Time-oriented and hierarchic characteristics of a road network in a watershed area using network analysis
2007
Nakazawa, M.(Forestry and Forest Products Research Inst., Tsukuba, Ibaraki (Japan)) | Suzuki, H. | Oka, M. | Tanaka, Y. | Yoshida, C. | Kondo, K. | Matsumoto, T.
We analyzed the time-oriented and hierarchic characteristics of a road network in a watershed area using network analysis. Toei and Shitara towns (upper stream), Horai town (middle stream), and Shinshiro city (lower stream) in the Higashimikawa Forest Planning Area in Aichi Prefecture were chosen as our study areas. We compared their respective changes in the indices of network analysis from 1990 to 1999. In addition, the target values of the indices for connectedness were examined, and the road density required to achieve them was calculated. As a result, it was found that some of the forest roads constructed over the past 10 years were circular, and contributed to the development of the road-network. On the other hand, strip roads did not contribute much to their development, although the effects of the reduction of mean entire-forest access distance to the nearest road and the increase in circular roads were confirmed. The indices we used in this study changed significantly from the lower-stream toward the upper-stream areas, and we found that the characteristics of the road-network were affected by the process of determination of geographical continuity. The index alpha=20% was derived as the target value to develop road-networks, and the required road density was calculated to be around 4 m/ha in mountainous areas.
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