[H-TT30] GEOMORPHOLOGICAL APPLICATIONS OF HIGH-DEFINITION TOPOGRAPHY AND GEOPHYSICAL DATA IN THE ANTHROPOCENE

[HTT30-P04] Drainage density and relative relief for the Kitakami Mountains, Japan

*小口 高¹ (1.東京大学空間情報科学研究センター)

キーワード：水系密度、起伏、流路、地形計測

Drainage density has been frequently used as a parameter representing terrain texture. My previous study investigated the relation between drainage density and relative relief for mountains in the Matsumoto region, central Japan, based on geomorphometric work using contour maps and raster digital elevation models. The result indicates that the density of drainage lines along deeply incised channels decreases with relative relief, whereas that of drainage lines along shallow hollows increases with relative relief, and the total drainage density tends to be constant irrespective of relief. These observations were attributed to frequent slope failures leading to the decline of channel banks. The present study applies the same geomorphometric methodology to four mountainous watershed in the Kitakami Mountains, Northeast Japan. The results indicate that the relations between drainage density and relative relief for deep and shallow channels are similar to those for the Matsumoto region, confirming the applicability of previous findings. However, the density of drainage lines along shallow hollows for the Kitakami region tends to be higher than the Matsumoto region for the same relative relief, especially when relative relief is large. This may be ascribed to weaker rainfall intensity in the Kitakami region, which limits the integration of shallow channels by small-scale shallow failures on mountain slopes near ridges.