• 한국농공학회지
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• 제26권4호
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• pp.52-65
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• 1984

In general precise estimation of hourly of daily distribution of the long-term run-off should be very important in a design of source of irrigation. However, there have not been a satisfying method for forecasting of stationar'y long-term run-off in Korea. Solving this problem, this study introduces unit-hydrograph method frequently used in short-term run-off analysis into the long-term run-off analysis, of which model basin was selected to be Sumgin-river catchment area. In the estimation of effective rainfall, conventional method neglects the Soil moisture condition of catchment area, but in this study, the initial discharge (qb) occurred just before rising phase of the hydrograph was selected as the index of a basin soil moisture condition and then introduced as 3rd variable in the analysis of the reationship between cumulative rainfall and cumulative loss of rainfall, which built a new type of separation method of effective rainfall. In next step, in order to normalize significant potential error included in hydrological data, especially in vast catchment area, Snyder's correlation method was applied. A key to solution in this study is multiple correlation method or multiple regressional analysis, which is primarily based on the method of least squres and which is solved by the form of systems of linear equations. And for verification of the change of characteristics of unit hydrograph according to the variation of a various kind of hydrological charateristics (for example, precipitation, tree cover, soil condition, etc),seasonal unit hydrograph models of dry season(autumn, winter), semi-dry season (spring), rainy season (summer) were made respectively. The results obtained in this study were summarized as follows; 1.During the test period of 1966-1971, effective rainfall was estimated for the total 114 run-off hydrograph. From this estimation results, relative error of estimation to the ovservation value was 6%, -which is mush smaller than 12% of the error of conventional method. 2.During the test period, daily distribution of long-term run-off discharge was estimated by the unit hydrograph model. From this estimation results, relative error of estimation by the application of standard unit hydrograph model was 12%. When estimating by each seasonal unit bydrograph model, the relative error was 14% during dry season 10% during semi-dry season and 7% during rainy season, which is much smaller than 37% of conventional method. Summing up the analysis results obtained above, it is convinced that qb-index method of this study for the estimation of effective rainfall be preciser than any other method developed before. Because even recently no method has been developed for the estimation of daily distribution of long-term run-off dicharge, therefore estimation value by unit hydrograph model was only compared with that due to kaziyama method which estimates monthly run-off discharge. However this method due to this study turns out to have high accuracy. If specially mentioned from the results of this study, there is no need to use each seasonal unit hydrograph model separately except the case of semi-dry season. The author hopes to analyze the latter case in future sudies.

• 한국수자원학회논문집
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• 제32권3호
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• pp.291-300
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• 1999

하천치수를 고려한 프랙탈 차원의 개념을 실제 강우-유출 모형에 적용시키는 방안으로써 스나이더 합성단위유량 도법을 택하였으며, 5대강 수계의 29개 유역에 대한 지형자료와 관측단위유량도 자료를 이용하여 4가지 형태의 스나이더형 관계식을 유도하였다. 29개 유역에 대한 분석과 2개 유역에 대한 검증 결과 하천길이의 프랙탈적인 성질을 이용하고 기계산된 자료는 기계산된 값을 이용하는 스나이더형 관계식이 가장 좋은 결과를 보여주었다. 하천차수 유역중심에서 출구까지의 하천길이( Lca )중 Lca 는 프랙탈적인 성질이 없고 유역중심의 상류에 해당하는 주하천 구간인 ( Lma - Lca )만이 1.027의 프랙탈 차원을 갖는다는 가정을 하였으며, 이를 이용하여 우리날 수계를 대표 할 수 있으며 작업대상 지형도축척에 의해 발생하는 하천길이의 프랙탈적인 영향을 고려할 수 있는 새로운 스나이더형 공식을 제안하였다.

• 대한토목학회논문집
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• 제36권3호
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• pp.439-449
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• 2016

유역의 지형학적특성을 이용한 합성단위도법을 제시하였다. 합성단위도 산정을 위하여 19개 유역에 대하여 6개 지형학적 인자를 사용하였으며, 전체유역을 유역면적 $ 200km^2$을 기준으로 2개의 군집으로 분류하였다. 19개 유역을 대상으로 군집별로 표준화된 지형학적 인자와 유역별 대표단위도의 첨두비유량 및 첨두시간과의 회귀식을 제시하였으며, Nash와 Clark 단위도를 유도하였다. 합성단위도의 모의정확도 검증을 위해 추가적으로 선택한 6개 유역에서 2010-2011년에 발생한 145개 강우-유출사상에 적용하여 경험식을 사용한 Clark모형의 적용결과와 비교하였다. 검증결과 기존의 합성단위도법에 비해 높은 정확도를 나타내었으며, 이러한 결과는 미계측 유역에서의 적용 가능성을 보여주었다.

• 한국농공학회지
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• 제19권2호
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• pp.4377-4384
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• 1977

The curvilinear hydrograph can be replaced by an equivalent triangular hydrograph which is more easily constructed and, for routing through reservoirs or stream channels, gives results about as accurate as those obtained using the curvilinear hydrograph. A synthetic hydrograph is prepared using the data from a number of watersheds to develop a dimensionless unit hydrograph applicable to ungauged watersheds. The dimensionless unit hydrograph for the NakDong River Basin was prepared from the unit hydrographs of a variety of nine subwatersheds. The equation for the peak rate of flow (unit volume of runoff in 1.0mm) was derived as {{{{ { q}_{p } = { 0.21AR} over { {T }_{p } } }}}} The results summarized in this study are as follows: 1) It found that the watershed lag time (Lg, hrs) could be expressed by Lg=0.253(L.Lca)0.4171 The product L.Lca is a measure of the size and shape of the watershed. Correlation coefficient for Lg was 0.97 which defined with high significance. 2) The base length of the unitgraph, in hours, was adopted as Tb=17.51+2.073Lg with high significant correlation coefficient, 0.92. 3) Time in hour from start of rise to peak rate (TP) generally occured at the position of 0.289 Tb with some indication of higher values for larger watershed. 4) Triangular hydrograph is a dimensionless unitgraph prepared from the 40 unitgraphs. The equation is shown as {{{{ { q}_{p } = { K.A.R} over { { T}_{p } } }}}}. The constant K=0.21 is defined to NakDong River basin. 5) In the light of the results analyzed in this study, average errors in the peak discharge of the Trjangular unitgraph was estimated as 5.34 percent to the peak of observed average unitgraph. Each ordinate of the Triangular unitgraph was approached closely to the observed one.

• 한국수자원학회논문집
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• 제43권7호
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• pp.635-643
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• 2010

작은 규모 유역의 홍수 유출량을 산출하기 위해서 유역을 대표하는 하나의 단위유량도를 많이 적용해 왔다. 이 때 단위유량도의 첨두유량과 첨두 발생시간은 단위유량도를 결정하는 특성치로 취급된다. 본 연구에서는 국내에서 $8.5\;km^2$ 정도의 소규모 유역에서도 강우 사상별로 단위유량도의 첨두유량과 발생시간은 상당히 변동되는 것을 보이고 분석하였다. 그리고 동일 소유역에서 단위유량도 변동의 주요인으로 강우 사상별 평균 강우강도라고 보고 강우 사상별 강우강도와 단위유량도의 첨두유량 및 발생시간의 관계를 각각 지수함수식으로 제시하였다. 결과적으로 사용 자료상의 제약 등으로 단위유량도 첨두치에상당한 분산을 동반하는 한계는있지만 연구된 대로 단위유량도의첨두유량 및 첨두 발생시간과 강우의 평균적인 회귀 관계는 단위유량도 이론의 보완적 측면에서 수문학적 가치를 갖는다.

• 물과 미래
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• 제13권2호
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• pp.35-47
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• 1980

본 연구는 유역을 폐선형계로 본 강우와 유출간의 해석으로부터 1시간대표단위유량도를 유도하기 위한 알고리즘을 개발한 것이다. 단위도 유도에 필요한 기저유출과 직접유출의 분리는 본 연구에서 개발된 다변굴곡법에 의하였으며, 종래의 방법들에 비해 비교적 좋은 결과를 주었다. 초과우량의 산정을 위해서는 $\Phi$ index 법의 개념을 각 시간별로 적용하는 수정 $\Phi$ index 법을 개발 적용함으로써 종래의 $\Phi$ index 법의 약점을 보완할 수 있었다. 이와 같은 방법으로 직접유출과 이에 상응하는 초과우량을 결정한 후 각 호우집단별로 1시간단위도의 시간별 종거를 시산에 의해 결정하되 관측수문곡선을 재연토록 함으로써 구간별 지수함수형의 단위도를 유도하였다. 본 연구의 타당성 검정을 위하여 낙동강의 남하 및 동촌 지점과 금강의 용 담 지점의 1시간대표단위도를 유도하고 그 결과를 합성단위도법 및 Nakayasu 방법에 의한 결과와 비교 검토하였으며, 단위도의 유도에 사용하지 않은 호우사상에 대하여 유도된 1시간 대표단위도를 적용함으로써 관측치와 산정치를 비교하였다. 본 해석의 일반화를 위하여 주 프로그램과 3개의 부 프로그램(초과우량 산정, 회선누적, 크기배열)으로 구성되어진 컴퓨터 프로그램을 개발하였으며, 이 프로그램은 타 유역에 그대로 적용이 가능토록 되어 있다.

• 한국농공학회논문집
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• 제54권3호
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• pp.65-74
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• 2012

In this study, three different unit hydrograph methods (NRCS, Snyder and Clark) in the HEC-HMS were compared to find better fit with the observed data in the Namgang-Dam watershed. The Sancheong, Shinan, and Changchon in Namgang-Dam watershed were selected as the study watersheds. The input data for HEC-HMS were calculated land use, digital elevation map, stream, and watershed map provided by WAter Management Information System (WAMIS). Sixty six storms from 2004 to 2011 were selected for model calibration and validation. Three unit hydrograph methods were compared with the observed data in terms of simulated runoff volume, and peak runoff for the selected storms. The results showed that the coefficient of determination ($R^2$) for the peak runoff was 0.8295~0.9999 and root mean square error (RMSE) was 0.029~0.086 mm/day for calibration stages. In the model validation, $R^2$ for the peak runoff was 0.9061~0.9916 and RMSE was 0.030~0.088 mm/day which were more accurate than calibrated data. Analysis of variance showed that there was no significant difference among the three unit hydrograph methods.

• 한국농공학회논문집
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• 제50권3호
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• pp.17-27
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• 2008

In this study, three different unit hydrograph methods (Snyder, SCS, Clark) in the HEC-HMS were compared to find better fit with the observed data in the small agricultural watershed. Baran watershed, having $3.85km^2$ in size, was selected as a study watershed. The watershed input data for HEC-HMS were retrieved using HEC-GeoHMS which was developed to assist making GIS input data for HEC-HMS. Rainfall and water flow data were monitored since 1996 for the study watershed. Fifty five storms from 1996 to 2003 were selected for model calibration and verification. Three unit hydrograph methods were compared with the observed data in terms of simulated peak runoff, peak time and total direct runoff for the selected storms. The results showed that the coefficient of determination ($R^2$) for the observed peak runoff was $0.8666{\sim}0.8736$ and root mean square error, RMSE, was $5.25{\sim}6.37\;m^3/s$ for calibration stages. In the model verification, $R^2$ for the observed peak runoff was $0.8588{\sim}0.8638$ and RMSE was $9.57{\sim}11.80\;m^3/s$, which were slightly less accurate than the calibrated data. The simulated flood hydrographs were well agreed with the observed data. SCS unit hydrograph method showed best fit, but there was no significant difference among the three unit hydrograph methods.

• 한국수자원학회논문집
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• 제42권1호
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• pp.75-92
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• 2009

본 연구의 목적은 한국 산악유역에서의 지형 상사를 규명하여 보고, 이를 이용하여 한국형 지형수문단위도를 유도하고 검증하는 데 있다. 실제로 실무에서는 홍수분석을 위하여 가장 일반적으로 단위도법이 사용되어 왔으나, 한국 유역에의 적합성, 조절 매개변수 산정의 불확실성 등에 있어서 많은 어려운 점을 내포하고 있었다. 본 연구에서는 한국의 40여개의 산악 소유역의 지형자료를 수집하고 분석하여 다양한 한국 지형상사를 규명하여 보았다. 다음에는 기존의 지형수문곡선 이론에 이를 적용하여 한국형 지형수문단위도 기법을 개발하고 검증하여 보았다. 개발된 공식은 각각 한국형 지형형태학적 순간단위도, 한국형 지형형태-기후학적 순간단위도, 그리고 한국형 지형형태-기후학적 단위도로 구분할 수 있다. 이들 기법은 한국형 단위도법, 강우-유출 관계의 비선형성, 기상자료의 사용, 그리고 적용의 간편성 등의 장점을 가지고 있으며, 앞으로 한국 산악 미계측 유역의 홍수 분석을 위하여 사용될 수 있을 것이다.

• 한국환경과학회지
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• 제24권4호
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• pp.437-447
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• 2015

Estimation of runoff peak is needed to assess water availability, in order to support the multifaceted water uses and functions, hence to underscore the modalities for efficient water utilization. The magnitude of storm rainfall acts as a primary input for basin level runoff computation. The rainfall-runoff linkage plays a pivotal role in water resource system management and feasibility level planning for resource distribution. Considering this importance, a case study has been carried out in the Hancheon basin of Jeju Island where distinctive hydrological characteristics are investigated for continuous storm rainfall and high permeable geological features. The study aims to estimate unit hydrograph parameters, peak runoff and peak time of storm rainfalls based on Clark unit hydrograph method. For analyzing observed runoff, five storm rainfall events were selected randomly from recent years' rainfall and HEC-hydrologic modeling system (HMS) model was used for rainfall-runoff data processing. The simulation results showed that the peak runoff varies from 164 to 548 m3/sec and peak time (onset) varies from 8 to 27 hours. A comprehensive relationship between Clark unit hydrograph parameters (time of concentration and storage coefficient) has also been derived in this study. The optimized values of the two parameters were verified by the analysis of variance (ANOVA) and runoff comparison performance were analyzed by root mean square error (RMSE) and Nash-Sutcliffe efficiency (NSE) estimation. After statistical analysis of the Clark parameters significance level was found in 5% and runoff performances were found as 3.97 RMSE and 0.99 NSE, respectively. The calibration and validation results indicated strong coherence of unit hydrograph model responses to the actual situation of historical storm runoff events.