• Korean Journal of Hydrosciences
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• 제4권
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• pp.21-32
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• 1993

The estimates of both runoff depth and peak runoff by the basin runoff curve numbers, which are CN-II for antecedent moisture condition- II and CN -III for antecedent moisture condition-III, obtained from hydrological soil-cover complexes of 26 watersheds are investigated by making use of the observed curve numbers, which are median curve number and optimum curve number, computed from 250 rainfall-runoff records. For gaged basins the median curve numbers are recommended for the estimation of both runoff depth and peak runoff. For ungaged basin, found is that for the estimate of runoff depth CN-II is adequate and for peak runoff CN-II is suitable. Also investigated is the variation of the runoff curves during storms. By the variable runoff curve numbers, the prediction of runoff depth and peak runoff can be improved slightly.

• 물과 미래
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• 제24권2호
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• pp.97-108
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• 1991

유역의 수문학적 토양피복형으로부터 유역 또는 합성곡선번호를, 강우-유출기록으로부터 관측곡선 번호를, 관측곡선번호의 중앙치로서 중위유선번호를 산정하였다. 유출기록을 기준으로 평가할 경우 AMC-II조건의 CN-II에 의하면 과소하게, AMC-III조건의 CN-III에 의하면 과대하게 유효강우량이 산정된다. 따라서 유효강우량산정의 개선방안으로 CN-II와 CN-III의 중간값인 조정곡선번호가 정의될 수 있다. 중위곡선번호에 의하여 산정된 유출이 관측치에 가장 근접하게 되는 점을 감안하면 계측유역의 대표곡선번호로서 중위곡선번호가 사용될 수 있다.

• 물과 미래
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• 제25권4호
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• pp.87-95
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• 1992

우리나라 26개 유역의 수문학적 토양피복형으로부터 유도된 유출곡선번호((AMC-II 조건에 대한 CN-II와 AMC-III조건에 대한 CN-III)와 동일유역의 250개 강우-유출사상으로부터 유도된 관측유출곡선번호(유역중립곡선번호와 최적곡선번호)를 이용하여 유효강우량과 \ulcorner두유출의 산정의 적용성이 검토되었다. 미계측유역에서 유효강우량에는 CN-III이, \ulcorner두유출에는 CN-II가 적합하고 강우-유출기록이 있는 유역에서는 유역중립곡선번호가 가장 타당한 것으로 나타났다. 강우지속기간에 곡선변화를 나타내는 시변성 곡선번호를 이용하여 해석한 결과 유효강우량과 \ulcorner두유출에 다같이 개선이 나타났다.

• 한국농공학회논문집
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• 제52권6호
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• pp.85-94
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• 2010

The objective of this study is to estimate the flood runoff for three guaged stations within Namgang-Dam watershed which are operated by KWATER. For a flood runoff simulation, HEC-HMS was applied and the simulated runoff was compared with observed from 2004 to 2008. The watershed area of Sancheong, Shinan, and Changchon were 693.6 $km^2$, 413.4 $km^2$, and 346.48 $km^2$, respectively. The average runoff ratio of observed runoff for three watersheds were 0.725, 0.418, and 0.586, respectively. The dominant land cover of three watersheds are forest with the value of 71.6 %, 73.1 %, and 82.0 %. Three different cases according to the potential maximum retention of forest areas for calculating the curve number were applied to decrease the error between the simulated and observed. The simulated peak runoff of case 3 which applied the 90 % of potential maximum retention of curve number which is equivalent to AMCI for all the AMCI, AMCII, and AMCIII conditions showed least root mean square error (RMSE). The case 1, which was suggested by previous study, showed high discrepancy between the simulated and observed. Since the forest area consists of more than 70 % for all three watersheds, the application of curve number for forest is critical to improve the estimation errors. Further research is required to estimate the more accurate curve number for forest area.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회 논문집
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• pp.578-582
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• 2005

In this study, the conceptual foundation and development process of the Antecedent soil Moisture Condition(AMC) in SCS runoff curve number method are reviewed. Although the runoff volume is very sensitive with AMC condition, the AMC class limits developed in SCS(1972) are used in rainfall-runoff analysis without careful consideration. Tn this study, following the SCS curve number development process, rainfall-runoff characteristics of the Jang-Pyung subbasin subject to the Pyung-Chang River basin are analyzed to evaluate the reasonability of the AMC class limits at present. The New AMC class limits are proposed by the sensitive analysis of the antecedent rainfall - curve number value. As a result, the classification value of AMC-I with II is 22mm of antecedent 5-day rainfall amount, and the classification of AMC-II with III is 117mm in growing season. When the New AMC class limits are applied to Jang-Pyung subbasin, AMC probability distribution shows that the AMC-II has increased remarkably even though the AMC-I has a little higher value. But the AMC-III has the smallest one. According to the conceptual basis of the curve number method, the AMC probability distribution, the New AMC class limits adopted, gives reasonable results.

• 한국물환경학회지
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• 제23권6호
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• pp.829-836
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• 2007

For the purpose of managing non-point sources, water quality control basins (WQCBs) are often designed to capture rainfall events smaller than extreme events. The design rainfall statistics and runoff capture rates for sizing a WQCB should be derived from the local long-term continuous rainfall record. In this study, the 31-year continuous rainfall data recorded in Busan is analyzed to derive the synthesized runoff capture curve incorporated with SCS curve number.

• 한국농공학회논문집
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• 제51권6호
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• pp.11-16
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• 2009

This study is to suggest the SWAT model as inputs for the estimation of CN (Curve number) if we do not have hourly rainfall and runoff data in the ungaged watershed. The daily CNs were estimated by using SWAT model for Chungju dam watershed and the CNs by hourly rainfall and runoff data in the same period with daily CN estimation were also estimated. Then the daily and hourly CNs were compared each other. The CNs by SWAT model were larger than the actual CNs. 7.4% larger in AMC-I, 1.2% in AMC-II, and 6.3% in AMC-III respectively. If we consider various uncertainties in the estimation of CN, the error of 6.8% could be acceptable for the application in the field.

• 한국농공학회논문집
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• 제47권3호
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• pp.59-68
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• 2005

The rainfall-runoff potential of Jangseong reservoir watershed was studied based on SCS (Soil Conservation Service, which is now the NRCS, Natural Resources Conservation Service, USDA) runoff curve number (CN) technique. Precipitation and reservoir operation data had been collected. The rainfall-runoff pairs from the watershed for ten years was estimated using reservoir water balance analysis using reservoir operation records. The maximum retention, S, for each storm event from rainfall-runoff pair was estimated for selected storm events. The estimated S values were arranged in descending order, then its probability distribution was determined as log-normal distribution, and associated CNs were found about probability levels of Pr=0.1, 0.5, and 0.9, respectively. A subwatershed that has the similar portions of land use categories to the whole watershed of Jangseong reservoir was selected and hydrologic monitoring was conducted. CNs for subwatershed were determined using observed data. CNs determined from observed rainfall-runoff data and reservoir water balance analysis were compared to the suggested CNs by the method of SCS-NEH4. The $CN_{II}$ measured and estimated from water balance analysis in this study were 78.0 and 78.1, respectively. However, the $CN_{II}$, which was determined based on hydrologic soil group, land use, was 67.2 indicating that actual runoff potential of Jangseong reservoir watershed is higher than that evaluated by SCS-NEH4 method. The results showed that watershed runoff potential for large scale agricultural reservoirs needs to be examined for efficient management of water resources and flood prevention.

• 한국수자원학회논문집
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• 제36권2호
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• pp.183-193
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• 2003

강우의 지속시간을 처리하는 방법에 따라 AMC조건과 강우의 시간분포인(1차, 2차, 3차, 4차 모멘트)가 유출에 미치는 연관성을 연구하였다. 연구결과 강우를 10분위로 고려하는 경우, CN은 AMCIII조건에서 1차 및 2차 모멘트와 상관성을 보였으나 그 외의 조건에서는 상관성이 없었다. 또한 첨두유출비(QP/Q)는 AMC I조건에서 3차 및 4차 모멘트와 상관성을 보였으며, AMCIII조건에서는 1차 및 2차 모멘트와 상관성을 보였다. 강우의 전체 지속시간을 고려하는 경우, CN은 AMC I조건에서 모든 시간분포인자와 상관성을 보였으나 AMCIII조건에서는 1차 및 2차 시간분포인자와 상관성을 보였다. 그리고 첨두유출비(QP/Q)는 AMC I조건에서 3차 및 4차 시간분포인자와 상관성을 보였으나 그 외의 조건에서는 거의 상관성을 보이지 않았다. 따라서 보다 정확한 CN 산정을 위해 강우의 시간분포와 제시된 시간분포인자를 고려할 것을 제안하였다.

• 한국물환경학회지
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• 제26권4호
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• pp.590-597
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• 2010

NRCS Curve Number (CN) method is widely used for practical purposes in the field by engineers and researchers to calculate direct runoff from total rainfall. However, CN is obtained from antecedent moisture condition and soil characteristics and so it has some problems due to its uncertainty. Therefore this study estimated CN of a watershed using asymptotic CN method which can estimate CN by rainfall and runoff data and compared the result with representative CN given by WAMIS. And we performed runoff simulation for rainy season of Bocheong stream by CN regression equation. From the result, we showed that it could be more reasonable to simulate direct runoff using watershed CN regression equation than WAMIS CN. Furthermore, we knew that the equation is more sensitive to small rainfall event.