The frequency of heavy rain is increasing due to global climate change in many countries, thus the storm water management has become an important social issue in urban and suburban areas. At the same time, the improvement of past flood control facilities, such as artificial levees and underground sewage, has led to the loss of wetland habitats and biodiversity and has caused another social problem. The construction and management of retarding basin at the place adjacent to the river can contribute not only to preventing flood damage but also to conserve biodiversity of wetlands if appropriately designed. Furthermore, by devising programs that make use of the space of the retarding basin wetlands, it is possible to simultaneously realize flood control, biodiversity conservation, and utilization. I conducted a research on the flora of soil seed banks as an educational program in a special school for the handicappers in Asahata wetland, Shizuoka, Japan. Furthermore, the impact of this program on psychology of the students by questionnaires and interviews.
We found totally 47 species from soil seed banks of the Asahata wetland. The species density of the seed bank was significantly higher than that of the above-ground vegetation. Six species, Penthorum chinense, Persicaria foliosa var. paludicola, Monochoria korsakowii, Isoetes japonica, Chara braunii, and a species of Nitella, observed in the seed bank study was endangered species which were listed in the national red list. These plants and soil containing the seeds were used as materials for vegetation restoration of the wetland. Positive impressions were obtained from participating students. From the soil that looks as if nothing at first glance, the process of various plants appearing and growing over time had a special effect on the psychology of the students. Students who participated in the program tended to participate positively in the management of wetlands such as mowing. A virtuous circle was born by feeding back the result of the biological survey in the vegetation managed by the student in the environmental education program. It was suggested that wisdom of human welfare and conservation of biodiversity can be compatible by using a retarding basin wetland which is a flood control facility wisely.