EFFECT OF RATES OF WEATHERING AND EROSION ON HYDROGEOMORPHIC PROCESSES

本研究试图量化长期侵蚀速率和风化速率，以揭示水文地貌过程与风化-侵蚀系统平衡之间的关系。结果表明：(1)对阿尾山试验流域近10年的直接观测结果与^<10>Be估算的剥蚀率进行了比较，表明泥石流是该地区主要的水文地貌过程，其重现周期约为100年。(2)基于TCN方法和地球化学物质平衡模型计算了北阿尔卑斯陡峭花岗岩盆地的长期化学风化速率。结果表明，剥蚀速率大于500mm /kyr时，物理侵蚀作用大于化学风化作用。(3)根据地球化学物质平衡模型计算的阿布库马山温和花岗岩盆地的长期化学风化速率与剥蚀速率之比为74%。这一数值远高于已有报道的短期比值（17%），表明化学风化作用在该区剥蚀中起主要作用。

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.