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

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 26Al 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 deg. This result suggests that the basin topography is not in a morphometric steady-state, but is evolving dynamically.