• Korean Journal of Ecology and Environment
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• v.40 no.1
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• pp.155-162
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• 2007

Water balance is the major factor in forest ecosystem, and is closely related to the vegetation and topographic characteristics within a watershed. The hydrologic response of a forest watershed was investigated with the hydrological model. The deterministic, lumped parameter model (BROOK90) was selected and used to evaluate the applicability of the model for simulating daily runoff on the steep, forested watershed. The model was calibrated and validated against the streamflow data measured at the Bukmoongol watershed. The deviation in runoff volume $(D_v)$ was -1.7% for the calibration period, and the $D_v$ value for the validation period was 4.6%. The correlation coefficient (r) and model efficiency (E) on monthly basis were 0.922,0.847, respectively, for the calibration period, while the r- and E-value for the validation period were 0.941, 0.871, respectively. Overall, the simulated streamflows were close to the observations with respect to total runoff volume, seasonal runoff volume, and baseflow index for the simulation period. BROOK90 model was able to reproduce the trend of runoff with higher correlation during the simulation period.

• Korean Journal of Ecology and Environment
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• v.40 no.1
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• pp.31-39
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• 2007

Monitoring data of 48 agricultural irrigation reservoirs from 1999 to 2004 was analyzed for water quality characteristics including biochemical oxygen demand $(BOD_5)$, chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), and chl-${\alpha}$. Land uses of the watersheds associated with these reservoirs were determined for residential, forest, upland, paddy and miscellaneous, and regressed against water quality characteristics. Correlation analysis showed that forest land use was negatively correlated with all the water quality characteristics implying it's beneficial effects in water quality perspectives. Other land uses including residential, upland, and paddy generally illustrated positive correlation with water quality characteristics, which indicates most human activities of the watershed could degrade water quality of the receiving water bodies. Paddy land use partially contributed to the water quality degradation in contrast to the previous studies. It might be attributed to the relatively clean water quality of the study area, where even slight pollutant loading could degrade sensitively water quality. Further investigation is recommended for the effect of proximity as well as land use portions on the water quality of receiving water body.

• Korean Journal of Ecology and Environment
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• v.45 no.3
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• pp.302-313
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• 2012

Long-term trends (e.g. 1997~2010) of chlorophyll a and water quality properties of the Yeongsan River were analyzed by using water quality monitoring data collected by the water information system, ministry of environment. Nine monitoring stations were selected along the main channel of the river, and parameters of BOD, COD, TN, TP, conductivity, TSS and chlorophyll a were collected for surface water monthly through the monitoring system. Trends of water quality and chlorophyll a were analyzed by the Seasonal Mann-Kendall Test and LOWESS (Locally Weighted Scatter-plot Smoother). The results showed that the water quality parameters, including chlorophyll a, were improved in all stations except Station WC in the most-upper region, where water quality data for the determined parameters were increased, indicating a reduction in water quality. Based on the results from LOWESS analysis, chlorophyll a (algal blooms), BOD and COD recently began to increase after 2007 suggesting that an additional study on the cause of these increases in organic pollution, as well as a better management system for the region are required.

• Korean Journal of Ecology and Environment
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• v.44 no.3
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• pp.280-291
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• 2011

Bottom-up approaches to control of Microcystis aeruginosa blooms were comparatively investigated through an in situ mesocosm experiment using aquatic plants (Iris pseudoacorus). In the mesocosm experiments, floating I. pseudoacorus, seemed to be effective in controlling massive M. aeruginosa blooms in an agricultural reservoir, exhibiting a close coupling with temporal variations in Chl-a and DO concentration. Shading by floating I. pseudoacorus resulted in a reduced phytoplankton abundance inhibiting light energy availability. Moreover, I. pseudoacorus may suppress phytoplankton growth through the excretion of chemical substances, likes a allelopathy, that inhibit phytoplankton photosynthetic activity. The $^{15}N$ atom % of I. pseudoacorus showed higher values than POM, suggesting that I. pseudoacorus assimilates DIN predominantly compared to phytoplankton, which was mostly M. aeruginosa. This result strongly suggests that the M. aeruginosa bloom should be regulated by aquatic plants, like I. pseudoacorus, this approach can affect zooplankton composition. This is the first study that has used stable isotope tracers to evaluate the biomanipulation efficiency through floating I. pseudoacorus.

• Korean Journal of Ecology and Environment
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• v.43 no.3
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• pp.400-408
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• 2010

The growth and microcystins production characteristics of three species of Microcystis (M. aeruginosa, M. ichthyoblabe, M. viridis) isolated from Yeongchun dam and Ankei dam in Kyungpook Province, South Korea were investigated at temperatures of $15{\sim}35^{\circ}C$ and light intensities of $35{\sim}180\;{\mu}mol\;m^{-2}\;s^{-1}$. All of the three species exhibited the highest growth rates (${\mu}_{max}$) over the $30^{\circ}C$. The maximum growth rates of M. aeruginosa and M. ichthyoblabe was observed at $70\;{\mu}mol\;m^{-2}\;s^{-1}$, while M. viridis showed maximum growth rate at $35\;{\mu}mol\;m^{-2}\;s^{-1}$. The maximum production of total microcystins was observed at $20^{\circ}C$, and the production of microcystins decreased according as temperature increase. The highest microcystins production of M. aeruginosa, M. ichthyoblabe and M. viridis observed at light intensities of $120\;{\mu}mol\;m^{-2}\;s^{-1}$, $70\;{\mu}mol\;m^{-2}\;s^{-1}$ and $35\;{\mu}mol\;m^{-2}\;s^{-1}$, respectively. The concentration of microcyst in production and microcystin types of three species according to temperatures and light intensities showed clear difference between the species.

• Korean Journal of Ecology and Environment
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• v.43 no.3
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• pp.418-427
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• 2010

In the four swamps of Jjokjibeol, Mokpo, Upo and Sajipo in the Upo wetland, the nitrogen nutrients, phosphorus nutrients and chl-$\alpha$ had been observed during the period from April 2005 to December 2009 on monthly basis. Based on the results, the fluctuations of trophic state in the Upo wetland were estimated. Measurements of the nitrogen nutrients such as $NO_3$-N, $NH_3$-N and T-N showed to be generally decreased in comparison with those in the precent studies. Yet the T-N was still considerably higher than the general concentration level of eutrophication and algal blooming. $PO_4$-P and T-P showed to have reduced considerably in comparison to precedent studies. However, T-P also turned out to be dissolved over the nutrient standard. Nitrogen nutrients and phosphorus nutrients were the lowest in Jjokjibeol in the Upo wetland. The chl-$\alpha$ concentrations were the highest at summer periods in Jjokjibeol and Mokpo. However, the highest at non-summer periods in Upo and Sajipo. Among the four swamps, Upo had the highest density on average of chl-$\alpha$, and Mokpo the lowest. Through TRIX (Trophic Index) analysis evaluating trophic state of the Upo wetland, all four swamps were estimated of poor water quality (eutrophication).

• Korean Journal of Ecology and Environment
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• v.43 no.3
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• pp.349-355
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• 2010

This study aims at the augmentation of reliability of the long-term rainfall runoff model. To do so agricultural water uses are evaluated by analyzing the effects of small scale irrigational hydraulic structures on long term runoff processes and thereby rainfall-runoff model is modified considering them. As a result the simulation results of the sub-basins having more agricultural reservoirs than the others are disagreed with the observations. The 2nd quarter simulation results show similar trend to it. Especially the farming seasonal results of the drought year as the year of 2008 have many negative discharge values due to the lack of agricultural water uses. This result come from the water uses input data corresponding to not real water uses but water demands. In this study the formulas are derived to estimate the discharges and return ratios and the long term rainfall-runoff model is reformulated based on these. It is confirmed that the errors of the simulation results could be reduced by considering the effects of small scale irrigational hydraulic structures and the reliability of the simulation results improved greatly.

• Research in Plant Disease
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• v.17 no.3
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• pp.381-385
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• 2011

Effects of temperatures, relative humidity, pH, and dry periods on conidial germination of Alternaria dauci were evaluated under in vitro conditions. Conidial germination was accelerated at over 95% relative humidity in $15^{\circ}C$ to $25^{\circ}C$ condition. Conidial germination was rapidly reduced at 5 regardless of relative humidity conditions. More than 50% of the conidial germination were initiated within 2 h at $25^{\circ}C$ through pH 5 to 7. The highest conidial germination of A. dauci was on 0.2% of carrot leaf extract. Conidia could survive longer than 12 h, even though its germination decreased. After a 12 h dry period, around 10% of conidia revived and germinated when conidia were hydrated again. These results could be used as the useful information on conidial germination of A. dauci and ecology of Alternaria leaf blight.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1269-1273
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• 2005

자연 친화적 하천관리는 현 치수위주의 하천정비 관행으로 인한 하천의 환경 기능의 훼손을 막고, 제도적으로 자연 친화적으로 하천 사업을 추진하기 위해서 수변조사, 계획, 설계, 시공, 모니터링, 그리고 유지관리 등 일련의 체계적인 절차에 따라 하천 사업을 시행하는 것이다. 특히 이러한 표준 절차 가운데 수변조사는 하천의 특성을 결정짓는 여러 가지 자연적, 인공적 형성과정들과 그 과정들을 지배하는 생태학적 원리들을 파악하여 하천사업의 정비주제와 방향을 설정하는데 도움을 준다. 모니터링은 계획과 설계, 시공을 통해 실시된 하천사업의 효과를 평가하고, 공법적용에 따른 하천의 변화과정을 파악하여 유지관리 및 적응관리를 위한 근거를 제시하는 과정이다. 수변조사 및 모니터링 매뉴얼은 건설교통부가 수행한 '자연친화적 하천정비기법 개발' 의 연구성과로서, 경기도의 탄천, 충청북도의 달천 그리고 경기도 오산천을 대상으로 각 관련분야의 전문가가 참여하여 직접 적용$\cdot$검증한 결과를 바탕으로 제작한 것이다. 이는 하천의 관리 및 하천관련 사업을 자연 친화적으로 수행하기 위하여 필요한 '수변조사'와 '모니터링'에 대한 일반적인 절차와 방법을 체계화 한 것이다. 특히 수변조사 매뉴얼의 경우는 $\ulcorner$하천설계기준$\lrcorner$의 '제12장 하천환경조사'를 보완하는 관계에 있다. 하천설계기준에서 제시한 하천환경조사는 본 수변조사 매뉴얼상과 동일한 절차와 양식을 따르고 있다. 하천설계기준에서 자세하게 기술하지 못한 조사방법, 정리, 분석, 평가에 대한 내용을 구체적으로 적용하여 이를 보완하고 있다.은 안양천 웹페이지(http://anyang.river.or.kr)에서 구현되고 있으며, 앞서 설명한 바와 같이 1단계 프론티어 사업으로 설치된 4개의 하천수위, 2개의 지하수위 관측시설과 함께, 2단계에 (주)웹솔루스에서 자체적으로 설치 운영하고 있는 2개소의 하수관거 모니터링 관측시설, 그리고 안양시에서 운영하고 있는 5개소의 강우관측소와 7개소의 수위관측소를 모두 통합하여 실시간 자료를 제공하고 있다. 수위자료는 10분단위의 텍스트정보와 그래프형태로 지원되며, 검색기간 설정을 통해 원하는 기간내의 자료를 선별, 검색할 수 있다.. 또한 이와 같은 기초적인 정보를 바탕으로 하류하천의 탁수 피해를 최소화할 수 있는 선택취수탑의 운영방안을 수립할 수 있다 본 연구에서는 이를 위해 선택취수탑 주위의 성층흐름을 기존의 실험자료와 수치해석을 통하여 분석하였고, 온도성층구조나 취수구의 위치변화에 따른 방류수 수질특성을 조사하였다.쇄파대(artifical reef)와 같은 완충지대를 갖는 호안을 축조함으로써 월파량을 감소시키는 대안으로 제시하고자 한다. 본 연구 수행을 통해 태풍 내습시 발생 가능한 자연재해에 대한 사전 방지를 목적으로 태풍피해의 원인을 제시하고 이를 해결하여 현재의 방재대책이 항구적인 방재대책으로 전환될 수 있는 방안 마련의 기초 자료로 활용되기를 기대한다., L-arabinose, 및 D-galactose; 제3차(第三次) 가수분해물(加水分解物)(C)에서 L-rhamnose, D-xylose, L-arabinose 및 D-galactose, 비가수분해물(非加水分解物)(C')에서 D-xylose와 D-galactose를 검출(檢出)하였다. (4) 구성당(構

• Journal of Korea Water Resources Association
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• v.40 no.5
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• pp.383-396
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• 2007

The studies on efficiency of flood control reservoir has been introduced into four categories including direct flood control contribution by reservoir, flow-duration change and environmental-ecological change in downstream of dam and flood damage estimation of flood plain. In spite of all the previous approaches, the quantification of the effect of reservoir on the flood control in planning stage is quite complex due to lack of a standard for quantifying feasibility of project. In this study, we develop a methodology that can clearly and accurately quantify the flood damage reduction together with the existing flood level reduction at downstream. The proposed approach uses three appraisal standards of flood control: 'potential safety', 'relative risk' and 'absolute risk' according to the risk by stage. The developed methodology was applied to the Namhan river basin with the storm event of July, 2006. The result shows the damage reduction of 4,189 billion won was estimated. The economic benefits for the flood control effect by dam will greatly contribute to the public understanding of the importance and the effect of the flood control by dam.