Classification of villages and rivers in mountainous area based on geology and topology, and problems of river management in the society in population decline

Abstract

In the society of population decline, the activities of the local residents are considered to be decreasing. When activities related to river management decrease or disappear, some rivers will change their conditions. It will be essential to consider what local government should do despite the financial difficulty. In this research, the condition of mountainous rivers and villages around Kanto region is investigated and classified into six groups based on the geomorphological conditions. The difference of the river channel shape and sediment transport, which are affected by geomorphology, affects the characteristics of disaster and water use type that decide location of villages and the way of river utilization. By interviewing to river managers, it was clarified that the biggest problem of mountainous rivers is thick growth of vegetation. The problem is remarkable in some specific geomorphological condition, but the response of local people is different because of the difference of accessibility to the river.