In recent years, because flood damage has become more frequent and because precipitation is projected to increase in the future, River Basin Disaster Resilience and Sustainability by All efforts have become an urgent issue. For this study, an internet-based questionnaire survey was administered to clarify the level of awareness of flood control policies on a nationwide scale. The questionnaire survey revealed that 73.1% of respondents felt that flood damage has increased in recent years, reflecting many people's feeling that flood damage risk is increasing. However, about half of respondents were not at all familiar with the new flood control policy concept. Moreover, only 4.9% of the total respondents were familiar with the policy concept. Awareness of the actual menu of River Basin Disaster Resilience and Sustainability by All was found to be low.

　Estimation of the return level of daily rainfall commonly employs the "annual maximum series" (AMS) method. However, the sample size of annual maxima is usually very small. Moreover, if the sample includes extremely large annual maxima values, then these few extreme data affect the accurate estimation of the return level and return period. The meta-statistical approach proposed in recent years enables more robust estimates than the AMS method because estimation is done with a large sample. For this study, we evaluated the accuracy of quantile estimation of observed rainfall data and rainfall data simulated using the Compound Poisson Model by application of the Meta statistical Extreme Value (MEV) distribution and the Simplified Meta statistical Extreme Value (SMEV) distribution. Additionally, we estimated the relation between the fitness of the probability distribution to daily rainfall and the accuracy of quantile estimation by adopting multiple daily rainfall probability distributions. Results indicated that the different sample sizes of daily rainfall in both distributions affect the accuracy of quantile estimates at high non-exceedance probabilities because of the sample size of daily rainfall used for parameter estimation. That sample size affects the number of extreme value samples. Furthermore, the relation between the sample dispersion, depending on the sample size of daily rainfall and the goodness of fit of daily probability distributions, affected the quantile estimation accuracy.

　In Tokyo, it is reported that certain springs have been depleted temporarily since the late 2010s in accordance with long-term increase in temperature and decreased relative humidity. Among the springs in Tokyo that the authors have been observing since 2005, the spring at Hikawa Shrine (Shinagawa Ward) has also been depleted frequently during winter (dry season) since the late 2010s. For this study, daily precipitation and potential evaporation during April 1972 – December 2023 at the meteorological station "Tokyo" of the Japan Meteorological Agency were used as inputs, then the groundwater runoff for the period mentioned above was calculated using the three-layer tank model. Less runoff occurred when the spring at Hikawa Shrine became depleted, as in winters of 2017, 2019, 2021, and 2023. Although the potential evaporation in February showed an increasing trend (p < 0.05), long-term trends of precipitation and groundwater runoff during January−March were not significant (p < 0.05). Lower runoff during these months was observed frequently in late 2010s and early 2020s, which might have led to depletion of the spring at Hikawa Shrine. This phenomenon should therefore be considered from the perspective of interannual variation of the climate rather than long-term climatic changes.

　The land of Iran is divided by the Alborz Mountains and the Zagros Mountains. Each region has difficulties of water resource management attributable to different factors. The southwestern side of the Zagros Mountains, which is presumed to be rich in water resources, faces challenges in securing drinking water because of deteriorating water quality. Moreover, in the severely arid region of the northeastern side of the Zagros Mountains, industry is supported by water delivered from other basins. Nevertheless, challenges posed by water resource management in the region have not yet been resolved. New water supplies invariably create additional demand for water. For addressing water resource issues in Iran, demand-side countermeasures must be pursued. Especially, efficient water use in the agricultural sector, which consumes about 90% of water resources, is expected to be effective.