• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.609-616
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• 2005

A high ammonia nitrogen ($NH_3-N$) concentration has been recursively observed every winter season in Geum River, which hindered chemical treatment processes at a water treatment plant. A flushing discharge from Daecheong Dam was often considered to dilute $NH_3-N$, but information on the quantitative effect of flushing on the downstream water quality was limited. In this study, the impact of a short-term reservoir flushing on the downstream water quality was investigated through field experiments and unsteady water quality modeling. On November 22, 2003, the reservoir discharge was increased from $30m^3/sec$ to $200m^3/sec$ within 6 hours for the purpose of the experiment. The results showed that flushing flow tends to reduce downstream $NH_3-N$ concentrations considerably, but the effectiveness was limited by flushing amount and time. An unsteady river water quality model was applied to simulate the changes of nitrogen concentrations in response to reservoir flushing. The model showed very good performance in predicting the travel time of flushing flow and the effect of flushing discharge on the reduction of downstream $NH_3-N$ concentrations at Maepo and Geumnam site, but a significant discrepancy was observed at Gongju site.

• Atmosphere
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• v.22 no.3
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• pp.357-365
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• 2012

High spatio-temporal resolution hydrologic components can give important information to monitor natural disaster. The objective of this study is to create high spatial-temporal resolution gridded hydrologic components using TOPLATS distributed land surface model and evaluate their accuracy. For this, Andong dam basin is selected as study area and TOPLATS model is constructed to create hourly simulated values in every $1{\times}1km^2$ cell size. The observed inflow at Andong dam and soil moisture at Andong AWS site are collected to directly evaluate the simulated one. RMSEs of monthly simulated flow for calibration (2003~2006) and verification (2007~2009) periods show 36.87 mm and 32.41 mm, respectively. The hourly simulated soil moisture in the cell located Andong observation site for 2009 is well fitted with observed one at -50 cm. From this results, the cell based hydrologic components using TOPLATS distributed land surface model show to reasonably represent the real hydrologic condition in the field. Therefore the model driven hydrologic information can be used to analyze local water balance and monitor natural disaster caused by the severe weather.

• Ecology and Resilient Infrastructure
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• v.4 no.1
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• pp.3-11
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• 2017

In this study, change in vegetation on bars was analyzed using the data on hydrology and river morphology with on-site photographic monitoring data for the sites of interest of the Naeseong Stream during the period from March 2013 to July 2016 when the impoundment of Yeongju Dam began. The effect of flow condition on burial and removal of vegetation covered on bar surfaces was elucidated by comparison of on-site photographic monitoring data with continuous water level plotted with on the cross-section profile. In 2014 burial happened due to late flood, while July flood caused burial and removal in 2016. On the contrary vegetation increased in 2015 due to low flow without flood. Results of this study showing natural changes in vegetation will be reference to changes which is expected to be caused by dam impoundment.

• Journal of the Korean Institute of Landscape Architecture
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• v.34 no.1 s.114
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• pp.107-119
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• 2006

The Korea Water Resources Corporation(KOWACO) proposed bidding for an alternative design for Hwabuk Multi-purpose Dam in March of 2004. The site is located in Hakseong-ri, Goro-myeon, Gunwi-gun, Gyeongsangbuk-do and has adrainage area of $87.52km^2$. The purpose of this project is to establish an environmentally friendly plan for minimizing the damage that was caused by the construction of the Hwabuk Multi-purpose Dam. The design principle of KOWACO was the restoration of the natural environment, a harmonious landscape, and the creation of a space of regional and local culture. The basic concept of this project involves an ecological-restoration axis and a functional-connection axis. The site is divided into four spaces: (1) the space of memory and symbol, (2) the space of nature and ecology, (3) the space of regional and local culture, and (4) the space of the regional economy. There are four sub-spaces in the space of memory and symbol: the track forest, the time forest, the memory room, and the sun plaza. There are three sub-spaces in the space of nature and ecology: the habitat of aquatic birds, the wind forest, and the eco-corridor. There are five themed parks in the space of regional and local culture: the culture and relic room, the wildflower garden, the ecological pond, the insect observation park, and the pyogo maze. There are three areas in the space of the regional economy: the forest pension, the waterside pension, and the community center, as Dungdungi village was reorganized to serve as a lodging complex. These themed parks, working together, can offer an effective space for nature, culture, rest, and experience.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.638-646
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• 2018

The purpose of this study was to investigate the long-term habitat morphological alteration resulting from a large dam and weirs in the Tamjin River. To achieve this, we carried out a hydrograph analysis and a substrate size distribution analysis. We also estimated the channel width, bar area and vegetation encroachment using aerial photographs taken before and after the construction of the dam and weirs. The result of the hydrological analysis showed that flooding downstream was greatly reduced with small peaks occurrence after the dam construction. Interestingly, normal hydrographs in the main channel appeared just after tributary conjunction. There was a similar pattern in the substrate size analysis. Despite coarsened substrate just downstream of the dam site, more sand appeared again after introduction of the tributary. However, there was an increase in the bar area downstream of the dam's channels with most bars covered with vegetation. The channel width increased at the upper area of weirs through impoundment, but decreased downstream because of vegetation encroachment. This study indicate that unregulated tributary plays an important role in restoring hydro-physical habitat conditions in mainstream channels below a large dam. However, numerous weirs could be a causal factor to accelerate habitat deterioration in the dam downstream channels.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.811-822
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• 2019

Environmental flows in the downstream sections of Yongdam Dam, Wonju Stream Dam, and Hongcheon River were estimated with selected target fish species such as Nigra for the site of Yongdam Dam, Splendidus for the site of Wonju Stream Dam, and Signifer for the site of Hongcheon River by considering endangered and domestic species. Physical habitat analysis was performed to estimate environmental flows for the study sites by applying the Physical Habitat Simulation (PHABSIM) and RIVER2D which combined hydraulic and habitat models. Based on the monitored data for ecological environment, the Habitat Suitability Index (HSI) for the target species was estimated by applying the Instream Flow and Aquatic Systems Group (IFASG). In particular, based on the result of fish monitoring, the HSI for each stage of the growth for target species was analyzed. As a result, the Weighted Usable Area (WUA) was maximized at $4.9m^3/s$ of flow discharge during spawning, $5.8m^3/s$ during the period of juvenile, and $8.9m^3/s$ during the adult fish season at the downstream section of Yongdam Dam. The result of the Wonju Stream Dam showed an optimal environmental flow of $0.4m^3/s$, $1.0m^3/s$, and $1.5m^3/s$ during the period of spawning, juvenile, and adult. The habitat analysis for the site of Hongcheon River, which is a non-regulated stream, produced an optimum environmental flow of $5m^3/s$ in the spawning period, $4m^3/s$ in the juvenile stage and $6m^3/s$ in the adult stage.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.4
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• pp.224-232
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• 2004

Sedimentation changes related with bottom shear stress attenuation at JangHang channel in the Keum River Estuary, where several huge coastal constructions including an estuarine dam have been conducted for last 2 decades, were evaluated for 7 cases to figure out passage hindrance through the channel by a hydrodynamic model using hind-casting technique from 1988 to 2000 at every 2 years interval. Due to the construction of Keum River Estuary Dam, the maximum bottom shear stress rapidly lessened to $0.2-0.6N/m^2$ compared to$1-2N/m^2$ in natural status. Especially it marks below the critical shear stress of $0.4N/m^2$ resulting in severe siltation in the channel just after the closing of dam gates in 1994. It is concluded that the dam may block the tidal energy propagation to upstream and directly results in sedimentation environment in front of dam site. It is also revealed that at least 20% of passage hindrance of small fishing boats through the channel could be counted due to sedimentation by analysis of predicted mean spring tides.

• The Journal of Engineering Geology
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• v.2 no.1
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• pp.19-35
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• 1992

aThe elastic properties of the fault zone (width; 3~12m), the shattered zone (width; over 40m) and the fresh rock zone distributed under the core foundation of fill dam in granitic gneiss have widely different range. The deformation moduli of the fresh rock zone, the fault zone and the shattered zone obtained from in situ rock tests - Plate Load Test and Bore Hole Deformation Test - show a range of $42,000~168,000kg/\textrm{cm}^2,{\;}963~2,204kg/\textrm{cm}^2{\;}and{\;}1,238~2,098kg/\textrm{cm}^2$, respectively. The differential settlements hetween the fault zone and the fresh rock zone are expected after the dam construction. Therefore, the displacement of foundation and concrete fill are evaluated using FEADAM 84 program of finite element analysis. The geometric distribution of discontinuifies obtained from the site mapping and drilling is considered in the finite element analysis. The analysis shows that the differential settlements between the fault zone and the fresh rock zone is about 6cm, while that of concrete fill is within 0.5cm.

• The Journal of Engineering Geology
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• v.30 no.3
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• pp.279-288
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• 2020

Sand dams are formed by installing beams across rivers and filling the secured space with water and a permeable material, such as sand, which stores the water in available pore space. These structures have mainly been reported in Kenya, Africa. This study proposes a sand dam design that improves structural safety and water intake. First, to increase the stability of the concrete wall of the dam, steel barbed wire connections are proposed for construction. Second, by using geotextile fabrics, evaporation may be reduced from 45% to 8%, and horizontal permeable discharge could be reduced markedly, therefore improving water storage capabilities. In addition, the water intake increased by ~2.4 times that of the previous design. Third, filtration efficiency is improved by selecting a sedimentary site for improved water quality. Finally, the installation of a tensiometer is suggested for monitoring the sand dam.

• Geotechnical Engineering
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• v.4 no.2
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• pp.33-44
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• 1988

The Taechong Dam completed in 1980 is a composite dam at which a junction was formed partly by butting the core against the end face of the concrete gravity section and partly by the core overlapping the upstream face of the concrete. In order to evaluate the performance of the junction, the interfaces between the concrete dam and core of the embankment dam were well instrumented with total pressure cells and piezometers. A nonlinear incremental finite element analysis simulating its construction behaviour was carried out under plane strain conditions. Material parameters for the core are determined from triaxial tests on the specimens, sampled in the quarry site and compacted to the field dry density at the field moisture content. Material parameters for the filter, transition materials and the rockfill are estimated from literature. When compared with the earth pressures measured at the interfaces, the analytical results show good agreement in the core, however, there are some discrepancy in the shell. A nonlinear model for pore pressure response is used successfully to predict the pore pressures at the interface in the core.