Details of a Researcher - IRIE Mitsuteru

Classification of River Sediment Fractions in a River Segment including Shallow Water Areas Based on Aerial Images from Unmanned Aerial Vehicles with Convolution Neural Networks Reviewed

Irie M., Arakaki S., Suto T., Umino T.

Remote Sensing 16 ( 1 ) 2024.1

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Remote Sensing

Riverbed materials serve multiple environmental functions as a habitat for aquatic invertebrates and fish. At the same time, the particle size of the bed material reflects the tractive force of the flow regime in a flood and provides useful information for flood control. The traditional riverbed particle size surveys, such as sieving, require time and labor to investigate riverbed materials. The authors of this study have proposed a method to classify aerial images taken by unmanned aerial vehicles (UAVs) using convolutional neural networks (CNNs). Our previous study showed that terrestrial riverbed materials could be classified with high accuracy. In this study, we attempted to classify riverbed materials of terrestrial and underwater samples including that which is distributed in shallow waters where the bottom can be seen using UAVs over the river segment. It was considered that the surface flow types taken overlapping the riverbed material on images disturb the accuracy of classification. By including photographs of various surface flow conditions in the training data, the classification focusing on the patterns of riverbed materials could be achieved. The total accuracy reached 90.3%. Moreover, the proposed method was applied to the river segments to determine the distribution of the particle size. In parallel, the microtopography was surveyed using a LiDAR UAV, and the relationship between the microtopography and particle size distribution was discussed. In the steep section, coarse particles were distributed and formed riffles. Fine particles were deposited on the upstream side of those riffles, where the slope had become gentler due to the dammed part. The good concordance between the microtopographical trends and the grain size distribution supports the validity of this method.

DOI： 10.3390/rs16010173

Quantitative Evaluation of Suspended Solid Runoff from Large-Scale Landslide Areas Presumed to Be the Source of Turbid Water Reviewed

Irie M., Nakagawa A., Higashi T.

Water (Switzerland) 15 ( 18 ) 2023.9

Authorship：Lead author,　Corresponding author Publishing type：Research paper (scientific journal) Publisher：Water (Switzerland)

In the uppermost stream of the Mimikawa River, in northern Miyazaki Prefecture, the contribution to river turbidity of a huge, collapsed slope alternating sandstone and mudstone layers was qualitatively shown in our previous study. In this study, the water level and turbidity were continuously observed, to obtain a quantitative estimation of this contribution. The conversion equation from the water level to the flow rate is required, but field measurements during the flooding term in the mountainous site are difficult. In this study, a high-resolution survey was conducted, and the relationship was determined via a small-scale hydraulic model shaped using a 3D printer from the survey results, to determine the relationship between the water level and the flow rate. The flow rate time series was reproduced with the distributed runoff model that is verified with the flow rate converted from the water level. The flow rate and turbidity load time series were also estimated from the long-term rainfall. The area of the bare soil surface of each small basin was obtained via satellite image analysis, and the soil yield from each surface condition was calculated. Furthermore, the amount of turbidity produced upstream of Kamishiiba Dam was calculated for each small basin. It was estimated that 24% of the turbidity was generated from the small basin covering 5.7% of the total catchment area. This study showed that it is possible to verify the hydrological model by obtaining the water-level–discharge relationship, even in the mountains, where it is difficult to observe the discharge on-site, via small-scale hydraulic model experiments.

DOI： 10.3390/w15183186

Tracing sediment transport history using mineralogical fingerprinting in a river basin with dams utilizing sediment sluicing Reviewed

Ito K., Matsunaga M., Itakiyo T., Oishi H., Nukazawa K., Irie M., Suzuki Y.

International Journal of Sediment Research 38 ( 3 ) 469 - 480 2023

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：International Journal of Sediment Research

Sediment causes a serious problem in relation to dam function. A cooperative sediment sluicing operation has been under way since 2017 to prevent sediment from accumulating in dams in the Mimi River, Miyazaki, Japan. To achieve a smooth and stable operation, it is very important to determine the sediment source and a sediment transport system to maintain the dam's function. In the current study, the source and transport of sediment from the Mimi River basin have been analyzed with X-ray diffraction (XRD) to reveal the peaks of mineral species. The sediment samples were collected in the Mimi River basin from the Tsukabaru Dam to the sea in an area including 4 dams and 5 tributaries. In addition, the minerals in samples collected in 2014, before the start of the sediment sluicing operation, and from 2018 to 2020, after the start of the operation, were analyzed. An evaluation of the similarity of the sediment at each sampling point based on the X-ray diffraction peaks of mineral species showed that sediment distributed upstream was transported downstream in the year when the sediment sluicing was done. This result indicates that the sediment sluicing operation at dams ensured the continuity of the sediment distribution in the Mimi River basin. In addition, an investigation done in 2020 showed that sediment particles very similar to those of the upstream tributaries were deposited downstream because of extensive flooding caused by a large typhoon. The management of sediment transport has the greatest importance in a river basin where a dam is to be constructed. It is possible to trace the history of the sediment distribution and movement resulting from the operation of sediment sluicing by using sediment mineral analysis.

DOI： 10.1016/j.ijsrc.2022.12.002

Prediction of the discharge in Pech River for the flood warning system, based on the time series of snow cover area and meteorological data Reviewed

HOSSAINI Hossaini Mir Mohammad Mones, IRIE Mitsuteru

Journal of Arid Land Studies 32 ( 3 ) 93 - 93 2022.12

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：日本沙漠学会

Floods in the arid areas provide fertile soil and water resources, enabling agricultural production. Based on its productivity, towns with a large population have developed along the riverbanks. On the other hand, large flood beyond the expectation will cause enormous human and economic damage. The Pech River, our study site, is a tributary of the Kunar River, which runs through eastern Afghanistan. The catchment area of the river is populated by 35.5% of the population and has 21% of the agricultural land of Kunar province.The main source of the river discharge is melted snow in the upper mountainous areas, and the maximum discharge that appears in the following spring changes depending on the amount of snowfall in the previous winter. In the year of heavy snowfall in the upper mountainous areas, the residential areas and the agricultural lands along the river experienced severe inundation.Therefore, it is necessary to predict the peak discharge in spring in advance and provide appropriate flood warnings so that the local residents can take evacuation and damage mitigation measures. In this study, we tried to develop a method for predicting the peak discharge based on the fluctuation of snow cover area evaluated with satellite images, temperature, and rainfall of the upper reaches of the Pech River.First, the boundary of the river catchment was identified based on the DEM of 30 m mesh acquired by Advanced Land Observing Satellite (ALOS). Next, the Snow cover distribution data between 2008 and 2018 at weekly intervals was downloaded from the National Snow & Ice Data Center (NSIDC) database, and the catchment area was extracted. Daily temperature and precipitation data at the station nearby the catchment stored in the database of National Oceanic and Atmospheric Administration (NOAA) were expected as the parameter explaining the snow melting process in spring.We tried to reproduce the discharge of the Pech River using these explanatory variables related to the process of snowfall and snowmelt with some statistical and stochastic methods. The multi-regression analysis and Neural Network were examined to reproduce the discharge fluctuation of Pech River.

DOI： 10.14976/jals.32.3_93

Estimating the impact of rainwater harvesting system installation on floods using hydrological models Case study: Nyabugogo valley, Kigali Reviewed

ALINE Uwineza, IRIE Mitsuteru

Journal of Arid Land Studies 32 ( 3 ) 92 - 92 2022.12

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：日本沙漠学会

Rwanda, a landlocked country located in East Africa, is under the temperate climate due to the high altitude though near to the equator. 5.3% of the territory is covered by water bodies, lakes, and rivers. Both rainy and dry season come twice a year with frequent inundations and water shortage. Kigali, the capital city, and the most populated city in the country, is affected by floods during rainy season. Nyabugogo valley, the downtown of the capital is the typical affected area with devastating damage. The mitigation measures such as widening Mpazi drainage channel were taken by the government based on a number of researches. However, the inundation still occurs every year. This research aims to propose rainwater harvesting (RWH) that can supply water to each household, as a mitigation measure to floods. In order to assess the effect of RWH installation on the flood control, Runoff modeling and simulation of Flood inundation was carried out.Nyabugogo river catchment area, delineated using DEM, is 1663.95 km2. The dominant land cover is forest (65%) and crop land (22%). Run-off from the upper catchment area was simulated using SWAT model with input data of elevation, soil, and land use data. The simulation was done for 3 years 2011-2013 and calibrated using SWAT CUP.IRIC Nays2Dflood Model was used to simulate and visualize the flooded area with the input data of the discharge simulated by the above modeling and water level at downstream of the flooded area for the flood event reported on March 2nd and 3rd 2020. The boundary conditions were set along the river, with two inflow points: Nyabugogo river and Mpazi outlet. The maximum water depth and the maximum velocity were observed at the confluence of the two streams; and flood extended throughout the valley. The accuracy of the simulation was checked by comparison with the sentinel2 satellite images.The RWH system installation will be simulated and its hydrological impact on flood will be assessed as the final outcome of this research. Rainwater harvesting system installation, additionally to reducing flood mitigation, can contribute to improvement of the population’s health and sanitation, which aligns with the SDGs. Knowing the extent at which RWH can reduce flood, will open to further studies on design and cost analysis of the system.

DOI： 10.14976/jals.32.3_92

Farmers’ preferences of the agricultural inputs for rice farming in Senegal River Basin, Mauritania: A best-worst scaling approach Reviewed International coauthorship

MARUYAMA Yuki, UJIIE Kiyokazu, AHMED Cherif, DIAGNE Mandiaye, IRIE Mitsuteru

Journal of Arid Land Studies 32 ( 3 ) 69 - 69 2022.12

Language：English Publishing type：Research paper (scientific journal) Publisher：日本沙漠学会

In Mauritania, consumption of rice, which is a staple food, is increasing rapidly, because rice takes less time to cook than other cereals such as millet, sorghum, and maize. To meet this growing demand, Mauritanian food policy encourages rice imports. However, the 2008 food crisis led to rice shortage, owing to a steep rise in the price of imported rice. To ensure overall food security, the government has adopted certain agricultural policies and projects to bolster rice production in the Senegal River Basin. Under these circumstances, numerous previous studies suggested solutions for improving productivity and efficient farm management. Whereas, these studies were leaded by the field observation to grasp current farm condition and the questionnaire survey for understanding the actual amount of inputs (e.g. fertilizer and pesticide) and harvest, the preferences and perceptions of local farmers regarding rice farming have been neglected. In order to achieve the sustainable agricultural development, cooperation of local farmers is indispensable. Therefore, farmers’ perceptions should be taken into consideration of agricultural policy making.In this study, we attempted to evaluate the farmers’ preferences of the agricultural inputs for rice farming quantitatively in Mauritania. Furthermore, we clustered farmers with similar preferences and tried to discuss the heterogeneity of preferences based on the characteristics of each group.In order to evaluate these farmers’ preferences, a best-worst scaling (BWS) method was applied with 29 farmers on March, 2018. BWS is a method to evaluate preferences by choosing “most important attribute” and “least important attribute” one by one. In this survey, six attributes which are seed fertilizer, pesticide, irrigation, labor and machinery were assumed. Moreover, based on these results, farmers who have the similar preferences was grouped by a cluster analysis.As the results, while most farmers value seeds and irrigation in rice production, pesticide and labor tend to be neglected. In addition, based on a cluster analysis, farmers were grouped into three groups: (1) group that emphasizes irrigation, (2) group that places the highest priority on agricultural machinery, and (3) group that prefers seeds.On the other hand, as a characteristic of each group, Group 1 includes many farmers engaged in rice production on paddy filed equipped with irrigation facilities, and it can be seen that they understand the importance of irrigation. In group 2, farmers have relatively large-scale paddy field. In order to improve the efficiency, agricultural machineries are emphasized.

DOI： 10.14976/jals.32.3_69

Modeling of Sediment Transportation in Ichkeul Lake for the Estimation of the Influence of the Constructions of the Reservoirs in the Upper Streams Reviewed International coauthorship

Irie M., Kotegawa H., Kawachi A., Ouni H., Tarhouni J.

Water (Switzerland) 14 ( 13 ) 2022.7

Authorship：Lead author,　Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Water (Switzerland)

Rich ecosystems such as estuaries and brackish lakes are vulnerable to the effects of human activities and are prone to environmental changes. In particular, the salt environment, which is the backbone of the environment, might be affected not only by direct modifications such as dredging but also in ways that were not initially envisioned. Ichkeul Lake, located in the northern part of Tunisia, is a shallow brackish lake registered as a UNESCO World Natural Heritage Site. The construction of reservoirs upstream of the inflowing river in the 1980s reduced the amount of freshwater inflow. That only had been thought to be the cause of the increase in salinity in Ishkeul Lake. On the other hand, the sedimentation in the reservoirs upstream was remarkable, and the supply of sediment from the reservoirs upstream to the Ichkeul Lake was stopped. Changes in sediment out-flow may have reduced lakebed altitude and enhanced seawater intrusion. However, the environmental protection measures for the lake so far have focused only on improving the water budget and have not been quantitatively evaluated for sediment transportation. In this study, we first estimated the water budget of the lake. Then the re‐suspension by wind disturbance in the lake was estimated from the correlation with the wind speed based on laboratory experiments and field measurements. The outflow of the sediment estimated with these two models was compared with the sediment volume trapped in the upstream reservoirs that would have flowed into the lake if there had been no construction of the dams. Based on this, we evaluated whether the lake is cur-rently erosive or cumulative. As a result, the estimated annual outflow of sediment to the sea was 4300 tons/year. It was estimated that the construction of the reservoirs upstream changed the trend of lakebed height from accumulation to erosion.

DOI： 10.3390/w14131984

Development of Automated On-site Analysis Method Using a Smart Device as Detection System for Autocatalytic Reactions Reviewed

MANAKA Atsushi, KABURAGI Kaori, FURUYAMA Shoichi, TAFU Masamoto, IRIE Mituteru

BUNSEKI KAGAKU 71 ( 4.5 ) 217 - 220 2022.4

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society for Analytical Chemistry

DOI： 10.2116/bunsekikagaku.71.217

IDENTIFICATION OF THE ORIGIN OF TURBID WATER FLOWING INTO KAMISHIIBA DAM AND SOIL EROSION CONTROLL WITH FLOCCULANTS Reviewed

HIGASHI Takayoshi, IRIE Mitsuteru

Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) 77 ( 2 ) I_583 - I_588 2021.9

Authorship：Last author,　Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society of Civil Engineers

Kamishiiba reservoir has the problem of the turbid water inflow from the upstream catchment area. The main sediment yield is on the bare ground surface after the landslide. In this study, the surface soil and river channel sediments in the catchment area were sampled for examining the similarity with the suspended solid in the turbid water inflow to the reservoir by the mineralogical method. The topsoil of the slope suspected as the cause of the turbidity was aggregated with PIC to examine the possibility of suppressing runoff. In the PIC sprayed area, the soil erosion by raindrop impact can be greatly suppressed, but cracks that developed over time reduced resistance to surface lateral flow, and the sediment yield increases slightly.

DOI： 10.2208/jscejhe.77.2_i_583

Differentiation of river sediments fractions in uav aerial images by convolution neural network Reviewed

Takechi H., Aragaki S., Irie M.

Remote Sensing 13 ( 16 ) 2021.8

Authorship：Last author,　Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Remote Sensing

Riverbed material has multiple functions in river ecosystems, such as habitats, feeding grounds, spawning grounds, and shelters for aquatic organisms, and particle size of riverbed material reflects the tractive force of the channel flow. Therefore, regular surveys of riverbed material are conducted for environmental protection and river flood control projects. The field method is the most conventional riverbed material survey. However, conventional surveys of particle size of riverbed material require much labor, time, and cost to collect material on site. Furthermore, its spatial representativeness is also a problem because of the limited survey area against a wide riverbank. As a further solution to these problems, in this study, we tried an automatic classification of riverbed conditions using aerial photography with an unmanned aerial vehicle (UAV) and image recognition with artificial intelligence (AI) to improve survey efficiency. Due to using AI for image processing, a large number of images can be handled regardless of whether they are of fine or coarse particles. We tried a classification of aerial riverbed images that have the difference of particle size characteristics with a convolutional neural network (CNN). GoogLeNet, Alexnet, VGG-16 and ResNet, the common pre-trained networks, were retrained to perform the new task with the 70 riverbed images using transfer learning. Among the networks tested, GoogleNet showed the best performance for this study. The overall accuracy of the image classification reached 95.4%. On the other hand, it was supposed that shadows of the gravels caused the error of the classification. The network retrained with the images taken in the uniform temporal period gives higher accuracy for classifying the images taken in the same period as the training data. The results suggest the potential of evaluating riverbed materials using aerial photography with UAV and image recognition with CNN.

DOI： 10.3390/rs13163188

Effect of Physical Parameters on the Transparency of Ichkeul Lake’s Waters, North–East of Tunisia Reviewed International coauthorship

Ouni H., Irie M., M’barek N.B., Tarhouni J., Tlatli-Hariga N., Dias J.M.

Environmental Science and Engineering 957 - 961 2021.4

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Environmental Science and Engineering

The construction of dams on the Ichkeul Lake rivers, along with drought, has increased the sedimentation problem and caused the decrease of its storage capacity. Therefore, this work aims to highlight the factors responsible for water clarity deterioration. Through the multi-date MODIS imagery analysis, a Water Turbidity Index (WTI) was used to assess the turbidity of the lake and a Delft3D-FLOW hydrodynamic model was used to determine the effect of wind, water level, temperature, and salinity on the turbidity of the lake’s waters. The effect of prevailing wind was analyzed for the two hydrological years 2014–2015 (R2 = 0.3989) and 2015–2016 (R2 = 0.4219). It was found that the water transparency decreases with the increase of wind speed. Besides, the model calibration showed the sensitivity of water temperature and salinity to the lake’s bed roughness. Contrariwise, the water level was not significantly influenced. Consequently, the use of roughness n = 0.018 decreases the errors between observed and simulated data. Altogether, the methodology used in this work allows decision makers to monitor the temporary and spatial water turbidity fluctuations in the Ichkeul Lake.

DOI： 10.1007/978-3-030-51210-1_149

Gradients of flow regulation shape community structures of stream fishes and insects within a catchment subject to typhoon events Reviewed

Nukazawa K., Shirasaka K., Kajiwara S., Saito T., Irie M., Suzuki Y.

Science of the Total Environment 748 2020.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Science of the Total Environment

Alterations in natural flow regimes caused by dams can significantly alter the aquatic habitats of stream organisms. However, few studies have characterized flow regulation to assess its impacts on stream fauna in the context of interannually variable extreme floods. This study aims to understand the variation in stream animals along flow regulation gradients due to hydropower dams in a catchment experiencing typhoons. We observed freshwater fishes and stream insects at fully regulated sites (receiving residual flow), moderately regulated sites (receiving hydropower outflow), and nonregulated site (tributary) in the Mimi River catchment in southern Japan, in summer and winter from 2010 to 2018. We computed indicators of hydrologic alteration (IHA) in each calendar/water (July to June) year from 2007 to 2017 and selected subsets of IHA based on principal component analysis (PCA) and variance inflation factor. The largest variance was mainly explained by minimum discharge levels (e.g., 30-day annual minimum) and flow variability among IHAs, distinguishing the moderately regulated and nonregulated sites from fully regulated sites because of residual flow and suppressed high pulses in the fully regulated sites. Generalized additive models revealed that annual maxima of specific discharge were most significant predictors of fish and insect metrics while its effects were generally inconsistent between summer and winter. Non-metric multidimensional scaling revealed that insect communities were clustered into the regulation extents in both seasons. The differences in winter fauna between the regulated and nonregulated sites, characterized by Ephemeroptera-Plecoptera-Trichoptera abundance, were associated with maximum discharge and high pulse numbers. Fish community variation did not correspond to flow regime gradients. Our findings on mechanistic ecohydrological consequences of various flow regulations, supported by long-term observations, will be useful for river managers attempting to compensate for alterations in flow regime and ecological integrity.

DOI： 10.1016/j.scitotenv.2020.141398

Effective removal of fluoride and phosphate pollution using mixtures of dicalcium phosphate dihydrate (DCPD) and Tunisian reservoir sediment containing calcium carbonate Reviewed

Tafu M., Sasakawa N., Murthy H.S., Takamatsu S., Manaka A., Irie M., Toshima T.

Euro-Mediterranean Journal for Environmental Integration 5 ( 1 ) 2020.4

Publishing type：Research paper (scientific journal) Publisher：Euro-Mediterranean Journal for Environmental Integration

The removal of fluoride from environmental surface water and groundwater is an important environmental issue in Tunisia. Notably, Tunisia also faces a shortfall in reservoir capacity due to the buildup of sediment containing calcium carbonate. Dicalcium phosphate dihydrate (DCPD, CaHPO4·2H2O) reacts effectively with fluoride to form stable fluorapatite (FAp, Ca10(PO4)6F2), and the addition of calcium carbonate (CaCO3) effectively inhibits the release of phosphate generated during this reaction. In this study, we tested the potential for fluoride removal using a mixture of DCPD and Tunisian reservoir sediment. The release of phosphate from the reaction of DCPD with fluoride was successfully inhibited using the sediment. The application of the DCPD–sediment mixture led to a high rate of fluoride removal (15–19 mg/g), such that the resulting water met the World Health Organization (WHO) recommended limit for fluoride in water (1.5 mg/L). This removal rate is five to ten times those achieved with conventional fluoride adsorbents such as bone char. Based on these results, the utilization of Tunisian reservoir sediment seems to be an effective solution for removing fluoride from aqueous environments.

DOI： 10.1007/s41207-019-0135-8

Changes in fluoride removal ability of chicken bone char with changes in calcination time Reviewed

Kikuchi M., Arioka Y., Tafu M., Irie M.

International Journal of Ceramic Engineering and Science 2 ( 2 ) 83 - 91 2020.3

Publishing type：Research paper (scientific journal) Publisher：International Journal of Ceramic Engineering and Science

Changes in fluoride removal ability of chicken bone char (CBC) were investigated by both remained amounts of carbon including organic substances and crystallite size of hydroxyapatite in the CBC. Carbon contents in CBC were controlled by heating time at 600°C. Although temperature for crystal-grain growth for HAp, 650°C, was higher than 600°C, crystallite size of HAp in CBC increased with heating time. Fluoride ion removal ability positively related to the amount of remaining carbon and negatively related to the square of crystallite size, as an index of surface area, of HAp. These results suggested that fluoride ion removal from water by CBC is not only by ion exchange and/or dissolution-precipitation process, but also by adsorption by carbon and/or temporal capture of fluoride ion by microstructure of carbonate in CBC before immobilize it in apatite structure.

DOI： 10.1002/ces2.10034

Application of image identification by artificial intelligence to aerial pictures taken from UAV for Wadi channel management

Irie M., Takechi H.

The 5th International Symposium on Flash Floods in Wadi Systems, Urban Flood Risk Management: Mitigation and Adaptation Measures in the MENA Region 2020.2

Language：English Publishing type：Research paper (international conference proceedings)

The effect of optimism bias and governmental action on siltation management within Japanese reservoirs surveyed via artificial neural network Reviewed International coauthorship

Tobias Landwehr, Sameh Ahmed Kantoush, Claudia Pahl-Wostl, Tetsuya Sumi, Mitsuteru Irie

Big Earth Data 4 ( 1 ) 68 - 89 2020.1

Language：Japanese Publishing type：Research paper (scientific journal)

Reservoirs are installed as long-term assets to guarantee water and energy security for decades, if not centuries. However, the effect of siltation undermines reservoirs’ sustainability because it significantly reduces the reservoirs’ original capacity. The present paper attempts to evaluate the global reservoir siltation problem with the optimism bias theorem introduced by Kahneman and Tversky and applied to infrastructural mega-projects by Flyvbjerg and Ansar using artificial neural networks (ANNs) algorithms for large Japanese reservoirs. Japan possesses suitable long-term data and a legal directive concerning the sediment capacity siltation duration, which serves as a valid guide to check whether, over the past 100 years, engineers, planners and managers were capable of judging the sediment input correctly. Various ANN models were established to emulate Japanese reservoir siltation behavior. The networks demonstrate that reservoirs in Japan suffer from optimism bias. In contrast to the law, the dead storage volume of an average dam is supposed to reach capacity after 52 years. This finding joins the overall observation that mega-projects generally and globally suffer from optimism bias. The emulations were subsequently screened for a presumed influence of governance actions, namely, indicating plus monitoring and the change in the market competition situation. While reservoir siltation appears to continue regardless of the level of competition in public procurement, monitoring directives appear to have a considerable impact on improved siltation management, which demonstrates that dedicated governance action can significantly strengthen the sustainable behavior of key infrastructure elements such as reservoirs.

DOI： 10.1080/20964471.2020.1711632

Evaluation of Consumer Preferences for Rice in Mauritania:A Best-worst Scaling Application Reviewed

MARUYAMA Yuki, UJIIE Kiyokazu, IRlE Mitsuteru, Cherif AHMED, Bouya Ould AHMED

Journal of Rural Economics 91 ( 4 ) 478 - 483 2020

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Agricultural Economics Society of Japan

In West African countries,domestic rice production should be improved to overcome the dependence on imported rice. In order to achieve that,upgrading the domestic rice value chain needs to improve for maintaining high competitiveness of domestic rice relative to imported rice. This study investigates consumer preferences of rice in Mauritania.We used best-worst scaling and latent class analysis. The results emphasize the importance of cleanliness attributes in consumer choice and identify three latent segments: "preferences for price and cleanliness attributes","strong preference for cleanliness attributes",and "preference for clean rice with high swelling capacity and safety attributes".

DOI： 10.11472/nokei.91.478