A study on mehcanisms and effects of river runoff in cold region: Fundamental systems of soil, water and organism in cold region (4)
1997
Yamanashi, M. (Senshu Univ., Bibai, Hokkaido (Japan). Hokkaido Coll.)
It is well known that turbidity increase during snowmelt season and storm rainfall of summer season in river flow. Although the reason why the highest degree level of turbidity during snowmelt season in not clear. This paper aims to study the mechanisms of these phenomena through field observations and the theoretical analysis, M. Yamanashi et al. (1995) suggest that the high degree level of turbidity during snowmelt season depends on surface flow on the mountainous basin and turbidity during summer season in mainly caused by a sheering force between the river bed and river flow. There is possibility to analyze runoff mechanism through the observation of turbidity according his suggestion. As basin covered by deep snow during snowmelt season, it is impossible to observe directly ground surface. Only surface flow from gaps near riverside between ground surface and the bottom of snow pack can be observed. The maximum snowmelt intensity, which is the equivalent of rainfall, is about 3 to 4 mm/hr. On the other hand, such rainfall intensity, 3 to 4 mm/hr during summer seasons does not cause so high turbidity in river flow. This paper clarify the conditions of turbidity occurrence due to surface flow, that is runoff component, during snowmelt season and summer season under assumption that water content plays the important role
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