• 한국수자원학회논문집
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• 제51권3호
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• pp.221-233
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• 2018

최근 기후변화로 인한 국지성 호우 및 태풍 피해가 자주 발생하고 있다. 이와 같은 피해를 저감하기 위해서는 정확한 강우의 예측과 홍수량 산정이 필요하다. 그러나 지점 및 레이더 강우 시 공간적 오차를 포함하고 있고, 유출 모형에 의한 유출수문곡선 역시 보정을 실시하더라도 관측유량과 오차를 가지고 있어 불확실성이 존재한다. 따라서 본 연구에서는 확률론적 강우 앙상블을 생성하여 강우의 불확실성을 확인하였다. 또한 유출 결과를 통해 수문 모형의 불확실성을 확인하였고, 블랜딩 기법을 이용하여 하나의 통합된 유출 수문곡선을 제시하였다. 생성된 강우앙상블은 강우강도 및 지형적인 영향으로 레이더가 과소 관측이 될 때, 강우 앙상블의 불확실성이 큰 것을 확인하였고, 블랜딩 기법을 적용하여 산정된 최적 유출 수문곡선은 유출모형의 불확실성을 크게 줄이는 것으로 나타났다. 본 연구 결과를 활용한다면, 정확한 홍수량 산정 및 예측을 통해 집중호우로 인한 피해를 줄일 수 있을 것으로 판단된다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.2215-2219
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• 2009

For model calibration in rainfall-runoff modeling, streamflow data at a specific outlet is obviously required but is not sufficient to identify parameters of a model since numerous parameter combinations can result in very similar model performance measures (i.e. objective functions) and indistinguishable simulated hydrographs. This phenomenon has been called 'equifinality' due to inherent parameter uncertainty involved in rainfall-runoff modeling. This study aims to investigate catchment responses in time and space to various uncertain parameter sets in distributed rainfall-runoff modeling. Seven plausible (or behavioral) parameter sets, which guarantee identically-good model performances, were sampled using deterministic and stochastic optimization methods entitled SCE and SCEM, respectively. Then, we applied them to a computational tracer method linked with a distributed rainfall-runoff model in order to trace and visualize potential origins of streamflow at a catchment outlet. The results showed that all hydrograph simulations based on the plausible parameter sets were performed equally well while internal catchment responses to them showed totally different aspects; different parameter values led to different distributions with respect to the streamflow origins in space and time despite identical simulated hydrographs. Additional information provided by the computational tracer method may be utilized as a complementary constraint for filtering out non-physical parameter set(s) (or reducing parameter uncertainty) in distributed rainfall-runoff modeling.

• 대한토목학회논문집
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• 제28권3C호
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• pp.167-178
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• 2008

본 연구에서는 실제 풍화토 사면에 대하여 침투해석과 안정해석을 수행하여 강우에 따른 사면의 붕괴를 재현하였다. 불교란시료를 채취하여 불포화토 물성을 실험적으로 직접 획득하여 실제 강우량에 의하여 침투해석을 수행한 결과, 토사층과 암층의 경계부를 중심으로 간극수압이 증가하는 경향이 나타났다. 또한 안정해석을 수행한 결과 안전율이 1.0미만으로 감소하여 실제 사면의 붕괴를 재현할 수 있었다. 또한 설계 강우강도에 의하여 침투해석을 수행한 결과 선행강우 및 강우기간에 따른 침투효과를 고려하기 곤란하였다. 이로 인하여 토사층의 수두변화가 크게 발생하지 못하였고 사면의 안전율이 1.0이상으로 나타났다. 또 다른 붕괴 사면의 경우에는 불포화토의 정수들을 인공신경망기법으로 추정하였다. 침투해석 결과 토사층과 연암층 경계부를 중심으로 포화대가 뚜렷하게 형성되었으며 이로 인하여 토사층의 안전율이 1.0미만으로 감소하였다. 이러한 기법을 통하여 실제 사면의 붕괴를 재현하는 것이 가능하다고 판단된다.

• 한국수자원학회논문집
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• 제41권7호
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• pp.747-759
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• 2008

본 연구에서는 관측강우의 통계특성 및 발생특성을 가장 적절하게 재현해 주는 강우모형을 선정하고자 하였다. 강우모형으로 Poisson과정에 근거한 점과정모형인 RPPM, NS-RPPM, modified NS-RPPM을 고려하여 모의자료에 대한 통계분석을 수행하였다. 그 결과, NS-RPPM과 modified NS-RPPM을 이용하여 모의된 자료가 여러 집성시간의 통계치를 적절하게 재현하였다. 또한 modified NS-RPPM을 이용하여 모의된 자료가 관측자료와 가장 유사한 발생특성을 가지는 것을 알 수 있었다. 특히, 홍수, 산사태 등 자연재해의 발생에 큰 영향을 주는 큰 강도를 가지는 강우를 관측치와 가장 유사하게 재현하였다. 모의된 강우사상의 총 강우량, 강우기간, 강우사상 간의 간격을 관측강우와 비교해본 결과 또한 modified NS-RPPM이 가장 좋은 결과를 보였다. 본 연구의 결과를 종합해 볼 때, 강우의 장기 모의를 위해 modified NS-RPPM을 이용하는 것이 가장 적절할 것으로 판단된다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.152-152
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• 2022

Only employing historical data limits the estimation of the full distribution of probable Tropical Cyclone (TC) risk due to the insufficiency of samples. Addressing this limitation, this study introduces a semi-physical TC rainfall model that produces spatially and temporally resolved TC rainfall data to improve TC risk assessments. The model combines a statistical-based track model based on the Markov renewal process to produce synthetic TC tracks, with a physics-based model that considers the interaction between TC and the atmospheric environment to estimate TC rainfall. The simulated data from the combined model are then fitted to a probability distribution function to compute the spatially heterogeneous risk brought by landfalling TCs. The methodology is employed in South Korea as a case study to be able to implement a country-scale-based vulnerability inspection from damaging TC impacts. Results show that the proposed model can produce TC tracks that do not only follow the spatial distribution of past TCs but also reveal new paths that could be utilized to consider events outside of what has been historically observed. The model is also found to be suitable for properly estimating the total rainfall induced by landfalling TCs across various points of interest within the study area. The simulated TC rainfall data enable us to reliably estimate extreme rainfall from higher return periods that are often overlooked when only the historical data is employed. In addition, the model can properly describe the distribution of rainfall extremes that show a heterogeneous pattern throughout the study area and that vary per return period. Overall, results show that the proposed approach can be a valuable tool in providing sufficient TC rainfall samples that could be an aid in improving TC risk assessment.

• 한국수자원학회논문집
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• 제47권10호
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• pp.959-972
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• 2014

본 연구에서는 멀티프랙탈 이론을 기반으로 시 공간 격자강우장 생산 모형을 충주댐 상류유역에 발생한 9개의 홍수 사상에 대하여 검증하였다. 이를 위하여 기상청의 레이더 강우자료에 대한 시공간 멀티프랙탈 특성을 분석하였으며, 로그 포아송 분포와 3차원 웨이브렛 함수 기반의 시 공간 격자 강우생산 모형을 활용하여 관측강우의 멀티프랙탈 특성을 재현하는시 공간 가상강우장을 생산하였다. 생성된 가상강우장을 S-RAT 분포형 수문모형에 입력값으로 적용하여 유역출구에서의 반응을 관측강우 및 시공간적으로 균등한 분포를 가진강우장에 대하여 산출된 유역출구에서의 반응과 비교하였다. 관측 강우장과 가상강우장, 관측강우장과 저해상도 강우장에 대하여 RMSE, RRMSE, MAE, SS, 그리고 NPE, PTE 등을 이용하여 오차분석을 수행한 결과, 평균적으로 첨두홍수량은 20.03% 증가하였고, 첨두시간은 0.81% 감소하였다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2001년도 학술발표회 발표논문집
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• pp.93-98
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• 2001

This study was performed to analyse the rainfall and the rainfall-runoff characteristics of a rural watershed. The Sangwha basin($105.9km^{2}$) in the Geum river system was selected for this study. The arithmetic mean method, the Thiessen's weighing method, and the isohyetal method were used to analyse areal rainfall distribution and the Huff's quartile method was used to analyse temporal rainfall distribution. In addition, daily runoff analyses were peformed using the DAWAST and tank model. In the model calibration, the data from June through November, 1999 were used. In the model calibration, the observed runoff depth was 513.7mm and runoff rate was 45.2%, and the DAWAST model simulated runoff depth was 608.6mm and runoff rate was 53.5%, and the tank model runoff depth was 596.5mm and runoff rate was 52.5%, respectively. In the model test, the data from June through November, 2000 were used. In the model test, the observed runoff depth was 1032.3mm and runoff rate was 72.5%, and the DAWAST model simulated runoff depth was 871.6mm and runoff rate was 61.3%, and the tank model runoff depth was 825.4mm and runoff rate was 58%, respectively. The DAWAST and tank model's $R^{2}$ and RMSE were 0.85, 3.61mm, and 0.85, 2.77mm in 1999, and 0.83, 5.73mm, and 0.87, 5.39mm in 2000, respectively. Both models predicted low flow runoff better than flood runoff.

• 한국농공학회논문집
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• 제60권1호
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• pp.47-57
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• 2018

This study implemented the rainfall-runoff analysis of the Mekong River basin using the SWAT (Soil and Water Assessment Tool). The runoff analysis was simulated for 2000~2007, and 11 parameters were calibrated using the SUFI-2 (Sequential Uncertainty Fitting-version 2) algorithm of SWAT-CUP (Calibration and Uncertainty Program). As a result of analyzing optimal parameters and sensitivity analysis for 6 cases, the parameter ALPHA_BF was found to be the most sensitive. The reproducibility of the rainfall-runoff results decreased with increasing number of stations used for parameter calibration. The rainfall-runoff simulation results of Case 6 showed that the RMSE of Nong Khai and Kratie stations were 0.97 and 0.9, respectively, and the runoff patterns were relatively accurately simulated. The runoff patterns of Mukdahan and Khong Chaim stations were underestimated during the flood season from 2004 to 2005 but it was acceptable in terms of the overall runoff pattern. These results suggest that the combination of SWAT and SWAT-CUP models is applicable to very large watersheds such as the Mekong for rainfall-runoff simulation, but further studies are needed to reduce the range of modeling uncertainty.

• 한국농공학회논문집
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• 제65권6호
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• pp.37-49
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• 2023

Rainfall data is one of the most important data in hydrologic modeling. In this study, the impacts of spatial resolution of precipitation data on hydrological responses were assessed using SWAT in the Santa Fe River Basin, Florida. High correlations were found between the FAWN and NLDAS rainfall data, which are observed weather data and simulated weather data based on observed data, respectively. FAWN-based scenarios had higher maximum rainfall and more rainfall days and events compared to NLDAS-based scenarios. Downstream areas showed lower correlations between rainfall and peak discharge than upstream areas due to the characteristics of study site. All scenarios did not show significant differences in base flow, and showed less than 5% of differences in high flows among NLDAS-based scenarios. The impact of resolution will appear differently depending on the characteristics of the watershed and topography and the applied model, and thus, is a process that must be considered in advance in runoff simulation research. The study suggests that applying the research method to watersheds in Korea may yield more pronounced results, and highlights the importance of considering data resolution in hydrologic modeling.

• 한국제4기학회:학술대회논문집
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• 한국제4기학회 2004년도 하계학술대회
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• pp.24-25
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• 2004

It is well known that there is an inverse relationship between the strength of Indian summer monsoon Rainfall (ISMR) and extent of Eurasian snow cover/depth in the preceding season. Tibetan snow cover/depth also affects the Asian monsoon rainy season largely. The positive correlation between Tibetan sensible heat flux and southeast Asian rainfall suggest an inverse relationship between Tibetan snow cover and southeast Asian rainfall. Developments in Regional Climate Models suggest that the effect of Tibetan snow on the ISMR can be well studied by Limited Area Models (LAMs). LAMs are used for regional climate studies and operational weather forecast of several hours to 3 days in future. The Eta model developed by the National Center for Environmental Prediction (NCEP), the Fifth-Generation NCAR/Penn State Mesoscale Model (MM5) and Regional Climate Model (RegCM) have been used for weather prediction as well as for the study of present-day climate and variability over different parts of the world. Regional Climate Model (RegCM3) has been widely . used for various mesoscale studies. However, it has not been tested to study the characteristics of circulation features and associated rainfall over India so far. In the present study, Regional Climate Model (RegCM-3) has been integrated from 1 st April to 30th September for the years 1993-1996 and monthly mean monsoon circulation features and rainfall simulated by the model at 55km resolution have been studied for the Indian summer monsoon season. Characteristics of wind at 850hPa and 200hPa, temperature at 500hPa, surface pressure and rainfall simulated by the model have been examined for two convective schemes such as Kuo and Grell with Arakawa-Schubert as the closure scheme, Model simulated monsoon circulation features have been compared with those of NCEP/NCAR reanalyzed fields and the rainfall with those of India Meteorological Department (IMD) observational rainfall datasets, Comparisons of wind and temperature fields show that Grell scheme is closer to the NCEP/NCAR reanalysis, The influence of Tibetan snowdepth in spring season on the summer monsoon circulation features and subsequent rainfall over India have been examined. For such sensitivity experiment, NIMBUS-7 SMMR snowdepth data have been used as a boundary condition in the RegCM3, Model simulation indicates that ISMR is reduced by 30% when 10cm of snow has been introduced over Tibetan region in the month of previous April. The existence of Tibetan snow in RegCM3 also indicates weak lower level monsoon westerlies and upper level easterlies.