Denudation rates and threshold slope in a granitic watershed, central Japan

Abstract

Abstract This study examines the relationship between long-term denudation rates and mean catchment slope in a mountainous watershed in central Japan. The denudation rates were determined from 26 Al measurements for fluvial sediments obtained from the outlets of the whole basin and nine sub-catchments. The denudation rates ranged from 200 to 2000 mm kyr −1 , increasing exponentially with increasing mean slope of the catchments, but declining abruptly for the catchments with mean slope above 38°. This result suggests that the basin topography is not in a morphometric steady-state, but is evolving dynamically.