The Fundamental Studies Concerning the Land Development Works in the Lower Area of the Kino-Kawa River Plain

Abstract

The author, having investigated geographically the formation of land surface feature and the development of land utilization concerning plain, of the lower Kinokawa, Wakayama District, has made here a summary of various findings. By using aerial photograph, the area was surveyed though so far little investigation has been done into these matters mentioned-above and more data are needed on these points.The results obtained are as follows:1) The plain situated on the lower Kinokawa is classified into eight landform types. The floodplain lies in the upper region than the area that links Minami-narukami where is on the left bank of the Kinokawa river with Umehara on the right bank. The author has been further grouped the area into two large classes: The upper and lower surfaces. The lower surface is observed at the foot districts along a mountain, as compared with piecemeal distribution of the upper one except the lower region as a whole.The lower surface of delta is looked at the back area of beach ridge nearest to the coast and the district where is the junction area the river Waka and Wada, in contrast to the upper surface of delta on the both banks of Kinokawa river mouth is widely distributed round the sand mound where Wakayama Castle is built, and then the beach ridge or the sand dune branches off three main courses along the shore line. This indicates their growing process of the shore line.2) It may be permitted to arrange the channel race as seen on the plain in three classes; a) point bars are observed upon the district where floodplain shifts towards the delta, and b) the floodplain score routes are studded with the floodplain for the most part. c) abandoned courses distribute a bit continuously extending over the floodplain to the delta.3) Though one-time Kinokawa river wears away foot edge of the northern fan land, however, after that that gradually turns off the course to the south. Considered the tendency of the course changes in the historical period, the river is turning the course to the south on the upper area and to the north on the lower one revolving around the Nakasu- village.From prehistory to ancient times, the river Kinokawa goes through nearly the present Waka-gawa river course. But about A.D. 1, 000, the main course emptied into the sea from the Kitajima- Village to the oura via the Nezumi-jima. The author supposes the present Kino-kawa river course was formed in the years of 1, 600 or there about.4) On the land development work it was not considerably active in the middle age, however, in the ancient times the land utilization was carried out widely extending over the floodplain forward the delta. In the recent times there are two development works: a) the land-utilization of tidal marshy land and sand dune area, and b) re-development of ex-cultivated land buried by the river activity.Viewed the aerial photograph and archives, the developmental process on this plain is not so easy as we imagined. According to the archives, devastated field of the cultivated land comes to 3-4 times in the Matsushima and its neighbourhood, in comparison with the landscapes of development works in the ancient times are left in the district along the terrace cliff of the right bank and in the Iwahashi hill lands west of left bank.