• Nuclear Engineering and Technology
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• 제54권8호
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• pp.3034-3042
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• 2022

The results of radioecological monitoring of the cooling pond Beloyarsk NPP (Russia) have been presented. The influence of waste technological waters of thermal and fast NPP reactors on the content of artificial radionuclides in surface waters and bottom sediments of the Beloyarsk reservoir has been studied. The long-term dynamics of the specific activity of ⁶⁰Co, ⁹⁰Sr, ¹³⁷Cs and ³H in the main components of the freshwater ecosystem at different distances from the source of radionuclide discharge has been estimated. Critical radionuclides (⁶⁰Co and ¹³⁷Cs), routes of their entry and periods of maximum discharge of radioisotopes into the cooling pond have been determined. It is shown that the technology of electricity generation at Beloyarsk NPP, based on fast reactors, has a much smaller effect on the flow of artificial radionuclides into the freshwater ecosystem of the reservoir. During the entire period of monitoring studies, the decrease in the specific activity of radionuclides from NPP origin in surface waters was 4.3-74.5 times, in bottom sediments 10-505 times. The maximum discharge of artificial radionuclides into the reservoir was noted during the period of restoration and decontamination work aimed at eliminating emergencies at the AMB thermal reactors of the first stage of the Beloyarsk NPP.

• 한국물환경학회지
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• 제33권3호
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• pp.326-333
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• 2017

The lakes and reservoirs have been reported as important sources of carbon emissions to the atmosphere in many countries. Although field experiments and theoretical investigations based on the fundamental gas exchange theory have proposed the quantitative amounts of Net Atmospheric Flux (NAF) in various climate regions, there are still large uncertainties at the global scale estimation. Mechanistic models can be used for understanding and estimating the temporal and spatial variations of the NAFs considering complicated hydrodynamic and biogeochemical processes in a reservoir, but these models require extensive and expensive datasets and model parameters. On the other hand, data driven machine learning (ML) algorithms are likely to be alternative tools to estimate the NAFs in responding to independent environmental variables. The objective of this study was to develop random forest (RF) and multi-layer artificial neural network (ANN) models for the estimation of the daily $CO_2$ NAFs in Daecheong Reservoir located in Geum River of Korea, and compare the models performance against the multiple linear regression (MLR) model that proposed in the previous study (Chung et al., 2016). As a result, the RF and ANN models showed much enhanced performance in the estimation of the high NAF values, while MLR model significantly under estimated them. Across validation with 10-fold random samplings was applied to evaluate the performance of three models, and indicated that the ANN model is best, and followed by RF and MLR models.

• 한국습지학회지
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• 제20권4호
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• pp.417-423
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• 2018

축산 지역 하류에 위치한 농업용 저수지의 강우시 유입, 유출수 분석을 통해 축산지역의 강우 유출 특성과 저류지에 의한 축산계 비점 오염물질의 저류형 시설에 의한 유출 저감 효율을 분석하였다. 급경사지에 위치한 한우 축산 지역의 비점 오염물질 유출은 주로 초기세척현상에 의해 발생됨을 알 수 있었으며 강우시의 유입수 농도는 비강우시에 비해 SS농도가 가장 높게 발생하고 있으며 T-P도 4배 이상 증가하는 양상을 보인다. 반면 총질소는 평균 30% 증가하는 것으로 나타나는데 질소항목으로 보면 질산성 질소는 거의 변화가 없는 반면에 암모니아성 질소가 2배 이상 증가하고 있다. 저류형 비점 제거시설 효율 분석 결과 비강우시 총인 제거효율이 53%로 가장 높고 부유물질은 37% 제거되고 있다. 유기물질은 10% 내외, 총질소는 5% 이내로 제거되며 부영양화로 녹조가 번성하는 하절기에는 오히려 유출수의 질소농도가 더 높아지는 경우도 빈번히 발생하고 있다. 강우시의 유입수 농도는 비강우시에 비해 SS농도가 가장 높게 발생하고 있으며 T-P도 4배 이상 증가하는 양상을 보인다. 강우시 부유물질의 제거효율은 60%로 나타나고 있으며 총인은 22% 제거되어 비강우시에 비해 제거효율은 감소하고 있다. 환경부의 비점제거시설 기준보다 9배 이상의 용량을 지니고 있지만 비점 전용 시설로 활용되지 못하는 탓에 장마철에 거의 만수 상태로 담수하여 비점제거 효율에 있어서는 충분한 효과를 보이지 못하고 있는 것으로 나타나 저수지의 용량 뿐 아니라 수문관리 등 유지관리도 비점 제거효율에 영향을 미치는 중요 인자로 분석되었다.

• 토지주택연구
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• 제5권3호
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• pp.203-214
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• 2014

The purpose of this paper is to introduce two integrated urban development projects in Japan that take full advantage of flood-control reservoirs: the Tetsugakudo Park Collective Housing Development Project and the Koshigaya Lake Town Project. The former project - implemented cooperatively by the Tokyo metropolitan government in charge of river management, Shinjuku and Nakano wards (in Tokyo) responsible for park management, and the Urban Renaissance Agency, a housing project developer - set a significant precedent for three-dimensional river use by realizing the three-dimensional integrated development of a flood control reservoir, a park, and collective housing. The Koshigaya Lake Town Project, launched as a drastic storm water management measure for a low-lying area often plagued by flooding, has achieved a sustainable coexistence between the waterfront environment and the urban living environment, with an artificial flood-control reservoir as the core for urban development. This project is fully committed to environmental coexistence through the optimal use of local environmental resources, with the cooperation of the central government, Saitama Prefecture and Koshigaya City.

• 한국물환경학회지
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• 제30권5호
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• pp.491-502
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• 2014

As meteorology is the driving force for lake thermodynamics and mixing processes, the effects of climate change on the physical limnology and associated ecosystem are emerging issues. The potential impacts of climate change on the physical features of a reservoir include the heat budget and thermodynamic balance across the air-water interface, formation and stability of the thermal stratification, and the timing of turn over. In addition, the changed physical processes may result in alteration of materials and energy flow because the biogeochemical processes of a stratified waterbody is strongly associated with the thermal stability. In this study, a novel modeling framework that consists of an artificial neural network (ANN), a watershed model (SWAT), a reservoir operation model(HEC-ResSim) and a hydrodynamic and water quality model (CE-QUAL-W2) is developed for projecting the effects of climate change on the reservoir water temperature and thermal stability. The results showed that increasing air temperature will cause higher epilimnion temperatures, earlier and more persistent thermal stratification, and increased thermal stability in the future. The Schmidt stability index used to evaluate the stratification strength showed tendency to increase, implying that the climate change may have considerable impacts on the water quality and ecosystem through changing the vertical mixing characteristics of the reservoir.

• Geomechanics and Engineering
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• 제29권1호
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• pp.65-77
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• 2022

Determination of strength properties of intact rock using artificial cores has been considered in recent years. In this study, some relationships for estimating the static properties of dolomudstone cores of the Asmari reservoir were presented using artificial cores prepared from cuttings of two wells, southwest of Iran. For this purpose, first natural cuttings (NC) and 33 cores including dolomite limestone (dolomudstone), anhydrite and anhydrite dolomite were prepared between depths of 1714 and 2208 meters. Petrographic, physical, mechanical and dynamic tests were performed on cores, NC and artificial cuttings (AC) which was prepared from the residuals of dolomudstone cores. For preparing the artificial cores, the average porosity of the dolomudstone cores was considered and determined using four methods. Artificial and natural cuttings were classified as dolomite limestone and dolomite limestone to calcareous dolomite, respectively. Using ordinary Portland cement (OPC), water, AC and NC artificial cores were prepared. Results of evaluating the proposed relationships using statistical criteria showed that the static properties of the artificial cores can be used to predict the static properties of the dolomudstone cores.

• 한국환경과학회지
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• 제24권8호
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• pp.1023-1036
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• 2015

A reliable streamflow forecasting is essential for flood disaster prevention, reservoir operation, water supply and water resources management. This study proposes a hybrid model for river stage forecasting and investigates its accuracy. The proposed model is the wavelet packet-based artificial neural network(WPANN). Wavelet packet transform(WPT) module in WPANN model is employed to decompose an input time series into approximation and detail components. The decomposed time series are then used as inputs of artificial neural network(ANN) module in WPANN model. Based on model performance indexes, WPANN models are found to produce better efficiency than ANN model. WPANN-sym10 model yields the best performance among all other models. It is found that WPT improves the accuracy of ANN model. The results obtained from this study indicate that the conjunction of WPT and ANN can improve the efficiency of ANN model and can be a potential tool for forecasting river stage more accurately.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(1)
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• pp.410-411
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• 2005

• 한국물환경학회지
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• 제24권3호
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• pp.365-377
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• 2008

Large artificial dam reservoirs and associated downstream ecosystems are under increased pressure from long-term negative impacts of turbid flood runoff. Despite various emerging issues of reservoir turbidity flow, turbidity modeling studies have been rare due to lack of experimental data that can support scientific interpretation. Modeling suspended sediment (SS) dynamics, and therefore turbidity ($C_T$), requires provision of constitutive relationships ($SS-C_T$) and accounting for deposition of different SS size fractions/types distribution in order to display this complicated dynamic behavior. This study explored the performance of a coupled two-dimensional (2D) hydrodynamic and particle dynamics model that simulates the fate and transport of a turbid density flow in a negatively buoyant density flow regime. Multiple groups of suspended sediment (SS), classified by the particle size and their site-specific $SS-C_T$ relationships, were used for the conversion between field measurements ($C_T$) and model state variables (SS). The 2D model showed, in overall, good performance in reproducing the reservoir thermal structure, flood propagation dynamics and the magnitude and distribution of turbidity in the stratified reservoir. Some significant errors were noticed in the transitional zone due to the inherent lateral averaging assumption of the 2D hydrodynamic model, and in the lacustrine zone possibly due to long-term decay of particulate organic matters induced during flood runoffs.

• 한국환경과학회지
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• 제9권2호
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• pp.115-123
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• 2000

The dynamics of water quality and phytoplankton population had examined by monthly sampling from the upper to the lower part of watergate in an artificial Shihwa Reservoir in which situated near newly cities and incustrial complex on the west coast of Korea from January 1997 to December 1998. Among environmental factors, yearly average concentration of chl-a, TN and TP seemed to eutrophic or hypertrophic conditions that ranged 146.4~245.8 $\mu\textrm{g}$/$\ell$, 1.6~2.7 mg N/$\ell$, 258~448 $\mu\textrm{g}$ P/$\ell$, 26.9~80.7 $\mu\textrm{g}$/$\ell$, 1.0~2.4 mgN/$\ell$ and 74~239 $\mu\textrm{g}$P/$\ell$ respectively. Water quality was extremely deteriorated to consistently accumulation into inner reservoir by load of pollutants from autochthonous and allochthonous until early July 1997 after embankment. Water pollution of Shihwa Reservoir was remarkble on the biological condition with largely persistent bloom of phytoplankton and increase rate of standing crops was 2.4/yr. The development trend of phytoplankton in water ecosystem were closely related to increse and decrease of physico-chemical factors and those scale seemed to control by nutrient contents. Inflow of seawater into reservoir to object of repair of water quality. As to see dominant species, composition of those composed to mostly freshwater algae before inflow of seawater such as Selenastrum capricornutum of green algae, cyclotella atomus, C. meneghiniana of diatom and Microcystis spp. of blue-green algae and the other hand brackish algae were dominated after inflow of seawater such as Chaetoceros dicipiens, Skeletonema costatum of diatom, Dinophysis acuminata, Gymnodinium mikimotoi, G. sanguineum, Gyrodinium spirale, Prorocentrum minmum of dinoflagellate and Eutreptiella gymnastica of euglenoid. Moreover, small flagellates including Chroomonas spp. of cryptomonad were abundant throughout the year. The cause of water deterioration during fill of the freshwater were complexly supported with extra and intra parameters. The variation pattern of phytoplankton were related to water temperature and salinity by inflow of seawater based to plentiful nutrients. The dynamics of phytoplankton were assessed to ecosystem that clearly condition of dominant by unique or a few angel species seasonally.