• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.4
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• pp.9-17
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• 2012

This study was aimed to characterize non-point source (NPS) pollutant runoff and estimate event mean concentrations (EMCs) from a small rural watershed located at the headwater area of the Gyeongan stream. The study watershed consists of the two major landuse, forest (72 %) and paddy field (28 %). The nine rainfall events ranging from 18.5 to 192.6 mm in amount were monitored in this study. Stream flow was measured at the watershed outlet using a water level gauge, while a number of water samples for each event were collected and analysed for water quality. Event pollutant loads varied greatly depending on rainfall events varying from 22.6 to 3,134.2 mg/L, 0.32 to 24.56 mg/L, 0.090 to 1.320 mg/L, and 2.3 to 149.8 mg/L for SS, TN, TP, and COD, correspondently. The respective mean EMCs were estimated by 104.2, 1.00, 0.168, and 7.9 mg/L. The Pearson correlation analysis showed that COD EMC was significantly correlated with those of SS, TN, and TP. Rainfall runoff ratio appeared to be negatively correlated with EMCs of SS, TP, and COD, although not statistically significant. The event loads from the largest rainfall was greater than the sum of those from the remaining eight events. The study results suggest that the appropriate management of intensified storm events are of greater importance in curbing NPS loads, while the estimated EMCs provide base data for the unit pollutant loads determination for the forest-paddy composite upstream watershed.

• Journal of Korean Society on Water Environment
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• v.30 no.4
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• pp.441-451
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• 2014

Streamflow is typically divided into two components that are direct runoff and baseflow, it is required to analyze and estimate behaviors of those two flow components to understand watershed characteristics so that watershed management plan can be effective in pollutant reductions. Since pollutant load behaviors in a stream or river are variable by flow component behaviors, best management practices need to be applied in a watershed based on the pollutant load behaviors varying with flow components. Thus, baseflow behaviors were analyzed separating baseflow from streamflow data collected from fifteen streamflow gaging stations in the 4 major river watersheds which are the Han river, Nakdong river, Guem river, and Yeongsan Somjin river watersheds. Moreover, precipitation trends throughout the 4 River Systems were investigated, thus daily precipitation data were collected from sixty-five locations. The Hank river watershed displayed the largest precipitation (925.2 mm) in summer but the lowest precipitation (71.8 mm) in winter, indicating the watershed has the most fluctuating precipitation characteristic. While the precipitation trends in the Four River Systems varied, a distinct feature in baseflow trends was not found, moreover baseflow percentages to streamflow were typically greater than 50% in the Four River Systems. As shown in this study, it would be expected significant amount of pollutants could be contributed to the stream in the form of baseflow at the watershed.

• Journal of Environmental Science International
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• v.15 no.4
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• pp.349-357
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• 2006

The purpose of this study is to evaluate the water pollution degree in the Mid-Nakdong River watershed regarding to landcover types using GIS method. As a result of landcover classification, rate of urban appeared highly on Daegu Metropolitan city. Also, rate of agriculture showed highly in the riparian zones of the Nakdong and Guemho River and rate of forest appeared highly in the borders of the study area. To identify the groups of watershed with similar landcover patterns using the Cluster Analysis. According to the cluster analysis, the fifty sub-watersheds were grouped in three clusters, 'Urban watershed', 'Agriculture watershed', 'Forest watershed'. The proportion of urban area in each cluster had a positive correlation with water pollution degree. Otherwise, the proportion of agriculture in the Agriculture watershed had a high positive correlation with water pollution degree. Therefore, it is necessary to estimate environmental capacity of water duality considering ecological and environmental characteristics of watershed ecosystem and expand water duality monitoring systems to small stream.

• Journal of Korean Society on Water Environment
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• v.26 no.5
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• pp.802-809
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• 2010

An automatic calibration tool of Hydrological Simulation Program-Fortran (HSPF), Parameter Estimation (PEST) program, was applied at the Imha lake watershed to get optimal hydrological parameters of HSPF. Calibration of HSPF parameters was performed during 2004 ~ 2008 by PEST and validation was carried out to examine the model's ability by using another data set of 1999 ~ 2003. The calibrated HSPF parameters had tendencies to minimize water loss to soil layer by infiltration and deep percolation and to atmosphere by evapotranspiration and maximize runoff rate. The results of calibration indicated that the PEST program could calibrate the hydrological parameters of HSPF with showing 0.83 and 0.97 Nash-Sutcliffe coefficient (NS) for daily and monthly stream flow and -3% of relative error for yearly stream flow. The validation results also represented high model efficiency with showing 0.88 and 0.95, -10% relative error for daily, monthly, and yearly stream flow. These statistical values of daily, monthly, and yearly stream flow for calibration and validation show a 'very good' agreement between observed and simulated values. Overall, the PEST program was useful for automatic calibration of HSPF, and reduced numerous time and effort for model calibration, and improved model setup.

• Hwankyungkyoyuk
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• v.20 no.4
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• pp.12-26
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• 2007

The purpose of this research is to develop a water environmental education (EE) program using streams, based on the core ideas of ENVISION and materializing elements that were extracted in this research. This research realized the elements and presented a model of the water EE program using a local stream. First, this research developed a basic model of a water EE program using streams by extracting 10 materializing elements and realizing the elements in 4 stage-procedural model. The 10 materializing elements were 1. experiencing the process of inquiry, 2. inquiring local environments, 3. self-directing learning and mutual interaction with colleagues, 4. collecting real data and interpreting, 5. utilizing the ICT(information and communication technology), 6. inquiring with the view point of the 'Environmental Studies for EE', 7. inquiring with the watershed concept, 8. inquiring with the integrating and the holistic view point, 9. pursuing the macroscopic understanding about environment, and 10. connecting the real world phenomena with the environmental concepts and theories. This research materialized these 10 elements in 4 stage model, following the previous ENVISION research, which are 1. preparing stage and visual assessment, 2. writing the report of the inquiry plan, 3. collecting the real data in the environment and performing the investigation, and 4. presenting the inquiry results. Second, with using this basic model, this research developed and presented a model of the specific water EE program using a case stream called 'Baig Cheon' stream, which is a local stream. This research is considered to have a considerable meaning in developing a EE program with ENVISION ideas for the watershed concept and inquiry with environmental science using local streams. The developed model can help the professional development of teachers and teacher education of water EE.

• The Journal of the Korea Contents Association
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• v.11 no.9
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• pp.246-253
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• 2011

Several problems occurred due to the use of the wrong water cycle system in the watershed. This was caused by a dry stream in the lower parts of the tributaries and the deterioration in value of usage by water pollution in accordance with water storage. This was maintained for a long period of time in the reservoir which secured the agricultural water. As a result of the operational status in the agricultural reservoirs focused on Chungcheongnam-do and Daejeon metropolitan city, a dry stream appeared because hydraulic retention time(HRT) in the majority of reservoirs was maintained for 8 months of the year. The water quality in the agricultural reservoir was fairly related to the water cycle system due to rainfall and input of pollutants from the population and livestock in the watershed. Consequently, the storage water volume and the time period of the water in the reservoir should be controlled by the reduction of the pollution load in the water and the prevention of a dry stream. Also, the water cycle system in the watershed should be improved by maintaining a short HRT of the reservoir.

• Korean Journal of Ecology and Environment
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• v.45 no.1
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• pp.62-71
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• 2012

Lake Doam watershed was surveyed to evaluate non-point source discharge characteristics and discharge load including several water quality parameters in Song Stream from July 2009 to July 2011. Concentrations of water pollutants were high during the rainfall period, especially, SS, TP and COD showed increasing tendencies toward cumulative water discharge but TN did not show much difference. SS, TP and COD had an initial flush effect of over 50 mm rainfall event but there was no clear tendency for rainfalls below that level. Event mean concentration (EMC) regarding the rainy and dry period showed large differences. Especially rainy season EMC (SS, TP, COD) demonstrated an increasingly high tendency. EMCs of COD, SS, TN and TP measured for twelve rain events were as high as 26.1, 866.0, 4.68 and 0.605 mg $L^{-1}$, respectively. COD, SS, TN and TP loadings from the highland agricultural region of the Song Stream watershed were 34,263, 1,250,254, 2,673 and 933 kg $yr^{-1}\;km^{-2}$, respectively, which were relatively higher than the results of other stream systems. Therefore, it is strongly recommended that long-term monitoring and non-point pollution reduction programs for the highland agricultural area to continue. Furthermore, this non-point source pollution loading research acquired from the highland agricultural area could be the base for reassessment.

• Journal of Korean Society on Water Environment
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• v.25 no.3
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• pp.452-458
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• 2009

This study was carried out to assess the effect of discharge loading at sewage treatment plants (STP) on water quality in Kyoungan stream. The seasonal variations of water quality (BOD, COD, SS, TN, and chl.a) at site 1(Mesanribo) were similar with those at site 2(Sehabo). BOD, COD, SS, and chl.a concentration were also similar except for TN and TP concentration which were lower than those at site 1. The BOD, COD, TN, TP and chl.a concentration at site 2 in dry period were higher than that of wet period. The ratios of BOD, TP, COD, SS discharge loading at all STP in Kyoungan stream watershed to delivery loading at site 2 were 0.69, 0.54, 0.48, 0.31, and 0.26 on average, respectively. Both site 1 and site 2, the seasonal variations of discharge loading at STP did not showed any relationship with those of water quality. The mean ratios of inflow loading at site 1 to delivery loading at site 2 were relatively high that ranged from 0.43 to 0.61. In dry period, the ratios of discharge loading at STP in Sehabo watershed to delivery loading at site 2 were below 0.2 except for BOD (0.24), and decreased <0.1 in wet period. While, SS loading from watershed between site 1 and site 2 to delivery loading at site 2 ratios increased in wet period.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.2244-2248
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• 2008

This study was focused on estimated Stream Maintenance Flow and performed for simulate securing Stream Maintenance Flow in New town development area. Tributary streams were made of 6 small streams, joined Gong-ji Stream and Eu-am lake finally. For estimate Stream Maintenance Flow used Kajiyama and SWAT models for calculate available flow in study area. As a result the annual average stream flow dry years were $2,300{\sim}136,000\;m^/day3$, the annual average stream flow wet years were $4,800{\sim}136,031\;m^3/day$. The coefficient of determination($R^2$) and Nash-sutcliffe coefficient(EI) for comparison between Kajiyama and SWAT models were 0.88, 0.78 respectively.

• Magazine of the Korean Society of Agricultural Engineers
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• v.23 no.1
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• pp.64-74
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• 1981

The stream morphological characteristics of watershed have important influence upon the analysis of runoff. In this study, the effect of the map scale on the stream morphological characteristics was used on the data taken from 15'(1:50, 000) and 7'30"(1 :25,000) topographic maps which could cover the whole Miho River basin This basin are the first tributary of the Geum. River. Otherwise, the longitudinal stream bed profile was calculated by Yang's theoretical stream bed profile, equilibrium profile and actual profile. In the result of this investigation the conclusion is that the resultant relationship obtained from different topographic maps in the scale on the same stream system has come upon the same result as the stream morphological characteristics. Therefore, the great amount of time and effort can be saved in studing the stream morphological charecteristics by using the 15' instead of the 7'30"map system excluding the first order streams.