Classification of rivers based on fluvial land forms and debris transport processes in Yaku Island, southern Japan.

在形态计量分析和实地考察的基础上，对日本南部尖阁列岛的地形条件、碎屑产生和搬运过程进行了探讨。日本山区的平均海拔高度与平均地形高度呈显著正相关。雅库岛的最高点在这条回归线附近绘制，表明该岛的地形足以承受其海拔高度。雅库岛中部地区是海拔最高的地区，其地势低于其他地区。雅库岛在低海拔地区的起伏度很高，在高海拔地区的起伏度很低。在海岸的高起伏区，有陡峭的山谷。在岛中部的低起伏区，低起伏面分布在山脊上。在通过大起伏区的上中游，河床上填满了最大直径为3-10米的巨型砾石。随着河道坡度的减小，最大粒径向下游逐渐减小，说明这些巨型砾石的输送受分选过程的影响。在这些河段与干流汇合的支流中，有许多滑坡的伤痕。在交界处，这些支流在干流的谷底发育冲积锥体。河床和冲积锥的沉积物包括几米大小的砾石。雅库岛独特的地貌条件可以归因于该岛的隆起特征。巨大的区块产量是由于地质特征所致。这些地块有时在与干流的支流交界处形成滑坡坝。大规模的泥石流或洪水，由支流源头的山体滑坡或大坝决口引起，运输了如此巨大的砾石。

Based on morphometric analysis and field survey, the relief condition, debris production and transport processes of Yaku Island, Southern Japan are discussed. Mean altitude and mean relief derived from Japanese mountains show a strong positive relationship. The highest point on Yaku Island plots near this regression line indicating that the relief of the island is high enough for its altitude. The relief in the central area of Yaku Island, which is the area with the highest altitude, is lower than in other regions. Yaku Island has very high relief in lower altitude areas and very low relief in higher altitude areas. In the high relief areas of the coast, there are deep valleys with steep slopes. In the low relief areas of the central part of the island, low relief surfaces are distributed on the ridges. In the upper-middle reaches through the large relief area, huge gravels, whose maximum diameters are 3-10m, fill on the riverbed. Gradual downstream decrease of maximum diameter according to the decrease of channel slope shows that these huge gravels were transported being affected by sorting process. There are many landslide scars in the tributaries which join the main stream in these reaches. At the junctions these tributaries develop alluvial cones on the valley floor of the main stream. The deposits of the riverbed and the alluvial cones include several meters size gravels. The distinctive relief conditions of Yaku Island can be attributed to the uplift characteristics of the island. Huge block production owes to the geological characteristics. These blocks sometimes formed landslide dams at the tributary junctions with the main stream. Large debris flows or torrential floods, caused by landslides in the tributary heads or burst of the dams, transported such huge gravels.