• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.167-167
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• 2021

2018년 재해연보에 따르면 최근 10년간 자연재해는 태풍과 호우에 의한 평균피해액이(301,680백만원) 전체 재해평균피해액(344,124백만원)의 87.6%로 나타났다. 이처럼 물 관련 재해가 다른 재해에 비해 상대적으로 큰 비중을 차지하는 대표적 원인은 국지성 집중호우의 발달과 개발로 인한 불투수면적의 증가 및 지표면 유출량의 증가등이 있다. 이러한 요인들로 하천범람이 지속적으로 증가하고 있으며 이에 대응할 치수계획수립이 필요한 실정이다. 세종특별자치시의 하천기본계획(2020.01)에 따르면 세종특별자치시의 금남면 도남리의 도남천지구는 제방고 및 여유고 부족과 인명 및 재산피해 우려 지역으로 하천재해 위험지구로 선정되었다. 따라서 본 연구의 목적은 도남천지구에 강우-유출모형을 적용하여 빈도별 월류위치 파악과 하천범람지도를 작성하여 대피범위등 유역치수계획수립시 기초자료에 활용 되고자 한다. 강우분석을 위한 강우관측소 선정은 티센망 확인을 통하여 공주시(반포중) 강우관측소를 선정하였다. 강우분석은 자료기간이 짧은 강우관측소에서도 확률강우량을 산정할 수 있는 지역빈도해석을 하였으며 분석결과 적합한 확률분포형은 GEV인 것으로 나타났다. 빈도별 홍수량 산정을 위해 HEC-HMS모형을 이용하였으며 산정방법은 깅우-유출 관계 분석 방법에 의한 다양한 합성단위도 방법중 일관성과 객관성이 입증되어 온 Clark단위도 법을 사용하였다. 산정한 홍수량을 HEC-RAS모형에 적용하여 월류구간을 파악하였으며 월류위치 및 대피범위를 가시화 하기 위해 HEC-GeoRAS모형을 사용하여 빈도별 하천범람지도를 작성하였다. 본 연구는 도남천지구에 빈도별 하천범람지도를 작성 하였다. 이를 통하여 하천범람시 대피범위등 유역치수계획 수립 시 도움이 될 것으로 판단된다.

• Journal of Korea Water Resources Association
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• v.43 no.6
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• pp.559-569
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• 2010

This study proposes an empirical method for estimating the concentration time and storage coefficient of a basin using the Nash unit hydrograph. This method is based on the analytically derived concentration time and storage coefficient of the Nash model. More fundamentally, this method recursively searches convergent number of linear reservoirs and storage coefficient of linear reservoir representing the basin given. This method is to overcome the problem of HEC-HMS to use an optimization technique to estimate the basin concentration time and storage coefficient. The proposed method was applied to the Bangrim station of the Pyungchang river basin, also found to estimate physically reasonable values.

• Journal of Korea Water Resources Association
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• v.37 no.5
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• pp.407-424
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• 2004

Using geomorphoclimatic unit hydrograph(GCUH), we estimated the fitness to calculate the mountainous area discharge and flash flood trigger rainfall(FFTR). First, we compared the GCUH peak discharge with the existing report using the design storm at the Dukcheon basin. Second, we compared the HEC-HMS(Hydrologic Engineering Center-Hydrologic Modeling System) model and GCUH with the observed discharge using the real rainfall events at the Taesu stage gage. Third, GCUH and NRCS(Natural Resources Conservation Service) were used for calculating FFTR and proper calculation method was shown. At the Dukcheon basin, the comparison result of using design storm was shown in Table 11, and it was not in excess of 1.1, except for the 30 year return period. In case of real rainfall events, the result was shown in Table 12, and GCUH discharges were all larger than the HEC-HMS model discharges, and they were very similar to the observed data at the Taesu stage gage. In this study, we found that GCUH was a very proper method in the calculation of mountainous discharge. At the Dukcheon basin, FFTR was 12.96 mm in the first 10 minutes when the threshold discharge was 95.59 $m^3$/sec.

• Journal of Wetlands Research
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• v.7 no.3
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• pp.41-48
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• 2005

Generally the estimation of effective rainfall is important in the rainfall-runoff analysis. So, we must pay attention to selecting more accurate effective rainfall estimation method. Although there are many effective rainfall estimation methods, the NRCS method is widely used for the estimation of effective rainfall in the ungaged basin. However, the NRCS method was developed based on the characteristics of the river basin in USA. So, it may have problems to use the NRSC method in Korea without its verification. In the NRCS method, the antecedent precipitation of 5-day is usually used for the estimation of effective rainfall. The main purpose of this study is to investigate the suitable antecedent precipitation day in Korea river basin through the case study. This study performs the rainfall-runoff simulation for the Tanbu river basin by HEC-HMS model under the condition of varying the antecedent precipitation day from 1-day to 7-day and performs goodness of fit test by Monte Carlo simulation method. The antecedent precipitation of 2-day shows the most preferable result in the analysis. This result indicates that the NRCS method should be applied with caution according to the characteristics of the river basin.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.682-686
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• 2005

Recently some urban areas have been flooded due to heavy storm rainfalls. Though major causes of these floodings may be attributed to localized heavy rainfalls, other factors are related to urban flooding including deficiency of storm sewer network capacity, change of surface runoff due to covered open channels, and operational problems of storm drainage pump stations. In this study, hydrologic and hydraulic analysis of Sutak basin in Guri city were carried out to evaluate flooding problems occurred during the heavy storm in July, 2001. ArcView, a world most widely used GIS tool, was used to extract required data for the hydrologic analysis including basin characteristics data, concentration times, channel routing data, land use data, soil distribution data and SCS runoff curve number generation from digital maps. HEC-HMS, a GIS-based runoff simulation model, was successfully used to simulate the flood inflow hydrograph to Sutak pumping station.

• Journal of Environmental Science International
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• v.24 no.4
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• pp.393-401
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• 2015

Rainfall-runoff model of Jeju Oedo Stream was used to compute the optimal unit hydrograph by HEC-HMS model that reflecting on watershed characteristics. Each rainfall event was comparatively analyzed with the actual flow measurement using Clark, Snyder and SCS synthetic methods for derived unit hydrograph. Subsequently, the null hypothesis was established as p-value for peak flow and peak time of each unit hydrograph by one-way ANOVA(Analysis of variance) was larger than significance level of 0.05. There was no significant difference in peak flow and peak time between different methods of unit hydrograph. As a result of comparing error rate with actual flow measurement data, Clark synthetic unit graph best reflected in Oedo Stream as compared to other methods, and error rate of Clark unit hydrograph was 0.02~1.93% and error rate at peak time was 0~2.74%.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.389-389
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• 2020

최근 이상기후의 영향으로 게릴라성 호우 및 태풍과 같은 자연재해의 발생 요인이 증가하고 있다. 특히 여름철 집중호우는 농경지의 범람, 도심지역 저지대의 침수피해 유발, 하천 주변 저지대 및 수공구조물의 안전을 위협하고 있다. 이에 따라 본 연구에서는 HEC-RAS 5.0.3을 활용하여 금강 유역의 2차원 침수 모의를 수행하고, 그 적용성을 평가하고자 한다. 대상지역은 금강 수계 하천기본계획 보고서의 하천 횡단면도와 평면도를 활용하여 모형을 구축하였으며, 강우자료는 인근 기상관측소의 관측자료를 수집하였다. HEC-HMS를 이용하여 강우에 의한 유출량을 산정하였으며, 산정된 유출량을 HEC-RAS에 입력하여 수위를 계산하고 2차원 모의기능을 이용하여 침수해석을 수행하였다. HEC-RAS의 2차원 침수 모의 기능은 기존 1차원 하천 수위 모의와의 연계하여 하천기본계획 수립을 위한 침수 해석 등에 널리 활용될 수 있을 것이라 판단되고, 본 연구의 결과는 침수 모의 적용성 분석의 기초자료로 활용될 수 있을 것으로 기대된다.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.5
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• pp.107-113
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• 2009

The purpose of this study is to estimate the design flood runoff for ungaged forest watershed to reduce the flood damage in national park. Daewonsa watershed in Jirisan National Park was selected as study watershed, of which characteristic factors were obtained from GIS data. Flood runoff was simulated using SCS unit hydrograph module in HEC-HMS model. SCS Curve Number (CN) was calculated from forest type area weighted average method. Huff's time distribution of second-quartile storm of the Sancheong weather station, which is nearest from study watershed, was used for design flood runoff estimation. Critical storm duration for the study watershed was 3 hrs. Based on the critical duration, the peak runoff for each sub-watershed were simulated. It is recommended to monitor the long-term flow data for major stream stations in National Park for a better reliable peak runoff simulation results.

• Journal of Environmental Science International
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• v.24 no.4
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• pp.425-435
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• 2015

A number of projects for development have been done continuously due to the increase of tourist in Jeju Island. However flood disaster countermeasure due to urbanization is not considered during this development projects. This study is to make basic process for the flood estimation in Han stream of Jeju Island. The variation of stream discharge due the every 5 years' land use change from 1980 to 2005. Data for flood events (rainfall and discharge) were collected for HEC-HMS model. Clark method was used for unit hydrograph analysis. For the estimation of Clark unit hydrograph parameters, Kraven II and Sabol's empirical equations were applied. The peak discharge increased 9.9~33.67% and total discharge amount increased 12.53~30.21%. Also, time of concentration for peak discharge was reduced by 10 minutes for each event.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.2
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• pp.9-17
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• 2011

Based on the statistical annual report, there are 17,649 reservoirs are operating for the purpose of agricultural water supply in Korea. 58 % of entire agricultural reservoirs had been constructed before 1948 which indicate the termination of required service life and rest of those reservoirs have also exposed to the dam break risk by extreme flood event caused by current ongoing climate change. To prevent damages from dam failure accident of these risky small size dams, it is necessary to evaluate and manage the structural and hydrological safety of the reservoirs. In this study, a simplified evaluation method for hydrologic safety of dam is suggested by using Rational and Creager formula. Hydrologic safety of small scale dams has evaluated by calculating flood discharge capacity of the spillway and compares the results with design frequency of each reservoir. Applicability and stability of suggested simplified method have examined and reviewd by comparing the results from rainfall-runoff modeling with dam break simulation using HEC-HMS. Application results of developed methodology for three sample reservoirs show that simplified assessment method tends to calculate greater inflow to the reservoirs then HEC-HMS model which lead lowered hydrologic safety of reservoirs. Based on the results of application, it is expected that the developed methodology can be adapted as useful tool for small scale reservoir's hydrologic safety evaluation.