• 한국환경과학회지
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• 제23권1호
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• pp.7-23
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• 2014

This study estimates unit for the nonpoint source(NPS), classified according to the existing Level-1(large scale) land cover map, by monitoring the measurement results from each Level-2(medium scale) land cover map, and verifies the applicability by comparison with previously calculated units using the Level-1 land cover map. The NPS pollutant loading for a basin is evaluated by applying the NPS pollutant unit to Dongcheon basin using the Level-2 land cover map. In addition, the BASINS/HSPF(Better Assessment Science Integrating point & Non-point Sources/Hydrological Simulation Program-Fortran) model is used to evaluate the reliability of the NPS pollutant loading computation by comparing the loading during precipitation in the Dongcheon basin. The NPS pollutant unit for the Level-2 land cover map is computed based on precipitation measured by the Sangju observatory in the Nakdong River basin. Finally, the feasibility of the NPS pollutant loading computation using a BASINS/HSPF model is evaluated by comparing and analyzing the NPS pollutant loading when estimated unit using the Level-2 land cover map and simulated using the BASINS/HSPF models.

• 한국물환경학회지
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• 제23권3호
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• pp.332-338
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• 2007

In this study the flow duration curves for Nakdong river basin are analyzed. The TANK model is used as a hydrologic simulation model whose parameters are estimated from 8-day intervals flow data measured by NIER Nakdong River Water Environment Laboratory. As a comparison result between generated natural and present river flow, the present river flow is higher than the natural river flow in the up- and mid-stream of Nakdong river, while the present river flow is lower than the natural river flow in the down stream of Nakdong river.

• 한국측량학회지
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• 제27권3호
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• pp.375-384
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• 2009

2002년 3월에 발사되어 현재까지 임무 수행중인 GRACE위성의 관측자료는 극지방 빙하의 융해, 빙하 지각균형 조정, 해수면 변화, 하천유역의 저수량변화, 대규모 지진 등 지구시스템의 질량재분배에 대한 연구에 활발히 이용되고 있다. 본 연구에서는 GRACE위성의 Level-2 월별 중력장 모델을 이용하여 2002년 8월부터 2009년 1월 사이 양자강유역의 육지저수량 변화를 분석하였으며, 특히는 2003년, 2006년 및 2008년에 수행된 삼협댐의 3단계 저수과정에 의한 삼협댐 지역에서의 중력변화를 등가수분두께로 계산하여 살펴보았다. 연구결과, 연구기간 내의 양자강유역은 뚜렷한 연변화와 계절변화를 나타내었으며, 연변화의 진폭은 2.3cm로 계산되었다. 또한, 실제 수자원통계자료 및 수문관측자료와의 비교를 통하여 GRACE위성자료 이용 가능성을 확인하였으며, 이는 향후 위성중력자료를 이용하여 하천유역 내에서의 물의 이동 및 주기적인 변화 연구에 큰 도움이 될 것으로 판단된다.

• 한국농공학회지
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• 제32권1호
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• pp.103-109
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• 1990

The application of the Log-Pearson Type m distribution recommended by Water Resources Council, U. S. A. for flood frequency analysis requires the estimation of the regionalized skew coefficient. In this study, regionalized skew coefficients are estimated using a weighted regression model which relates at-site skews based on logarithms of observed annual flood peak series to both basin characteristics and precipitation data in the Han river and the Nakdong river basin. The model is developed with weighted least squares method in which the weights are determined by separating residual variance into that due to model error and due to sampling error. As the result of analysis, regionalized skews are estimated as - 0.732 and - 0.575 in the Han river and the Nakdong river basin, respectively.

• 한국농공학회지
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• 제41권5호
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• pp.53-67
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• 1999

In this study, regional frequency analysis is used to determine each subbasin drought frequency with watershed runoff which is calculated with Tank Model in Nakdong river basin. L-Monments methd which is almost unbiased and nearly normal distribution is applied to estimate paramers of drought frequency analysis of monthly runoff time series. The duration of '76-77 was the most severe drought year than othe rwater years in this study. To decide drought frequency of each subbasin from the main basin, it is calculated by interpolaing runoff from the frequency-druoght runoff relationship. and the linear regression analysis is accomplished between drought frequency of main basin and that of each subbasin. With the results of linear regression analysis, the drought runoff of each subbasin is calculated corresponing to drought frequency 10,20 and 30 years of Nakdong river basin considering safety standards for the design of impounding facilities. As the results of this study, the proposed methodology and procedure of this study can be applied to water budget analysis considering safety standards for the design of impounding facilities in the large-scale river basin. For this purpose, above all, it is recommanded that expansion of reliable observed runoff data is necessary instead of calculated runoff by rainfall-runoff conceptual model.

• Water Engineering Research
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• 제1권4호
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• pp.267-277
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• 2000

This study reports an examination of the sensitivity of water resources in the Keum River basin to climate change. Assuming a doubling in $CO_2$ concentrations, a cooperative study provided four climate change scenarios for this study, which have been translated into temperature and precipitation scenarios on a basin scale. The study utilized these temperature and precipitation data for each climate change scenario as inputs to the NWS-PC model to generate the corresponding streamflow scenario over the Keum River basin. A reservoir simulation model for the Dae-Chung Dam in the Keum River basin has been developed with an object-oriented simulation environment, STELLA. For each streamflow scenario, the performance of the reservoir was assessed in terms of reliability, resiliency, and vulnerability. Although the simulation results are heavily dependent on the choice of the climate change scenarios, the following conclusions can be clearly concluded: (1) the future streamflow over the Dae-Chung Dam tends to decease during the dry period, which seriously increases competitive water use issues and (2) flood control issues predominate under the $2CO_2$-High case.

• 한국수자원학회논문집
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• 제42권1호
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• pp.51-60
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• 2009

임진강유역은 유역의 2/3가 북한에 위치하고 있어 신뢰성 있는 강우 및 수문정보를 획득할 수 없었다는 점이 지금까지 홍수 피해를 가중시킨 요인 중의 하나로 지적되어 왔다. 본 연구에서는 상습적으로 홍수피해를 겪고 있는 임진강유역의 홍수피해를 경감하기 위한 노력의 일환으로서 임진강유역에 설치된 수문레이더를 활용하여 임진강 수계 전체에 대한 홍수유출을 모의하고자 하였다. 강우 및 최근 토양자료 등의 수문자료 확보가 곤란한 유역에 대하여 자체 개발한 분포형모형의 적용 가능성을 검토하였다. 수문곡선 결과 가용자료의 부족으로 인해 부분적으로 관측값과 불일치하는 경우도 있었지만, 첨두유량 및 전체적인 패턴은 비교적 양호한 결과를 보여줌으로써 실무적용가능성을 확인할 수 있었다.

• 한국농공학회논문집
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• 제66권4호
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• pp.51-57
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• 2024

This study was conducted on how to simulate runoff, which was done using existing physical models, using an LSTM (Long Short-Term Memory) model based on deep learning. Tancheon, the first tributary of the Han River, was selected as the target area for the model application. To apply the model, one water level observatory and four rainfall observatories were selected, and hourly data from 2020 to 2023 were collected to apply the model. River water level of the outlet of the Tancheon basin was simulated by inputting precipitation data from four rainfall observation stations in the basin and average preceding 72-hour precipitation data for each hour. As a result of water level simulation using 2021 to 2023 data for learning and testing with 2020 data, it was confirmed that reliable simulation results were produced through appropriate learning steps, reaching a certain mean absolute error in a short period time. Despite the short data period, it was found that the mean absolute percentage error was 0.5544~0.6226%, showing an accuracy of over 99.4%. As a result of comparing the simulated and observed values of the rapidly changing river water level during a specific heavy rain period, the coefficient of determination was found to be 0.9754 and 0.9884. It was determined that the performance of LSTM, which aims to simulate river water levels, could be improved by including preceding precipitation in the input data and using precipitation data from various rainfall observation stations within the basin.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.156-156
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• 2019

In this study, a gated recurrent unit (GRU) network is constructed based on a deep neural network (DNN) with the aim of restoring the missing daily flow data in river basins. Lai Chau hydrological station is located upstream of the Da river basin (Vietnam) is selected as the target station for this study. Input data of the model are data on observed daily flow for 24 years from 1961 to 1984 (before Hoa Binh dam was built) at 5 hydrological stations, in which 4 gauge stations in the basin downstream and restoring - target station (Lai Chau). The total available data is divided into sections for different purposes. The data set of 23 years (1961-1983) was employed for training and validation purposes, with corresponding rates of 80% for training and 20% for validation respectively. Another data set of one year (1984) was used for the testing purpose to objectively verify the performance and accuracy of the model. Though only a modest amount of input data is required and furthermore the Lai Chau hydrological station is located upstream of the Da River, the calculated results based on the suggested model are in satisfactory agreement with observed data, the Nash - Sutcliffe efficiency (NSE) is higher than 95%. The finding of this study illustrated the outstanding performance of the GRU network model in recovering the missing flow data at Lai Chau station. As a result, DNN models, as well as GRU network models, have great potential for application within the field of hydrology and hydraulics.

• 한국환경과학회지
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• 제11권10호
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• pp.1125-1131
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• 2002

This study was performed to plan pollutant loading allocation by sub-watershed at Kumho river basin located in the north Kyeongsang province. HEC-geoHMS which is extension program of ArcView was used to extract sub-watershed. To simulate water quality, Qua12eu model was calibrated and validated. BOD was simulated under several scenarios to evaluate reduction effects of pollutant loading. Uniform treatment and transfer matrix method was considered. Effects of headwater flow rate and efficiency waste water treatment plant were also considered.