To stabilize the capacity of the downstream detention pond, the recommendations of upstream two adjusted check dams in Dongmen Creek, Hengchun, Taiwan are provided. Moreover, to investigate the effects of various types of check dams on sediment transport and fluvial bed variations, the flume experiments were used. The results show that as the horizontal bars in the second dam are gradually removed, the elevation decreases and the knick points move upstream at a constant velocity. However, the first dam causes sediment deposit that flushed from second dam,and the changes in elevation and knick points do not significantly affect the trend between two dams. In addition, large
amounts of sediment transport causes substantial slope change during the initial stages of adjusting a check dam. The sediment transport and slope stabilize when half the number of horizontal bars are removed from the second dam.
Therefore, gradually cutting down the check dam can slow the change in knick points and prevent the disaster caused
by large amounts of sediment being suddenly deposited in the river.
Key Words: adjusted check dam, cutting down, fluvial bed variation, knick point, sediment transport.