Since the beginning of the Anthropocene epoch, as a result of human activities strongly affecting the global environment, numerous water-related difficulties such as floods, droughts, and conflicts have emerged worldwide. To understand and predict these effects and difficulties, "socio-hydrology" was established as an empirical discipline to elucidate the dynamics of human–water interaction in an integrated manner. About a decade has passed since this new discipline was established. Although the overall picture and framework of socio-hydrology is gradually emerging, the challenges and possibilities of interdisciplinary water research are becoming apparent through collaboration among hydrologists and humanities and social scientists in the field of socio-hydrology. This study reviews developments of socio-hydrology to date and the challenges and possibilities for interdisciplinary water research identified in this field. The findings provide a perspective for the promotion of interdisciplinary water research in Japan, pointing out challenges of interdisciplinary water research including a "lack of common language," "differences in scientific philosophies among disciplines," and "scale issues of time, space, and organization.” To address these issues, we proposed "value systems," "governance," "culture," and "history" as research frames for advancing interdisciplinary water research in Japan and Asia.

　In two-dimensional planar simulation of surface water flow using a structural grid, quasi-depressions of certain kinds which do not exist in actual terrain occur. For this study, such depressions are named "four-neighborhood depressions." The potential maximum storage capacity because of these depressions is investigated for a mountainous area. Results showed that a lower resolution of DEM is associated with greater amounts of storage, and that most storage occurs in cells corresponding to river channels. The analysis was also conducted for a flat land using high-resolution DEM. Results showed that although the storage caused by four-neighborhood depressions spreads over the entire area: its depth is shallow. Therefore, its influence on the distribution of inundation depth as predicted by flood simulation would not be large for shallow depressions.