Abstract
The distribution of a ditch around a paddy field in the Isawa alluvial fan was investigated and considered. The lattice-like waterway network was accepted in the northern flat area. Among those, ditches of ground material were an average of 135.5 m/ha (N=4). In a little rolling southern past area, although regularity was not accepted in the distribution form of a ditch, ditches of a ground material showed an average of 196.6 m/ha (N= 3) and a high value. The wide ground ditches with the flow, which becomes important in the scene and habitats in the spring, existed mostly (25-57 m/ha) in the southern area.
