• Journal of Environmental Health Sciences
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• v.31 no.1
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• pp.1-6
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• 2005

This study was conducted to identify the runoff characteristics of non-point source according to rainfall in Nam watershed. Land-uses of the Nam watershed were surveyed paddy field 4.5%, crop field 6.8%, mountainous 78.7%, urban 2.4%, and etc. 7.7%. Mean runoff coefficients in each area were observed Ⅰ area 0.08, Ⅱ area 0.08, and Ⅲ area 0.05. In the relationship between the rainfall and peak-flow, correlation coefficients(r) were investigated Ⅰ area -0.8609, Ⅱ area 0.6035, and Ⅲ area -0.4913. In the relationship between the antecedent dry period and first flow runoff, correlation coefficients(r) were investigated Ⅰ area -0.9093, Ⅱ area -0.1039, and Ⅲ area -0.7317. The discharge of pollutant concentrations relates to the flow rate of storm-water. In the relationship between the rainfall and watershed loading, exponent values of BOD, COD, SS, and T-N were estimated to 1.2751, 1.2003, 1.3744, and 1.1262, respectively.

• Journal of Korea Water Resources Association
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• v.38 no.12 s.161
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• pp.1061-1072
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• 2005

A hydrological grey model is developed to forecast short-term river runoff from the Naju watershed located at upstream of the Youngsan estuary dam in Korea. The runoff of the Naju watershed is measured in real time at the Naju streamflow gauge station, which is a key station for forecasting the upstream inflow and operating the gates of the estuary dam in flood period. The model's governing equation is formulated on the basis of the grey system theory. The model parameters are reparameterized in combination with the grey system parameters and estimated with the annealing-simplex method In conjunction with an objective function, HMLE. To forecast accurately runoff, the fifth order differential equation was adopted as the governing equation of the model in consideration of the statistic values between the observed and forecast runoff. In calibration, RMSE values between the observed and simulated runoff of two and six Hours ahead using the model range from 3.1 to 290.5 $m^{3}/s,\;R^2$ values range from 0.909 to 0.999. In verification, RMSE values range from 26.4 to 147.4 $m^{3}/s,\;R^2$ values range from 0.940 to 0.998, compared to the observed data. In forecasting runoff in real time, the relative error values with lead-time and river stage range from -23.4 to $14.3\%$ and increase as the lead time increases. The results in this study demonstrate that the proposed model can reasonably and efficiently forecast runoff for one to six Hours ahead.

• Water for future
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• v.28 no.3
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• pp.175-186
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• 1995

Characteristics of runoff and groundwater qualities from a pasture and field were investigated. Flumes and monitoring wells were installed and water qualities of $NO_3$-N, TP and TKN were monitored from Aug. 1993 to Aug. 1994. Runoff from the pasture which was a sandy soil with cobbles mostly formed with seeping water at the bottom of it. But once overland flow occurred because of heavy rainfall, runoff increased sharply. $NO_3$-N concentration in pasture runoff was relatively stable ranging between 0.241-3.962mg/l. TP and TKN concentrations were stable but sharply increased once overland flow occurred. $NO_3$-N concentration in pasture groundwater was relatively stable regardless of depth of monitoring wells but TP and TKN concentrations were smaller in deeper wells. Runoff from the field which was flat and covered well with Sudan grass and surface residue was relatively small and $NO_3$-N, TP and TKN concentrations in runoff were stable and seemed unaffected by flow rate. $NO_3$-N concentration in field groundwater increased at the rate of 2.2mg/l per 100 m during a growing season as groundwater flows through the field. No significant differences in TP and TKN concentrations between the upper and lower areas in field groundwater were detected.

• KCID journal
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• v.9 no.2
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• pp.43-50
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• 2002

To provide the basic information for the water quality improvement of the Seomjin River Basin, the water qualities of the Churyeong-cheon watershed were investigated from May in 1999 to September in 2002. Annual total runoff at the Churyeong-cheon watersh

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.610-614
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• 2004

장기 유역 유출모형인 SWAT에 도시지역의 영향을 적절히 고려할 수 있도록 SWMM 모형을 포함시킨 SWAT-SWMM 결합모형을 테스트하기 위해 시험유역에 적용하였다. 이로부터 SWAT 모형과 SWAT-SWMM 결합모형에 의한 수문순환요소(지표수, 지하수, 하천유출, 증발산 등)를 비교${\cdot}$분석하였다. 또한 각 모형이 수문순환요소를 모식하는 방법을 비교${\cdot}$분석하여 SWAT-SWMM 결합모형을 개선하였다.

• Journal of Environmental Science International
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• v.11 no.12
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• pp.1205-1215
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• 2002

To evaluate the change for water quality after the water gate operation in Shiwha lake, in situ survey were conducted on september in 2000 and January, march, jane in 2001. Chemical characteristics and eutrophication level was estimated from the survey data. The water quality of the Shihwa lake was greatly affected by pollutant load from rainfall, and formation of stratification in summer and winter was increased to effect on nutrient release from sediment. Especially, high concentration of chlorophyll-a was occurred in autumn, due to increased nutrient, high water temperature and low salinity after rainfall runoff. The mean concentration of DIN, DIP were 0.346mg/L, 0.0217mg/L in surface water and 0.826mg/L, 0.0415mg/L in bottom water, respectively, which were over III grade of seawater standard. Also high percentage of ammonia nitrogen to DIN in bottom water for autumn and winter was affected by released nutrient from sediment. Correlation analysis of chlorophyll-a versus TSS was shown that organic matter was affected by autochthonous organic matter stem from the algae, these factor showed reverse correlation about salinity. Closely correlations among to the water quality constituent in continuity survey was appeared. The results of eutrophication index estimation showed the high potentiality of red tide occurrence in Shiwha lake, particularity in summer or fall. Overall water quality was greatly improve to compared with measuring data during 1997~1998 at the beginning water gate operation, which reported by KORDI. Therefore, to improve of water quality in Shiwha lake, we need to establish of management plan about nutrient release from sediment, rainfall runoff, maximum of seawater exchange.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.243-243
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• 2015

Low-flow simulation and forecasting is one of the emerging issues in hydrology due to the increasing demand of water in dry periods. Even though low-flow simulation and forecasting remains a difficult issue for hydrologists better simulation and earlier prediction of low flows are crucial for efficient water management. The UN has never stated that South Korea is in a water shortage. However, a recent study by MOLIT indicates that Korea will probably lack water by 4.3 billion m3 in 2020 due to several factors, including land cover and climate change impacts. The two main situations that generate low-flow events are an extended dry period (summer low-flow) and an extended period of low temperature (winter low-flow). This situation demands the hydrologists to concentrate more on low-flow hydrology. Korea's annual average precipitation is about 127.6 billion m3 where runoff into rivers and losses accounts 57% and 43% respectively and from 57% runoff discharge to the ocean is accounts 31% and total water use is about 26%. So, saving 6% of the runoff will solve the water shortage problem mentioned above. The main objective of this study is to present the hydrological modelling approach for low-flow simulation and forecasting using a model that have a capacity to represent the real hydrological behavior of the catchment and to address the water management of summer as well as winter low-flow. Two lumped hydrological models (GR4J and CAT) will be applied to calibrate and simulate the streamflow. The models will be applied to Seolmacheon catchment using daily streamflow data at Jeonjeokbigyo station, and the Nash-Sutcliffe efficiencies will be calculated to check the model performance. The expected result will be summarized in a different ways so as to provide decision makers with the probabilistic forecasts and the associated risks of low flows. Finally, the results will be presented and the capacity of the models to provide useful information for efficient water management practice will be discussed.

• Applied Biological Chemistry
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• v.40 no.4
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• pp.334-341
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• 1997

In the laboratory experiment, concentration and rate of runoff of 7 pesticides were measured under the simulated rainfall. Total runoff rate of metolachlor, alachlor, chlorothalonil, chlorpyrifos, EPN, phorate and captafol were 57.0, 14.2, 13.2, 7.9, 7.2, 7.1 and 2.8%, respectively, and the average runoff concentrations were 940, 399, 55, 7.0, 9.3, 151 and 7.0 ppb, respectively. Significant relationship was observed between the runoff rate and water solubility in the laboratory experiment(r=0.923). Even though not very high, relatively significant results were obtained in other experimental conditions. Based on the results, runoff rate prediction$[Y=0.2812{\times}10exp(0.261logWS-0.366)+0.3594{\times}10exp(-0.545logKoc+1.747)+0.3594{\times}10exp(-0.362log\;Kow+1.105]$ and conversion equations were calculated to investigate the possibility of estimating runoff rate in the field by natural rain. Calculated runoff rate by conversion equation was similar to experimental result with captafol in the field while 6 times higher result was obtained by the prediction equation. Therefore, those prediction and conversion equations derived from the laboratory experiment data and physicochemical properties of the pesticides could be used for the prediction of field runoff rate of pesticides by natural rainfall.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.689-698
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• 2000

The quality of stormwater runoff has been a major concern in water quality preservation. Characteristics of heavy metals and conventional pollutants in surface runoff from industrial complex, during the first flush, were not completely understood, Generally, separated sewer system is known for their water quality with untreated wastewater during storm events. In this study, the quality and characteristics of surface runoff from the industrial complex were investigated. The target area in the industrial complex catchment was divided 4 sub-areas, and the quality of stormwater runoff from the selected drainage areas was investigated using a grab sampling method. The petro-chemical industry and the junkyard discharged relatively high concentration of conventional pollutants, such as BOD, COD, SS, and TN through the first flush runoff samples. On the other hand, a higher level of heavy metals was found in the first flush runoff from the metal-mechanical industry and the scrap storage yard. For metals, Fe, Zn and Cu were the most prevalent species found in the first flush runoff from all sites for every surface runoff samples, while Pb, As, Cd, Cr and Ni were the least prevalent species and Hg was not found in any sample at any site. These results suggest that the nature of pollutants in surface runoff from the industrial complex was related to the type of industry, and the concentration of pollutants was determinated by the degree of exposed pollutant sources and the characteristic of rainfall events at the sites.

• Journal of Korea Water Resources Association
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• v.47 no.9
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• pp.767-776
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• 2014

Changes in climate have largely increased concentrated heavy rainfall, which in turn is causing enormous damages to humans and properties. Floods are one of the most deadly and damaging natural disasters known to mankind. The flood forecasting and warning system concentrates on reducing injuries, deaths, and property damage caused by floods. Therefore, the exact relationship and the spatial variability analysis of hydrometeorological elements and characteristic factors is critical elements to reduce the uncertainty in rainfall-runoff model. In this study, grid resolution depending on the topographic factor in rainfall-runoff models presents how to respond. semi-distribution of rainfall-runoff model using the model GRM simulated and calibrated rainfall-runoff in the Gamcheon and Naeseongcheon watershed. To run the GRM model, input grid data used rainfall (two event), DEM, landuse and soil. This study selected cell size of 500 m(basic), 1 km, 2 km, 5 km, 10 km and 12 km. According to the resolution of each grid, in order to compare simulation results, the runoff hydrograph has been made and the runoff has also been simulated. As a result, runoff volume and peak discharge which simulated cell size of DEM 500 m~12 km were continuously reduced. that results showed decrease tendency. However, input grid data except for DEM have not contributed increase or decrease runoff tendency. These results showed that the more increased cell size of DEM make the more decreased slope value because of the increased horizontal distance.