NUMERICAL ANALYSIS OF TURBIDITY AND ITS OCCURANCE IN SMALL MOUNTAINOUS BASIN

lt is well known that turbidity increases during snowmelt season and storm rainfall of summer season in river flow. Although the reason for the highest degree level of turbidity during snowmelt season is not clear. M. Yamanashi et al. (1995) suggested that the high degree level of turbidity during snowmelt season depends on surface flow on amountainous basin and the turbidity during summer season is mainly caused by a shearing force between river bed and river flow. There is a possibility to analyze runoff mechanism through the observation of turbidity according his suggestion. The maximum snowmelt which is equivalent to rainfall intensity is about 3 to 4 mm/hr. 0n the other hand，such rainfall intensity, 3 to 4 mm/hr during summer season does not cause so high turbidity in river flow. This paper studies the mechanisms of the turbidity increase in mountainous river flow through field observations and theoretical analysis. The conditions of turbidity variation by using turbidity occurrence and also inverse estimation method of turbidity occurrence are clarified under the assumption that soil-water content plays an important role