• Journal of Korea Water Resources Association
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• v.36 no.6
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• pp.999-1012
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• 2003

The objective of this study is to test the applicability of CN values suggested using land cover and treatment classification of satellite image. Applicability test is based on the comparison of observed effective rainfall and computed one. The 3 case study areas, where are the upstream of Gyeongan stage station, the upstream of Baekokpo stage station Pyungchang River basin, and the upstream of Koesan Dam, are selected to test the proposed CN values and the hydrologic and meteorologic data, Landsat-7 ETM of 2000, soil map of 1:50,000 are collected for the selected areas. The results show that the computed CN values for three study cases are 71, 63, 66, respectively, and the errors between observed and computed effective rainfall are within about 30%. It can be concluded that the proposed CN values from this study for land cover and treatment classification of satellite image not only provides more accurate results for the computation of effective rainfall, but also suggest the objective CN values and effective rainfall.

• Journal of Soil and Groundwater Environment
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• v.11 no.1
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• pp.65-76
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• 2006

This paper outlines the methodology of grid-based water balance for estimating the spatial distribution of recharge, which is applied to Woedo catchment in the northern area of the Jeju Island. The catchment is divided into grids and a daily water balance in each grid is computed for the period of 5 years. Daily rainfall data in each grid is interpolated from the data of 10 rainfall gauging stations. The spatial distributions of parameters such as SCS curve number, soil water retention capacity and crop coefficients are derived from GIS analyses of soil and land use characteristics. The SCS curve number is obtained by calibrating simulated runoffs with respect to the observed runoffs. The results show that the average annual rainfall increases from 1,665 mm/year to 3,382 mm/year in accordance with the topographic elevation, and the average annual recharge varies from 372 mm/year to 2,576 mm/year according to the average annual rainfall increases. Spatial variability of recharge is the highest among the water balance components such as rainfall, direct runoff, evaprotranspiration and recharge because the rate of runoff and evapotranspiration in the area with relatively low rainfall is higher than the other area.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.387-391
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• 2012

경인아라뱃길은 인천 서구 오류동과 서울 강서구 개화동을 연결하는 뱃길로 선박의 항해를 위한 주운수로와 두 개의 갑문으로 이루어져 있다. 홍수시 굴포천 상류유역의 홍수량이 열결 수로를 통하여 서해로 배제되며, 굴포천 하류유역의 경우 연결 암거를 통해 홍수량 일부를 서해로 방류한다. 본 연구에서는 2011년 발생한 7월 호우사상에 대하여 경인아라뱃길 유역의 홍수량 및 홍수위의 변화를 검토하였다. 강우-유출 모의는 Clark 유역추적법을 적용하여 14개의 소유역별 홍수량을 산정하였으며, Muskingum-Cunge 방법을 적용하여 하도추적을 수행하였다. 소유역에 대한 홍수 도달시간과 저류상수는 각각 Kirpich 방법과 Russel 공식을 이용하였고, 유출곡선지수값은 AMC-III를 적용하였다. 강우자료는 서울기상청과 인천기상대의 2011년 7월 호우사상을 사용하였으며, 하도의 홍수위 분석은 부정류 해석방법을 이용하였다. 분석 결과, 경인아라뱃길의 각 지점 홍수위는 제방고보다 전체적으로 낮았다. 100년 빈도 홍수량에 대해서 홍수방어가 가능한 경인아라뱃길은 2011년 7월말 호우사상에 대하여 안전한 것으로 판단된다.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.4
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• pp.67-74
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• 2007

Rational method has been widely used to calculate peak runoff drainage design or small watershed because of simplicity and convenience. Runoff coefficient(C) is the most important parameter in the rational method which varies according to rainfall intensity, return period, rainfall duration time and soil characteristics. In practice, constant which is value of C in rational formula has been used from the table, originally based on ASCE. These table value does not consider the upper conditions of the depending factors, hence peak runoff calculation could be in correct. Therefore to calculate C in this paper we have devised an improved formula, considering relationship with rainfall duration, return period and CN of NRCS method. This formula is considered to be more reliable and helpful to the hydrologists and engineers to predict correct peak runoff.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.442-448
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• 2009

Recently, the natural disaster has occurred as a heavy snow fall, drought and flood by abnormal weather. The damage of human and property by flood is most serious problem among those natural disaster. In order to prepare structural or non-structural measure, to estimate exact flood discharge is important element. This study analyze frequency of hour-unit rainfall data and estimate probability flood discharge by HEC-HMS as changing method of runoff analysis. Also, this study analyze the peak flood discharge sensibility according to Curve Number(CN) with the return period. As a result of estimation of probability flood discharge with the variety CN, to select Antecedent Moisture To select suitable condition(AMC) is important parameter because flood discharge is estimated 40% gap according to AMC.

• Journal of Korea Water Resources Association
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• v.34 no.6
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• pp.713-724
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• 2001

Hydrologists have tried to develop monthly runoff simulation models which are important factor in wafer resources planning. One of the models called Kajiyama formu]a is widely used for monthly runoff simulation in Korea. In recent work by Xiong and Guo (1999), they suggested Two-parameter monthly water balance model to simulate the runoff and showed that the model can be used for the water resources planning program and the climate impact studies. However, they estimated two parameters of transformation of time scale, c and of the field capacity, SC by the trial and error method. Therefore, the purpose of this study is to suggest the estimation methodologies of c and SC, and compare Kajiyama formula with a Two-parameter monthly water balance model to simulate the runoff in Han river and IHP representative basins in Korea. The c is estimated by using the relationship of actual and potential evaporations, and SC is estimated from association with CN. We show that the estimated c and SC can be used as the initial or optimal values in the model.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.2
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• pp.199-209
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• 2000

Recently, GSIS is introduced in the various fields. Especially in hydrology, the useful of GSIS is emphasized to analyze parameters, which are necessary for the analysis of watershed. In this paper, to estimate the direct runoff volume, I used the SCS-CN method which was useful to calculate direct runoff volume in a watershed that was not observed. But because SCS-CN method must treat a great number of spatial data, if we use the GSIS, we can treat numbers of the data easily. GSIS databases is constructed by using the data which is related to soil type, landuse. And runoff curve number was estimated by means of these databases in the study area. Also, the area of covered each subbasin rainfall gauge station was estimated by thiessen polygon network technique. The direct runoff volume was calculated by these subbasin area to the rainfall gauge station. I knew, from this study, that using GSIS, I can calculate parameters needed in direct runoff volume analysis, fast, exactly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.404-411
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• 2019

In this study, the HEC-HMS was applied to determine rainfall-runoff processes for the Gokgyuchun basin. Several sub-basins have large-scale reservoirs for agricultural needs and they store large amounts of initial runoff. Three infiltration methods were implemented to reflect the effect of initial loss by reservoirs: 'SCS-CN'(Scheme I), 'SCS-CN' with simple surface method(Scheme II), and 'Initial and Constant rate'(Scheme III). Modeling processes include incorporating three different methods for loss due to infiltration, Clark's UH model for transformation, exponential recession model for baseflow, and Muskingum model for channel routing. The parameters were calibrated using an optimization technique with trial and error method. Performance measures, such as NSE, RAR, and PBIAS, were adopted to aid in the calibration processes. The model performance for those methods was evaluated at Gangcheong station, which is the outlet of study site. Good accuracy in predicting runoff volume and peak flow, and peak time was obtained using the Scheme II and III, considering the initial loss, whereas Scheme I showed low reliability for storms. Scheme III did not show good matches between observed and simulated values for storms with multi peaks. Conclusively, Scheme II provided better results for both single and multi-peak storms. The results of this study can provide a useful tool for decision makers to determine master plans for regional flood control management.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.05a
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• pp.249-254
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• 2003

분석에 이용된 격자망은 동곡, 고로, 미성, 병천, 효령 및 무성지점에 각각 12개, 30개, 45개, 76개, 46개 및 1265개의 조격자를 구성하였으며 하천의 수로방향 및 경사형태를 세분화하기 위하여 각 지점에 대하여 8개, 24개, 24개, 44개, 12개 및 64개의 세격자로 분할하였다. AGNPS를 이용한 첨두유량의 모의발생 결과치가 동곡, 고로, 미성, 병천, 효령 및 무성지점에서 측정값과 비교하여 각 호우사상별로 상대오차가 1.0~25.0%, 4.0~27.0%, 7.0~29.2%, 2.0~23.9%, 3.0~25.0% 및 3.6~21.0%의 차이를 나타내었다. 분석결과에서 AMCII조건에서는 관측치와 분석결과치가 유사하게 나타났으나 AMCI조건에 대해서는 상대적으로 작은 값을 보였으며 AMCIII조건에서는 다소 큰 값으로 분석되었다. SCS방법에서 제안하는 AMC조건별 CN값을 우리 실정에 적합하도록 수정 보완하기 위한 수정 유출곡선지수 $CN_{m}$ /I과 $CN_{m}$/III을 재구성하였으며, 여기에 적용되는 수정 유출 곡선지수식의 계수 a를 추정한 결과, 기왕에 발표된 연구결과와 거의 일치된 경향을 나타내었다. 제안된 수정 CN식을 이용하여 산정한 결과치와 관측치는 거의 유사하게 나타났다. AGNPS모델에 의한 유출량 산정에 있어 수문학적 토양피복형수(CN)의 결정을 위하여 선행강우량과 토양의 공극율 및 지형인자인 각 셀마다의 유역경사를 이용하여 관계식(CN =f($X_1$, $X_2$, $X_3$))을 유도하였으며, 분석 결과에서 CN이 선행강우량과 가장 밀접한 관계가 있음을 알 수 있었으며 유역경사, 토양의 공극율 순으로 나타났다..88mg/$\ell$~의 범위로 나타났다. 무태교 지점에서의 총인의 농도는 0.52mg/$\ell$~0.99mg/$\ell$~의 범위이었다. 신천에 금호강물을 혼합한 이후에도 부유물질, 생화학적산소요구량, 암모니아태 질소, 총인 등의 농도가 개선되지 않았다. 즉 금호강물의 혼합은 신천수질환경사업소에서 배출되는 방류수에 함유되어 있을 2차 오염물질의 희석이라는 이점외의 수질개선효과는 확인되지 않았다.l years and a new type of transfer crane has been developed. Design concepts and control methods of a new crane will be introduced in this paper.and momentum balance was applied to the fluid field of bundle. while the movement of′ individual material was taken into account. The constitutive model relating the surface force and the deformation of bundle was introduced by considering a representative prodedure that stands for the bundle movement. Then a fundamental equations system could be simplified considering a steady state of the process. On the basis of the simplified model, the simulation was performed and the results co

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.17-24
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• 2018

The HEC-HMS model was applied to identify the rainfall-runoff processes for the Anseongchun basin, where the lower part of the stream has been damaged severely by tropical storms in the past. Modeling processes include incorporating with the SCS-CN model for loss, Clark's UH model for transformation, exponential recession model for baseflow, and Muskingum model for channel routing. The parameters were calibrated through an optimization technique using a trial and error method. Sensitivity analysis after calibration was performed to understand the effects of parameters, such as the time of concentration, storage coefficient, and base flow related constants. Two storm water events were simulated by the model and compared with the corresponding observations. Good accuracy in predicting the runoff volume, peak flow, and the time to peak flow was achieved using the selected methods. The results of this study can be used as a useful tool for decision makers to determine a master plan for regional flood control management.