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Drainage Density and Relative Relief in Humid Steep Mountains with Frequent Slope Failure
Author(s) -
Oguchi Takashi
Publication year - 1997
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/(sici)1096-9837(199702)22:2<107::aid-esp680>3.0.co;2-u
Subject(s) - geology , drainage density , drainage , digital elevation model , terrain , channelized , erosion , drainage basin , geomorphology , landslide , elevation (ballistics) , channel (broadcasting) , hydrology (agriculture) , structural basin , geotechnical engineering , geometry , geography , cartography , remote sensing , ecology , telecommunications , mathematics , engineering , computer science , electrical engineering , biology
Previous studies in Japanese mountains have shown that drainage density ( D ) correlates negatively with relief ( R ) and the erosion rate ( E ), whereas elsewhere both R and E correlate positively with D . To investigate the inconsistency, this paper compares two types of D–R relations for eight mountain river basins in central Japan. R is computed from a digital elevation model for 1109 morphometric samples of area 0·5 km × 0·5 km. Drainage networks in these cells were first constructed by map criteria applied previously in Japan — deeply notched V‐shaped contours with an angle <53°. The resulting D correlates negatively with R , confirming preceding studies. When drainage lines along shallower hollows were added, however, the calculated D essentially constant. These relations arise from active landsliding in high‐relief terrains, which has eroded steep channel banks into gentle ones. The decline of channel banks with increasing R is accelerated in terrains underlain by soft rocks, because of rapid erosion. The constant D for all the drainage lines indicates a uniform frequency or spacing of ridges and hollows on hillslopes in rugged humid mountains. Because the D–R and D–E relations for Japan reflect a uniquely Japanese physiographic setting characterized by frequent landsliding, they differ from those relations for other regions where channelization by gullying predominates. © 1997 by John Wiley & Sons, Ltd.