Page - 488 - in Book of Full Papers - Symposium Hydro Engineering

the individual cross-sections, using the following equation (Hoey and Sutherland, 1991):         1 1 50.01 1 2 1 2 2/ xx xxzz BRI n ii n i ii                  (14) wherex denotes the transverse distance from the left bank to the i position, and z is the difference between the bed elevation at the iposition ( iz ) and the mean bed elevation. Fig. 8 shows the change of BRI for each run. BRI increased in both Runs-1 and 2 with time. BRI was great in the areas where the bed scoured and the sediment deposited, indicating that the change in the bed elevation was significant and dynamic. BRI was greater in Run-2 where discharge was 15.13 m3/s than in Run-1 where discharge was 9.00 m3/s. In addition, BRI was greater at the 1,100 m and 1,400 m downstream at No. 2 than at the 400 m and 600 m at No. 1. This showed that a higher discharge enhanced the dynamics of the bed with the sediment supply upstream, and that the river was more dynamic at the 1,400 m downstream at No. 2 than in the immediate downstream of the dam, being affected more by the sediment supply. 5. CONCLUSIONS In this study, a numerical simulation has been conducted to investigate the efficiency of the plans as a preliminary study. The effect of sediment supply was evaluated in the Naeseongcheon Stream under discharge conditions that were dependent on the dam operation. The sediment supply location candidates determined as a riffle or as a curved region where the secondary flow is formed to effectively perform sediment supply. The bed elevation in the immediate downstream of the dam decreased over time. In addition, as time passed, the sediment pulse scoured and moved to the downstream of the channel, and then deposited at positions where the flow velocity decreased. BRI, representing the dynamics of the bed, increased with time, and was found to be greater in the channel downstream than upstream. In addition, as discharge increased, BRI increased because the higher discharge 488