• 한국농공학회논문집
• /
• 제60권5호
• /
• pp.135-147
• /
• 2018

The objective of this study was to analyze the characteristics of combined 1D/2D inundation simulation of riverside farmland using the Hydrologic Engineering Center - River Analysis System (HEC-RAS). We compared and analyzed inundation simulation results between 1D and combined 1D/2D hydraulic simulation using HEC-RAS. Calibration and validation of stream stage were performed using three rainfall events. The coefficient of determination ($R^2$) and root mean square error (RMSE) between simulated and observed stream stage were 0.935 - 0.957 and 0.250 m - 0.283 m in calibration and validation, respectively. The inundation area showed no significant difference in 1D and combined 1D/2D simulation ($8.48km^2$ in 1D simulation, $8.75km^2$ in combined 1D/2D simulation). The average inundation depth by 1D simulation was 1.4 m deeper than combined 1D/2D simulation. In the lower inundation depth, the inundation area by combined 1D/2D simulation was larger than inundation area by 1D simulation. As the inundation depth increased, the inundation area by 1D simulation became wider. In the case of the 1D/2D combined simulation, low elevation areas along 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 stage as the mainstream when the stream is overflowed. Therefore, the inundation area seems to be overestimated in those sections. In other regions, the inundation areas tend to be broken depending on overflow by each stream cross-section. In the case of river flooding, the overflow is expected to flow to 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/2D inundation simulation reflected the topographical characteristics of low-lying farmland.

• 한국수자원학회논문집
• /
• 제41권9호
• /
• pp.919-927
• /
• 2008

도시지역의 하천수와 지하수의 교류를 평가하기 위하여 대구지역을 선정하였다. 연구대상지역에는 낙동강, 금호강 및 25개 하천이 총 유로길이 240 km로 유하하고 있다. 하천수와 지하수의 교류량의 산정은 Darcy식을 이용하였다. 연구대상지역을 16개 소유역으로 나누어서 계산하고 그 결과를 비교하였다. 교류량 산정에는 지하수위, 하천수위, 투수계수, 대수층 두께 및 하천과 가장 근접한 우물과의 거리를 적용하였다. 소유역별 지하수의 하천 유출량, 하천수의 지하수함양량 및 교류량을 산정하였다. 연구 대상지역에서 하천으로 유출하는 지하수량은 약 $72{\times}10^6m^3/year$이고 지하수를 함양하는 하천수량은 약 $35{\times}10^6m^3/year$이었다. 하천수와 지하수의 교류량은 약 $108{\times}10^6m^3/year$이고 하천수와 지하수의 교류량 수지는 약 $37{\times}10^6m^3/year$이었다. 하천수와 지하수의 교류량은 고령교 유역에서 약 $29{\times}10^6m^3/year$로 가장 많고 달창댐 유역에서 약 $0.2{\times}10^6m^3/year$로 가장 적게 발생하였다. 교류량 산정 결과 연구대상지역 에서는 하천수와 지하수의 교류가 대단히 활발하며 소유역간 차이가 큼을 알 수 있었다. 이들 결과로부터 도시지역의 지표수와 지하수의 교류량을 보다 정도 높게 파악하기 위한 연구가 필요한 것을 알 수 있었다.

• 한국물환경학회지
• /
• 제24권4호
• /
• pp.442-451
• /
• 2008

We analyzed characteristics of rainfall-runoff for the channel of Yongwon area made by a new port construction. And we conducted inundation analysis on the region of lower elevation near the coast. SWMM5 was calibrated with the storm produced by the typhoon Megi from August 19 to August 20 in 2004, and was verified with the storm from August 22 to August 22 in 2004. We performed hydraulic channel routing of Yongwon channel about typhoon Megi from August 19 to August 20 in 2004 by UNET model which is a hydraulic channel routing. The simulated runoff hydrographs were added to the new stream as lateral inflow hydrographs and a watershed runoff hydrograph was the upstream boundary condition. The downstream boundary condition data were estimated by the measured stage hydrographs. The maximum stage that was calculated by hydraulic channel routing was higher than the levee of inundated region in typhoon Megi. Thus we can suppose an inundation to have been occurred. We performed inundation analysis about typhoon Megi from August 19 to August 20 in 2004 and flood discharge of return period 10~150 years. And we estimated each inundation area. The inundation areas by return periods of storms were estimated by 3.4~5.7 ha. The causes of inundation are low heights of levee crests (D.L. 2.033~2.583 m), storm surges induced by typhoons and reverse flow through the coastal sewers (D.L. -0.217~0.783 m). A result of this study can apply to establish countermeasure of a flood disaster in Yongwon.

• 한국농공학회논문집
• /
• 제59권1호
• /
• pp.81-96
• /
• 2017

Along with climate change, it is reported that the scale and the frequency of extreme climate events (e.g. heavy rain, typhoon, etc.) show unstable tendency of increase. In case of Korea, also, the frequency of heavy rainfall shows increasing tendency, thus causing natural disaster damage in downtown and agricultural areas by rainfall that exceeds the design criteria of hydraulic structures. In order to minimize natural disaster damage, it is necessary to analyze how extreme precipitation event changes under climate change. Therefore a new design criteria based on non-stationarity frequency analysis is needed to consider a tendency of future extreme precipitation event and to prepare countermeasures to climate change. And a quantitative and objective characteristic analysis could be a key to preparing countermeasures to climate change impact. In this study, non-stationarity frequency analysis was performed and inundation risk indices developed by 4 inundation characteristics (e.g. inundation area, inundation depth, inundation duration, and inundation radius) were assessed. The study results showed that future probable rainfall could exceed the existing design criteria of hydraulic structures (rivers of state: 100yr-200yr, river banks: 50yr-100yr) reaching over 500yr frequency probable rainfall of the past. Inundation characteristics showed higher value in the future compared to the past, especially in sections with tributary stream inflow. Also, the inundation risk indices were estimated as 0.14 for the past period of 1973-2015, and 0.25, 0.29, 1.27 for the future period of 2016-2040, 2041-2070, 2071-2100, respectively. The study findings are expected to be used as a basis to analyze future inundation damage and to establish management solutions for rivers with inundation risks.

• 한국산학기술학회논문지
• /
• 제22권6호
• /
• pp.349-356
• /
• 2021

우리나라는 1960년대 이후, 공산품의 수출 증가로 인하여 경제성장을 거듭하며, 도시화 및 산업화가 급격하게 진행됨에 따라 교량 등과 같은 교통 기반시설이 급격하게 증가하였다. 교통기반시설 중 교량의 규모가 대형화되면서 교량의 상부 구조물에 대한 안정성 검토가 활발하게 이루어지고 있으나 교량 하부 구조물을 대상으로 한 세굴 안정성 검토는 충분히 이루어지지 못하고 있다. 본 연구에서는 교량의 하부 구조물인 교각에서 발생하는 세굴 현상에 따른 대규모 재해를 예방하기 위한 기초 연구로서 17개의 교각 세굴심 산정식을 바탕으로 계산된 교각 세굴심 깊이와 수리 모형실험을 바탕으로 측정된 세굴심에 대하여 단순선형회귀모형을 활용하여 분석하였다. 그 결과, 교각 세굴심 산정공식 중 가장 우수한 방법은 Coleman(1971)방법이 선정되었으며, 교각 세굴심 산정에 가장 유효한 방법은 Froehlich(1987) 방법으로 확인되었다. 또한, 단순회귀모형을 활용하여 검토한 결과 CSU(1993), Coleman(1971) 및 Froehlich(1987) 교각세굴심 산정식이 국내 하천특성을 반영하여 가장 유사한 세굴심을 예측 할 수 있음을 확인하였다. 본 연구의 결과는 향후 하천설계에 있어 우리나라 환경에 적합한 세굴심을 산정하는데 활용할 수 있을 것으로 기대된다.

• 한국수자원학회논문집
• /
• 제39권11호
• /
• pp.905-914
• /
• 2006

유역의 정확한 강우-유출관계를 모의하기 위해서는 모형의 적용과 더불어 관측자료의 정확한 평가 및 검증이 병행되어야 한다. 본 연구에서는 SSARR모형을 금강유역에 적용하여 모의결과를 주요제어지점인 공주지점의 유량과 비교하였다. 분석결과 이수기시 저수위 구간에서 상당한 오차가 발생하였으며, 이에 대한 원인 분석을 위해 과거 관측유량자료(Rating Curve)의 신뢰도분석 및 유량 재관측($'03{\sim}'05$년)을 실시하였고, 유출성분 분석기법을 활용한 장기유출량을 산정하여 제어지점의 수리특성을 명확히 분석하고자 하였다. 분석결과 SSARR 모의결과 및 유출성분분석에 의한 장기유출량 산정결과는 재관측된 유량과 근사한 것으로 분석되었으나, 기존의 관측유량은 지점의 공간적 특성에 기인한 수리학적 영향으로 인해 평 갈수기시 약 $10{\sim}20%$ 과대 산정된 것으로 분석되어 이에 관한 보정 및 지속적인 모니터링이 필요하다.

• 한국농공학회지
• /
• 제39권6호
• /
• pp.88-98
• /
• 1997

In this study, pumping capacity in the area of natural river estuary is estimated by the quantitative analysis using finite element method. The study area is Iga-ri pumping station in the estuary of Seojung-chun which runs to the East coast. First of aH, hydraulic properties and effects of different seawater levels are analyzed in this area. Variations of groundwater level caused by pumping and properties of seawater intrusion are analyzed, then compared the case of reinforcing the existing intake weir with the case of setting up an weir at the upper stream. The observed data of groundwater drawdown caused by pumping during drought period and seawater intrusion are compared with results of the analysis done by groundwater model using finite element method, and it is found that both are similar. Accordingly, groundwater model used in this study reflects well the variation of groundwater level caused by pumping.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 2003년도 학술발표논문집
• /
• pp.463-466
• /
• 2003

The physically based distributed modelling system, MIKE SHE, has been applied to the upper sub-watershed of the Gyeongancheon watershed. A horizontal grid square was constructed to represent the spatial variations in watershed characteristics, landuse, soil, and rainfall distributions. The hydraulic model MIKE 11 was also coupled with the MIKE SHE to simulate river flow in the main and tributaries of Gyeongancheon. The simulated daily stream flow at the outlet of the watershed was compared to the observed data for the period of 1988 to 1991. The results demonstrated the applicability of a comprehensive hydrological modelling system as management tool for watershed and floodplain.

• 한국수자원학회논문집
• /
• 제30권1호
• /
• pp.15-22
• /
• 1997

하천형성의 중요한 요인이 되는 사행하천의 흐름은 막곡호안에 많은 영향을 준다. 특정한 하천에 대해 하도개량을 적용시키기 위한 일반적인 기준을 기술하기는 어려우나 토목 설계자에게 어떤 원칙과 지침을 제공하는 것은 대단히 중요하다. 본 고정상 실험연구의 목적은 평균유속과 유로만곡부에서의 곡률변경으로 최대 유속의 크기를 구하여 매번의 수리모형실험을 실시하지 않고도 중소하천의 개수에 이용할 수 있는 자료를 제공함에 있다.

• 물과 미래
• /
• 제11권1호
• /
• pp.47-58
• /
• 1978

This study is concerned with the analysis of the formulas which give both the quantity of the total, suspended and bed loads as functions of stream and sediment characteristics. The numerical analysis of sediment discharge formulas is described and the computer program for the following 4 formulas are developed; (1) Einstein's Formula (2) Toffaleti's Formula (3) Brown's Formula (4) Kikkawa's Formula In the analysis of these formulas, the hydraulic data of the river in the downstream of the Han River are used, and these formulas have been tested by application and comparison with observed data and the results computed by the computer. In these methods and procedures, the most satisfactory and convenient formula is selected. The design and planning of the river channel regulation works are determined by computing the river bed variation by using the sediment discharge computed from the selected formula.