• 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.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.221-231
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• 2009

This study was carried out to comparatively identify characteristics of turbid water influence in Imha Reservoir, Soyang Reservoir, and Daecheong Reservoir in Korea. We used 3 years dataset from 2002 to 2004 and analyzed seasonal water quality characteristics, particular parameters in association with turbidity, and light transparency to figure out the trends. All parameters to be used in the study were total phosphate (TP), total nitrogen (TN), chlorophyll-${\alpha}$ (Chl), suspended solids (SS), Secchi depth (SD), conductivity, and verticallight extinction coefficienct($K_d$), euphotic zone ($Z_{eu}$), and critical depth ($Z_p$). All parameters depend on season and watershed. Suspended solids from Soyang Reservoir were usually caused by TP, mainly related to living wastes and agricultures in upper stream. Daecheong Reservoir was influenced by organic matters related to large phytoplankton biomass in summer and inorganic suspended solids by nutrients in the winter. However, in case of Imha Reservoir, turbid water, consisted in silt and clay through heavy precipitation remained in the waterbody to decrease water transparency along with TP and caused the light limitation in winter. Overall results suggest that it was necessary to establish various management programs because the reasons occurring turbidity were varied according to the reservoir circumstances.

• Proceedings of the Korea Water Resources Association Conference
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• 1999.05a
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• pp.209-214
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• 1999

• Journal of Korean Society on Water Environment
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• v.29 no.6
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• pp.825-831
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• 2013

The Suwon stream which consists of a mountainous reach, an artificial reservoir and an urban reach provides benthic macroinvertebrates with various habitats. This study was conducted to find out the influence of reservoir sluice control and water quality on benthic macroinvertebrates community in the Suwon stream from June to August, 2011. As a result, substrate composition showed little difference between the upper site (S2) and the lower site of the reservoir (S3). At site S3, water velocity was fastest, and water temperature was lowest due to the intermediate depth discharge of the reservoir. Cheumatopsyche brevilineata which prefer fast water velocity was dominant at site S3. Some biotic indices (H', J, and R) of site S3 decreased significantly whereas Benthic Macroinvertebrate Index (BMI) showed little difference between site S2 and site S3. EPT showed a negative correlation with water temperature. The sluice control of the reservoir leaded variations of water velocity and temperature, and seemed to make the state of aquatic ecosystem worse.

• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.3
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• pp.16-22
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• 2002

The effect and the overall optimal operation of artificial aeration devices for mixing of thermally stratified water reservoir are under study, and its brief introduction is made. The study site is Yeoncho Lake in Geojae island, which is well known for its eutrophication problems in the summer. A few samplings have been made before and after the operation of two types of artificial aerators, and the effect is believed to be positive. Also, design methodology for such artificial aerators is reviewed and a few are applied to the case of Yeoncho Lake. Schladow's[1993] proposal is believed most proper based on the information we have gathered by now. In addition, a simple numerical experiment is also peformed to see the overall effect of the device on the flow and temperature profile.

• Environmental Engineering Research
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• v.20 no.3
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• pp.290-297
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• 2015

This paper presents the evaluation of the impact of climate change on water resources and yield capacity of Asa and Kampe reservoirs. Trend analysis of mean temperature, runoff, rainfall and evapotranspiration was carried out using Mann Kendall and Sen's slope, while runoff was modeled as a function of temperature, rainfall and evapotranspiration using Artificial Neural Networks (ANN). Rainfall and runoff exhibited positive trends at the two dam sites and their upstream while forecasted ten-year runoff displayed increasing positive trend which indicates high reservoir inflow. The reservoir yield capacity estimated with the ANN forecasted runoff was higher by about 38% and 17% compared to that obtained with historical runoff at Asa and Kampe respectively. This is an indication that there is tendency for water resources of the reservoir to increase and thus more water will be available for water supply and irrigation to ensure food security.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.3
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• pp.51-58
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• 1997

Determining sizes and the locations of reservoirs in the water distribution system(WDS) with multi-reservoirs is much difficult than that with single reservoir. The extended period simulation(EPS) models provide more comprehensive analysis of water distribution systems than the steady-state models can do. Therefore, EPS models should be applied to the WDS with multi-reservoirs. This study is to investigate the variations of required reservoir sizes and residual nodal pressures according to reservoir locations. In this study, EPS was applied to analyze an artificial and a real WDS under several water demand patterns. As a result, it was found that water demand patterns make no significant differences in the determining of the reservoir size, if they have similar peaking factors. And the variations of the peaking factor should be carefully checked in the design and the analysis of the WDS with multi-reservoirs, because the peaking factor itself will affect the minimum allowable sizes of reservoirs in those systems.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.30-30
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• 2023

This study aims to establish the multi-reservoir operation system model in the Upper Mun River Basin which includes 5 main dams namely, Mun Bon (MB), Lamchae (LC), Lam Takhong (LTK), Lam Phraphoeng (LPP), and Lower Lam Chiengkrai (LLCK) Dams. The knowledge and AI technology were applied aiming to develop innovative prototype for SMART dam-reservoir operation in future. Two different sorts of reservoir operation system model namely, Fuzzy Logic (FL) and Constraint Programming (CP) as well as the development of rainfall and reservoir inflow prediction models using Machine Learning (ML) technique were made to help specify the right amount of daily reservoir releases for the Royal Irrigation Department (RID). The model could also provide the essential information particularly for the Office of National Water Resource of Thailand (ONWR) to determine the short-term and long-term water resource management plan and strengthen water security against flood and drought in this region. The simulated results of base case scenario for reservoir operation in the Upper Mun from 2008 to 2021 indicated that in the same circumstances, FL and CP models could specify the new release schemes to increase the reservoir water storages at the beginning of dry season of approximately 125.25 and 142.20 MCM per year. This means that supplying the agricultural water to farmers in dry season could be well managed. In other words, water scarcity problem could substantially be moderated at some extent in case of incapability to control the expansion of cultivated area size properly. Moreover, using AI technology to determine the new reservoir release schemes plays important role in reducing the actual volume of water shortfall in the basin although the drought situation at LTK and LLCK Dams were still existed in some periods of time. Meanwhile, considering the predicted inflow and hydrologic factors downstream of 5 main dams by FL model and minimizing the flood volume by CP model could ensure that flood risk was considerably minimized as a result of new release schemes.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.22 no.5
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• pp.57-67
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• 2019

Water-Birds are the birds that occupy the highest proportion in Korea, inland wetlands and reservoirs provide them with a good environment as habitat, but their habitats have been losing because of thoughtless development. Therefore, artificial plant islands in reservoirs are important for improving habitat environment and providing food resources. However, there are no research and standards on the built and management of artificial plant islands. So this study is to find out the density of bird using artificial plant island as habitat through monitoring using UAV focus on the Cheonho-reservoirs located in Seobuk-gu, Cheonan-si(Middle Chungcheong Province). Further, the correlation analysis with environmental factors was conducted to determine the effect of artificial plant islands as habitats for water-birds. The supervised classification of the three-time images taken by the drone identified 244 white-billed ducks and 46 mandarin ducks. The utilization rate was different for each photographed date, and more individuals were identified in wet artificial plant islands than dry ones. As a result of analyzing the utilization follow environmental factors, the distance from the trail showed a significant correlation, and the other factors did not have a statistically significant effect. This study is the first case of the UAV monitoring method of the water-birds using artificial plant islands in the reservoir, and can be used as the basic data for the built and management.

• ALGAE
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• v.19 no.2
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• pp.107-114
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• 2004

Patterns of epilithic algal colonization on artificial substrata (unglazed ceramic tiles) were investigated from 23rd April to 3rd July 1999 at weekly intervals over a 10 weeks period outside and inside the mesocosm in Togyo reservoir within the Civilian Passage Restriction Line near Demilitarized Zone (DMZ) in Korea. The highest standing crops of epilithic algae was 1,798$\cdot$10³ cells$\cdot$$cm^{-2}$ outside the mesocosm on 26th June and also inside the mesocosm those was 2,391$\cdot$10³ cells$\cdot$$cm^{-2}$ on 26th June, 9 weeks after the experiment began. The dominants outside the mesocosm were Achnanthes minutissima, Navicula bicephala, Oscillatoria angusta, Synedra delicastissima, S. tenuissima, S. ulna v. danica and Tabellaria flocculosa, and those inside the mesocosm were Achnanthes minitissima, Coenochloris polycocca, Fragilaria crotonenesis, Peridinium cinctum, Synedra delicatissima, Tabellaria flocculosa and Ulothrix subtilissima. Diatoms were most abundant and Achnanthes minutissima was the most important species colonizing on the tiles. Chlorophyll-a content was highest value of 5.4 mg$\cdot$$m^{-2}$ on 19th June after 8 weeks growth outside the mesocosm and was 24.4 mg$\cdot$$m^{-2}$ on 26th June, 9 weeks after the experiment began on tiles inside the mesocosm. It was also shown that unglazed ceramic tiles were a more suitable substratum for colonization than the glass slides. Consequently the substratum selection plays an important role in the colonization by the epilithic algal community.