• Water Engineering Research
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• v.5 no.1
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• pp.17-36
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• 2004

This paper evaluated the water resources aspect of the operating results of the Daecheong Multipurpose Dam for the last 21 years. The elements that were evaluated included the amount of water supply from the dam. volume of outflow from the regulating dam, changes in the runoff volume at the dam site and downstream, and variations in the water supply capacity of the Daecheong Multipurpose Dam and the Geum River Barrage Dam situated in the estuary. The rainfall-runoff model was used to evaluate the changes in the runoff volume, and the water balance analysis system was used to evaluate the variations in the dams'water supply capacities. The volume of domestic and industrial water supply from the Daecheong Multipurpose Dam increased to 6.1 times for the last 21 years from 61${\times}$$10^6$$m^3$ in 1981 to 375${\times}$$10^6$$m^3$in 2001. The rate of outflow to inflow of the Daecheong Dam was analyzed 1.30 times in dry season, 1.12 times in semi-dry season, and 0.90 times in rainy season. The volume of inflow to the Geum River Barrage Dam down- stream after the dam's construction increased to 1.25 times in dry season and 1.02 times in semi-dry season and decreased to 0.94 times in rainy season. The water supply capacity of the estuary barrage dam almost did not change in cases with or without the Daecheong Multipurpose Dam, but storages were largely affected by the outflows of the Daecheong Multipurpose Dam.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.5
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• pp.1039-1049
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• 2015

The inflow estimation at large multipurpose dam reservoir is carried out by considering the water balance among the discharge, the storage change during unit time interval obtained from the observed water level near dam structure and area-volume curve. This method can be ideal for level pool reservoir but include potential errors when the inflow is influenced by the water level slope due to backwater effects from upstream flood inflows and strong wind induced by typhoon. In addition, the other uncertainties arisen from the storage reduction due to sedimentation after the dam construction and water level noise due to mechanical vibration transmitted from the electric power generator. These uncertainties impedes the accurate hydraulic inflow measurement requiring exquisite hydrometric data arrangement for reservoir waterbody. In this study, the distributed hydrologic model using UBC-3P boundary setting was applied and its feasibility was evaluated. Finally, the modeling performance has been verified since the calculated determination coefficient has been in between 0.96 to 0.99 after comparing with observed peak inflow and total inflow at Namgang dam reservoir.

• Journal of Korea Water Resources Association
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• v.38 no.1
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• pp.25-35
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• 2005

Nowaday the amount of water resource to generate the hydro-power energy has decreased as that of the water supply has increased. In case that the national market of the energy will be in free competition, the energy producer need to suggest the amount of the optimal supply with the hydrological reliability for a deal. In this study the optimal reservoir operation was performed by the linear programming and the optimal reliabilities of inflows and the power supply were obtained by the one dimensional search technique to estimate the energy with the optimal inflow reliability which the power system of the Yongdam multipurpose dam in Geum river can produce. And the main results were presented.

• Journal of Korea Water Resources Association
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• v.53 no.2
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• pp.97-105
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• 2020

Recently, Artificial Neural Network receives attention as a data prediction method. Among these, a Long Shot-term Memory (LSTM) model specialized for time-series data prediction was utilized as a prediction method of hydrological time series data. In this study, the LSTM model was constructed utilizing deep running open source library TensorFlow which provided by Google, to predict inflows of multipurpose dams. We predicted the inflow of the Yongdam Multipurpose Dam which is located in the upper stream of the Geumgang. The hourly flow data of Yongdam Dam from 2006 to 2018 provided by WAMIS was used as the analysis data. Predictive analysis was performed under various of variable condition in order to compare and analyze the prediction accuracy according to four learning parameters of the LSTM model. Root mean square error (RMSE), Mean absolute error (MAE) and Volume error (VE) were calculated and evaluated its accuracy through comparing the predicted and observed inflows. We found that all the models had lower accuracy at high inflow rate and hourly precipitation data (2006~2018) of Yongdam Dam utilized as additional input variables to solve this problem. When the data of rainfall and inflow were utilized together, it was found that the accuracy of the prediction for the high flow rate is improved.

• Korean Journal of Hydrosciences
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• v.7
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• pp.37-49
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• 1996

This study aims at suggesting an alternative to improve flood controling capacity according to the cument design criteria for the existing Soyanggang Multi-purpose Dam which was constructed 20 years ago as the largest dam in Korea. The peak inflow of the adopted probable maximum flood (PMF) at the time of construction was 13,500 $m^3$/s. However, the newly estimated peak inflow of the PMF is 18,000 $m^3$/s which is 1.34 times bigger than the original one. This is considered to be due to the accumulation of the reliable flood and storm event records after construction, and due to the increasing tendency of the local flood peaks according to the influence of world-wide weather change. The new estimation of the probable maximum precipitation (PMP) was based on the hydro-meteorological method suggested by the guideline of the World Meteorological Organization (WMO). The unit hydrograph which was applied for the estimation of PMF was derived through linear programming algorithm by minimizing the sum of absolute deviations of the calculated and recorded flood hydrographs. In order to adopt the newly estimated PMF as a design flood, following four alternatives were compared : (1) allocation of more flood control space by lowering the normal high water level, (2) construction of a new spillway in addition to the existing spillway, (3) construction of a new dam which has relevant flood control storage at the upstream of the Soyanggang dam, (4) raising the existing dam crest. The preliminary evaluation of these alternatives resulted in that the second alternative is most economic and feasible. So as to stably cope with the newly estimated PMF by meeting all the current functions of the multipurpose dam, a detailed study of an additional spillway tunnel has to be followed.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.1 s.12
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• pp.33-40
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• 2004

The objective of this study is to develop single dam operation models for flood control using Fuzzy control technique, which can improve flood controllability. We set control rules by water level and inflow, and developed three models Fuzzy I, II, III according to rule to decide outflow. Fuzzy I model consists of six rules considering only flood control and Fuzzy II model considers the effect of water use by increasing water level at the end of flood control period as well as flood control during the same period. Finally, Fuzzy m is an adaptive model designed to perform multipurpose dam operation for both flood control and water use simultaneously based on a control rules.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.503-506
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• 2003

The DAWAST model was originally developed to consider daily variation in the unsaturated soil water storage and it is a conceptual lumped model. Return flows from agricultural, domestic and industrial water were included to the original result of model simulation to calibrate model parameter. Daily inflow to the Daechung multipurpose dam was applied to verify the DAWAST model considered return flows. Simulation results were comparable to the inflows of dam operation reasonably.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.549-559
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• 2017

The complementary relationship hypothesis for areal evapotranspirations was validated in the regional-scale area of multipurpose dam basins in Korea and the long-term water balances were indirectly identified. Annual actual evapotranspiration ($ET_A$) was assumed the difference between total annual precipitation and total annual inflow and the available moisture was assumed the total precipitation. The seasonally varying pan coefficient (kp) is estimated as the ratio of the $ET_{pan}$ and the evapotranspiration calculated by FAO Penman-Monteith equation ($ET_{PM}$). The complementary relationships using ground observation data of $ET_P$ and $ET_A$ in the multipurpose dam basins follow generally the typical pattern that $ET_P$ and $ET_A$ is complementary and converges to equivalent evapotranspiration ($ET_W$) under the extreme wet environment. However, $ET_A$ of Juam dam was estimated relatively greater than other basins and exceeds even $ET_P$ at certain range with high moisture availability, which can be understood as the results of possible over-estimation of precipitation or under-estimation of dam inflow. It is expected that the use of evapotranspiration complementary relationship for validating hydrological water balances will contribute to controlling uncertainties in estimating dam inflows during flood season in particular.

• Journal of Environmental Science International
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• v.25 no.9
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• pp.1253-1267
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• 2016

After large-scale flooding damage occurred along the Imjin river in 1996, 1998, and 1999, the Hantan river flood control dam was planned, and it has since been under construction. Unlike existing dams in Korea, the Hantan river flood control dam will remain fully open except during high floods, when the dam will store flood water temporarily to reduce flood peaks and flood water volume downstream. During past flooding seasons, floating debris has caused difficulties in the management of large-scale dams. Most of the existing multipurpose dams in Korea have installed nets to collect floating debris based on many years of experience with and data about inflow and distribution of floating debris in the dams. For the Hantan river flood control dam, however, collection of data about inflow and distribution of floating debris is not possible as the dam is located near the border area between North and South Korea. In order to devise a preliminary plan to collect floating debris in the Hantan river flood control dam, an EFDC hydrodynamic model was used to analyze the behavior of floating debris during high floods. The Lagrangian particle tracking method was utilized to simulate the behavior of floating debris in the dam. Based on the analysis of paths and final destinations of the particles, seven collection points were selected where it seemed to be effective to collect floating debris, as debris is likely to accumulate there in high density.

• Water for future
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• v.28 no.3
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• pp.187-195
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• 1995

This study aims at suggesting an alternative to improve current capacity of flood control for the existing Soyanggang multi-purpose dam which was constructed 20 years ago as a largest dam in Korea. The newly estimated value of the probable maximum precipitation(PMP) is 760.0 mm which is based on the hydrometeorological method. The peak inflow of 1000 years return period at the time of construction was 13,500$m^3$/s. However, the newly estimated peak inflow of the PMF is 18,100$m^3$/s which is 1.34 times bigger than the original one. In order to adopt the newly estimated PMF as a design flood, following four alternatives were compared; (1) allocation of more flood control space by lowering the normal high water level, (2) construction of a new spillway in addition to the existing one, (3) raising the existing dam crest, (4) construction of a new dam which has relevant flood control storage at the upstream of the Soyanggang multipurpose dam. The preliminary evaluation of these alternatives resulted in that the second alternative is most economical and feasible. So as to stably cope with the newly estimated PMF by meeting all the current functions of the multi-purpose dam, a detailed study of an additional spillway tunnel has to be followed.