This study investigates the importance of aridity correction when weather data are used for reference evapotranspiration computation. Correction is important when weather data are measured in dry conditions. However, the correction procedure and its impact have not been thoroughly investigated, and such corrections have rarely been applied. This study aims to illustrate the impact of aridity correction, by accepting a FAO’s suggested procedure, with reinvestigating some of the input data and the parameters used. In this study, the aridity correction was applied to five weather station datasets located in the Urmia Lake Basin of Iran, where the basin is in a semi-arid climate. The results of the analysis indicated that the correction significantly improved the reference evapotranspiration estimation, particularly when weather data measured at stations surrounded by dry-type land were used. Sensitivity analysis indicated that the reference evapotranspiration was overestimated by more than 15% or approximately 250 mm yr^-1 without correcting the weather data observed at the dry weather stations. Overestimation occurred primarily during dry summers in the study area. This type of correction is very important for irrigation water planning and management using weather data observed at dry conditions, called ‘non-reference weather data’.

  The Republic of the Marshall Islands has been hit by a drought caused by the El Niño. It is important to secure freshwater resources to sustain people lives in the capital, Majuro. There is a fresh groundwater lens on Laura Island (called Laura Lens) in Majuro Atoll. In this study, the present up-coning situation that has occurred in Laura Lens was investigated. The electrical conductivity (EC) of the groundwater in the monitoring wells to estimate the boundary depth of Laura Lens as well as in resident's shallow wells the boundary location on the groundwater surface, which correspond to an EC of 200 mS/m, was observed. They were interpolated by the depths, coordinates and EC values. Using these data, we estimated the storage volume of Laura Lens from 2010 to 2013. Groundwater observation results showed that the up-corning caused by the severe drought that occurred in 1998 had been observed. It was also found that the storage volume of Laura Lens decreased after the occurrence of up-corning. However, from the trend of the storage volume of Laura Lens, it was clarified that rainwater recharge to groundwater and its pumping volume had been maintained in a well-balanced state. Therefore, it was not necessary to conserve the freshwater lens. However, the follow-up research is expected to obtain further information on the current Laura Lens.

  In order to cope with the increase in water demand in the Fukuoka metropolitan area, the Fukuoka Water Way has been in operation since 1983, supplying approximately one-third of the water demand. Numerical calculations were performed to reproduce the deterrence and resilience against sudden pump stoppage during power outages in long-distance high-head upstream pumping pipelines, and the validity of numerical models of pumps, valves, pipelines, one-way surge tanks was verified through verification with actual measurement data. The numerical model was able to reproduce the sudden drop and rise in pipeline pressure caused by the sudden pump stoppage, confirming the feasibility of evaluating water hammer effects using the numerical model.

  Rice terraces are vulnerable agricultural land in terms of water resources. This study aimed to evaluate the impact of low rainfall on irrigation in terraced rice paddies. For this purpose, we developed a terraced rice paddy water balance model that could be used to calculate the water level for each paddy field. Using this model, the impact of low rainfall on irrigation water was analyzed using index values to represent the degree of water shortage, the number of days where water shortages occurred, and the number of drought days. Data were obtained from ensemble climate prediction members extracted based on the return period of low rainfall. The results have shown that under normal conditions, there was a shortage of irrigation water in all the rice paddies. For each low rainfall, the increase in each indicator value was proportional to the increase at that return period. The increase in the degree of water shortage depended on the method of water intake. However, a discussion based on the distribution of rice paddies in terraced rice paddies showed that the water management during low rainfall periods was different to the calculation process used in the model.