Field experiment was conducted in 2022 and 2023 to examine the effects of irrigation to taro at the Andosol field in Ise plain, Japan. In 2022, we conducted furrow irrigation only two times because of frequent and large amount of rainfall. There is no significant difference in soil water content, matric potential, and yield between furrow irrigation and control plots. In 2023, we prepared three experimental plots. In the first plot, no irrigation was conducted (control plot). Furrow irrigation was conducted in the second plot (furrow-irrigation plot). Irrigation was conducted with perforated pipes in the third plot (perforated-pipe plot). According to the long-term precipitation data monitored at the meteorological station about 9 km north from the study site, the drought in this year may occur once in 5 years. Yields were significantly increased by irrigation. However, there is no significant difference in yield between furrow-irrigation and perforated-pipe plots, although there is large difference in soil moisture conditions observed by the sensors installed at the middle of furrows. According to the result of root-distribution measurement, substantial number of roots in furrow irrigation plot was located not only center of the furrow but also near the edge of the furrow, which might absorb irrigation water supplied from the edge of the furrow.

This study conducted a questionnaire survey targeting users of a day-use hot spring facility in a region with minimal adoption of agrivoltaic systems. By employing structural equation modeling, the study aimed to clarify the factors shaping acceptance attitudes toward agrivoltaic systems, providing a foundation for understanding resident attitudes in regions facing similar challenges. The results revealed that approximately one-third of respondents exhibited a NIMBY (Not In My Back Yard) tendency. Four factors—"interest and concern," "trust," "perceived benefit and social necessity" and "perceived risk"—were identified as influencing "acceptance attitudes." "Perceived benefit and social necessity" had a direct positive impact, while "interest and concern" and "trust" exerted indirect positive effects. In contrast, "perceived risk" had both direct and indirect negative effects on acceptance. Furthermore, unlike in other energy facilities, "trust" alone did not sufficiently suppress "perceived risk," suggesting a unique challenge in promoting agrivoltaic systems. Based on these findings, it is essential to enhance residents' perceptions of usefulness and necessity through educational activities, provide targeted information tailored to specific demographic attributes, and disseminate concrete measures to address anxiety factors in order to facilitate smooth community acceptance.

This study proposed a simple model to quantitatively evaluate shrinkage characteristics of saturated slurry clay with different initial water contents. This model requires only two parameters, that is, water content at the bending point of the soil shrinkage characteristic curve and void ratio after drying, which can be determined by a simple drying shrinkage test. The accuracy of the proposed model was verified by drying shrinkage tests conducted on saturated slurry clay specimens with various initial water contents and dimensions and dried using different drying methods. The changes in the volume of slurry clay specimens were continuously evaluated using image analysis. The proposed method was validated based on the test results.

Agricultural reservoirs could be damaged by overflow of embankment due to debris flow at torrential rain. In this study, a scale model was created based on collected samples and assumed flow volume from the disaster-affected reservoir, and a practical evaluation method for water level fluctuations within the reservoir was proposed using model and numerical experiments. As a result, sediment was deposited on the upstream side of the reservoir. The debris flow generally flows into the reservoir, and the water level rises. Both the unsteady flow calculation and the water/sediment balance calculation were able to accurately examine the experimental results. In evaluating the overflow water depth, calculation result was obtained on the safe side by using the flow coefficient of water only.