Understanding drainage basin systems

"Landform is an environmental factor which greatly influences water environment and wildlife habitat. On the other hand, it is a natural condition which provides both strong limitations and large possibilities to human lives. This paper describes how we can understand local characteristics and systematic structures of drainage basins by careful study of landform. As a concrete example, a landform classification map and a geologic map of Asakawa River basin of northern Nagano Prefecture in central Japan have been compiled from available publications, photogeologic interpretation, and route surveys. I further analyzed the land use of the area from the past to the present and its relation to geographic and geologic features. The landform is the form of the unevenness of earth's surface and it is continuously changing. The landform has two characteristics. One is the characteristics of form, and the other is the characteristics of geomorphic processes. In the past natural history and human history were explained separately because of the difference of interest and difference of time scale. However, integrated analyses incorporating various temporal and spatial axes are indispensable for understanding the structure of the environmental characteristics and the environmental basement (geoscientific environmental base) of the drainage basins. Time-series understanding of mutual interaction between landform-geology and natural and social environment would provide very effective insight for the above purpose. Relevance and time-space changes of all environmental elements must be clearly understood in order to plan reasonable management of the drainage basin systems. Various views of the people of locality must be adjusted for realizing appropriate drainage basin management and analytical results presented above will undoubtedly form the basis for broad agreement regarding the drainage system management."