Seite - 484 - in Book of Full Papers - Symposium Hydro Engineering

(a) Initial bed (b) Time= 0:04 (c) Time=0:18 (d) Time=1:06 Fig. 2 Comparison of longitudinal bed changes between numerical and experimental results: times are written as (hour:min). 4. ANALYSIS OF RIVER CHANGES BY SEDIMENT SUPPLY IN NAESONGCHEON RIVER DOWNSTREAM OF YOUNGJU DAM 4.1 NUMERICAL CONDITION To supply sediment effectively for improving the river environments at a dam downstream, the spatial range and location, the sediment supply method, and the quantity and size of the supplied sediment should be determined. Locations of sediment supply are determined as a riffle with a sufficient flow where the tractive force may be easily secured, or as a curved region in which a secondary flow is generated to increase the effect of the sediment supply and improve the river environment. The numerical model was applied to the Yeongju Dam downstream. The Yeongju Dam is located at the Naeseongcheon River upstream, which is the first tributary of the Nakdong River (Fig. 3). The curved regions, No. 1 and No. 2, were chosen as the sediment supply locations (Fig. 3). Secondary flow at meandering channel is generated in the immediate downstream of Yeongju Dam, No. 1. No. 2 484