• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.4
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• pp.76-86
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• 2000

The objective function of reservoir storage error was suggested to simulate daily reservoir inflow. DAWAST model, UMAX, LMAX, FC,CP, CE were calibrated. Daily reservoir inflow was imulated with calibrated parameters and reservoir storage was simulated on a daily basis. The simulated results were compared with the monthly results by Gajiyama equation and ten-day results by Tank rainfall-runoff model through equal value lines and hydrographs . DAWAST model showed the best results compared with Gajiymama equation and Tank model. Especially, DAWAST model showed a good agreement in dry periods. NEW concept using objective function of storage error was believed to be satisfactory and to be applied in estimating reservoir inflow.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42
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• pp.17-23
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• 2000

A decision support system for determining reservoir capacity, named as KORESIDSS (KOwaco's REservoir SIzing Decision Support System), was developed. The system is composed of three subsystems; a database/information subsystem, a model subsystem, and an output subsystem. This system is operated using MS-Windows with a GUI (Graphic User Interface) system developed using Visual Basic 5.0. As a continuous runoff model, the DAWAST model (DAily WAtershed STreamflow model) developed by Noh(1991) was and its analysis module was developed. This system was applied to a newly-planned dam, the Cheongyan Dam, Which will be located in Cheongyang-Gun, Chungcheongnam-Do and it was proved to be applicable in determining reservoir storage.

• Journal of Korean Society on Water Environment
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• v.29 no.6
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• pp.799-807
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• 2013

Reservoir sedimentation is one of the major concerns for sustainable reservoir operation. Since sediment concentration of the rivers in the Himalayan Mountain is very high, a proper sediment management scheme is necessary. This paper presents long-term reservoir sedimentation and sediment flushing based on the gate operation. Focused on the reservoir to be constructed for the Patrind hydropower project in Pakistan, 4 different flushing scenarios were proposed in this study to prevent successive sedimentation. By extending flushing period and by increasing the flushing discharge for 2 times, the flushing rate increases up to 53.2% and 43.6% in proportion to flushing period and discharge, respectively. Based on the simulation presented in this paper, it is expected to establish efficient sediment management plan to increase hydro power generation and sediment flushing simultaneously.

• Journal of Soil and Groundwater Environment
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• v.20 no.7
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• pp.121-134
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• 2015

Spatial and temporal changes in algal population in Yongdam reservoir and ecological factors that induced the changes in the size and composition of algal population were investigated by monthly sampling at ten locations in the reservoir. Nutritional state of the reservoir was identified to be phosphorus-limited with nitrogen to phosphorus (N : P) ratio much greater than 17 in most samples. Algal population was dominated by three taxonomic groups, diatoms, chlorophytes and cyanobacteria. Although explosive algal growth was not observed in the summer, algal population showed transition with time of the dominant algal type from diatoms in the winter to cyanobacteria in the summer. Chlorophyta was not the dominant group in the reservoir although they maintained relatively stable number of cells in the reservoir and showed increase in population from March to May. The application of statistical methods revealed that the factors inducing changes in cell number of each group were water temperature for diatoms and cyanobacteria and phosphorus concentration for chlorophyte. Fluctuation of cyanobacterial population was mainly observed near the inlet of tributaries while diatoms showed higher variation inside the reservoir.

• KCID journal
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• v.18 no.1
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• pp.68-80
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• 2011

To provide a operation rule curve for reservoir with low ratio of watershed area to paddy field area, Duckyong reservoir with watershed area of $15.8km^2$ and paddy field area of 1,071ha was selected, in which 4 meters are being heightened and full water levels will be increased from EL.26.0m to EL.30.0m, total water storages from 365.6M $m^3$ to 708.0M $m^3$. There was no operation rule curve that satisfied over 90% reliability of water supply in reservoir with watershed area of 1.48 times of paddy field area. The differences between observed and simulated reservoir daily water storages were minimized to determine parameters for simulating reservoir inflow in case of paddy field area of 550ha from 1991 to 2010. A operation rule curve was drawn to have a maximum storage with total water storage, which was in paddy field area of 700ha with ratio of 2.3 between watershed area and paddy field area. This case showed that annual irrigation water supply was 668M $m^3$ and instream flow of 57M $m^3$, water supply reliability of 55.6% in normal operation, and annual irrigation water supply was 605M $m^3$ and instream flow of 38M $m^3$, water supply reliability of 95.6% in withdrawal limited operation. Water supply reliabilities showed 35.6% without flood regulation and 17.8% with flood regulation in existing reservoir before heightening.

• Geosciences Journal
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• v.22 no.6
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• pp.1027-1039
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• 2018

Seismic attributes are often used to identify lithology and evaluate reservoir properties. However, interpretation based only on structural attributes and without knowledge of the Vp/Vs ratio can limit the ability to evaluate changes in heavy oil reservoirs. These limitations are often due to less obvious impedance differences. In order to investigate pieces of evidence of a heavy-oil shaly-sand reservoir from seismic data, besides geochemistry, we studied seismic attributes and characterized the reservoir using seismic stack data and well logging data. The study area was the Muglad rift basin in South Sudan. We conducted a seismic complex analysis to evaluate the target reservoir. To delineate the frequency responses of the different lithological units, we applied the spectral decomposition method to the target reservoir. The most unexpected result was continuous bands of strong seismic reflectors in the target reservoir, which extended across the borehole. Spectral decomposition analysis showed that the low-frequency zone of 25 Hz dominant frequency was consistent with instantaneous attributes. This approach can identify lithology, reveal frequency anomalies, and filter the stacked section into low- and high-frequency bands. The heavy-oil reservoir zones exhibited velocity attenuation and the amplitude was strongly frequency dependent.

• Journal of Korean Society on Water Environment
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• v.23 no.1
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• pp.52-63
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• 2007

The objectives of this study were to setup a laterally-averaged two-dimensional eutrophication model in Daecheong Reservoir, and to validate the model under two different hydrological conditions; drought year (2001) and wet year (2004). The suggested modeling approach was found to be very effective to simulate the dynamic variations of water temperature, nutrients, dissolved oxygen, and algae in the reservoir. The model satisfactorily replicated the algal bloom that happened between Janggae (Sta.4) and Haenam (Sta.5) during summer of 2001, although the peak concentration was slightly underestimated due to the laterally averaged assumption. The allochthonous phosphorus and algae induced from upstream and So-oak stream during several rainfall events were found to be most significant sources of algal bloom in 2001. In contrast to draught year, the flood events happened during summer months of 2004 tended to remove the hypolimnetic anaerobic conditions and dilute the dissolved phosphorus in the upper reach of the reservoir, and in turn mitigated algal bloom. It implies that the impact of hydrological and hydrodynamic conditions on the reservoir water quality is highly significant, and a drought year may be more vulnerable to algal bloom in the reservoir.

• Journal of Environmental Impact Assessment
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• v.21 no.3
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• pp.367-380
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• 2012

There are many long and round shape shores due to terrain characteristics in Daecheong reservoir. Therefore it is indicated different spatial distribution of algae every year since the stream is being regulated by these terrain characteristics and reservoir operation about inflow and outflow discharge. Also oversupply of nutrient salt from tributaries of Daecheong reservoir where pollutants were concentrated generates massive growth of algae and depending on hydrological, reservoir operation condition, those proliferated algae at the stagnant tributaries moves to the mainstream of Daecheong reservoir which could create problems of water quality. In this study, it was analyzed the tendency of algae generation by examining algae occurring status for the last 4 years since 2008, and implemented hydraulic analysis at Daecheong reservoir through numerical tracer simulation by applying 3-dimensional hydrodynamic model, ELCOM. Also it was implemented a quantitative analysis of causal relationship based on the algae generation tendency and hydraulic behavior at Daecheong reservoir. Through numerical tracer simulation in this study, it could be noticed the degree of spread of inflow indicated similar trend to the algae occurring status at Daecheong reservoir and verified the different tendency of algae generation in 2011 unlike previous year caused by the rise of water temperature.

• Journal of Life Science
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• v.19 no.11
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• pp.1562-1567
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• 2009

Heavy metal contamination levels in Andong reservoir and Imha reservoir were measured with heavy metal contents in both water and sediment, and analyzed with heavy metal accumulation level in inhabitant fish, Carassius auratus, using an inductively coupled plasma spectrometer and an atomic absorption spectrometer. High levels of heavy metal contents in water, sediment and the tissues of C. auratus were detected. Likewise, relatively high levels of As were detected in water and sediment from Andong reservoir. In addition, higher levels of Cr, Cu, Cd and As content were detected in muscle and bone tissues of fish from Andong reservoir than those from Imha reservoir. As a result, the heavy metal content of water, sediment and inhabitant fish, C. auratus, in Andong reservoir was higher than Imha reservoir. We proposed that heavy metal contamination in water and inhabitant fish is attributed to various metals derived from abandoned mines and farmlands that are upstream of Andong reservoir.

• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.1060-1067
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• 2006

Water quality in the Daecheong reservoir has been deteriorated by algal bloom due to nutrient supply from the upstream of the Daecheong reservoir after heavy rainfall. Algal bloom is propagated from eutrophicated tributary into the main body of the reservoir according to the hydrological conditions. This study is aimed to estimate the water current and temperature effect by the simulation of dam spill flow control using water quality model, CE-QUAL-W2 in 2003. Water current was resulted in nutrient transport from upstream of main reservoir and nutrients were delivered up to downstream by fast water velocity. Algal blooms occurred in stagnate zone of reservoir downstream as the current of downstream was retarded according to dam outflow control. Consequently water balance in stagnate zone triggered a rise of water temperature in summer. It affected algal bloom in the embayment of the reservoir. The simulation result by outflow control scenarios showed that spill flow augmentation induced in water body instability of stagnate zone so that water temperature declined. It could be suggested that outflow control minimize algal bloom in the downstream in the flooding season as long as water elevation level is maintained properly.