• 한국농공학회논문집
• /
• 제51권6호
• /
• pp.11-16
• /
• 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
• /
• 제47권6호
• /
• pp.3-14
• /
• 2005

Accurate estimation of the spatial distribution of rainfall is critical to the successful modeling of hydrologic processes. The objective of this study is to evaluate the applicability of spatially distributed rainfall data. Spatially distributed rainfall was calculated using Kriging method and Thiessen method. The application of spatially distributed rainfall was appreciated to the runoff response from the watershed. The results showed that for each method the coefficient of determination for observed hydrograph was $0.92\~0.95$ and root mean square error was $9.78\~10.89$ CMS. Ordinary Kriging method showed more exact results than Simple Kriging, Universal Kriging and Thiessen method, based on comparison of observed and simulated hydrograph. The coefncient of determination for the observed peak flow was 0.9991 and runoff volume was 0.9982. The accuracy of rainfall-runoff prediction depends on the extent of spatial rainfall variability.

• 한국수자원학회논문집
• /
• 제33권2호
• /
• pp.159-167
• /
• 2000

본 연구는 낙동강수계인 위천 유역의 최하류 군위 지점에 대해 추계학적 모형인 Box-Jenkin의 승법 ARIMA 모형과 상태공간모형 이론적 토대로 하여 계절별 월 유출량을 모의하였다. 다변량 시계열 모형인 상태공간모형의 입력변수로 월 유효우량과 균등기간의 관측된 월 유출량을 사용하여 군위지점의 월 유출량을 예측한 결과 다변량 시계열 모형인 승법 ARIMA모형에 비하여 표준오차가 작게 나타났으므로, 유효우량과 유출량을 함께 이용하는 상태공간 모형을 이용하여 합리적인 유출량 예측이 가능하도록 하였다. 본 논문은 월 유출량 기록치 및 유효우량 자료를 분석하여 승법 ARIMA 모형 및 상태공간 모형에 적용하였으며, 상태공가 모형의 이론을 적용하여 VAR(P)의 P값을 구하기 위해 시차에 의한 AIC 값을 이용하였다. VARMA 모형은 정준상관계수를 이용한 상태공간 모형을 구하여 구축하였다. 따라서, 본 논문에서는 구축된 상태공간 모형을 사용하여 위천유역의 군위 지점에서 장·단기 유출량을 예측하여 수자원의 장·단기전략 수립에 도움을 주기 위함이다.

• 한국물환경학회지
• /
• 제35권1호
• /
• pp.72-77
• /
• 2019

Soil type in LID infiltration practices plays a major role in runoff reduction efficacy. In this study, the effects of infiltration rate of foundation ground under bioretention on annual runoff reduction rate was evaluated using LIDMOD3 which is a simple excel based model for evaluating LID practices. A bioretention area of about 3.2 % was required to capture surface runoff from an impervious area for a 25.4 mm rainfall event. The relative error of runoff from bioretention using LIDMOD3 is 10 % less than that of SWMM5.1 for a total rainfall event of 257.1 mm during the period of Aug. 1 ~ 18, 2017, hence, the applicability of LIDMOD3 was confirmed. Annual runoff reduction rates for the period 2008 ~ 2017 were evaluated for various infiltration rates of foundation ground under the bioretention which ranged from 0.001 to 0.600 m/day and were converted to annual runoff reduction for hydrologic soil group. The runoff reduction rates within hydrologic soil group C and D were steeply increased through increased infiltration rate but not steep within hydrologic A and B with reduction rates ranging from 53 ~ 68 %. The estimated time required to completely empty a bioretention which has a storage depth of 0.632 m is 3.5 ~ 6.9 days and we could assume that the annual average of antecedent rainfall is longer than 3.5 ~ 6.9 days. Therefore, we recommended B type as the minimum hydrologic soil group installed LID infiltration practices for high runoff reduction rate.

• 한국농공학회논문집
• /
• 제51권1호
• /
• pp.1-9
• /
• 2009

The objective of this paper was to evaluate the auto-calibration with multi-objective optimization method to calibrate the parameters of the Soil and Water Assessment Tool (SWAT) model. The model was calibrated and validated by using nine years (1996-2004) of measured data for the 384-ha Baran reservoir subwatershed located in central Korea. Multi-objective optimization was performed for sixteen parameters related to runoff. The parameters were modified by the replacement or addition of an absolute change. The root mean square error (RMSE), relative mean absolute error (RMAE), Nash-Sutcliffe efficiency index (EI), determination coefficient ($R^2$) were used to evaluate the results of calibration and validation. The statistics of RMSE, RMAE, EI, and $R^2$ were 4.66 mm/day, 0.53 mm/day 0.86, and 0.89 for the calibration period and 3.98 mm/day, 0.51 mm/day, 0.83, and 0.84 for the validation period respectively. The statistical parameters indicated that the model provided a reasonable estimation of the runoff at the study watershed. This result was illustrated with a multi-objective optimization for the flow at an observation site within the Baran reservoir watershed.

• 대한토목학회논문집
• /
• 제28권6B호
• /
• pp.709-721
• /
• 2008

본 연구에서는 격자기반 운동파 강우유출모형 KIMSTORM을 개선한 ModKIMSTORM을 유역면적 $2,293km^2$의 남강댐 유역을 대상으로 적용성을 검토하였다. 공간해상도 500 m의 GIS 입력자료(DEM, 토지피복도, 유효토심도, 토양종류도 등)를 구축하였으며, 5개 태풍(2000년 사오마이, 2002년 루사, 2003년 매미, 2004년 메기, 2006년 에위니아) 및 2개 강우사상 (2003년 5월, 2004년 7월)을 적용하여 모형을 검보정하였다. 모형의 자동평가 기능을 이용하여 모의유량을 실측유량과 비교하였으며, 유역의 출구지점에 대한 매개변수 보정결과 결정계수($R^2$), 모형효율(E), 유출용적편차($D_v$), 첨두유량의 상대오차 ($EQ_p$), 첨두시간의 절대오차($ET_p$)의 평균은 각각 0.984, 0.981, 3.63%, 0.003, 0.48 hr로, 검정에서는 $R^2$, E, $D_v$, $EQ_p$, $ET_p$의 평균이 각각 0.937, 0.895, 8.08%, 0.138, 0.73 hr로 분석되었다. 매개변수와 관련하여 초기토양수분함량이 유출용적에 민감하였고, 하천조도계수가 첨두유량에 가장 민감한 변수로 나타났다. 호우기간동안의 공간적인 결과로부터 수문학적 요소의 작용을 살펴봄으로써 호우시 유역관리에 대한 정보를 얻을 수 있었다.

• 대한토목학회논문집
• /
• 제28권6B호
• /
• pp.697-707
• /
• 2008

격자기반 운동파 강우유출모형 KIMSTORM(grid-based KIneMatic wave STOrm Runoff Model)은 유역의 지표흐름, 지표하흐름 및 하천흐름의 시간적 변화와 공간적 분포를 모의할 수 있다. 본 모형은 유닉스 운영체제의 C++언어로 개발되었으며, 각 셀에서의 흐름을 모의하기 위하여 단방향흐름 알고리즘과 격자기반 수문학적 물수지요소를 채택하고 있으나 운영에 몇몇 제약사항이 있다. 본 연구에서는 기존모형을 개선하고자 하였으며, MS Windows 운영체제에서 실행 가능하도록 FORTRAN 90 언어를 이용하여 ModKIMSTORM을 개발하였다. 기존모형에 비해 개선된 주요사항으로, 물리적 기반의 침투기법인 GAML(Green-Ampt & Mein-Larson) 침투모형 추가, 격자 유출심과 Manning 조도계수에 의한 논에서의 지표유출 제어, 지표격자의 기저유출 요소 추가, 공간강우와 지점강우의 처리, 전 후 처리부문 개발, 5개 평가항목(피어슨의 결정계수 $R^2$, Nash & Sutcliffe 모형효율 E, 유출용적 편차 $D_v$, 첨두유출의 상대오차 $EQ_p$, 첨두시간의 절대오차 $ET_p$)을 이용한 모의결과의 자동 평가 기능을 개발하였다. 추가적으로, 모형의 계산효율을 향상시키고 지표격자의 기저유출을 하천격자로 이송하기 위하여 쉘정렬 알고리즘을 채택하였다. 모형의 입력자료는 ESRI ArcInfo W/S 또는 ArcView와 같은 GIS 소프트웨어 및 MS Excel을 이용하여 간단히 구축할 수 있으며, 모의결과의 공간적 분포를 확인할 수 있는 토양수분, 지표유출, 유출심 및 유속분포도는 BSQ, ESRI ASCII Grid, ESRI Binary Grid 및 IDRISI Raster 형식으로 출력할 수 있도록 개선하였다.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 2000년도 학술발표회 발표논문집
• /
• pp.412-418
• /
• 2000

The purpose of this study is estimation of daily runoff in the watershed with insufficient hydrological data using tank model. In order to estimate, twentysix watersheds were selected to calibrate tank model parameters that were defined by a trial and error method. Results were correlated with characteristics of watershed. Relationships between the parameters and the watershed characteristics were derived by a multiple regression analysis. The simulation results were in agreement with the observed data.

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

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2016년도 학술발표회
• /
• pp.164-164
• /
• 2016

Radar rainfall estimates have been widely used in calculating rainfall amount approximately and predicting flood risks. The radar rainfall estimates have a number of error sources such as beam blockage and ground clutter hinder their applications to hydrological flood forecasting. Moreover, it has been reported in paper that those errors are inter-correlated spatially and temporally. Therefore, in the current study, we tested influence about spatio-temporal errors in radar rainfall estimates. Spatio-temporal errors were simulated through a stochastic simulation model, called Multivariate Autoregressive (MAR). For runoff simulation, the Nam River basin in South Korea was used with the distributed rainfall-runoff model, Vflo. The results indicated that spatio-temporal dependent errors caused much higher variations in peak discharge than spatial dependent errors. To further investigate the effect of the magnitude of time correlation among radar errors, different magnitudes of temporal correlations were employed during the rainfall-runoff simulation. The results indicated that strong correlation caused a higher variation in peak discharge. This concluded that the effects on reducing temporal and spatial correlation must be taken in addition to correcting the biases in radar rainfall estimates. Acknowledgements This research was supported by a grant from a Strategic Research Project (Development of Flood Warning and Snowfall Estimation Platform Using Hydrological Radars), which was funded by the Korea Institute of Construction Technology.