HEC-RAS를 이용한 하천변 농경지의 1, 2차원 연계 침수 모의

Abstract

The objective of this study was to analyze the characteristics of combined 1D/2D inundation simulation of riverside farmland using the HydrologicEngineering Center – River Analysis System (HEC-RAS). We compared and analyzed inundation simulation results between 1D and combined 1D/2Dhydraulic simulation using HEC-RAS. Calibration and validation of stream stage were performed using three rainfall events. The coefficient ofdetermination (R2) and root mean square error (RMSE) between simulated and observed stream stage were 0.935 - 0.957 and 0.250 m - 0.283 m incalibration and validation, respectively. The inundation area showed no significant difference in 1D and combined 1D/2D simulation (8.48 km2 in 1Dsimulation, 8.75 km2 in combined 1D/2D simulation). The average inundation depth by 1D simulation was 1.4 m deeper than combined 1D/2Dsimulation. In the lower inundation depth, the inundation area by combined 1D/2D simulation was larger than inundation area by 1D simulation. Asthe inundation depth increased, the inundation area by 1D simulation became wider. In the case of the 1D/2D combined simulation, low elevation areasalong the river bank were inundated widely. Compared to 1D/2D combined simulation, the flood radius in some sections was longer in 1D simulation. In the 1D analysis, because the low altitude riverside farmlands are also assumed to stream, it is calculated that riverside farmlands have the same stageas the mainstream when the stream is overflowed. Therefore, the inundation area seems to be overestimated in those sections. In other regions, theinundation areas tend to be broken depending on overflow by each stream cross-section. In the case of river flooding, the overflow is expected to flowto the lower area depending on the terrain, such as the results of the combined 1D/2D simulation. It is concluded that the results of combined 1D/2Dinundation simulation reflected the topographical characteristics of low-lying farmland.