Abstract
Authors have investigated the characteristics of the land-form and the land-use classification about landslides on the agricultural land at the catchment area of Sawada reservoir in Zennyu district, Ozo-cho, Kita-ku, Kobe city.
The results obtained are summarized in the following.
1) On the surface we have found the reaces of the landslide movement, collapses, crevices, depressions, and theirrigation reservirs which are the ruins of depression.
2) We have found some crevices at the higher part of collapses area. It is considered that the crevices will become the cause of the configurational transformation in future.
3) When we analized the slope angle of the surface adopting the check method, the mean slope angle was 12°48'. A surface slope from 0°to 13°holds 61% of the whole area.
4) Judging from the cross-sectioning of the terraced farms, the average slope is 5°4', and average of profile-leveling is 6°47', which was quite gentle.
5) The irrigation ponds tiered on the ridges of the east and the southeast. There were many irrigation ponds, each small in area, which were poorly distributed from the point of view of function. And such distribution as tier ponds on the ridge is one of the characteristics of landslides in the agricultural land of the Kobe Group.
6) The configuration on the surface show up that we can distinguish between valleys and ridges at the downside of the slope and indistinguish them at the upside.
7) There were many small paddy fields and the area of those which were distributed as terraced paddy fields were under 200m2. On account of the leakage of the water and so on, some paddy fields were changed into dry fields by reclassification of land.
8) The ratio of the area of cultivated farms to the area of levees was 5: 3. The area of levees was wide in the extreme; therefore the proportion of land under cultivation was very low.
9) In the parts of the valley there were many collapses of levees and the negrected fields. But the parts of the hill were comparatively stable. The partial collapses caused by the movement of the landslides were small in scale. They were small in area, narrow in width, and low in height. But the angle of the inclination of the partical collapses was large.
10) The landslides have the long time elapsed in this catchment area, the velocity of the transforming movement of the surface is slow, and the transformation is gradually going on.
11) It is necessary to established rational irrigation policy for increasing the productivity of the land. It is necessary to carry into effect a land adjustment project adapting an inclined plan for increasing the rate of cultivation and for effectively putting into practice the plan of land conservation.
