• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.499-508
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• 2011

We analyzed the variations of water quality with flow regime alterations to determine the characteristics of the stream where the stream management is considerably difficult due to the high variability of the flow rates. In this study, both flow rates and water qualities were monitored at the tributaries, 34 in count, of both Geum River and Sabgyo Lake Basins. The variation of water qualities were divided into 2 types, based on their stream flow rates, known as Type I and Type II. If the water quality of a stream increases during low flow rate periods compared with high flow rate periods, it is classified as Type I; if the water quality of the stream increases during high flow rate periods compared with low flow rate periods, it falls under Type II. The analysis for the variations of water qualities, of all 43 basins, resulted to 24 basins under Type I and Nineteen 19 basins under Type II. The variations of water qualities were analyzed first by using Regression Analysis followed by Statistical Analysis. The average slope of the variations of water qualities and the slope of the standard deviations were 0.00135 and 0.00477, respectively. The Probability Distributions of both Type I and Type II basins were 61.1% and 38.9%, respectively. The basin having a probability distribution of 61.1% and is also known as Type I, increases during periods of low flow rates, due to the presence of point sources. Therefore, the basin should be enforced with stream management. Before the stream management can be implemented in all streams falling under Type II, the sources of contaminants should first be estimated. These contaminants can be classified into two parts, the first is Point source pollution and the second is Non-point source pollution, where the Non-Point source pollution can be sub-divided into two types, with storm runoff and without storm runoff.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.868-876
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• 2011

A five-year field monitoring was conducted to monitor characteristics of suspended solid (SS) export from paddy fields. The observed EMCs of SS ranged 1.2~517 mg/L (avg. 52.1 mg/L) during storm period. The concentration of SS during non-storm period were 1.1~349.5 mg/L (avg. 36.1 mg/L). Monthly load of SS was high during summer when rainfall amount was high. The load was higher than that of May when tillage effect is expected. There was no significant relationship between SS EMCs and rainfall or drainage amount. However, effects of rainfall and drainage were found to be significant for event load of SS. But, there was no apparent relationship between rainfall amount of cropping period and load of SS for that period. The observed SS load was 164.8~456.0 kg/ha (avg. 301.2 kg/ha) and mostly occurred during storm period. This study results also suggested that SS load estimation by USLE equation for paddy field could be overestimated, if not carefully handled. Monitoring studies for various climate, soil, and agricultural management are required to get better scope of SS export from paddy fields.

• KIEAE Journal
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• v.14 no.3
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• pp.15-21
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• 2014

In this study, we developed a modular rainwater infiltration system that can be applied for general purposes in urban areas to prepare for localized heavy rain caused by climatic change. This study also analyzed the system's effects on reducing runoff. An analysis of the system's effects on reducing runoff based on rainfall data and monitoring data obtained between September 2012 and December 2013 after the system was installed showed that approximately 20~22% of the runoff overflowed from the infiltration facility. Also, an analysis of the runoff that occurred during the monsoon season showed that 25% of the runoff overflowed through the storm sewer system of the urban area. These results show that the rainwater overflows after infiltrating the detention facility installed in the area during high-intensity rainfall of 100mm or higher or when precipitation is 100mm for 3~4 days without the prior rainfall. According to precipitation forecasts, torrential rainfall is becoming increasingly prevalent in Korea which is increasing the risk of floods. Therefore, the standards for storm sewer systems should be raised when planning and redeveloping urban areas, and not only should centralized facilities including sewer systems and rainwater pump facilities be increased, but a comprehensive plan should also be established for the water cycle of urban areas. This study indicates that decentralized rainwater management can be effective in an urban area and also indicates that the extended application of rainwater infiltration systems can offer eco-friendly urban development.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.536-542
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• 2000

The purpose of this study is to evaluate the effect of stream quality by the farmer＇s livestock wastes management in a typical small agricultural watershed. AGNPS model has the capability to adjust the level of pollutant load from farmstead and the fertilization level of upland field. A small agricultural watershed(4.12 $\textrm{km}^2$) which has as livestock farmhouses located in Gosan-myun, Ansung-gun was selected. AGNPS data were prepared by using Arc/info and Idrisi. 4 storm events in 1999 was used for runoff calibration, and 2 storm event which is measured in hourly-base at 4 locations along the stream were used for water quality(TN, TP) calibration. Model＇s behavior to stream quality for 3 cases was investigated. First, the variation of pollution produced from the cattle shed affected little to the stream quality because the cattle sheds were roofed. Second, the good management of ground in farmstead affected to stream quality with 11% and 17% decrease in TN and TP, respectively. Third, the reduction of fertilization level to upland field affected to stream quality with 27.2% and 38.5% decrease in TN and TP, respectively.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.790-794
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• 2006

도시화 면적이 증가하면 불투수 면적이 증가하고 그에 따라 도시 하천의 평상시 유출이 감소한다. 도시유역의 평상시 수량을 회복시키는 방법으로는 침투 증진시설(투수성 포장, 침투 트렌치, 침투 측구 등)의 설치, 하수의 고도처리 후 방류, 저수지에 의한 유황 개선, 지하철 용출수 활용 등이 있다. 우리나라의 경우에 일부 도시하천의 수량 감소가 심각한 상황에 이르고 있으며 이를 해결하고자 하는 노력이 최근에 나타나고 있다. 수량을 회복하려면 유량 평가를 위한 현장조사, 수량회복 계획, 재원의 반영, 수량회복 시설의 설치 및 관리의 순서로 단계별 사업이 수행되어야 한다. 계획 단계의 과업에서 필요한 사항은 여러 가지 수량 회복방법의 영향을 정량 평가하는 것이다. 이에 핵심이 되는 것은 수량 회복 요소를 포함하거나 추가한 수문순환평가 도구이다. 본 연구는 기존의 수문 모형을 수정하여 침투 트렌치 모의기능을 갖도록 하는 것과, 이를 가지고 침투 트렌치의 수량 회복 효과를 분석하는 것이다. 침투 트렌치를 모의하도록 SWMM(Storm Water Management Model) 모형을 수정하였으며, 수정된 SWMM으로 학의천 배수유역 중 특정 소유역을 대상으로 하여 시험수행을 실시하였다. 학의천 배수유역 중 9번 소유역을 대상으로 도시 연속유출모의를 수행하여 침투 트렌치의 효과를 분석하였다. 9번 소유역의 경우 산지가 거의 80 %이며, 불투수율과 현지여건, 도로상황을 고려할 때 길이 100 m 규격의 트렌치 약 $10{\sim}20$개 정도가 설치 가능한 것으로 검토되었다. 그러나 현실성을 감안하여 시범수행에서는 10개의 트렌치를 설치하여 그 효과를 분석하였다. 9번 소유역 145번 지점의 유황을 분석한 결과 저수량$(Q_{275})$은 $0.0177m^3/s$에서 $0.0190m^3/s$로, 갈수량$(Q_{355})$은 $0.0176m^3/s$에서 $0.0189m^3/s$로 약 7%가 증가하는 것으로 분석되었다. 결과로부터 침투 트렌치는 저수량 및 갈수량을 증가시키는 보조수단이 될 수 있다.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1711-1715
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• 2006

최근 급격한 도시화는 홍수량 증가 및 갈수 시 하천의 건천화 등 유역의 유출특성 변화를 가져왔다. 본 연구에서는 이러한 문제를 해결하는 방안 중 하나인 투수성 포장의 유역 내 수문학적 효과를 분석하였다. 이를 위해 투수성 포장을 이용한 수리모형 실험 및 수치모형(SWMM)을 병행하여 수행하였다. 연구에 사용한 수치모형은 기존 도시유출 모형인 SWMM(Storm Water Management Model) 모형에 투수성 포장의 수문학적 효과를 고려할 수 있도록 수정된 모형이며, 수리모형 실험 결과를 토대로 수치모형의 중요 매개변수를 추정하였다. 또한 실험에 의해 관측된 지표 및 지하수 유출량과 수치모형에 의해 산출된 자료를 비교.분석하여 수정된 SWMM 모형의 유용성을 평가하였다. 강우강도가 65 mm/hr, 90 mm/hr, 95 mm/hr인 강우를 4시간씩 공급하는 경우에 대한 3가지 수리모형 실험을 수행하였다. 수리모형실험 결과 강우강도는 지표면 유출의 크기에 직접적인 영향을 미치고 있었으며 지하수 유출량은 강우강도 보다는 지하수위 조건에 더 큰 영향을 받는 것으로 분석되었다. 수리모형 실험결과 및 수치모형 모의결과를 비교 분석한 결과, 토양 함수량 및 지하수위 변동 특성은 초기에서 정상상태로 전이되는 부분과 강우 정지 후 감소되는 부분에서 수리모형 실험과 다른 양상을 보였다. 지하수위는 실험 시 발생하는 공기층의 포집이 많은 영향을 미치고 있음을 알 수 있었고, 함수량 변화에 있어서는 수치모형(SWMM)의 모의 결과가 과도하게 감소하는 특성을 보여 주고 있었다. 즉, 유출량의 특성은 비슷한 양상을 보이고 있으나 지하수위 변화 및 토양 내 함수량 변화 예측에 있어서는 그 정확도가 떨어지는 것으로 평가되었다. 그러나 본 연구결과를 통하여 투수성 포장과 지하수에 관련된 매개변수의 집적과 분석결과는 현장기술 적용 시 매개변수의 유용한 선택과 도시유역의 물 순환 건전화 대안기술 적용에 효과적인 방법론을 제시할 수 있을 것으로 사료된다.

• Journal of Korean Society on Water Environment
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• v.32 no.1
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• pp.108-114
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• 2016

Sediment-laden water leads to water quality degradation in streams; therefore, best management practices must be implemented in the source area to control nonpoint source pollution. Field monitoring was implemented to measure precipitation, direct runoff, and sediment concentrations at a control plot and straw-applied plot to examine the effect on sediment reduction in this study. A hydrology model, which employs Curve Number (CN) to estimate direct runoff and the Universal Soil Loss Equation to estimate soil loss, was selected. Twenty-five storm events from October 2010 to July 2012 were observed at the control plot, and 14 storm events from April 2011 to July 2011 at the straw-applied plot. CN was calibrated for direct runoff, and the Nash-Sutcliffe efficiency and coefficient of determination were 0.66 and 0.68 at the control plot. Direct runoff at the straw-applied plot was calibrated using the percentage direct runoff reduction. The estimated reduction in sediment load by direct runoff reduction calibration alone was acceptable. Therefore, direct runoff-sediment load behaviors in a hydrology model should be considered to estimate sediment load and the reduction thereof.

• Journal of Korea Water Resources Association
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• v.42 no.2
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• pp.105-115
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• 2009

The objectives of this study are to deduce a problem of existing subcatchment width equation in Storm Water Management Model(SWMM) and to analyze the suitability of a new adjusted subcatchment width equation on both ideally assumed watersheds and an actual urban watershed area. The problems of existing subcatchment equation are issued on the theoretical review of the equation and from the model application on different types of simplified assumed watershed. The adjusted equation, proposed in this study, that considers the pipe flows in addition to the surface flows on small subcatchment can improve the limitation of existing equation when applied on the assumed watersheds. Also, Gunja watershed with 96.3 ha is selected and collected rainfall-runoff events for the feasibility study of the proposed equation on actual urban watershed area. The results represent that the simulated flows from adjusted equation rather than the simulated flows from existing equation are well agreed with observed ones.

• Journal of Environmental Science International
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• v.7 no.4
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• pp.451-460
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• 1998

The objectives of this study Is to evaluate the total runoff yield, peak flow and peak flow travel time depending on the urbanization, return period and rainfall patterns at the downstream of Manchon urban watershed in TaeGu City. SWM(Storm Water Management Model) is used for runog analysis based on 5 different steps of urbanization and 4 different types of Hufrs quartile according to 8 return periods. It is analyzed that the order of total runoff yield according to raiun patterns is Huffs 4, Huffs 2. Huffs 3 and Huffs 1 quartile, that of peak flow magnitude is Huffs 2, Huffs 1, Huffs 4 and Huffs 3 quartile at present development ratio. under the 60, 70, 80 and 90ft of urbanization to the 50% of urbanization by means of the rainfall patterns, the mean Increasing ratio of total runoff yield for each case is 4.55, 11.43, 16.07 and 20.02%, that of peak flow is 5.82, 13.61, 17.15 and 18.83%, the mean decreasing ratio of peak flow travel time Is 0.00, 2.44, 5.07 and 6.26%, the mean increasing ratio of runoff depth Is 4.51, 11.42, 16.02 and 20.05% respectively. the mean increasing ratio of total runoff yield by means of each and 19.71%. Therefore, as the result of this study. it can be used for principal data as to storm sewage treatment and flood damage protection planning in urban small watershed.

• Water for future
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• v.26 no.4
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• pp.85-95
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• 1993

Three purposes of this study are as follows: The first was the development of the extention method for the limited data observed in an urban drainage basin. The second was the analysis of the correlation between storm water runoff and NPS(non-point source) pollutant discharge, The last was the calculation of the monthly and annual specific NPS loads using the established correlation. the selected model was the SWMM monthly and annual specific NPs loads using the established correlation. The selected model was the SWMM (Storm Water Management model) developed by the US EPA(environmental Protection Agency). As a result of this study, the best correlation between storm wate runoff and NPS pollutants discharge was produced by the non-linear correlation between runoff rate(mm/hr)and specific loads rate(g/ha/sec)for all pollutants studied ; SS, COD, BOD, and TN. The best correlation through the analysis based on evently total mass was made by the linear correlation between the specific accumulated runoff(mm) and the specific accumulated loads(kg/ha) for CASE 1., and by the non-linear correlation for CASE 2. The NPS annual specific loads for the urban basin studied were 4933 kg/ha/year for SS, 775kg/ha/year for BOD, 3094kg/ha /year for COD,257kg/ha/year for TN, respectively. And the proportion of the NPS annual specific loads to the total annual specific loads were 42 % for SS, 13 % for BOD, 29% for COD, and 21 % for TN.