• Economic and Environmental Geology
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• v.36 no.6
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• pp.415-429
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• 2003

This study was objected to identify the difference of water quality and the characteristics of water contamination in adjacent bed-rock areas of Upper Hwajeonni and Guryongsan Formations in Miwon, Choongchungbuk-do, Korea. Water samples showed mainly (Ca, Mg)-$HCO_3$ type in Upper Hawjeonni Formation and (Ca, Mg)-$SO_4$ and (Ca, Mg)-$HCO_3$ types in Guryongsan Formation indicating the enrichment of $SO_4$ in major compositions. Groundwater quality could be divided into two groups based on the major weathering processes, implied by the ratio of bicarbonate to silica. Carbonate-silicate weathering predominates in Upper Hwajeonni Formation, and silicate weathering in Guryongsan Formation. Stream-water quality also appeared to be controlled by water-rock interaction. Cluster analysis identified three groups of groundwater and four groups of stream-water with distinctive geochemical characteristics. The results of factor analysis indicated that the levels of each chemical constituent in water samples derived from both natural weathering reactions and anthropogenic contamination sources. To delineate the pollution potential of water resources, Modified Pollution Index(M.P.I.) was developed. M.P.I. scores of water samples ranged from -0.08 to 0.18, with mostly positive along the rock quarry in Guryongsan Formation areas. M.P.I. scores appeared to be a useful predictor of metal contamination of water resources.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.4
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• pp.229-237
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• 2019

This study was conducted to estimate annual reference evapotranspiration (ET₀) for the agro-climatic zones for rice paddy fields in South Korea between 1980 and 2015. The daily ET₀ was estimated by applying the Penman-Monteith method to meteorological data from 61 weather stations provided by Korean Meteorological Administration (KMA). The average of annual ET₀ from 1980 to 2015 was 1334.1±33.89 mm. The ET₀ was the highest at the Southern Coastal Zone due to their higher air temperature and lower relative humidity. The ET₀ had significantly increased with 2.81 mm/yr for the whole zones over 36 years. However, the change rate of it was different among agro-climatic zones. The annual ET₀ highly increased in central zones and eastern coastal zones. In terms of correlation coefficient, the temporal change of the annual ET₀ was closely related to variations of four meteorological factors (i.e., mean, minimum temperatures, sunshine duration, and relative humidity). The results demonstrated that whole Korean agro-climatic zones have been undergoing a significant change in the annual ET₀ for the last 36 years. Understanding the spatial pattern and the long-term variation of the annual ET₀ associated with global warming would be useful to improve crop and water resource managements at each agro-climatic zone of South Korea.

• Water for future
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• v.19 no.3
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• pp.249-258
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• 1986

The purpose of this study is to estimate the PMP frequency factor for evaluation of the Probable Maximum Precipitation (PMP) in Korea. The value of PMP is the criterion of the determination of design rainfall in Planning and designing hydraulic structures, and water resources management. To obtain the object, 12 key stations were selected in which have the automatic rain0recording paper of 20 years, and the annual maximum rainfall values were calculated for each 7 durations(10 min., 1, 2, 4, 6, 12, 24 hr.). The statistics(mean, standard deviation)were estimated, and diagram which shows the relationship between mean annual maximum rainfall($$) and frequency factor for each durations were drawn. PMP was estimated by statistical method using the PMP frequency factor obtained from the diagram and statistics($$, Sn). The PMP-Duration Equation was derived from the envelope curve in order to obtain the PMP for an arbitrary duration. The isohyetal map of 24 hours PMP and PMP. DAD curve for the whole of Korea were drawn in accordance with the point PMP values.

• Journal of Wetlands Research
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• v.16 no.2
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• pp.173-185
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• 2014

Climate change has caused detrimental phenomena such as heavy rainfall which could aggravate soil erosion. Accordingly, it is needed to evaluate the groundwater recharge, baseflow, and soil erosion for the efficient management of water resources and quality. In this study, future climate change scenarios were applied to the H aean-myeon watershed which is a steep sloping watershed in South Korea to analyze groundwater recharge, baseflow, sediment. Also, the variation of groundwater recharge, baseflow, sediment was analyzed according to the change of slope (5 %). Simulated periods were divided into three terms (2013 ~ 2040 years, 2041 ~ 2070 years, 2071 ~ 2100 years). As a result of this study, average groundwater recharge and baseflow increased by 50 %, 42 %, and sediment decreased by 72 %, respectively. In these regards, the suggested method will positively contribute to hydro-ecosystem and reduction of muddy water at a steep sloping watershed.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.2
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• pp.109-120
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• 2007

The information on flowpath, storage, residence time, and interactions of water and carbon transport in a catchment is the prerequisite to the understanding and predicting of water and carbon cycling in the mountainous landscapes of Korea. In this paper, along with some up-to-date results, we present the principal methods that are currently used in HydroKorea and CarboKorea research to obtain such information. Various catchment hydrological processes have been examined on the basis of the water table fluctuations, the end-member mixing model, the cross correlation analysis, and cosmogenic radioactive isotope activity. In the Gwangneung catchment, the contribution of surface discharge was relatively large, and the changes in the amount, intensity and patterns of precipitation affected both the flowpath and the mean residence time of water. Particularly during the summer monsoon, changes in precipitation patterns and hydrological processes in the catchment influenced the carbon cycle such that the persistent precipitation increased the discharge of dissolved organic carbon (DOC) concentrated in the surface soil layer. The improved understanding of the hydrological processes presented in this report will enable a more realistic assessment of the effects of climate changes on the water resource management and on the carbon cycling in forest catchments.

• Spatial Information Research
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• v.20 no.3
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• pp.39-50
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• 2012

The objective of this study is the quantitative analysis of climate change effects by performing several statistical analyses with hydrometeorological data sets for past 30 years in Geum river watershed. Temperature, precipitation, relative humidity data sets were collected from eight observation stations for 37 years(1973~2009) in Geum river watershed. River level data was collected from Gongju and Gyuam gauge stations for 36 years(1973~2008) considering rating curve credibility problems and future long-term runoff modeling. Annual and seasonal year-to-year variation of hydrometeorological components were analyzed by calculating the average, standard deviation, skewness, and coefficient of variation. The results show precipitation has the strongest variability. Run test, Turning point test, and Anderson Exact test were performed to check if there is randomness in the data sets. Temperature and precipitation data have randomness and relative humidity and river level data have regularity. Groundwater level data has both aspects(randomness and regularity). Linear regression and Mann-Kendal test were performed for trend test. Temperature is increasing yearly and seasonally and precipitation is increasing in summer. Relative humidity is obviously decreasing. The results of this study can be used for the evaluation of the effects of climate change on water resources and the establishment of future water resources management technique development plan.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.29-41
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• 2017

Design rainfalls are one of the most important hydrologic data for river management, hydraulic structure design and risk analysis. The design rainfalls are first estimated by a point frequency analysis and the IDF (intensity-duration-frequency) curve is then constructed by a nonlinear regression to either interpolate or extrapolate the design rainfalls for other durations which are not used in the frequency analysis. It has been widely recognised that the more reliable approaches are required to better account for uncertainties associated with the model parameters under circumstances where limited hydrologic data are available for the watershed of interest. For these reasons, this study developed a hierarchical Bayesian based GLM (generalized linear model) for a regional frequency analysis in conjunction with a scaling function of the parameters in probability distribution. The proposed model provided a reliable estimation of a set of parameters for each individual station, as well as offered a regional estimate of the parameters, which allow us to have a regional IDF curve. Overall, we expected the proposed model can be used for different aspects of water resources planning at various stages and in addition for the ungaged basin.

• Journal of the Korean association of regional geographers
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• v.7 no.3
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• pp.44-58
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• 2001

The purpose of this study is to investigate the potential water condition of Honam region according to water budget analysis. For this purpose, the eight regions (Suncheon, Gwangju, Jhangheung, Damyang, Mokpo, Yosu, Huksando, Namwon) are selected as study area. The result is as follows. (1) The water surplus indicating the potential water condition is ordered as Yosu, Sunchon, Changhung, Namwon, Damyang, Huksando, Kwangju, Mokpo. So the potential water condition of Kwangju and Mokpo is worst among study regions. (2) The high water surplus region is corresponded to high precipitation and low actual evapotranspiration legions. (3) The potential water condition is to agree with several facts about the water resource condition of Honam region. For example, large scale dam of Honam region has been constructed for Kwangju and Mokpo city. This fact indicates that the potential water condition calculated by water budget analysis is corresponded to actual water resource condition. (4) Consequently, the water budget analysis is effective method for investigating the actual water condition and establishing the water resource management of specific regions.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.2
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• pp.94-100
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• 2013

In this study, we have investigated the water quality and flow rate at the 3 sites of main stream and 11 sites of the branch stream of Hwang River from January, 2007 to 2010, and analyzed the effects on Hwang River with the purpose of using the data for as the fundamental information for water quality improvement and water resource management in the water system of Hap-Cheon Lake Upper Stream. The flow rate at 3 sites of the main stream and 11 sites of the branch stream increased during the rainy season between June and September, and continuously decreased during the dry season starting from autumn to winter. The results of correlation analysis with Pearson correlation coefficient showed that $BOD_5$ and $COD_{Mn}$, $BOD_5$ and T-P, and $COD_{Mn}$ and TSS at the 3 sites of the main stream had high correlation with each other. We have also analyzed the correlation between Chl-a and major factors at the 3 sites of the main stream. Chl-a and the water temperature Negative correlation coefficient and that of Chl-a and $BOD_5$, $COD_{Mn}$ Positive correlation coefficient showed. The N/P ratio at all the 3 sites of the main stream was higher than 16 by DIN/DIP and T-N/T-P, indicating that phosphorus is acting as the limited nutrient.

• Economic and Environmental Geology
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• v.41 no.4
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• pp.427-442
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• 2008

Estimation of groundwater recharge is one of the most critical issues in sustainable management of groundwater resources. This study estimated groundwater recharge in the Junggwae-Boeun area in Ulsan City, by using the water balance and hydrogeological characteristics of geology and soil. Evapotranspiration was computed by using the Thornthwaite method, and direct runoff was determined by using the SCS-CN technique. Groundwater recharge was obtained as 266 mm/a (20.6% of the average annual precipitation, 1296 mm/a), with 779 mm/a (60.1%) of evapotranspiration and 119 mm/a (9.2%) of direct runoff. Precipitation and groundwater recharge was highly correlated, comparing with the relationships between precipitation and evapotranspiration, and between precipitation and direct runoff. This fact indicates that groundwater recharge responds more sensitively to precipitation than evapotranspiration and direct runoff do.