• Journal of the Korean association of regional geographers
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• v.7 no.4
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• pp.93-104
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• 2001

The purpose of this study is to analyze the geomorphic characteristics of two erosional basins with same geological conditions. The study areas, the Okcheon basin ($36^{\circ}\;14'{\sim}36^{\circ}\;20'\;N,\;127^{\circ}\;32'\;30"{\sim}127^{\circ}\;37'\;37"\;E$) and Jincheon basin($36^{\circ}\;48'{\sim}37^{\circ}\;03'\;N,\;127^{\circ}\;22'{\sim}127^{\circ}\;36'\;E$), are located on middle part of the Geum river. The geological maps, a summit level map, and a drainage network map are created and analyzed the geomorphic characteristics. The main results are as follows: 1) The Okcheon basin and Jincheon basin are typical erosional basin, in which basin floor are composed of granite. 2) The formation of Okcheon basin and Jincheon basin resulted from differencial erosion after upwarping. 3) Okcheon basin and Jincheon basin are available for specialized agriculture area and a site of new settlement with satisfactory to accessibility.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.6
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• pp.442-450
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• 2011

A three dimensional random walk particle tracking method is applied to the Saemangeum area in order to find stepwise environmental changes according to long term construction. Flow regime around Mangyeong, Dongjin and Geum river estuary changed greatly due to dike construction. It is distinctive that reduction of Byeonsan area's flow field and stagnant change in the northern part of the inner reservoir. Similar characteristics are found through the tidal excursion analysis. By analysis of the vertical mixing structures according to density stratification based on temperature and salinity variation, a salt wedge and very strong stratification arises in the inner part of the reservoir after final closure, while it has been well mixed or partially mixed estuary during construction. Shrinking of horizontal dispersion and vertical mixing capability may cause adverse effect on water quality not only inner part but also outer region of the Saemangeum reservoir.

• Economic and Environmental Geology
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• v.36 no.5
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• pp.329-338
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• 2003

The purpose of this study is to identify the temporal and spatial variation of stable isotopic compositions of surface waters and shallow ground waters at a local watershed(100$Km^2$) near the Muju area. For oxygen and hydrogen isotope analysis, water samples were collected from 19-22 sites during August, October 2001, through April 2002. Seasonal variation in the isotopic compositions of surface waters was clearly shown. However, the degree of such isotopic variation was highly attenuated in shallow ground waters because of mixing with preexisting ground waters. Isotope values of surface waters and ground waters were very similar in each season, indicating that precipitation/ground water/surface water interactions were very active and continuous in the watershed. Stable isotopic ratios of surface waters in the study area were lighter than those of the downstream reach of Geum River on south, indicating “latitude effect”. Both “altitude effect” and “amount effect” were also shown in the stable isotopic ratios of surface waters in the study area as well as seasonal variation of stable isotopes.

• Journal of Korea Water Resources Association
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• v.35 no.5
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• pp.575-581
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• 2002

This study evaluates the variation of estimation error of area-average rainfall due to rainfall seasonality. Both the cases considering and not considering the spatial correlation are compared to derive the characteristics of estimation error. Similar cases with different accumulation time without considering the rainfall seasonality are also investigated. This study was applied to the Geum-river basin with total 28 rain gauge measurements haying more than 30 years of daily rainfall measurements. As results of the study we found that: (1) The absolute estimation error of monthly area-average rainfall show strong seasonality like the total rainfall amount. However, the relative estimation error normalized by its mean was estimated to have similar values about 5 to 8% except January and December. (2) The relative estimation error of annual area-average rainfall estimated was found to have the estimation error about 3% of its annual mean. (3) However, the relative estimation error normalized by the standard deviation remains almost the same for both monthly and annual rainfall amounts, which was estimated about 11% of its standard deviation. (4) Finally, the estimation error without considering the spatial correlation was found to become almost twice the estimation error with considering the spatial correlation.

• Journal of Korean Society on Water Environment
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• v.33 no.3
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• pp.326-333
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• 2017

The lakes and reservoirs have been reported as important sources of carbon emissions to the atmosphere in many countries. Although field experiments and theoretical investigations based on the fundamental gas exchange theory have proposed the quantitative amounts of Net Atmospheric Flux (NAF) in various climate regions, there are still large uncertainties at the global scale estimation. Mechanistic models can be used for understanding and estimating the temporal and spatial variations of the NAFs considering complicated hydrodynamic and biogeochemical processes in a reservoir, but these models require extensive and expensive datasets and model parameters. On the other hand, data driven machine learning (ML) algorithms are likely to be alternative tools to estimate the NAFs in responding to independent environmental variables. The objective of this study was to develop random forest (RF) and multi-layer artificial neural network (ANN) models for the estimation of the daily $CO_2$ NAFs in Daecheong Reservoir located in Geum River of Korea, and compare the models performance against the multiple linear regression (MLR) model that proposed in the previous study (Chung et al., 2016). As a result, the RF and ANN models showed much enhanced performance in the estimation of the high NAF values, while MLR model significantly under estimated them. Across validation with 10-fold random samplings was applied to evaluate the performance of three models, and indicated that the ANN model is best, and followed by RF and MLR models.

• Journal of fish pathology
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• v.18 no.3
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• pp.197-204
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• 2005

This study was performed to understand morphological features and classification of different species of cercaria parasitized in Batillaia cummingi, a marine gastropod. Samples were collected from April 2004 to February 2005 in the mud flat of Naecho-do, which is located in the estuary of the Geum river of the Yellow Sea. The mud flat temperature of the study area ranged from 6$^{\circ}C$ to 27$^{\circ}C$ all around the year. Two species of cercaria, Pygidiopsis summus and Cercaria pseudogranifera, were detected through the gonad examination of the gastropod. The minimum and maximum infection rates of Pygidiopsis summus were 0.67% in October and 20.67% in August, respectively. However, P. summus was not detected in December. The infection rate of Cercaria pseudogranifera showed from 9.3% in June to 66.0% in December. These data indicate that Batillaia cummingi should be added as the intermediate host of these parasites.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.1
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• pp.85-92
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• 2008

This study was carried out to estimate heavy metal loads at plain area of the rural watersheds during farming season in 2006. The experimental area was belonging to Geum River watershed. That was located at the center of South Korea. Water samples were corrected at two kinds of aspects. One is regular sampling(every two month) and the other is irregular sampling(every rainfall event). The result showed that heavy metal properties of regular samples were highest at May and June with lively agricultural activities. Heavy metal concentration of irregular samples was lower than that of regular samples. But the heavy metal loads of irregular samples were high. The correlation between each heavy metals of regular samples was following as Mn-Cd > Mn-Fe > Mn-Al > Fe-Al > Al-Cd. The correlation of irregular samples was following as Fe-AI > Zn-Mn > Fe-Cd > Cd-Al. Loading rates of daily discharge the plain area of designed rural watershed during farming season were Al 3.070 kg/day, Cu 0.526 kg/day, Fe 0.745 kg/day, Zn 0.314 kg/day, Cd 0.010 kg/day, Cr 0.055 kg/day, Mn 0.140 kg/day and Pb 0.098 kg/day. Loading rate of discharge with heavy metals during the survey period was Al(577.23 kg) > Fe(140.08 kg) > Cu(98.93 kg) > Zn(58.99 kg) > Mn(26.34 kg) > Pb(18.51 kg) > Cr(10.34 kg) > Cd(1.93 kg).

• Journal of Korean Society on Water Environment
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• v.25 no.4
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• pp.615-623
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• 2009

The research of the determination of event mean concentration (EMC) was focussed combined sewer overflows and highway runoff in korea. But those of non-urban areas are few. In this study, EMC and unit loading on land use types in Nogok watershed were estimated by runoff loading of non-point source (NPS) on non-urban area. Two monitoring sites were equipped with an automatic velocity meter, flow meter, and water sampler. Monitoring was conducted at two monitering site during the rainy season. The results show that the EMC ranges in forest land use are 1.3~2.6 mg/L for BOD, 2.0~16.1 mg/L for SS, 0.1~2.1 mg/L for TN, and 0.12~0.49 mg/L for TP. The unit loading of NPS in this study was difficult to compare directly with that used conventionally because of the difference of field investigation. In near future, it needs to conduct more systematic and long-term research about NPS within the watershed. The results of this research can be used to estimate the total pollution load management system (TPLMS) program in korea.

• Journal of Korean Society on Water Environment
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• v.26 no.1
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• pp.61-70
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• 2010

The increase of impervious cover (IC) in a watershed is known as an important factor causing alteration of water cycle, deterioration of water quality and biological communities of urban streams. The study objective was to assess the impact of IC changes on the surface runoff characteristics of Kap Stream basin located in Geum river basin (Korea) using the Storm Water Management Model (SWMM). SWMM was calibrated and verified using the flow data observed at outlet of the watershed with 8 days interval in 2007 and 2008. According to the analysis of Landsat satellite imagery data every 5 years from 1975 to 2000, the IC of the watershed has linearly increased from 4.9% to 10.5% during last 25 years. The validated model was applied to simulate the runoff flow rates from the watershed with different IC rates every five years using the climate forcing data of 2007 and 2008. The simulation results indicated that the increase of IC area in the watershed has resulted in the increase of peak runoff and reduction of travel time during flood events. The flood flow ($Q_{95}$) and normal flow ($Q_{180}$) rates of Kap Stream increased with the IC rate. However, the low flow ($Q_{275}$) and drought flow ($Q_{355}$) rates showed no significant difference. Thus the subsurface flow simulation algorithm of the model needs to be revisited for better assessment of the impact of impervious cover on the long-term runoff process.

• Journal of Korea Water Resources Association
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• v.38 no.2
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• pp.167-177
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• 2005

In this study, the PRMS(Precipitation and Runoff Modeling System), developed by USGS(United States Geological Survey), was applied to the Yongdam dam watershed in the Geum River basin. The efficiency for runoff simulation and spatial characteristics of PRMS were evaluated. The runoff changes with the changes of subcatchments and HRUs were estimated. As results, the size of the subcatchment and HRV did not significantly affect the runoff at the exit of watershed. Consequently, the spatial characteristic of PRMS was shown as lumped type rather than semi-distributed. The geographical input data for Yongdam dam watershed were converted to the USGS Input type, and the parameters were calibrated using Rosenbrock optimization method, validated with the observed runoff data. The PRMS showed resonable agreements in the long-term continuous runoff simulation, if the accuracy of observed data is ensured.