• Journal of Wetlands Research
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• v.21 no.spc
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• pp.69-79
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• 2019

In Korea, more than 60% of the whole lands are mountainous area. Since many decades ago, hydroelectric power plants have been constructed and eco-friendly energy has been produced. Hydropower can cope with the rapidly changing energy supply and demand, and produce eco-friendly energy. However, when the reservoir is built, it is often inevitable to damage the environment due to construction of large structure. In this study, the optimal reservoir operation model was developed to maximize power generation by monthly operation for long-term operation planning. The dam operation model was developed using the linear programming which is widely used in the optimal resources allocation problems. And the reservoir operation model can establish monthly operation plan for 1 year. Linear programming requires both object function and constraints to be linear. However, since the power generation equation is nonlinear, it is linearized using the Taylor Expansion technique. The optimization results were compared with the 2009-2018 historical data of five hydropower reservoirs. As a result, the total optimal generation is about 10~37% higher than the historical generation.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.171-171
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• 2020

Decision making strategies should consider both adaptiveness and robustness in order to deal with two main characteristics of climate change: non-stationarity and deep uncertainty. Especially, robust strategies are different from traditional optimal strategies in the sense that they are satisfactory over a wider range of uncertainty and may act as a key when confronting climate change. In this study, a new framework named Robust Stochastic Dynamic Programming (R-SDP) is proposed, which couples previously developed robust optimization (RO) into the objective function and constraint of SDP. Two main approaches of RO, feasibility robustness and solution robustness, are considered in the optimization algorithm and consequently, three models to be tested are developed: conventional-SDP (CSDP), R-SDP-Feasibility (RSDP-F), and R-SDP-Solution (RSDP-S). The developed models were used to derive optimal monthly release rules in a single reservoir, and multiple simulations of the derived monthly policy under inflow scenarios with varying mean and standard deviations are undergone. Simulation results were then evaluated with a wide range of evaluation metrics from reliability, resiliency, vulnerability to additional robustness measures. Evaluation results were finally visualized with advanced visualization tools that are used in multi-objective robust decision making (MORDM) framework. As a result, RSDP-F and RSDP-S models yielded more risk averse, or conservative, results than the CSDP model, and a trade-off relationship between traditional and robustness metrics was discovered.

• Korean Journal of Ecology and Environment
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• v.42 no.3
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• pp.374-381
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• 2009

Ecological instream flow was quantitatively calculated based on the river characteristics and fish habitat in the downstream of Yongdam Reservoir. The river bed and width did not change from 1988 before the am construction to 2004 after the dam construction, but the bed sediment size was attenuated a little in 2004. According to result that investigate fishes, 4 family 11 species including Acheilognathus koreensis were collected. Among them, Zacceo koreanus of cyprinidae was dominant, and Coreoleuciscus splendidus did sub-dominant. The habitat suitability indexes were estimated for two fish species Zacco koreanus and Coreoleuciscus splendidus using Physical Habitat Simulation System (PHABSIM) considering the river characteristics. In Gamdong and Daeti sites, the optimal ecological flow for Z. koreanus and C. splendidus were $13.90\sim12.60\;m^3\;s^{-1}$ and $15.50\sim11.60\;m^3\;s^{-1}$, respectively. In contrast, the optimal flow for the two species in Bunam site were $7.00\;m^3\;s^{-1}$. The ecological instream flow in the downstream of Yongdam Reservoir was between normal and high flow rate.

• Journal of Korea Water Resources Association
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• v.35 no.1
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• pp.51-64
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• 2002

In this study, the formulation of the developed mixed-integer programming model for a multi-reservoir system including hydro-electric power generation (park et al., 2001) has been improved for multiple reservoir system operation using risk evaluation criteria. Sequential linear programming(SLP) was applied for the linearization of the hydro-electric energy term in the model. In order to allocate monthly reservoir release reasonably the value of weight for hydro-electric energy was assigned by level of power generation hour. The improved model was applied to the five reservoirs system in the Han river. And could be confirmed the availibility of new formulation appling risk evaluation criteria.

• Journal of Korea Water Resources Association
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• v.51 no.spc
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• pp.1127-1134
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• 2018

According to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), climate change increases the frequency of abnormal weather phenomenon. As the frequency of abnormal weather phenomenon increases, frequency of disasters related to water resources such as floods and droughts also increases. Drought is the main factor that directly affects water supply. Recently, the intensity of drought and the frequency of drought occurrence have increased in Korea. So, there is a need for water resource securing technology for stable water supply. Korean Water Plan mentioned that water reserves concept is necessary for stable water supply. Most multi-purpose reservoirs in Korea have emergency storage in addition to conservation storage used for water supply. However, there is no clear use standard for emergency storage. This study investigated the use of reservoir reserves for stable water supply. In order to consider the climate change impact, the AR5-based hydrological scenario was used as inflow data for the reservoir simulation model. Reservoir simulations were carried out in accordance with the utilization conditions of emergency storage and water supply adjustment standard. The optimal reserves for each multi-purpose reservoirs was estimated using simulation results.

• Journal of Korea Water Resources Association
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• v.54 no.2
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• pp.93-104
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• 2021

Due to climate change the sustainable water resources management of agricultural reservoirs, the largest number of reservoirs in Korea, has become important. However, the DIROM, rainfall-runoff model for calculating agricultural reservoir inflow, has used regression equation developed in the 1980s. This study has optimized the parameters of the DIROM using the genetic algorithm (GA) based on historical inflow data for some agricultural reservoirs that recently begun to observe inflow data. The result showed that the error between the historical inflow and simulated inflow using the optimal parameters was decreased by about 80% compared with the annual inflow with the existing parameters. The correlation coefficient and root mean square error with the historical inflow increased to 0.64 and decreased to 28.2 × 103 ㎥, respectively. As a result, if the DIROM uses the optimal parameters based on the historical inflow of agricultural reservoirs, it will be possible to calculate the long-term reservoir inflow with high accuracy. This study will contribute to future research using the historical inflow of agricultural reservoirs and improvement of the rainfall-runoff model parameters. Furthermore, the reliable long-term inflow data will support for sustainable reservoir management and agricultural water supply.

• Journal of Korea Water Resources Association
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• v.32 no.3
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• pp.281-289
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• 1999

Small-scale hydropower projects at existing agricultural reservoirs can contribute to produce electric energy by maximizing the use of releases from the reservoirs. The irrigation water duration, the reservoir hydropower simulation, and the nonlinear programming model are employed to estimate potential hydroelectric energy at an existing reservoir. The nonlinear programming model consists of finding a maximum hydroelectric energy subject to irrigation water demand constraints. The sample reservoir given a set of inflow and irrigation water is considered. The optimal solutions by the optimization model yield the most hydroelectric energy for the analysis period in the three methods. Consequently, the nonlinear programming model uses the most water for hydropower generation with respect to the total inflow of the sample reservoir. It is also found that additional storage by increasing the normal water level of the sample reservoir does not significantly increase the annual hydroelectric energy for the given reservoir. It is expected that the optimization model and the proposed procedure for estimating potential hydroelectric energy can be applied to evaluate feasibility analysis for small scale hydropower additions at existing agricultural dams.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1248-1252
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• 1999

To provide electricity power of good quality, it is essential to establish generation of electricity plan in electric power system based on accurate power-demand prediction and cope with changes of power-need fluctuating constantly. The role of hydraulic-power generation of electricity in electric power system is of importance because responding to electric power-demand counts or reservoir-type hydraulic-power generation of electricity which is designed for additional load in electric power system. So hydraulic-power generation of electricity must have fast start reserve. But the amount of water, resources of reservoir-type hydraulic-power generation of electricity is restricted and multi-used, so the scheduling of management by exact forecasting the amount of water is critical. That is why efficient hydraulic-power generation of electricity makes a main role on pumping up the utility of energy and water resource. This thesis introduced the example of optimal generation of electricity plan establishment which is used in managing reservoir-type hydraulic-power generation of electricity.

• Water for future
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• v.18 no.3
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• pp.225-233
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• 1985

To develop a simulation strategy of multi-reservoir operation in flood season, the single dam operations methed for the Chungju dam are investigated in the Han river basin. Thus, spillway rule curve, rigid ROM, and linear decision rules are applied for control operations, subject to the restrictions imposed by the river and the reservoir characteristics. The storage and release and control/utility efficiencies for several floods are calculated. The variation of control coefficients with respect to the return period are also examined. As the results of this comparative study, the optimal operation method can be selected in terms of the magnitude of flood. With inflow forecasting, the flood control operation can be greatly improved by variable coefficients rigid ROM and linear decision rules.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.5
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• pp.19-28
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• 2016

This study was to design the optimal locations of the water level monitoring to quantify the agricultural water use in irrigation area supplied from an agricultural reservoir. In most of agricultural areas without TM/TC (Tele-Monitoring and Tele-Control) or monitoring network, irrigation water have been supplied on conventional experience and agricultural reservoir have been operated based on the operating simulation results by HOMWRS (Hydrological Operation Model for Water Resources System). Therefore, this study quantified the amount of agricultural water use in an irrigation area (Musu Reservoir, Jincheon-gun) by establishing water level monitoring network and analyzed the agricultural water saving effect. According to the evaluation of the economic values for water saving effect, the saving agricultural water of 1.7 million ton was analyzed to have economic values of 0.85 million won as water for living, and 1.78 million won as water for industrial use. It is identified to secure economic feasibility of the new water monitoring network by establishing one monitoring point in the entrance, irrigation area and endpoint through the economic analysis.