• Journal of Korean Society on Water Environment
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• v.34 no.6
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• pp.688-702
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• 2018

Since the 1970s regulations against the pollution of drinking water have been introduced in Lake Paldang watershed area. To understand the effects of water environment management policies and the impacts of climate changes on Lake Paldang, a long-term comprehensive study of this watershed and the changes in its water environment is required. In this study, we analyzed changes in the weather, hydrology, sources of pollution, water quality, and algal development from 2000 to 2015 year based on the statistical data provided by several national information systems. While the population and amount of sewage in the Lake Paldang watershed increased by about 1.5 times, the amount of animal manure showed a decreasing trend during the same period. The wastewater also increased by about 1.5 times while the amount of water intakes rose by about 1.14 times. The water quality in front of the Paldang Dam, which is the representative monitoring site of the Lake Paldang, was stable. The annual average BOD concentration remained within 2 mg/L, which is a "Good (lb)" level according to the environment standards of Republic of Korea. The development of phytoplankton and harmful cyanobacteria were largely influenced by meteorological factors.

• Water for future
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• v.28 no.6
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• pp.169-181
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• 1995

No correction has been made for the rating curve of Goan Station since 1986 even though there has been a severe bed degradation until now. Furthermore, it was informed to Han River Flood Control Center that there was a difference between the discharge released from Paldang dam and the discharge observed at Goan station during 1990 flood. By considering such river bed changes, hydraulic model experiment with 1/100 scale was performed for the range of 2.2 km, which covers from Paldang dam to the downstream of Goan station. From this experiment, the rating curve was obtained by considering the discharges from Paldang dam and the corresponding water levels at Goan station. Also, the exsitingand the proposed rating curves were compared with those by computational method of RMA-2V.

• Journal of Korean Society on Water Environment
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• v.25 no.6
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• pp.855-862
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• 2009

This paper pointed out major problems of land use regulation policy surrounding Paldang Lake as follows: (1) inefficient management system, (2) inconsistent administrative management, (3) illogical selection of regulated area, (4) contradictory present system, and (5) controversial discharge control. Several regulation laws for the land-use surrounding Paldang Lake caused confusion of application and inefficiency of management. Amendment of regulation laws made it possible that the regulated area was developed, which resulted in the deterioration of water quality. In addition, successive regulations without scientific implementation overexpanded regulated area and focus on the discharge concentration of contaminated sources stimulated development of small size sources. To overcome these problems, we suggested reestablishment of regulated area, differentiation of regulation amendments, and flexibility in the application of regulation. It is necessary to arrange regulated area based on the efficient land use management and scientific implementation and then to mitigate land use regulation under the sustainable development. For the flexible application of regulation, it is required to amend the rule in response to the change of environmental condition and development of environmental techniques.

• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.504-511
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• 2007

Built-out issue of copper processing appearing recently in the Paldang watershed is a critical problem to deteriorate the basic framework of national water management policy as well as to be simply a copper-related problem. Up to now, Korea government has invested hard and relevant upstream areas have been victimized readily in a variety of field to comply its goal of 'Safe Water Supply'. Because of the reason, the desirable water quality level of the Paldang watershed has been maintained regardless of its dense population. Paldang drinking water management policy is based on residents' understanding which is considered as a 'social capital'. The issue raised in the aspect of water quality management policy should be reviewed on the basis of the 'social capital' concept. One regarding semiconductor industry as a potential industry to export many products in 10 years insists that the industry not be a simple private business but be a prominent part for national competitiveness. There is no doubt about this opinion. However, a nation should support environmental right-to-life of its people prior to any other tasks. In other words, it is really risky to give up people's right due to economic benefits. Therefore, it should not happen to trade 'life', the dignity of man, with national competitiveness which is likely to be preferred in these days. In addition, coherent policy not to destroy 'social capital' promoting Paldang drinking water resource management policy should be maintained.

• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.433-437
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• 2011

The study is conducted to evaluate loading of organic matter as seasonal changes during non-storm period into Lake Paldang which is used to a major drinking water source. Samples were taken in Lake Paldang intake during non-storm period and were analyzed loading of organic matter. From the results of the survey, improving of the water quality showed remarkable tendency depending on the changing periods from summer to fall and from fall to winter. Dilution effect from the increase of base run-off caused by the concentrated rainfall in rainy season, the characteristics of Korea's climate seems to have to be the reason. On the other hand, deteriorating of the water quality showed tendency depending on the changing periods from winter to spring and from spring to summer. Increase of Cyanobacteria etc. is explained by seasonal effects which are a small amount of the rainfall in winter and spring and gradational increase of water temperature.

• Journal of Korean Society on Water Environment
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• v.26 no.2
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• pp.317-325
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• 2010

This study was to investigate phytoplankton communities and to evaluate the effects of hydrological and physical-chemical environmental factors in major five dam reservoirs in the Han River water system. Annual average of chlorophyll a concentration in Lake Paldang, Lake Cheongpyeong and Lake Doam was higher than that of Lake Chungju and Lake Hoengseong. The opposite seasonal variation patterns of phytoplankton growth were observed in dam reservoirs; the highest biomass in spring of dry season in Lake Paldang, Lake Cheongpyeong which are the river-type reservoirs and Lake Doam where turbidity was high throughout the year, and in summer and autumn of rainy season in Lake Chungju and Lake Hoengseong which are the lake-type reservoirs, indicating that the seasonal pattern for growth of phytoplankton in on-river reservoirs is mainly determined by hydrologic characteristics. The dominant species of phytoplankton in Lake Paldang, Lake Cheongpyeong and Lake Doam, where the concentration of nutrients was relatively high, were Bacillariophyceae such as Stephanodiscus hantzschii, Aulacoseira granulata var. angustissima in Lake Paldang and Lake Cyeongpyeong and Nitzschia spp. in Lake Doam throughout all season. The dominant species of phytoplankton in Lake Chungju and Lake Hoengseong which showed the oligo-mesotrophic state, were Bacillariophyceae such as Stephanodiscus hantzschii, Cyclotella pseudostelligera in spring and winter, but Cyanophyceae such as Microcystis spp. in summer.

• Journal of Environmental Impact Assessment
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• v.29 no.5
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• pp.323-337
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• 2020

Long-term continuous data were used to investigate changes in air and water temperature and temperature hysteresis at Lake Paldang, the largest source of drinking water in South Korea. Based on the temperatures at Yangpyeong, near Lake Paldang, using a seasonal Mann-Kendall test, the rate of change of increase in temperature over the last 27 years (0.060℃/yr, 1993-2019) was higher than that of during 47 years (0.048℃/yr, 1973-2019). The air and water temperatures in Lake Paldang and its influent rivers had a high correlation (R > 0.9, p < 0.005); however, the water temperature increased at rate slower than the river water temperature, and the water temperature decreased slowly as the air temperature fell. The depth-averaged water temperature also changed more slowly than the surface water of the lake both when the air temperature was high and when it was low. This is likely because the lake has a larger area and a longer heat retention time than rivers, resulting in a greater hysteresis of water temperature at lake.

• Journal of Korean Society on Water Environment
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• v.24 no.2
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• pp.206-213
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• 2008

Fish fauna and community structure were investigated at 2003, 2004 and 2006 in Lake Paldang and its inflows. In this survey, we collected 54 species belong to 14 families. Family Cyprinidae take 51.9% (28 species), Cobitidae and Gobiidae occupied 7.4% (each 4 species), respectively. E. erythropterus (11.8%) was dominant species and L. macrochirus (10.2%), designated as an ecosystem-invasive alien fish species by Ministry of Environment, M. yaluensis (9.1%), Z. platypus (7.7%) and R. brunneus (6.7%) were dominated in turn. H. molitrix, C. lutheri, P. altivelis, S. microdorsalis, L. costata. S. gracilis majimae, A. rivularis, P. koreanus. S. scherzeri and O. platycephala were rare species (less than 0.1% in relative abundance). In-lake area, 36 species of fishes belonging to 11 families were collected, and 48 species of 13 families were from inflows. The number of Korean endemic species were 19 species (35.2%), and 4 kinds of exotic species (7.4%), that is, C. cuvieri, H. molitrix, L. macrochirus and M. salmoides were found at this survey area. It was revealed by the analysis of fish community that diversity and richness indices were prominent at tributaries, and dominance index was high at the main body of Lake Paldang. Fish fauna showed rapid decline after dam construction which make the mid-Han river systems to lentic ecosystem, so many of meander-riffle fishes were disappeared dramatically. But after 1990s when installation of small scale wastewater treatment plants started in watershed, the water quality of small tributaries was improved. And also, expansion of the natural macrophytic vegetation of littoral zone should contribute to the development of diverse fish fauna in Lake Paldang.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1295-1305
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• 2000

Status of the contaminated sediments in Lake Paldang was investigated. Sediment samples were taken at 34 points and analyzed in terms of ignition loss, CODer, total P and total N. The contamination level did not show any significant variation with depth of the sediments, which indicated the contaminants were recalcitrant. The type of P in the sediment was analyzed, and the sum of adsorbed P and NAI-P, that can be re-solubilized under the reductive condition, was found to be 20-30% of the total P. From the analysis of the water quality change along with the flowing path, it would be concluded that the effect of the sediments on the water quality is insignificant yet in Lake Paldang. However, long term analysis covering at least four seasons should be continued in order to get a more reliable conclusion. A depth profile map of the sediment in Lake Paldang was provided.

• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.889-896
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• 2007

From the direct outflow of Chungju Dam to the junction of water body and watershed in Paldang lake is the scope of this research. This study performed to investigate the main cause of water quality deterioration and the influenced region in the middle field range of the Namhan river Basin with the onsite measurement of water quality and flow rate simultaneously during spring dry season. The purpose of this study is to find out the time-spatial variation characteristics of water quality and flow rate. Following the flow direction $BOD_5$ and $COD_{Mn}$ concentration increased to the highest value of 3.7 mg/L, 5.9 mg/L at Wolgesa respectively. Chl.a concentration increased to $50mg/m^3$ or so at Kangsang, after that it decreased to $37mg/m^3$ at the junction of Paldang lake. Organic matter concentration variation trend showed similar than that of Chl.a. Also $BOD_5$ concentration tendency was similar to Chl.a in every measuring sites except Paldang lake mixing zone. The major factors of water quality deterioration in Namhan river and Paldang lake during dry season were algal bloom and followed internal production. High phosphorus load from Dalcheon and Seom river caused dry season algal bloom and internal production in transitional zone which was stagnant area in downstream of Namhan river.