A Field Study on Revival Conditions of Covered Rivers in Tokyo's 23 Wards

With the rapid urbanization of Tokyo, many rivers were covered with concrete, mainly to provide open spaces or roads and for the development of public sewerage lines, etc. Recently, there has been renewed interest in the importance of rivers in cities for the improvement of urban environment problems, e.g., heat islands, as well as to provide recreational spaces close to rivers for city dwellers. It is important to arrange green spaces along with access to rivers to improve the urban environment. This study was carried out to investigate the possibility of reviving the covered rivers in Tokyo's 23 wards. An evaluation index was made based on field research of the present condition of covered rivers: i.e., conditions of open spaces above covered rivers, water supply, and reservoir setting to rewater the rivers. Of the covered rivers examined, 0.7% qualified for revival with respect to all of these physical conditions. Research into the volume of sump water is expected to provide new methods for reviving covered rivers and the percentage of revival may increase.