| Abstract |
The purpose of this paper is to anaiyze topographical control concerning the formation of deposition in mountain streams. An analysis of the deposition with mud-flow by topographical control is carrie...d out with consideration given to the foIIowing: width, incline, bending angle and sinuous angle of stream. Summary of the results are as follows. As regards the width of the stream bed, bed depositions are formed with a large-scale mud-flow in the wide sections, and a smaII-scale mud-flow in the rela tive narrow sections, which are scoured among the terrace (wide deposition) or the vaIIey slope. In the width over th.e limit, the deposition volume is caused by not the width but by the length of the stream. Concerning the sinuous angle of the stream bed, in streams with a large sinuous angle, depositions are broken otT and only large stones are suspended. From these facts, the sinuous section with a large often function as "the joint spot" concerning the formation of depositions. As regards the incline and the bending angle of the stream bed, largescale deposition are formed in the gentle slope on the average, and small-scale depositions are formed in the bending section with a large angle. In the stream which has a wide, bending and sinuous section, there is high frequency the scours and depositions because of the intensive conditions. The more the condition for deposition is intensified, the more the stability(the period of scours and depositions) of the deposition is shorten, because the deposition with mud-flow frequency occur in the identical section. Generally speaking, mud-flow in the stream bed is selectively conditioned by topographical control in responce the energy of movement.show more
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