Author(s): Koso Mikami; Tomoyuki Noro; Takahiko Nagayama; Tomohiko Furuya; Masaharu Fujita; Takahisa Mizuyama; Takahiro Itoh

Linked Author(s): Takahisa Mizuyama, Takahiro Itoh

Keywords: Sediment runoff management. sediment check dam with shutter. sediment monitoring. bedload

Abstract: The total length of the Joganji River located in Toyama Prefecture in north-central Japan is 56 km. The river has an 18 km-long fan and the bed slope of the river from the source to the river mouth is 1/30, and the river is a quite steep torrent as known in all over the world. Operation of the trial shutter started from 2016, and four flood events were controlled and observed with the movable shutter. The opened shutter was closed when the free surface was below the top of the spillway of the check dam as the flood levels decreased after overflowing the top of the spillway during rising stage of the flood. After the shutter was closed and flooding decreased focused on four flooding, operation of the shutter was performed as follows: (1) Open operation when the free surface reached the downward movable shutter (flow depth: 1.0 m), (2) Open operation when free surface reached the upward movable shutter (flow depth: 3.0 m), (3) Open operation when the free surface reached the middle of four fixed horizontal steel pipes (flow depth is 5.75 m), and (4) without open operation, that means the movable shutter was not closed. Several differences in the active control of sediment runoff appeared during each flood, and data for optimal shutter operation was obtained, because the inflow/outflow of sediment discharge at the dam was calculated using several sensors and temporal variation in the bed of the storage area of the dam was measured.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221713

Year: 2022