| Title |
Analysis of Flood Level Reduction based on Optimal Location and Length of Lateral Overflow Weirs in Distributed Offline Retention Basins |
| Authors |
최준성(Choi, Junseong);김상혁(Kim, Sanghyeok);류지원(Ryu, Jiwon);장은경(Jang, Eunkyung);지 운(Ji, Un) |
| DOI |
https://doi.org/10.12652/Ksce.2026.46.3.0193 |
| Keywords |
분산형 오프라인 저류지; 홍수관리시설; 홍수 조절 효과; 횡월류 위어; 1차원 부정류 모의 Distributed offline retention basins; Flood control facility; Flood mitigation; Lateral overflow weir; Unsteady flow simulation |
| Abstract |
Climate change-induced extreme flooding necessitates complementary flood-management measures in addition to conventional levee-based approaches. Offline retention basins constructed within riparian zones have been considered a viable option, and distributing multiple basins along a river reach can increase effective storage and thereby enhance downstream flood-stage attenuation. Under unsteady hydrograph conditions, however, hydraulic interactions among offline basins may occur, implying that the flood-stage reduction estimated from individual-basin operations may not be directly transferable to integrated multi-basin operation. Therefore, this study performed one-dimensional unsteady-flow simulations using HEC-RAS for the Jangdong District, located in the upstream water-source protection area of Daecheong Dam in the Geumgang River, and comparatively evaluated flood-mitigation performance under individual and integrated operation scenarios by varying the location and length of the lateral weir. For the 100-year design flood hydrograph, the downstream peak-stage reduction obtained by a simple summation of the peak-stage reductions from individual-basin simulations was approximately 45 cm. In contrast, the unsteady-flow simulations explicitly accounting for integrated operation yielded a peak-stage reduction of approximately 41 cm, confirming that the additive estimate does not necessarily reproduce the integrated-operation outcome. Based on these findings, a stepwise unsteady-flow modeling workflow and application framework are presented to support the design of distributed offline retention basins while explicitly considering both individual and integrated operational conditions, as demonstrated for the Geumgang River case. |