Water often presents a threat to humankind, but is often regarded as a resource.From the former viewpoint,we study and educate students about natural disaster science, especially the science of water-related disasters. From the latter viewpoint, we study and educate students about water resources and water environment engineering. For each hydrological process, we specifically examine precipitation and flooding, especially statistic and stochastic analyses of precipitation and flood. Research areas we treat are hydraulic engineering, river engineering, hydrology, meteorology, and seismology.