Author(s): Haruki Watabe, Kazuhiko Kaitsuka, Minoru Sugiyama, Hirohisa Muramatsu, Takahiko Nagayama, Hiroshi Ogawa, Tsutomu Miike, Ayumi Miyamoto, Yuuchi Yamada, Takahiro Itoh, Takahisa Mizuyama
Linked Author(s): Haruki Watabe
Keywords: Bed variation, overlapping height, distance between dams, Sabo facilities, weir
Abstract: Two patterns of bed erosion are in downstream reach of the Sabo dam, one is the local scouring by an overflow in between main and counter dams, and the other is bed erosion due to imbalance of sediment transportation along downstream reach of the counter dam. Apron and counter dam are usually applied for countermeasure of erosion in downstream reach of the dam. More effective countermeasure in downstream reach is desired, because a horizontal distance and an overlapping height of the Sabo dam are determined empirically in Japanese standard of Sabo dam design. In present study, influences of Sabo facilities on the bed variations in downstream area of the dam are discussed experimentally for combinations of overlapping height, horizontal distance between dams and apron. Bed erosion depth is not noticeable around the counter dam, if the counter dam is set behind main dam such that the over flow from main dam can attack on the top of the counter dam in case of large magnitude of floods. Differences of overlapping height affect bed erosions in long downstream reach of the counter dam, and do not affect the sediment runoff at downstream end. Smaller overlapping height is desired to protect bed erosions around the counter dam. Apron protects bed surface between main and counter dams in small or middle magnitude of discharge in present flume tests, because the overflow attacks on the surface of the counter dam in large magnitude of discharge
Year: 2017