• Korean Journal of Environment and Ecology
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• v.38 no.3
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• pp.246-262
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• 2024

The survey conducted from 2018 to 2020 aimed to investigate the changes in fish fauna and community characteristics in the upper reaches of the Seomgang River, Korea. During the survey period, 35 sites were selected, resulting in the collection of 7,817 fish belonging to 12 families and 40 species. The dominant species was Zacco koreanus, with a relative abundance of 34.5%, followed by Z. platypus at 28.7%. Other significant species included Rhynchocypris oxycephalus (10.2%), Pungtungia herzi (5.3%), and Squalidus gracilis majimae (4.3%). Notably, four protected species - Acheilognathus signifer, Gobiobotia brevibarba, and Cottus koreanus, designated as class II endangered wildlife by the Ministry of Environment- were identified. These species predominantly inhabit the middle and lower reaches, except for Gobiobotia brevibarba, which is found in the upper reaches. Nineteen species, accounting for a 47.5% endemism rate, were endemic to Korea. The study also noted the presence of one climate-sensitive species, Cottus koreanus, and two exotic species, Carassius cuvieri and Micropterus salmoides. Community analysis indicated a trend of decreasing dominance and increasing diversity and richness from upstream to downstream, with a distinct division into uppermost reaches, upper reaches, middle and lower reaches, and lakes. The construction of the Hwaseong Dam has had a significant direct and indirect impact on the fish community. The habitat and abundance of endangered species such as R. pseudosericeus, A. signifer, and G. brevibarba decreased dramatically immediately after the dam's construction, transforming the submerged area from lotic to lentic environments. Approximately 20 years later, the habitats have stabilized, leading to an increase in the fish population and a recovery of the previously diminished endangered species. The river health (FAI) was also evaluated, with 27 sites rated as very good (A), seven as good (B), and one as fair (C). However, endangered species such as A. signifer continue to face threats from dam and river construction, while C. Koreanus has experienced a severe population decline due to river works. Additionally, the presence of the ecosystem-disrupting species M. salmoides in Hwaseong Lake raises concerns. To ensure a stable habitat for fish in the upper reaches of the Seomgang River, it is crucial to avoid indiscriminate river construction, urgently implement restoration policies for endangered species such as A. signifer, and develop management strategies to control the spread of invasive species such as bass.

• Water for future
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• v.25 no.3
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• pp.115-124
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• 1992

The peak flood discharge at a downstream station and the flood travel time between a pair of dams due to a specific flood release from the upper reservoir are computed using a hydraulic river channel routing method. The study covered the whole reservoir system in the Han River. The computed peak flood discharges and the travel times between dams were correlated with the duration and the magnitude of flood release rate at the upstream reservoir, and hence a multiple regression model is proposed for each river reach between a pair of dams. The peak flood discharge at a downstream location can be converted to the peak flood stage by rating curve. Hence, the proposed regression model could be used to forecast the peak flood stage at a downstream location and the flood travel time between dams using the information on the flood release rate and duration from the upper dam.

• Journal of The Geomorphological Association of Korea
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• v.28 no.3
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• pp.27-35
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• 2021

This study tried to reveal incision rate and its change by formation of lava plateau in the Cheorwon-Jeongok area. Incision rates of 0.421 m/ka and 0.101 m/ka in the upper and lower reaches of Hantan-gang, respectively, were calculated from sites before formation of lava plateau. These incision rates indicate that the upper and lower reaches of Hantan-gang have much higher and slightly lower incision rates than streams with similar distances from the Taebaek Mountains. However, sites after formation of lava plateau mostly showed incision rates ranging from 0.5 m/ka to 0.9 m/ka. Streams flowed on the lava plateau revealed 2-3 times higher incision rates than unrelated-streams or paleo-streams to formation of lava plateau did. These results suggest that incision rate in the study area was greatly influenced by formation of lava plateau and resultant geomorphic avulsion with rearrangements of stream.

• Journal of the Korean association of regional geographers
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• v.13 no.4
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• pp.409-421
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• 2007

The purpose of this paper is to consider the formation processes and depositional conditions of bars formed at the upper-stream part of Sayeon Dam since Sayeon Dam construction in 1964. Results of analyzing the shape characteristics of bars and their sediment grain size distribution are as follow: Firstly, bars are able to categorized as subaqueous bars (A, B), mid-channel bars(C, D), and tributary side-bars(E). Secondly, the outline of bars has longish along the flow path, and their height lowers more and more going towards downstream. Also the height of bar surface tend to heighten from flow path to mountain slope. However, the near part of A is comparatively higher than its distant part, A is defined as a subaqueous natural levee and back swamp. Thirdly, the average particle size of A and B become smaller toward mountain slope. In transportation style, ratio of suspended load become higher toward mountain slope. Fourthly, sorting is worse to very worse according with lake's random changable water level. Fifthly, bar A and B were formed by vertical sedimentation of sediments according as sediments transported along flow path in the subaqueous conditions were spreaded out of flow path. C and D were formed by bed load as flood level lowered. And E was formed by vertical sedimentation while stream flow stopped in tributary's mouth areas with the water level heightening.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.4
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• pp.57-65
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• 2015

This study investigates characteristics of time series spatial distribution on climate factors in Andong Dam basin by estimating precise spatio-temporal distribution of hydro-meteorological information. A spatio-temporal distribution by estimating Semi-Variogram based on spatial autocorrelation was examined using the data from ASOS and 7 hydro-meteorological observatories in Andong Dam basin of upper Nakdonggang River, which were installed and observed by NIMR(National Institute of Meterological Research). Also, temperature and humidity as climate variables were analyzed and it was recognized that there is a variability in watershed area by time and months. Regardless of season, an equal spatial distribution of temperature at 14 o'clock and humidity at 10 o'clock was identified, and nonequal distribution was noticed for both variables at 18 o'clock. From monthly spatial analysis, the most unequal distribution of temperature was seen in January, and the most equal distribution was detected in September. The most unequal distribution of humidity was identified in May, and the most equal distribution was seen in January. Unlike in forest, seasonal spatial distribution characteristics were less apparent;but temperature and humidity had respective characteristics in hydro-meteorology.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.179-190
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• 2019

In this study, a fish survey was conducted to investigate the habitat status of black shinner (Pseudopungtungia nigra) designated as endangered species level from the lower part of Yongdam Dam to the upper part of Daecheong Dam. Biodiversity analysis was performed on the basis of the number of fish emerged, and biological health and physical habitat environment were quantitatively analyzed using collected P. nigra. According to the survey, the habitat range of P. nigra was found from Banguri-myeon, Buri-myeon, Geumsan-gun, downstream of Yongdam Dam. The biodiversity analysis results of all species appeared to be low in overall dominance index and relatively high in species diversity and uniformity index. In addition, P. nigra collected in this study was confirmed to have normal growth and nutritional status by the full-length-weighted relativities and condition factor. The physical habitat environment of P. nigra was 0.3 - 0.6 m in depth, 0.3 - 0.7 m/s in flow rate, and bed materials showed high frequency of occurrence in the range of cobbles (64.0 - 256.0 mm) to boulders (>256.0 mm). These results are expected to be used as data for habitat restoration and management in the future as basic data on the spatial range and preferred physical habitat environment of P. nigra in Geumgang.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.37-37
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• 2012

The study aims to evaluate the complexity of relationships between the riparian states - China, Myanmar, Laos, Thailand, Vietnam and Cambodia - in the Mekong River Basin since the mid-1990s with special reference to the discourse on hydropower development. A special emphasis will be put on the influence of China on hydropower development. Although a variety of issues on the river basin have been discussed among the riparian states, none of them has been effectively implemented owing to the lack of China's commitment to the discussions for sustainable water management. Now, a new turning point is observed in the region with emergence of the issue on hydropower development, not only in the upper basin but also in the lower basin. The discourse on hydropower in Mekong has quickly drawn attention of the public, accelerated by the onset of construction of the Xayabury Dam in Laos since November 2010. The influence of China as the upstream country with its political, economic, and military power has increasingly grown in the region over the last few decades, and such trend recently intensifies together with an expansion of Chinese commercial interests in the region. Since the establishment of the Mekong River Commission (MRC) in 1995, the four MRC members have striven to push forward a sustainable use of water resources in the basin. But the legitimacy of the MRC system has been eroded due to the lack of participation by Myanmar and China, and in particular, the Chinese absence has made the four riparian states blind about the change of water regime due to the Chinese dams upstream. Environmental damages due to hydropower development might be possible, including a drop of fish yields, crop production, and damages to the river's ecosystems. Vietnam and Cambodia have already expressed their concerns over the dam construction towards China as well as Laos by pointing out detrimental impacts of the dams to their economies. China's move to collaborate with the other riparian states since 2010 has given a positive signal in terms of sustainable water management in the river. However, this phenomenon never confirms China's proactive contribution to the cooperative activities within the framework of the MRC system. Laos' initiative to build a new dam in the lower basin alarms those who are opposed to dam construction in the fear of its far-reaching damages to the environment. The question goes back to the year-long debate on policy priorities given to economic growth or the environment. The riparian states require wisdom based on a consensus about sustainable water use rather than hydropower development based on individual growth dreams.

• Korean Journal of Heritage: History & Science
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• v.44 no.2
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• pp.46-57
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• 2011

The aim of this study was to examine the current situation of otter inhabitation and conservation and to collect basic information for establishing appropriate policies. We conducted the study around the Bukhan river from April to October 2009, mostly focusing on otter distribution, feeding habits, threats, and conservation measures. We divided the study area into 2 sectors: the dam area and the stream. We found 39 spraint sites in the dam area and 70 in the stream area. A significant difference was observed in the number of spraint sites between the upper stream and the lower stream. To evaluate the feeding habit, we collected and analyzed the frequency and bulk occurrence of the spraints. Among the prey items, fish were the most numerous (36.99%) followed by amphibians (17.22%). Fish showed the highest bulk occurrence in the dam area, and the bulk occurrence of amphibians and insects seemed to increase in the stream area. However, the bulk occurrence in the dam area seemed to be lower than that in the stream area (ANOVA, F = 3.99, p < 0.05). Fyke nets and abandoned fishing nets were found to be the most threatening factors. Further research on the systematic management of otters and the use of stop grids is required for better conservation of otters.

• Journal of the Korean GEO-environmental Society
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• v.23 no.6
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• pp.5-17
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• 2022

The performance of the relief wells installed for the purpose of controlling seepage of the dam embankment is affected by various parameters such as diameter, spacing, penetration rate, permeability coefficient of the ground, thickness of the foundation layer. Therefore, when the relief wells are adopted for the purpose of reducing seepage pressure, these parameters should be sufficiently reviewed to determine the installation specifications of the relief wells. This study evaluated the effect of the length of the geosynthetics blanket on the performance of the relief wells installed in the downstream part of the dam embankment with blankets in the upstream and downstream part of the dam embankment as countermeasure methods to control seepage of the dam embankment. In the relationship between the length of the upstream and downstream blanket and the discharge, the discharge of the relief wells decreases as the length of the upstream blanket increases, and on the other hand, the discharge of the relief wells decreases as the length of the downstream blanket increases. In the upper and lower blanket length-spacing relationship, as the length of the upstream blanket increases, the spacing of the relief wells increases and as the length of the downstream blanket increases, the spacing of the relief wells decreases. Therefore, when installing the relief wells in parallel with the blanket, it was found that increasing the length of the upstream blanket is more efficient than increasing the length of the downstream blanket in order to minimize the discharge of seepage discharge and to ensure economic feasibility by wider installation of the relief wells.

• Journal of Korean Society on Water Environment
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• v.28 no.4
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• pp.582-594
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• 2012

A simple ecohydorlogic model that simulates hydrologic components and vegetation dynamics simultaneously based on equations of soil water dynamics and vegetation's growth and mortality is discussed. In order to simulate ungauged watersheds, the proposed model is calibrated with indirected estimated observation data set; 1) empirically estimated annual vaporization, 2) monthly surface runoff estimated by NRCS-CN method, and 3) vegetation fraction estimated by SPOT/VEGETATION NDVI. In order to check whether the model is performed well with indirectly estimated data or not, four upper dam watersheds (Andong, Habcheon, Namgang, Milyang) in Nakdong River watershed are selected, and the model is verified.