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In this paper the author tried to know the changes of the river bed in the Oyodo River in the Outer Zone of Southwest Japan. The results of this survey are summarized as follows : <BR>1) Judging from the records of the mean low water level, it can be recognized that since about 1960 the river bed has considerably lowered due to human activities. <BR>2) As to the lowest heights of the river bed, the quantity of degradation in the lower reaches of the Oyodo River since about 1960 as much as in its upper reaches since about 1955 has become increased remarkably. These facts are also recognized in the changes of the mean heights of the river bed and in the annual fluctuations of the amount of deposition or scouring in the river bed. <BR>3) The author was able to point out that there was something. to be directly proportional between the variations of the mean low water level and those of the mean heights of the river bed. <BR>4) Regarding the causes of the degradation of this river bed since about 1955 or 1960, it can be : considered that the effect of gravel mining in the river bed. Moreover, the tractional load which is washed away to the lower reaches becomes decreased due to the construction of sand catch dams. <BR>5) If it had not been for the human activities, for example the gravel mining etc., the annual vertical variations of this river bed would have shown as follows : <BR>Lower reaches : +0.83±1 cm/y.<BR>Upper reaches : +0.74±1 cm/y.
- 日本陸水学会の論文
日本陸水学会 | 論文
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