2010 Fiscal Year Final Research Report

EFFECT OF RATES OF WEATHERING AND EROSION ON HYDROGEOMORPHIC PROCESSES

Research Project

Project/Area Number	20700668
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Single-year Grants
Research Field	Geography
Research Institution	University of Tsukuba
Principal Investigator	HATTANJI Tsuyoshi University of Tsukuba, 大学院・生命環境科学研究科, 講師 (00418625)
Project Period (FY)	2008 – 2010
Keywords	地形
Research Abstract	This study attempted to quantify long-term erosion rate and weathering rate to unravel the relationship between hydrogeomorphic processes and balance in weathering-erosion system. The results are summarized as follows : (1) Denudation rate estimated from ^<10>Be was compared with that obtained from direct observation in recent 10 years for experimental watersheds in the Ashio Mountain, implying that debris flow with recurrence interval of about 100 years is a dominant hydrogeomorphic process in this area. (2) Long-term chemical weathering rates in steep granitic basins, North Alps are calculated based on TCN method and geochemical mass balance model. The result indicates that physical erosion overcomes chemical weathering if denudation rate exceeds 500 mm/kyr. (3) Ratio of long-term chemical weathering rate to denudation rate calculated from geochemical mass balance model was 74% for gentle granitic basins in Abukuma Mountains. This value is much larger than the reported short-term ratio (17%), implying that chemical weathering plays a major role for denudation in this area.