Abstract
During the Edo period, the Tokugawa Shogunate used two river improvement technologies, named "Kantou-ryu" and "Kishu-ryu". "Kishu-ryu" was developed in "Kishu" (the old name for Wakayama Prefecture). In the northern part of Wakayama Prefecture, the Kinokawa River flowed towards the west, and also created the river terraces. The purpose of this study was to find the origin of the "Kishu-ryu" technology and to research the development of the irrigation water systems on the upper and middle Kinokawa River basins from the end of the 11th century to the middle of the Edo period. The water used for irrigation on the Kinokawa River basins before the Edo period was taken from a small-scale weir across the branch rivers or from man-made ponds.
In conclusion, small-scale development of the irrigational water technologies was introduced by the manorial systems during the Medieval Japan. Subsequently, these systems disappeared gradually by the 16th century. At the end of the 16th century, the irrigation ponds were constructed and repaired by one of the Buddhist priests, named "Saint Ougo". In the Edo period after "Saint Ougo", large-scale irrigation canals and the embankments along the Kinokawa River were constructed by the Kishu clan. On this historical development, this paper found that the irrigational systems of the reclaimed rice fields on the Kinokawa River basins have changed from the development of cross direction into the large-scale development of parallel direction along the Kinokawa River.
