• Title, Summary, Keyword: first-flush

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Modeling to Low Impact Development (LID) size for reducing First Flush Effect in Urban area (도시지역의 초기세척효과 저감을 위한 LID 최적화)

  • Baek, Sang-Soo;Choi, Dong-Ho;Yoon, Kwang-Sik;Cho, Kyung Hwa
    • Proceedings of the Korea Water Resources Association Conference
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    • pp.181-181
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    • 2015
  • 최근 계속적인 도시화와 개발로 인해 불투수층이 증가함에 따라, 도시비점오염물질이 동반된 표면유출수가 증가하고 있다. 또한 도시 오염물질 배출특성 중 하나인 초기세척효과(First Flush Effect)가 대두되고 있다. 초기세척효과란 강우 시 강우초반에 고농도의 오염물질 나타나는 현상을 의미한다. 최근 이와 같은 도시 오염물질을 관리 및 저감을 위해 저영향개발(Low Impact Development)이 대안으로 나타나고 있다. 하지만 이러한 저영향개발을 분석 및 정량하기 위해서는 많은 실험적인 연구와 모델링이 필요하다. 본 연구에서는 광주광역시에 위치한 상업지구에 대해 모니터링과 LID 모델링을 실시하였고, 또한 Mass First Flush (MFF)라는 지표를 이용하여 최적 LID 크기를 산정하였다. 본 연구에선 나온 LID 크기는 1.2 mm부터 3.0 mm 정도로 나타났다. 이 결과는 향후 초기세척처리를 LID의 가이드라인으로 유용할 것이다.

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Determination of First Flush Criteria in Highway Stormwater Runoff using Dynamic EMCs (동적 EMC를 이용한 고속도로 초기우수 처리 기준 산정)

  • Kim, Lee-Hyung;Lee, Eun-Ju;Ko, Seok-Oh;Kim, Sung-Gil;Lee, Byung-Sik;Lee, Joo-Kwang;Kang, Hee-Man
    • Journal of Korean Society on Water Environment
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    • v.22 no.2
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    • pp.294-299
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    • 2006
  • The Ministry of Environment in Korea has introduced Total Pollution Load Management System (TPLMS) in major 4 large rivers to protect the water quality from possible pollutants. In order to successfully achieve the TPLMS, the nonpoint source should be controled by applying the best management practices in highly polluted areas. Of the various nonpoint sources, the highways are stormwater intensive landuses because of its high imperviousness and high pollutant mass emissions. The EMC (Event Mean Concentration) is an important parameter to correctly determine the pollutant mass loadings from nonpoint sources. However, it has wide ranges because of various reasons such as first flush phenomenon, rainfall and watershed characteristics. Even though the EMC is closely related to the first flush phenomenon, the relationship have not proven until present. Therefore, in this paper, the dynamic EMC method will be introduced to clearly make the relationship between EMC and first flush phenomenon. Also by applying the dynamic EMC method to monitored data, we found that the highly concentrated stormwater runoff was washed off within 20~50 minutes storm duration. The first flush criteria for economical treatment was also determined to 5~10 mm (mean=7.4 mm) as a cumulative rainfall.

Runoff Characteristics of NPS in Agricultural Area (포도재배지의 비점오염물질 유출특성)

  • Yi, Youn-Jeong;Lee, Jae-Woon;Kwon, Hun-Gak;Yoon, Young-Sam;Lee, Jae-Kwan
    • Journal of Environmental Science International
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    • v.20 no.10
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    • pp.1285-1295
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    • 2011
  • In this study, occurrence status of nonpoint pollutants and characteristics of discharge by each nonpoint pollutants were examined through monitoring on nonpoint pollutants caused when raining in vineyard belonging to the agricultural area of various land use patterns. Also, the first flush analysis limited to studies on the existing non-percolation area was applied to percolation area to ascertain availability and criteria of study. Various water quality and sluice of nonpoint pollutants were analyzed, based on which discharge of nonpoint pollutants in agricultural area was ascertained to be influenced greatly by artificial factors such as period, cultivation, management, etc. Meanwhile, the first flush phenomenon at agricultural area was ascertained to occur, and the first flush was quantified through calculation of the first flush ratio. If MFF30 is based, discharge load by each nonpoint pollutants caused when raining was investigated to include 40.8% on the basis of total discharge. In case of SS in pollutants showed the highest first flush phenomenon of 64.8%. Through such a result, calculation possibility of the initial rain criteria was ascertained, and it was determined that reliability-assured criteria were calculated through further monitoring.

Runoff Characteristics of Stormwater in Small City Urban Area (국내 중소 도시지역 강우유출수의 유출특성)

  • Lee, Hong-Shin;Lee, Seung-Hwan
    • Journal of Korean Society of Environmental Engineers
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    • v.31 no.3
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    • pp.193-202
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    • 2009
  • This study was conducted to identify the magnitude of first flush in small city urban area and to provide the basic information on the criteria of stormwater runoff management. Monitoring site was surrounded by residential area in Gumi city near to national industrial complex and the monitoring period was three months. Total watershed area was 24.9 ha, where 80% of the area is impervious (asphalt of pavement type). Periodic monitoring of conventional water quality parameters were conducted with six times of rainfall period. Event mean and site mean concentrations for all the parameters were calculated based on the analytical results. Particle size distribution was 9.82 ${\mu}m$ for $D_{0.1}$, 38.99 ${\mu}m$ for $D_{0.5}$ and 159.61 ${\mu}m$ for $D_{0.9}$ respectively. First flush phenomenon was detected highly in particulate solids than dissolved ones. The first flush criteria results by mass first flush contained between 44.4% to 58.5% pollutant mass during the first 30% of runoff volume. Mass first flush ratio and particle size distribution obtained in this study are expected to provide the basic information for the design and operation of non-point source treatment facility.

Loading Rates and Characteristics of Litter from Highway Stormwater Runoff (강우로 인해 고속도로로부터 유출되는 폐기물의 성상, 부하량 및 유출 특성)

  • Kim, Lee-Hyung;Kang, Joohyon
    • Journal of Korean Society on Water Environment
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    • v.20 no.5
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    • pp.415-421
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    • 2004
  • Litter wastes on highway runoff are gradually being considered one of the major pollutants of concern in protecting the integrity of receiving waters for beneficial use. The California State Water Resources Control Board has identified in their 303(d) list at least 36 water bodies where trash or litter is considered a pollutant of concern. The first TMDL adopted by the Region 4 (Los Angeles area) of the California State Water Quality Control Board was for trash in the Los Angeles River. The first flush characteristic study was developed to obtain first flush water quality and litter data from representative stormwater runoff from standard highway drainage outfalls in the Los Angeles area. Total captured gross pollutants in stormwater runoff were monitored at six Southern California highway sites over two years. The gross pollutants were 90% vegetation and 10% litter. Approximately 50% of the litter was composed of biodegradable materials. The event mean concentrations show an increasing trend with antecedent dry days and a decreasing trend with total runoff volume or total rainfall. Event mean concentrations were ranged 0.0021 to 0.259g/L for wet gross pollutants and 0.0001 to 0.027g/L for wet litters. The first flush phenomenon was evaluated and the impacts of various parameters such as rainfall intensity, drainage area, peak flow rate, and antecedent dry period on litter volume and loading rates were evaluated. First flush phenomenon was generally observed for litter concentrations, but was not apparent with litter mass loading rates. Litter volume and loading rates appear to be directly related to peak storm intensity, antecedent dry days and total flow volume.

Evaluation of Runoff Loads and Computing of Contribute ratio by First Flush Stormwater from Cheongyang-Hongseong Road (청양-홍성간 도로에서의 초기강우에 의한 유출부하량 평가 및 기여율 산정)

  • Lee, Chun-Won;Kang, Seon-Hong;Choi, I-Song;An, Tae-Ung
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.3
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    • pp.407-417
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    • 2011
  • Nowadays, the high land use, mainly used for urbanization, is affecting runoff loads of non-point pollutants to increase. According to this fact, increasing runoff loads seems like to appear that it contributes to high ratio of pollution loads in the whole the pollution loads and that this non-point source is the main cause of water becoming worse quality. Especially, concentrated pollutants on the impermeable roads run off to the public water bodies. Also the coefficient of runoff from roads is high with a fast velocity of runoff, which ends up with consequence that a lot of pollutants runoff happens when it is raining. Therefore it is very important project to evaluate the quantity of pollutant loads. In this study, I computed the pollutant loadings depending on time and rainfall to analyze characteristics of runoff while first flush storm water and evaluated the runoff time while first flush storm water and rainfall based on the change in curves on the graph. I also computed contribution ratio to identify its impact on water quality of stream. I realized that the management and treatment of first flush storm water effluents is very important for the management of road's non-point source pollutants because runoff loads of non-point source pollution are over the 80% of whole loads of stream. Also according to the evaluation of runoff loads of first flush storm water for SS, run off time was shown under the 30 minute and rainfall was shown under the 5mm which is less than 20% of whole rainfall. These are under 5mm which is regarded amount of first flush storm water by the Ministry of Environment and it is judged to be because run off by rainfall is very fast on impermeable roads. Also, run off time and rainfall of BOD is higher than SS. Therefore I realized that the management of non-point source should be managed and done differently depending on each material. Finally, the contribution ratio of pollutants loads by rainfall-runoff was shown SS 12.7%, BOD 12.7%, COD 15.9%, T-N 4.9%, T-P 8.9%, however, the pollutants loads flowing into the steam was shown 4.4%. This represents that the concentration of non-point pollutants is relatively higher and we should find the methodical management and should be concerned about non-point source for improvement on water quality of streams.

First flush modeling of the radial type surface runoff and a placement strategy for stormwater inlets to improve the effectiveness of the first flush treatment in a small impervious catchment (방사형 강우 유출의 초기세척 모의 및 소규모 불투수 배수구역에서의 초기우수 처리효과 상승을 위한 집수시설 배치 방안)

  • Kang, Joo-Hyon;Lee, Dong Hoon;Kim, Jin Hwi
    • Journal of Wetlands Research
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    • v.19 no.4
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    • pp.375-382
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    • 2017
  • In this study, general characteristics of dynamic behavior of stormwater runoff from a small impervious catchment was investigated from a series of simulations for a radial type surface runoff. Based on the simulation results, a better placement strategy for stormwater inlets to improve performance of a structural best management practice (BMP) was suggested. The degree of pollutant first flush from an ideal radial type impervious catchment was simulated using a 1-D diffusion wave equation coupled with a pollutant transport equation. The results showed that the first flush of the chemical oxygen demand was the strongest when the catchment length ranged 30-50m at a bed slope of 0.02. This result suggested that a required degree of the first flush can be intentionally obtained by just changing the locations and numbers of stormwater inlets, and thereby adjusting the catchment length. Particularly, the overall performance of a structural BMP in reducing pollutant load can be improved by placing the stormwater inlets at locations for obtaining a required first flush strength.

Zoning Suitability Analysis to Reduce First-flush Runoff Contamination in a Separated Sewer System (분류식 하수지역의 초기 유출수 오염저감을 위한 용도지구별 적지 분석)

  • Park, In-Hyeok;Ha, Sung-Ryong
    • Journal of the Korean Association of Geographic Information Studies
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    • v.11 no.2
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    • pp.13-27
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    • 2008
  • This paper aim to reorganize zoning areas for decreasing first-flush runoff contamination in a separated sewer system via suitability analysis, and to simulate the discharge pollution loads of first-flush runoff using SWMM. For these purposes, diffuse pollution, which is accumulated on a surface and first-flush runoff flow were investigated. Suitability conditions for zoning were defined using the results of these investigation and suitable zoning areas were analyzed for the each condition. AHP analysis was conducted to establish weights of the suitability conditions. The most suitable zoning areas were analyzed via overlaying weights and suitability conditions. From the result, it was noted that the most suitable zones for detached houses & apartments are location they already occupied. Some school areas analyzed were found to be suitable as commercial centers. Some zones within the area analyzed were found to be suitable for commercial zones. From results obtained from simulation, the zone re-organization showed BOD and SS concentration to reduce from 91.2% to 0.09% ans 72.74% to 0.31% respectively.

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Nonpoint Pollutants Sources Characteristics of Initial Surface Runoff on the Land Use Types (토지이용별에 따른 초기강우 유출량의 비점오염물 특성 분석)

  • Choi, Yun-Yeong;Jung, Se-Young;Choi, Jeong-Woo
    • Journal of Environmental Science International
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    • v.20 no.3
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    • pp.417-426
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    • 2011
  • This study was conducted to investigate runoff characteristics of non-point pollutants source at the urban and rural zones in sangju area. The monitoring was conducted with seven events for ten months and Event mean Concentration(EMC) and First Flush Effect(FFE) of SS and BOD were calculated on the result of the water quality parameters. During rainfall event, the peak concentrations of SS and BOD were observed after 3~4 hours of rainfall in rural areas. Whereas, the peak concentrations occurred within 1~2 hours after rainfall and then the highest concentration of NPS pollutants sharply decreased, showing strong first flush effect in urban areas. The cumulative load curves for NPS pollutants showed above the $45^{\circ}$ straight line, indicating that fist flush effect occurred in urban areas. The mean SS EMC values of rural areas ranged from 0.9~3.3mg/L, it was higher value when compare to urban areas. While the mean BOD values of urban areas were shown the highest values.

Characteristics of Non-point Source Pollutants Runoff from Agricultural and Industrial Areas in Lake Sihwa Watershed (강우시 시화호 농촌 및 공단유역의 비점오염물질 유출특성)

  • Kim, Sea-won;Choi, Kwangsoon;Kim, Dong-sup;Lee, Mikyung
    • Journal of Korean Society on Water Environment
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    • v.25 no.5
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    • pp.768-777
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    • 2009
  • The characteristics of stormwater runoff was examined on distinct types of agricultural and industrial area in Lake Sihwa watershed. During rainfall event, the peak concentrations of SS, $COD_{Mn}$, and TP were observed after 6~11 hours of rainfall in agricultural areas. Whereas, the peak concentrations occurred within the first one hour after rainfall and then the highest concentration of NPS pollutants sharply decreased, showing strong first flush effect in industrial areas. The strong first flush effect of suspended solid was apparent in agricultural areas, while those of organic matters and nutrients were clear in industrial areas. The cumulative load curves for NPS pollutants showed above the $45^{\circ}$ straight line, indicating that first flush effect occurred in industrial areas. The mean SS EMC values of agricultural areas ranged from 60~598 mg/L (Avg. 285 mg/L), it was higher value when compare to other areas. While the mean $COD_{Mn}$, TN, and TP EMCs values of industrial areas were shown the highest values as 67.7 mg/L, 12.1 mg/L and 2.1 mg/L respectively.