• Structural Engineering and Mechanics
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• v.72 no.2
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• pp.141-153
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• 2019

The effect of galleries on the earthquake behavior of dams should be investigated to obtain more realistic results. Therefore, a roller compacted concrete (RCC) dam with and without galleries are examined under ground motion effects. For this purpose, Cine RCC dam constructed in Aydın, Turkey, is selected in applications. The optimal mesh around galleries is investigated to obtain the most realistic results. Two-dimensional finite element models of Cine RCC dam with and without galleries are prepared by using ANSYS software. Empty and full reservoir conditions were taken into account in the time-history analyses. Hydrodynamic effect of the reservoir water was taken into account considering two-dimensional fluid finite elements based on the Lagrangian approach. It is examined that how principle stresses and displacements change by height and during earthquake. The dam-foundation-reservoir interaction was taken into consideration with contact-target element pairs. The displacements and principle stress components obtained from the linear analyses are compared each other for various cases of reservoir water and galleries. According to numerical analyses, the effect of galleries is clear on the response of RCC dam. Besides, hydrodynamic water effect obviously increases the principle stress components and horizontal displacements of the dam.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.2
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• pp.147-156
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• 2011

The purpose of multipurpose reservoir operation in flood season is to reduce the peak flood at a control point by utilizing flood control storage or to minimize flood damage by controlling release and release time. Therefore, the most important thing in reservoir operation for flood season is to determine the optimal release and release time. In this study, goal programming is used for the optimal reservoir operation in flood season. The goal programming minimizes a sum of deviation from the target value using linear programming or nonlinear programming to obtain the optimal alternative for the problem with more than two objectives. To analyze the applicability of goal programming, the historical storm data are utilized. The goal programming is applied to the reservoir system operation as well as single reservoir operation. Chungju reservoir is selected for single reservoir operation and Andong and Imha reservoirs are selected for reservoir system operation. The result of goal programming is compared with that of HEC-5. As a result, it was found that goal programming could maintain the reservoir level within flood control level at the end of a flood season and also maintain flood discharge within a design flood at a control point for each time step. The goal programming operation is different from the real operation in the sense that all inflows are assumed to be given in advance. However, flood at a control point can be reduced by calculating the optimal release and optimal release time using suitable constraints and flood forecasting system.

• Journal of the Korean Institute of Gas
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• v.28 no.2
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• pp.66-75
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• 2024

This paper presents development of a CO₂ injectivity analysis model using nodal analysis for the depleted oil reservoirs in Malaysia. Based on the final well report of an appraisal well, a basic model was established, and sensitivity analysis was performed on injection pressure, tubing size, reservoir pressure, reservoir permeability, and thickness. Utilizing the well testing report of A appraisal well, permeability of 10md was determined through production nodal analysis. Using the basic input data from the A appraisal well, an injection well model was set. Nodal analysis of the basic model, at the bottomhole pressure of 3000.74psia, estimated the CO₂ injection rate to be 13.29MMscfd. As the results of sensitivity analysis, the injection pressure, reservoir thickness, and permeability tend to exhibit a roughly linear increase in injection rate when they were higher, while a decrease in reservoir pressure at injection also resulted in an approximate linear increase in injection rate. Analyzing the injection rate per inch of tubing size, the optimal tubing size of 2.548inch was determined. It is recommended that if the formation parting pressure is known, performing nodal analysis can predict the maximum reservoir pressure and injection pressure by comparing with bottomhole pressure.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.1
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• pp.31-43
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• 2017

Recent studies about irrigation water use have focused on agricultural reservoir operation in irrigation period. At the same time, it is significant to store water resource in reservoir during non-irrigation period in order to secure sufficient water in early growing season. In this study, Representative Concentration Pathways (RCP) 4.5, 8.5 scenarios with the Global Climate Model (GCM) of The Second Generation Earth System Model (CanESM2) were downscaled with bias correlation method. Cumulative precipitation during non-irrigation season, October to March, was analyzed. Interaction between cumulative precipitation and carry-over storage was analyzed with linear regression model for ten study reservoirs. Using the regression model, reservoir drought response ability was evaluated with expression of excess and deficiency. The results showed that future droughts will be more severe than past droughts. Especially in case of non-exceedance probability of 10%, drought in southern region seemed to be serious. Nine study reservoirs showed deficiency range from 10% to 55%, which turned out to be vulnerable for future drought. Only Jang-Chan reservoir was secure for early growing season in spite of drought with deficiency of 8% and -2%. The results of this study represents current agricultural reservoirs have vulnerability for the upcoming drought.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.3
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• pp.11-22
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• 2010

An analysis method is proposed for the transient linear or nonlinear analysis of dynamic interactions between a flexible dam body and reservoir impounding compressible water under earthquake loadings. The coupled dam-reservoir system consists of three substructures: (1) a dam body with linear or nonlinear behavior; (2) a semi-infinite fluid region with constant depth; and (3) an irregular fluid region between the dam body and far field. The dam body is modeled with linear and/or nonlinear finite elements. The far field is formulated as a displacement-based transmitting boundary in the frequency domain that can radiate energy into infinity. Then the transmitting boundary is transformed for the direct coupling in the time domain. The near field region is modeled as a compressible fluid contained between two substructures. The developed method is verified and applied to various earthquake response analyses of dam-reservoir systems. Also, the method is applied to a nonlinear analysis of a concrete gravity dam. The results show the location and severity of damage demonstrating the applicability to the seismic evaluation of existing and new dams.

• Water for future
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• v.27 no.4
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• pp.69-84
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• 1994

The aim of this paper is suggest how to control the real time reservoir operation for the optimal operation of reservoir during the draught and the rainy season. The realease and the storage lead to the achievement or the deviation losses, higher or lower than the target level. Considering this deviation as one of the losses, putting the penalty on the losses, the way of optimal reservoir operation is discussed in order to minimize the penalty losses. This study draw the deviation losses' curve depending on the operation objectie for the Daechung Dam, and apply the optimal operation to the Dam by the linear programing technique, using the slope of the deviation curve as the losses coefficience for the objective function. Conclusively, in this paper I can combine the opposing subjects -the release and the storage- as one objective function by the deviation curve, and also show how to decide the criterion relate to the real time reservoir operation by analysing to what extent and how easily the objectives can be achieved, subject to the inflows.

• Water Engineering Research
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• v.3 no.1
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• pp.57-62
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• 2002

This research is intended to integrate long-term operation rules and real time operation policy for conservation & flood control in a reservoir. The familiar Yield model has been modified and used to provide long-term rule curves. The model employs linear programming technique under given physical conditions, i.e., total capacity, dead storage, spillways, outlet capacity and their respective elevations to find required and desired minimum storage fur different demands. To investigate the system behavior resulting from the above-mentioned operating policy, i.e., the rule curves, the simulation model was used. Results of the simulation model show that the results of the optimization model are indeed valid. After confirmation of the above mentioned rule curves by the simulation models, gate operation procedure was merged with the long term operation rules to determine the optimum reservoir operating policy. In the gate operation procedure, operating policy in downstream flood plain, i.e., determination of damaging and non-damaging discharges in flood plain, peak floods, which could be routed by reservoir, are determined. Also outflow hydrograph and variations of water surface levels for two known hydrographs are determined. To examine efficiency of the above-mentioned models and their ability in determining the optimum operation policy, Esteghlal reservoir in Iran was analyzed as a case study. A numerical model fur the solution of two-dimensional dam break problems using fractional step method is developed on unstructured grid. The model is based on second-order Weighted Averaged Flux(WAF) scheme with HLLC approximate Riemann solver. To control the nonphysical oscillations associated with second-order accuracy, TVD scheme with SUPERBEE limiter is used. The developed model is verified by comparing the computational solutions with analytic solutions in idealized test cases. Very good agreements have been achieved in the verifications.

• Korean Journal of Ecology and Environment
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• v.44 no.2
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• pp.214-225
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• 2011

The objectives of the study were to evaluate seasonal patterns of epilimnetic water quality, and determine interannual eutrophication patterns at the dam site of Yong-dam Reservoir using long-term data during 2002~2009. Ionic dilutions, based on specific conductivity, occurred in the summer period in response to the intense monsoon rain and inflow, and suspended solid analysis indicated that the reservoir was clear except for the monsoon. Seasonality of nitrogen contents varied depending on the types of nitrogen and responded to ionic dilution; Ammonia-nitrogen ($NH_4$-N) peaked at dry season but nitrate-nitrogen ($NO_3$-N) peaked in the monsoon when the ionic dilution occurred. The maxima of $NO_3$-N seemed to be related with external summer N-loading from the watershed and active nitrogen fixation of bluregreens in the summer. $NO_3$-N was major determinant (>50%) of the total nitrogen pool and relative proportion of $NH_4$-N was minor. Long-term annual $NO_3$-N and TDN showed continuous increasing trends from 2004 to 2009, whereas TP and TDP showed decreasing trends along with chlorophyll-a (CHL) values. Empirical model analysis of log-transformed nutrients and N : P ratios on the CHL showed that the reservoir CHL had a stronger linear function with TP ($R^2$=0.89, p<0.001) than TN ($R^2$=0.35, p=0.120). Overall results suggest that eutrophication progress, based on TP and CHL, is slow down over the study period and this was mainly due to reduced phosphorns, which is considered as primary nutrient by the empirical model.

• Water for future
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• v.20 no.2
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• pp.117-126
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• 1987

A Synthetic unit hydrograph method was suggested for the representation of a direct runoff hydrograph with empirical geomorphologic laws and geomorphologic parameters by applying geomorphologic instantaneous unit hydrograph theory and Rossois results of application of GIUH theory to the Nash Model which is a linear reservoir model. The shape parameter m and scale parameter k can be derived by the Horton's empirical geomorphologic laws $R_A,R_B,R_L$ when ordered according to Strahler's ordering Scheme, main stream length and using the maximum velocity for the dynamic characteristics of a river basin, The derived response function was tested on some observed flood datas and showed promising. For the determination of the shape parameter m, eq. (16) was showed applying and m showed a good regression with the size of basin area.

• Water for future
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• v.18 no.2
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• pp.143-152
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• 1985

A method is suggested for the reappearance of a surface runoff hudorgraph of a river basin by linking the hydrologic response of a catchment represented by the instantaneous unit hydrograph(IUH) with the Horton's empirical gemorphologic laws. The geomorphologic theory of the IUH developed by G. Itrube et al. and the geomorphoclimatic theory of the IUH developed by Bras et al. are used to derive the new hydrologic response function in consideration of geomorphologic parameters and climatic characteristics by applying to Sukekawa's rainfall-runoff model. The derived response function was tested for on some observed hydrographs in a natural watershed and showed promising, and by considering a drainage basin as m(1∼4) identical linear reservoir in series, it was founded that the model(m=2) is most applicable to predict hydrologic response regardless of the size of basins. A modelization algorithm of a basin using Sthahler's ordering scheme of drainage network will give good result in analysis of the surface runoff huydrograph by the method of this study.