• Journal of Korea Water Resources Association
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• v.51 no.9
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• pp.769-782
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• 2018

Estimation of design floods is typically required for hydrologic design purpose. Design floods are routinely estimated for water resources planning, safety and risk of the existing water-related structures. However, the hydrologic data, especially streamflow data for the design purposes in South Korea are still very limited, and additionally the length of streamflow data is relatively short compared to the rainfall data. Therefore, this study collected a large number design flood data and watershed characteristics (e.g. area, slope and altitude) from the national river database. We further explored to formulate a scaling approach for the estimation of design flood, which is a function of the watershed characteristics. Then, this study adopted a Hierarchical Bayesian model for evaluating both parameters and their uncertainties in the regionalization approach, which models the hydrologic response of ungauged basins using regression relationships between watershed structure and model. The proposed modeling framework was validated through ungauged watersheds. The proposed approach have better performance in terms of correlation coefficient than the existing approach which is solely based on area as a predictor. Moreover, the proposed approach can provide uncertainty associated with the model parameters to better characterize design floods at ungauged watersheds.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.1
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• pp.29-40
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• 2013

The object of this research is to elicit the ecological wetland's creating and maintaining conditions through GIS and AHP(Analytic Hierarchy Process) on common characteristics of wetland, by exploring the function of the long-standing and naturally created wetlands in South Han-river basin. Geomorphological, geologic, hydraulic & hydrological, pedological, environmental & ecological approaches of five categorizations were made based on the documents and precedent studies in order to perform the research object. Elicitation of the common creating and maintaining conditions on the objected wetlands through analysis of satisfactory conditions was conducted by performing an overlay analysis from the gathered information in each category and linking its result to each wetland. Also, elicitation of highly believable qualified analysis result was made by calculating the each factor's weight through application of AHP analysis method on each factor. The research result is expected to be applied effectively in suitability selection for creation of an artificial wetland and restoration and maintenance for naturally created wetlands when introducing the No Net Loss of Wetlands. In addition, with a new understanding on wetland and beyond the value of its conservativeness, this research result can be considered as a solution for Eco-Wetland's maintainable development.

• Korean Journal of Ichthyology
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• v.25 no.4
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• pp.200-207
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• 2013

We investigated developmental stages of egg and early life history of the Korean indigenous fish, Korean Chub Zacco koreanus from the South Han River in 2011 for phylogenetic study and conservation of this species. Eggs of Zacco koreanus were artificially fertilized by the dry method in the laboratory. The fertilized eggs were demersal, almost spherical in shape, transparent and unpigmented, with a pale yellow yolk, and no oil globule and average $3.09{\pm}0.07$ mm (n=10) in diameter. The hatching of the embryo took place in about 68 hrs after fertilization under water temperature of $20.0{\sim}23.0^{\circ}C$ and the newly hatched larvae were average $10.30{\pm}0.40$ mm (n=10) in total length (TL). Six days after hatching, the larvae grew up to $16.12{\pm}0.42$ mm (n=8) in TL and york sac absorption, mouth and anus opening were shown postflexion larvae stage. 17 days after hatching, most of fin-rays appeared at $18.21{\pm}0.38$ mm (n=6) in TL and brown spot appeared on the abdomen. 27 days after hatching, the larvae were brought up to $20.01{\pm}1.12$ mm(n=5) in TL and all their fin-rays were formed. 120 days after hatching, the larvae (juvenile) were $23.29{\pm}3.12$ mm (n=10) in TL and their body shape and color pattern were similar to the adult fish.

• Korean Journal of Environmental Biology
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• v.27 no.4
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• pp.414-424
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• 2009

The research was to get a biological assessment on Bokha stream and Dal stream, using the physicochemical factors and the epilithic diatom from June, 2008 to March, 2009. As a result, Bokha stream showed high consistency of total phosphorus ($0.041{\sim}0.886\;mg{\cdot}L^{-1}$), and total nitrogen ($0.336{\sim}10.532\;mg{\cdot}L^{-1}$). Also, the concentration of BOD showed most of the sites polluted as $2{\sim}5\;mg\cdot}L^{-1}$ except for the upstream sites. However, excluding downstream sites and other few sites, Dal stream had very clean water quality having total phosphorus less than $0.06\;mg\cdot}L^{-1}$, and total nitrogen less than $2.0\;mg\cdot}L^{-1}$. Out of the 12 total sites, 98 taxa of epilithic diatoms appeared: 67 taxa from Bokha stream, and 78 taxa from Dal stream. The results of the water quality assessment showed that, Bokha stream, having TDI level over 80, was mostly $\alpha$-mesosaprobic, which indicates a severe pollution. On the other hand, Dal stream, having TDI level below 50, was examined to be xenosaprobic and $\alpha$-oligosaprobic, which indicates a clean water quality. The correlation between DAIpo and TDI measured to be high in correlation coefficent (0.83) from the result of correlation analysis. When the water quality is good, there is an inclination of getting high correlation between chemical and biological water quality assessment results. TDI, which uses numerous taxa of diatoms, showed more stability than DAIpo, which uses less amount of taxa of diatoms to get its result.

• Journal of the Korean association of regional geographers
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• v.19 no.2
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• pp.352-361
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• 2013

This paper aims to analyze the root mean square errors of MODIS LST data and inland water temperature measurement data in order to use MODIS LST data as an input of numerical weather prediction model. MODIS LST data from July 2011 to June 2012 were compared to water temperature measurement data in the automated water quality measurement network. MODIS data have two composites: day-time and night-time. Monthly errors of day-time and night-time LST range $2{\sim}8^{\circ}C$ and $3{\sim}12^{\circ}C$, respectively. Temporally, monthly errors of day-time LST are less in fall and those of night-time LST are less in summer. Spatially, on the four major rivers including the Han, Nakdong, Geum, and Yeongsan rivers, the errors of Yeongsan river were the smallest, which location is the south-most among them. In this study, the errors of MODIS LST as an input of numerical weather prediction model were analyzed and the results can be used as an error level of MODIS LST data for inaccessible areas such as North Korea.

• Journal of Sericultural and Entomological Science
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• v.52 no.2
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• pp.123-128
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• 2014

We carried out an ecological survey for Ceratovacuna japonica, which lives in bamboos, at the experimental field of National Academy of Agricultural Science, Suwon and the several natural fields in Korea from 2010 to 2011. The releasing methods of C. japonica on Pseudosasa japonica was more effective at the brushing-off method than the pining-attached method. The successful rate of releasing was the highest at green house than others such as at outdoor, vinyl green house and in a insects net conditions. The survival limit of C. japonica was closely associated with the lowest temperature ($-10^{\circ}C$) of vegetative limit of P. japonica for over wintering because of two fields of Ilsan lake park and Guri ecological park showed falling down below $-15^{\circ}C$ two times in January. It provides for a reasonable distribution information of C. japonica that is restricted to south of Han River. However, the middle of Korea has rarely fallen down below $-10^{\circ}C$. Therefore, we consider that a successful rearing of C. japonica may be the most suitable in green house condition to overcome winter period.

• The Journal of Engineering Geology
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• v.33 no.2
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• pp.257-273
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• 2023

Hydrochemical characteristics and microbial communities of spring (Samtong), surface water, and groundwater in Cheorwon, Korea, were analyzed. Field surveys and water quality analyses were undertaken at 10 sampling points for five spring, two surface, and three groundwater samples on 15 December 2022. Hydrochemical analysis revealed that most water samples were Ca-HCO₃ type and that water-rock interactions were the predominant mineral source. Radon concentrations were <1 kBq m^-3 for surface water, 1~10 kBq m^-3 for spring water, and 1~1,000 kq m^-3 for groundwater. Microbial cluster analysis showed that the main phyla were Proteobacteria, Planctomyceta, Verrucomicrobia, Acidobacteria, and Actinomycetota.Non-metric multidimensional scaling (NMDS) analysis indicated that water temperature, pH, and Si content were closely related to microorganism content. NMDS and canonical correspondence analysis results revealed that environmental factors affecting spring water were temperature, and Mg and Si concentrations, particularly for Acidobacteria and Proteobacteria, and Pseudomonas brenneri. Both hydrochemical and microbial community analyses yielded similar results at some spring and groundwater sampling points, likely due to the effects of a basalt aquifer.

• Korean Journal of Plant Resources
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• v.32 no.2
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• pp.201-206
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• 2019

Alien invasive species are introduced with or without intent and spreading all over Korea. They are known to have negative effects on biodiversity such as economic and environmental damage and causing decrease or loss of native species. The habitats like wetland, reservoir and riverside are especially in danger of being invaded by alien species due to stress and disturbance. Therefore, Korea National Arboretum is steadily working on research and studies on managing alien invasive species. This research aims to collect basic information of Ludwigia peploides subsp. montevidensis (Spreng.) P.H. Raven which was found near riverside in Suwon-si and is concerned to become an invasive alien species. We expect the description, diagram and pictures of this taxon will be helpful for early detection and effective management.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.882-889
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• 2012

This study was surveyed that water physiochemical characteristics and phytoplankton incidence of main stream and Lake Doam near to Daegwallyeong agricultural area. Based on above results, it was conducted to get information overall water characteristics in south Han upstream river. COD value of Lake Doam was $6.1mg\;L^{-1}$ and T-P (Total phosphorous) from there was $0.26mg\;L^{-1}$ which was higher than the value of grade VI based on lake water living environment standard. Suspended solid was an average of 9.77 NTU which was higher than value of lake living standard. Concentration of phytoplankton was over $2.0{\times}10^3Cell\;mL^{-1}$ from July to September. It was considered that cyanobacteria were occurred due to massive influx of nutrient material by high temperature and rainfall during this season. Compare to Ontario's sediment quality guidelines, T-N and T-P was middle value between LEL and SEL in Lake Doam. This value means that contamination in water is serious. Therefore, it is considered that systematic management was needed to reduce and block contamination source.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.978-988
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• 2005

A three-dimensional dynamic model was applied to Lake Paldang, Han River in this study. The model was calibrated and verified using the data measured under different ambient conditions. The model results were in reasonable agreements with the field measurements in both calibration and verification. Utilizing the validated model, we analyzed the spatial and temporal distributions of temperature, current, residence time, and spreading pattern of incoming flows within the lake. Relatively low velocity and high temperature were computed at the surface layer in the southern region of the Sonae island. The longest residence time within the lake was predicted in the southern region of the Sonae island and the downstream region of the South Branch. This can be attributed to the fact that the back currents caused by the dam blocking occur mainly in these regions. Vertical thermal profiles indicated that the thermal stratifications would be occurred feebly in early summer and winter. During early spring and fall, it appeared that there would be no discernible differences at the vertical temperature profiles in the entire lake. The vertical overturns, however, do not occur during these periods due to an influence of high discharge flows from the dam. During midsummer monsoon season with high precipitation, the thermal stratification was disrupted by high incoming flow rates and discharges from the dam and very short residence time was resulted in the entire lake. In this circulation patterns, the plume of the Kyoungan stream with smallest flow rate and higher water temperature tends to travel downstream horizontally along the eastern shore of the south island and vertically at the top surface layer. The model results suggest that the Paldang lake should be a highly hydrodynamic water body with large spatial and temporal variations.