Experiments on the ascent behaviors of nine-spined sticklebacks (Pungitius sp. 1) were conducted in a submerged orifice weir and on an overflow weir in an experimental flume. The ascent behaviors of the fish were identified using a high-speed camera to measure the ground speeds and ascent routes of sticklebacks. The flow velocities in and around the orifice and on and around the overflow weir were measured using a three-dimensional velocity meter and particle tracking velocimetry. Stickleback swimming speed in the ascent route was calculated based on ground speeds and flow velocities. In the experiments with the orifice weir, most sticklebacks passed the middle area of the orifice, where flow velocity was relatively slow. Conversely, in the experiments with the overflow weir, most sticklebacks passed over the weir, where flow velocity was relatively fast. In the experiments with the orifice and with the overflow weir, the swimming speeds of sticklebacks were 8–39 and 9–21 times their body lengths, respectively. The results indicate that many sticklebacks ascend in areas where flow velocities were faster than their burst speed, which is defined as 10 times their body lengths.

  This study aimed to clarify the influence on fish ascent rate of designs and numbers of sloped weirs with V-shaped notches. Experiments were carried out using three types of sloped weir designs with V-shaped notches, with and without orifices. Experiments to compare the effect of the number of weirs were carried out using a further three types of top-sloped weir with V-shaped notches, with and without orifices. Oryzias spp., Carassius spp., and Misgurnus auguillicaudatus were tested in both the experiments. Experiments comparing the designs of weirs suggested that the orifices decreased the ascent rates of Carassius spp. and increased the ascent rate of Misgurnus auguillicaudatus; however, Oryzias spp. was not observed to ascend. Concerning the ascent rates of Carassius spp. and Misgurnus auguillicaudatus, there were no significant differences between the fully-sloped weir and the top-sloped weir. In the experiments comparing the number of weirs, we obtained similar approximate expressions between the number of weirs and normalized indices for ascent rates of Carassius spp. and Misgurnus auguillicaudatus for all weir types. However, Oryzias spp. was not observed to ascend, as was the case in the experiments using the sloped-weir designs.

  This study aims to evaluate groundwater distribution in irrigated upland farming areas with a subsurface dam and clarify its effects on storage ability. A field investigation was conducted in Kikai Island, in southwest Japan, to clarify the topography and groundwater levels. The geological stratum spatial conditions were visualized using Geographic Information System data from existing bore-well surveys, and a numerical model for groundwater analysis in a non-irrigated area with an existing subsurface dam was developed. Model parameters for groundwater analysis, including hydraulic conductivity and effective porosity, were estimated using measured groundwater level data. Using simulated groundwater flow data in relation to the existing subsurface dam, the groundwater storage effects of the dam were clarified and the possibility of enhancing groundwater usage for irrigation was identified. This method for estimating the parameters of groundwater analysis from groundwater level observations could be effective for groundwater development in cases where the stratum characteristic data are insufficient.

  To maintain a reliable agricultural pipeline, it is necessary to predict the degradation of the pipeline's performance over the long term and to systematically implement adequate pipeline renewal. Therefore, based on the data collected and published so far for each type of pipeline (ACP, SP, DICP, VP, FRPM, RC, and PC) a standard long-term accident ratio was verified. Based on accident data and Water Technology Research Center (WaTeR) data, the accident ratios obtained by the predictive equations for pipeline lifespan defined for DCIP, SP, and VP are generally considered to be in agreement. Finally, for ACP, RC, PC, and FRPM pipes unused in water service, a standard accident ratio was established from the accident data and the correction coefficient was established by pipe type and diameter.