• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.7
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• pp.38-48
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• 2003

Lake water quality assessment information is useful to anyone involved in lake management, from lake owners to lake associations. It provides lake water quality criteria, which can improve the ways how to manage out lake resources and how to measure current conditions. It also provides a knowledge base so that the lakes can be protected and restored. Here, the Freshwater Lake Water Quality Management System(FLAQUM) was developed. The results of FLAQUM application by scenario proved that pollutant load at rainfall by the nonpoint sources was much more than normal times at rainfall. From the result of Scenario I (pollutant source increase case), the concentrations of Boryeong freshwater lake were BOD 9.43mg/L, T-N 4.53 mg/L and T-P 0.21 mg/L, respectively, and those values exceed the standard of agricultural water. And in case of Scenario I and II(the present case) excluding Scenario III (pollutant source decrease case), all of T-N and T-P are either mesotrophication or eutrophication, on the other hand when 60% of pollution source is removed, the concentrations of Scenario III were BOD 3.21 mg/L, T-N 0.95 mg/L, T-P 0.11 mg/L, respectively, and which satisfies the standard of agricultural water quality.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.3
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• pp.77-86
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• 2005

A monitoring study has been conducted to identify hydrologic conditions, water quality and nutrient loading characteristics of small watershed in Juam Lake. Climate data of the watershed were collected; flow rate was measured and water quality sampling was conducted at the watershed outlet for this study. Water quality data revealed that T-P concentrations meet I grade of lake water quality standard during non-storm period, but degraded up to II-III grade of lake water quality standard during storm period. The observed T-N concentrations always exceeded lake water quality standard. Therefore, T-P was identified as limiting chemical constituent for eutrophication of Juam Lake. T-P concentration of non-storm period also revealed that point source pollution is not serious in the watershed. Three year monitoring results showed that the observed T-N losses were $10.85\~18.88$ kg/ha and T-P losses were $0.028\~0.323$ kg/ha during six month (Mar. - Oct.), respectively. Major portion of runoff amount discharged by a few storm events a year and nutrient load showed apparent seasonal variation. Huge runoff amounts were generated by intense storms, which make application of water treatment or detention facilities ineffective. Monitoring results confirmed that water quality improvement by abating nonpoint source pollution in rural watershed of monsoon climate should be focused on source control. T-P losses from paddy field seemed to consist of significant amount of total load from study watershed. Therefore, management of drainage from paddy field is considered to be important for preventing algal blooming problem in Juam Lake.

• Journal of Environmental Health Sciences
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• v.35 no.5
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• pp.365-375
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• 2009

Agriculture reservoirs need a systematic approach that can control water purity and water improvement. The area under study, Bunam Lake exceeds the agricultural water standard level due to contamination from the upper stream. When the Taean Enterprise City was planned, the water quality improvement plan was applied to minimize the environmental change. However, in order to continuously maintain the water quality in the Bunam Lake, it was essential to apply the Total Pollution Load Management System (TPLMs). In order to achieve the targeted water quality in the Bunam Lake, standard flow rates and targeted water quality levels were applied to obtain the loading capacity which is as follows : BOD 1,891.2 kg/d, T-N 1,945.7 kg/d, T-P 131.7 kg/d. Also, the regional development load was calculated as, BOD 1,083.6 kg/d, T-N 942.2 kg/d, T-P 61.8 kg/d, which is required to be deceased :- by BOD 378.4 kg/d, T-N 198.9 kg/d, T-P 31.6 kg/d in order to safely achieve the targeted water quality in the Bunam Lake.

• Journal of Korean Society on Water Environment
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• v.35 no.1
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• pp.43-54
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• 2019

The objective of this study was to assess the effect of policies on water quality management based on the changes in pollutants and water quality in Special Water Preservation Area (SWPA) of Lake Paldang watershed from 1990 to 2016. The population, total sewage and flow rate of wastewater in SWPA continuously increased from 1990 to 2016, while the location of new facilities for industrial and livestock facilities has been restricted. However, unlike the buffer zone in which industrial and livestock facilities were continuously reduced after implementing of TMDL, it was found that the effect of land-use regulations on industrial and livestock facilities in SWPA were mitigated by the increase in the size of large facilities. Since 1999 when the emission standard of public sewage treatment plants (STP) was changed, the water quality of Lake Paldang has increased despite the increase of pollutant source. Since emission standard of STP changed in 2012 (BOD 5 mg/L, TP 0.2 mg/L), BOD concentration in Lake Paldang has also improved to the level of water quality in the early 1990s where as TP concentration has remained at its lowest since 1990. BOD and TP average discharge concentration of 43 STP (${\geq}500m^3/day$) in 2016 have been maintained $1.7{\pm}0.7mg/L$ and $0.06{\pm}0.02mg/L$ respectively. While the discharged load of STP in SWPA was decreased by the concentration management, the contribution rate to the total discharged load of non-point pollutants increased to 70 % in 2015, and the contribution rate to the point discharged load of individual treatment facilities increased to 80 %.

• Journal of Environmental Impact Assessment
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• v.8 no.1
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• pp.81-92
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• 1999

This study discussed the appropriateness of organic matter indexes such as biochemical oxygen demand(BOD) and chemical oxygen demand with potassium permanganate($COD_{Mn}$) in water quality environmental standard of streams and lakes and the applicability of the items to water quality environmental standard to add or substitute COD with potassium dichromate ($COD_{Cr}$) and total organic carbon(TOC) being used as index of organic matter. And indexes of organic matter content and organic carbon concentration were distinguished between dissolved and particulate component in water sample to estimate their effect on pollutants loading in lake and stream. The ratio of $COD_{Cr}$/BOD was 5.1 under BOD concentration 3mg/L in river water quality environmental standard II, and 2.67 above it. This ratio was diminished to 2.04 when BOD concentration was more than 8mg/L, in river quality environmental standard IV. Also the ratio of $COD_{Mn}$/BOD showed 2.16 under 3mg/L(BOD), and 1.1 above it. This ratio is also diminished to 0.84 over 8mg/L(BOD). Accordingly, we should apply this ratio depending on the concentration level to add and change organic matter index of water quality environmental standard newly. The ratio $COD_{Cr}/COD_{Mn}$ both in lake and stream shows 2.37(r=0.986, p<0.001). But the ratios showed range of 2.34~2.50, which is no much difference of this ratio according to $COD_{Mn}$ concentration.

• Journal of Korean Society on Water Environment
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• v.29 no.6
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• pp.762-776
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• 2013

Load duration curve was applied to determine important water quality parameter control term for improvement of Paldang lake water quality. Load duration curve was analyzed with long term data from 1985 to 2012 including water quality, flow rate and climate state of Paldang water environment. From the result of flow rate patterns of paldang lake, differences between high and low flow rate of each year showed tendency of increase because rainfall characteristics of paldang lake watershed were changed by climate exchange. Both of land use state of upper Paldang lake watershed and number of limit excess from load duration curve indicated that seasonal action related with land use such as agricultural fertilizer distribution in upper watershed affected Paldang lake water quality. So focused BOD (biological oxygen demand) management during spring season from march to June is required to control organic materials in Paldand lake. The main affecting factor of TOC (total organic carbon) increase in Paldang lake was initial rainfall after march. T-N (total nitrogen) kept increasing during research period, so enhancement of T-N standard is needed to T-N control. Initial rainfall and increase of temperature during spring season from March to June showed a positive correlation with TP (total phosphorus) and Chl-a, respectively.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.587-597
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• 2023

We evaluated the eutrophication of Saemangeum Lake, which causes abnormal growth of algae, using the Carlson index. Eutrophication characteristics of Saemangeum Lake were analyzed. For the study, water quality surveys were conducted at 7 stations in Saemangeum Lake every month in 2021. The concentration of Chl.a was slightly higher in the Mankyeong water system in winter, and slightly higher in the Dongjin water system in spring and summer, but overall, except for some periods, the concentration was similar to or lower than the lake water quality environmental standard of class 3. COD showed water quality similar to or above the lake quality environmental standard of grade 4 in both the Mankyeong and Dongjin water systems in the summer and Autumn. TOC concentrations were within lake water quality standard 3 at all sites. Total phosphorus concentrations exceeded the lake water quality standard of Class 4 and were higher in January and August after rainfall. In the correlation analysis between water quality factors, the correlation of organic matter, total phosphorus, and total nitrogen to salinity was relatively high. This reflected the water quality characteristics of freshwater, brackish water, and seawater areas due to seawater inflow through the drainage gate and freshwater inflow through upstream rivers. According to the characteristics of eutrophication fluctuations in Saemangeum Lake by trophic state index, the indices of Chl.a, SD, and TN showed water quality in the early stage of eutrophication, while the TP index showed a severe eutrophication state. The magnitude of the eutrophication index among water quality components was TSI(TP) > TSI(TN) > TSI(SD) > TSI(CHL) in all water systems. Quadrant analysis of the deviation of TSI(CHL) from TSI(TP) and TSI(SD) on a two-dimensional plane showed that there was no limiting effect of total phosphorus on algal growth in all water systems. In addition, the factors af ecting light attenuation appeared to be dominated by small particulate matter from outside sources.

• Journal of Environmental Science International
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• v.11 no.12
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• pp.1205-1215
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• 2002

To evaluate the change for water quality after the water gate operation in Shiwha lake, in situ survey were conducted on september in 2000 and January, march, jane in 2001. Chemical characteristics and eutrophication level was estimated from the survey data. The water quality of the Shihwa lake was greatly affected by pollutant load from rainfall, and formation of stratification in summer and winter was increased to effect on nutrient release from sediment. Especially, high concentration of chlorophyll-a was occurred in autumn, due to increased nutrient, high water temperature and low salinity after rainfall runoff. The mean concentration of DIN, DIP were 0.346mg/L, 0.0217mg/L in surface water and 0.826mg/L, 0.0415mg/L in bottom water, respectively, which were over III grade of seawater standard. Also high percentage of ammonia nitrogen to DIN in bottom water for autumn and winter was affected by released nutrient from sediment. Correlation analysis of chlorophyll-a versus TSS was shown that organic matter was affected by autochthonous organic matter stem from the algae, these factor showed reverse correlation about salinity. Closely correlations among to the water quality constituent in continuity survey was appeared. The results of eutrophication index estimation showed the high potentiality of red tide occurrence in Shiwha lake, particularity in summer or fall. Overall water quality was greatly improve to compared with measuring data during 1997~1998 at the beginning water gate operation, which reported by KORDI. Therefore, to improve of water quality in Shiwha lake, we need to establish of management plan about nutrient release from sediment, rainfall runoff, maximum of seawater exchange.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.615-624
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• 2004

The distribution pattern of water quality parameters and phytoplankton biomass in upper inflow rivers of lake Paldang had surveyed. In North-Han river system, nutrient concentrations and algal biomass was below the standard of mesoand oligotrophy from lake Soyang to lake Paldang, maintaining good water quality, except the N5 site located near the Chuncheon-Si, showing high nutrients concentrations and algal biomass. The algal biomass of the South-Han river system showed oligotrophic level in the upstream near the lake Chungju, and increased along the flow direction showing eutrophic level in the downstream within the lake Paldang area. On the other hand, the highest concentrations of nutrients were detected in the middle stream near the Yeoju-Si and Yangpyung-Gun rather than in the downstream suggesting algal biomass in lake Paldang would not come from the upper river area but come from the growth within the lake area using nutrients from the upper inflow river.

• Journal of Wetlands Research
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• v.20 no.2
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• pp.173-180
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• 2018

The utilization of TOC(Total organic carbon), a new environmental standard, was evaluated for 30 lakes in the Nakdong River Basin, which is used for drinking and agricultural usage. The active use of water resources begins with securing satisfactory water quality. Since this allows people and nature to maintain stability of quality, water quality standards are being tightened to ensure good water quality. In order to improve the pollution level of organic matter in lakes in the living environment, it is important to use the appropriate organic substance index. The relationship between the newly introduced TOC and the existing COD(Chemical oxygen demand) in the targeted lake was positively correlated with the possibility of replacing the TOC with COD. However, the environmental grade standard using TOC is better than the environmental grade standard using COD, so it has the same effect as that of the grade of water quality using TOC as an organic substance factor. This indicates the limitation of TOC to directly replace existing COD when trying to determine or improve the quality level using organic indicators of lakes. Therefore, in order to secure the qualitative safety of the lake, it is required to strengthen environmental standards of TOC in terms of water quality grade. In addition, the correlation between TOC and COD shows a great difference depending on the utilization characteristics of the lake. This requires clear scientific identification, and it requires continuous monitoring of COD that has been used to accumulate indicators of lake organic matter.