| This is the first quantitative study investigating citizen-based river groups throughout Japan. Recently, river management faces multiple challenges, such as increased risk of disasters, the ageing of existing river protection facilities, and the growing awareness of environmental issues. However, funding for river management has been reduced because of a rapidly ageing and declining population. In this context, citizen-based river groups may be expected to cooperate with river managers to sustainably manage rivers. There are hundreds of river groups in Japan, but there are few reports detailing their information at a national level. The purpose of this study is to quantitatively investigate citizen-based river groups in Japan by analysing the following: (1) the number of people and amount of time they invest in river-related activities; (2) what kind of activities they do; and (3) when and where these activities occur. We investigated 207 river groups using questionnaires and interviews. Our results suggest that the total active mass of river groups accounts for 2% of that of river managers. Furthermore, the economic value of river group activities is estimated at 13% (65 million yen) of the official cost of river management in intangible sectors. |
