamp peatland, so that it caused a huge amount of carbon dioxide emission by forest fires and soil degradations. In order to conserve the groundwater level by the canal water level management, the canal backfilling and gate construction should be discussed in the civil engineering viewpoint. In this study, two-dimensional groundwater flow model related with the river flow condition and the land surface process was integrated for quantitative evaluation of the effect of canal repair management. Simulation results of groundwater level drawdown by the canal construction suggest the conservation of the hydrological environment and the CO2 emission reduction by canal management in the tropical swamp peatland.

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In Myanmar, economic activities are changing rapidly because they started
democracy 3 years ago. Especially, effective utilization of water resources and
forest resources is significant development theme.
We build water circulation analysis system based by BASINS-HSPF,
hydrologic outflow model. Because Myanmar has few precipitation data and
streamflow data, we used estimated precipitation data from TRMM satellite. And
got streamflow data in Sittang river on the spot. Additionally, we used
Hydroshed to get DEM data, SWAT to get maximum and minimum temperature data to
analyze evapotranspiration, GLCF to get land cover data. Moreover, there is low
precipitation regions in inland. In this region, There a lot of reservoir to
keep water. So we can’t ignore reservoir’s manual effect.
As a result, We verified BASINS-HSPF compared by streamflow data in Sittang river, and could identify
prime parameter. Additionally, we could introduce reservoir’s manual effect to
the model.

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This research has two purposes. The one is to understand hydrological phenomenon in Japan more deeply and the other is test for hyperresolurion global scale model. Recently, the climate change is progressing and the needs for deep understanding of water cycle is getting larger. Now, we have global scale model to monitor and predict water cycle and its resolution is 10km~100km. To answer the questions threw by addressing water cycle science, hydrologic model which has 1km resolution called hyperresolution is needed. However, there are too many obstacles to build hyperresolution global model(dataset, computer, observation, prediction). So building hyperresolution model in Japan area is beneficial as pilot test.

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Recent studies in forest hydrology have reported the existence of mountainous grounwater in weatherd bedrock and its considerbly quick response to rainfall input. Furthermore, the dynamics of mountainous groundwater in the bedrock influences on saturated subsurface flow, which is an important rainfall-runoff mechanism in mountainous catchments. This study introduces Time-Space Accounting Scheme (T-SAS) method to a distributed rainfall-runoff model representing mountainous groundwater to estimate the contribution of the groundwater flow in the total runoff volume. After the model testing with respect to hydrograph, variation of grounwater level and isotopic composition, we estimated the contribution, which result in 51±9% in the total runoff in 2011 at the study catchment.

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Inundation has much impact on quantity of water resources as well as regional climate. This study aims at developing in-land water cycle model considering inundation, especially evapotranspiration loss, and estimating river discharge and spatio-temporal changes of inundation area. This study presents basically following three ways of coupling river routing model to land surface model SiBUC . (1)Calculating river routing using kinematic wave equation. (2)Coupling to CaMa-Flood . (3) Interactive coupling between SiBUC and CaMa-Flood. The third way is expected that it enables SiBUC to estimate fluxes on land surface process considering horizontal transfer of surface water storage among sub-grids. These three presented ways are applied to White Nile river basin for mainly estimating water budget and spatio-temporal changes of inundation area in Sudd wetlands area, and compared among the results of them. As a result, a lot of water resource is lost in inundation due to evaporation.

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Flood envelope curve (FLEC) equation is derived by using six-parameter Depth-Area-Duration equation. Fitness of six parameter-equation Depth-Area-Duration (DAD) equation was compared with that of four-parameter DAD equation, and the result showed advance of six-parameter DAD equation. Comparison of present FLEC derived on the basis of present DAD equation and future FLEC showed clear  increase in specific discharge in future.

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Climate change may have some negative impact on water cycle, such as higher intensity of rainfall, increased risk of drought, and so on. In our previous study, as a method to estimate the hydrological impact of climate change, integrated meteorological / hydrological model was developed. The study showed that the integrated model wellsimulated the current hydrology in Yodo river basin. In this study, the impact of climate change on Yodo river basin is assessed by using the integrated model with GCM (General Circulation Model) output.

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Water release from irrigation ponds is introduced to mitigate flood disasters in Tanba and Sasayama area in Hyogo prefecture. Water stage of irrigation ponds is kept low in September and October of typhoon season that irrigation water is not required, and water storage for irrigation in spring and summer is recovered by inflow from November through late March. In this study, a water release method based on probable inflow volume in winter estimated by long-term rainfall-runoff simulation is investigated and the stormwater storage capacity of all irrigation ponds in the study area is compared with storage capacity in paddy field and storage capacity for flood control in Hitokura dam near the study area. Results show that the total storage capacity of irrigation ponds and paddy field in Tanba and Sasayama area is comparable to the storage capacity for flood control in Hitokura dam.

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We developed a prototype seamless method for simulation of distributed water circulation that integrates modeling of flood and inundation processes with the Distributed Water Circulation Model incorporating Agriculture Water Use (DWCM-AgWU). The prototype model was applied to the delta plain of the Chao Phraya River basin for the year of 2011. The model uses a two-dimensional analysis to model the flow of floodwaters into low-lying areas. Non-uniform flow in rivers was used to simulate the effect of back flow. Our model also takes into account the effects of elevated roads and railways on inundation during flooding and estimates overflows by modeling such roads and railways as weirs. Comparison of simulated and observed water levels at hydrological stations at Ayutthaya revealed simulation errors of 28%. The total extent of flooded areas simulated by our model was only 41% of that observed from satellite data.

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This research demonstrates the performance of basic triangle designing of gravity dam using the artificial swarm intelligence approaches such as PSO, ACO and GA. The obstacle to determine a basic triangle is to optimize the parameters to be designed as minimize 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 approaches are carried out. The first one is to employ the 0-extension approach to express the bilinear situation as one equation. The second one is to use the artificial swarm intelligence approach to optimize the dam parameters in bilinear processes. A given sediment height is reconsidered to know the upper limitation in managing the long-term dam sedimentation. It can be concluded that this research is useful and helpful in overcoming the difficulty of optimally designing the bilinear basic-triangle parameters and in managing the long-term sedimentation. 

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In the Central Asia, serious drought was induced by huge-scale irrigation project. For sustainable development, water demand must be estimated from the past to the future. However, strong regionality of irrigation makes estimating process difficult. Therefore, in situ measurement was performed in two sites in Uzbekistan and real irrigation process was observed. Utilized sensor were WET sensor (Delta-T), which can observe soil moisture and Ec and soil temperature, and DL/N70 (Koshin), which can observe ground water level. As a result of measurement, irrigation rule and its impact to Ec on soil. farmers did several times of irrigation per year dpends on its climate condition. As a future study, irrigation scheme in water circulation model is improved by its local rules.

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In
spite of the long-term analysis for agricultural water use, inundations and
droughts, which occur frequently nowadays, have been analyzed separately as
single and short-term phenomena. In recent years, however, it becomes necessary
to deal with both of them consecutively in order to reproduce extreme events in
large basin- and global –scales, and to manage a group of water use facilities
in integrated manners. In this research, taking the Chao Phraya River basin with
huge irrigation dams, controls of which affected inundations heavily in the downstream
of the basin in 2011, as a target basin, we modified the DWCM-AgWU model and,
as a result, presented the effectiveness and limitations of the modified model
application for carrying out consequent calculations for extreme events and
distinctive water use.

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This study aims at evaluating the spatio-temporal variability of surface soil moisture at a scale of 10⁴ km² and at assessing the precipitation effects on the spatio-temporal variability of soil moisture in a semi-arid region through the analyses of data over 13-year period. The results show that higher spatial variability of soil moisture is found at intermediate soil moisture, while lower spatial variability is at drier condition. It is also found that the effect of the precipitation on soil moisture variability is largest when higher spatial variability of precipitation occurs with drier initial soil moisture. Moreover, long-term mean spatial pattern of soil moisture depends partly on that of precipitation, though the dependence is larger when mean soil moisture is lower, since the spatial pattern of soil moisture changes during transition period between dry and wet conditions. The results provide an insight into the spatio-temporal variability of soil moisture at satellite footprint scale, especially induced by precipitation.

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Changes in vegetation traits are capable of affecting the exchanges processes of momentum, heat, and moisture between the atmosphere and the surface influencing climate over different spatial en temporal scales. Paraguay had dense forest cover until 1970 but due to agricultural expansion, the country lost two thirds of its Atlantic forest. This study aims to assess the impacts of the actual land cover changes, produced in Paraguay between the years 2000 and 1990, on the climate under wet and dry conditions. For this, the meso-scale numerical prediction model CReSiBUC was used to perform two sets of simulations for November (wet setting) and July (dry setting) 2006-2012. Each of these simulation sets used different vegetation scenarios and NDVI data but kept constant all other boundary and initial conditions. Thus, the potential effects of land-use change on precipitation were modeled and the mechanisms that may drive changes in local/regional climate were studied. 

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