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.

This study empirically clarifies how prior conditions and information-seeking behavior influence knowledge acquisition and attitude formation in the pre-adoption stage of Smart Farming Technologies (SFT) within community-based farming organizations, using a comparative analysis of adopter and non-adopter groups. The results indicate that larger cultivated areas and greater external engagement increase opportunities to observe local SFT use cases and to hear favorable peer evaluations, thereby promoting knowledge acquisition. Moreover, adopters exhibit strong expectations for labor saving, workload reduction, and the engagement of unskilled or younger operators, whereas non-adopters demonstrate pronounced concerns about machinery size incompatible with their field conditions. High-cost burden emerged as a common concern across both groups. These findings suggest that effective diffusion policies should support machinery sharing through inter-village collaboration, expand subsidies for outsourcing core operations, provide field visits and trial deployments tailored to regional characteristics, and encourage the development of compact, labor-saving machinery designed for small-scale or disadvantaged areas.

In water source heat pump systems, where the heat source/sink is in running water, a heat exchanger is installed in the waterway and heat is extracted from the running water by the heat pump and used in greenhouses. When a heat exchanger is installed in an irrigation canal for a long period of time, there is concern that the surface of the heat exchanger will be coated by aquatic plants and that trash will adhere to the heat exchanger and accumulate in the irrigation canal. In this study, the heat exchanger was covered with polyethylene sheeting to replicate a heat exchanger covered with trash. An experiment using a heat pump system composed of that heat exchanger was conducted in a waterway in the experimental facility to evaluate the effect of trash on the heat exchange characteristics and energy consumption efficiency (SCOP) of the heat pump system. The results show that when the heat exchanger was covered with trash, the heat transfer coefficient was reduced by up to 20.5% (at a flow velocity of 0.10 m･s^-1) at flow velocities between 0.05 and 0.70 m･s^-1, compared to the condition without trash. However, the effect on the quantity of heat and SCOP was relatively small, and when the flow velocity was above 0.90 m･s^-1, the effect was almost negligible.

This study conducted the questionnaire survey to clear the determinants of resident's participation for maintenance work of irrigation canal in Kanaya, Kitaochi and Amago district, Kora town Shiga Pref. The model that both maintenance work of irrigation canal on behavior and action, and determinant of preference for irrigation canal is used. As a result, factors that strongly influence resident's participation for maintenance work are that resident can judge that maintenance work is useful for their district, irrigation canal is managed, water in irrigation canal is clean and access to irrigation canal is easy. In addition, native-born residents were strongly influenced that continuation of maintenance work by residents, and residents born outside the town were strongly influenced by their awareness of neighborhood.

The mechanical properties of concrete are deteriorated by the development of cracks with a change in the stress-strain curve. In this study, concrete core samples were taken from in-service drainage facilities with developed cracks. The geometrical properties of cracks are evaluated by Acoustic Emission (AE) generation behavior based on compressive stress field. AE is quantitatively evaluated by SiGMA analysis, which evaluates the source location and its dynamic motion. The geometric properties of the cracks are visualized by X-ray CT and the crack angle relative to the loading direction is quantified. As a result, low frequency AE events are detected near vertical cracks. High frequency AE events are not detected same trend, which are located near horizontal cracks. It is presumed that this difference is due to the expansion of existing cracks and the propagation of cracks occurring depending on the crack angle. These results suggest that the crack propagation behavior under compressive stress changes depending on the crack angle.

Understanding the phreatic line (groundwater level) is crucial to evaluating the stability of small earth dams. This paper estimates the phreatic line of a small earth dam using Ground-Penetrating Radar (GPR). Firstly, scans with GPR in the longitudinal direction of the small earth dam were conducted to obtain the relative dielectric constants from the groundwater levels derived through borehole surveys. Comparisons were made with the relative dielectric constants measured by the Time Domain Reflectometry (TDR) method during this process. Subsequently, GPR measurements were carried out in the transverse direction using the obtained relative dielectric constants to estimate the phreatic line. The estimated phreatic line was compared with the results of a saturated-unsaturated seepage flow analysis to evaluate the accuracy of the estimation. Additionally, consideration was given to estimating the infiltration line using a combination of the GPR and TDR methods without relying on borehole survey results.