Event mean concentration and first flush effect from different drainage systems and functional areas during storms

Recently the Ministry of Environment in Korea has developed the total maximum daily load program in accordance with the target pollutant and its concentration goal on four major large rivers. Since the program is largely related to regional development, nonpoint source control is both important and topical. Of the various nonpoint sources, highways are stormwater intensive land uses since they are impervious and have high pollutant mass emissions from vehicular activity. The event mean concentration (EMC) is useful in estimating the loadings to receiving water bodies. However, the EMC does not provide information on the time varying changes in pollutant concentration or mass emissions, which are often important for best management practice development, or understanding shock loads. Therefore, in this study a new concept, the dynamic EMC determination method, will be introduced to clearly verify the relationship between EMC and the first flush effect. Three monitoring sites in Daejeon metropolitan city areas were equipped with an automatic rainfall gauge and a flow meter for accumulating the data such as rainfall and runoff flow. The dynamic EMC method was applied to more than 17 events, and the improved first flush criteria were determined on the ranges of storm duration and accumulated rainfall.

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Catchment based estimation of pollutant event mean concentration (EMC) and implications for first flush assessment

Journal of Environmental Management ◽

10.1016/j.jenvman.2020.111737 ◽

2021 ◽

Vol 279 ◽

pp. 111737

Author(s):

Thamali Perera ◽

James McGree ◽

Prasanna Egodawatta ◽

K.B.S.N. Jinadasa ◽

Ashantha Goonetilleke

Keyword(s):

First Flush ◽

Event Mean Concentration ◽

Mean Concentration

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Quantifying the Effects of Residential Infill Redevelopment on Urban Stormwater Quality in Denver, Colorado

Water ◽

10.3390/w13070988 ◽

2021 ◽

Vol 13 (7) ◽

pp. 988

Author(s):

Kyle R. Gustafson ◽

Pablo A. Garcia-Chevesich ◽

Kimberly M. Slinski ◽

Jonathan O. Sharp ◽

John E. McCray

Keyword(s):

Water Quality ◽

Green Infrastructure ◽

Stormwater Quality ◽

Dry Period ◽

Event Mean Concentration ◽

Fecal Indicator ◽

Water Quality Regulations ◽

First Flush Effect ◽

Urban Stormwater Quality ◽

Mean Concentration

Stormwater quality in three urban watersheds in Denver that have been undergoing rapid infill redevelopment for about a decade was evaluated. Sampling was conducted over 18 months, considering 15 storms. Results: (1) The first-flush effect was observed for nutrients and total suspended solids (TSS) but not for total dissolved solids (TDS), conductivity, pH, and fecal indicator bacteria; (2) though no significant differences on event mean concentration (EMC) values were found among the three basins, local-scale EMCs were higher than traditional city-wide standards, particularly some metals and nutrients, most likely because of the significantly higher imperviousness of the studied urban basins compared to city averages; (3) peak rainfall intensity and total rainfall depth showed significant but weak correlations with some nutrients and metals, and TDS; (4) antecedent dry period were not correlated with water quality, except for phosphorus and lead; (5) contrary to what was expected, total coliforms and Escherichia coli were not correlated with TSS; and (6) no significant correlations between water quality and land-use or zoning categories were found. It was concluded that locally focused stormwater monitoring can aid data-driven decision-making by city planners where redevelopment is occurring at local “neighborhood scales”, particularly for the implementation and management related to green infrastructure and water-quality regulations.

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Determination of NPS Pollutant Unit Loads from Different Landuses

Sustainability ◽

10.3390/su13137193 ◽

2021 ◽

Vol 13 (13) ◽

pp. 7193

Author(s):

Jiyeon Choi ◽

Baekyung Park ◽

Jinsun Kim ◽

Soyoung Lee ◽

Jichul Ryu ◽

...

Keyword(s):

Environmental Changes ◽

Oxygen Demand ◽

Runoff Coefficient ◽

Forest Land ◽

Event Mean Concentration ◽

Rainfall Events ◽

Total Phosphorous ◽

Mean Concentration

This study aimed to estimate pollutant unit loads for different landuses and pollutants that reflected long-term runoff characteristics of nonpoint source (NPS) pollutants and recent environmental changes. During 2008–2014, 2026 rainfall events were monitored. The average values of antecedent dry days, total rainfall, rainfall intensity, rainfall duration, runoff duration, and runoff coefficient for each landuse were 3.8–5.9 d, 35.2–65.0 mm, 2.9–4.1 mm/h, 12.5–20.4 h, 12.4–27.9 h, and 0.24–0.45, respectively. Uplands (UL) exhibited high suspended solids (SS, 606.2 mg/L), total nitrogen (TN, 7.38 mg/L), and total phosphorous (TP, 2.27 mg/L) levels, whereas the runoff coefficient was high in the building sites (BS), with a high impervious surface ratio. The event mean concentration (EMC) for biological oxygen demand (BOD) was the highest in BS (8.0 mg/L), while the EMC was the highest in BS (in the rainfall range <10 mm) and UL and forest land (in the rainfall range >50 mm). The unit loads for BOD (1.49–17.76 kg/km2·d), TN (1.462–10.147 kg/km2·d), TP (0.094–1.435 kg/km2·d), and SS (15.20–327.70 kg/km2·d) were calculated. The findings can be used to manage NPS pollutants and watershed environments and implement relevant associated management systems.

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Distribution of Event Mean Concentration (EMC) of Nitrogen and Phosphorous from a Combined Dairy and Crop Farming Watershed

10.13031/2013.21096 ◽

2006 ◽

Author(s):

K.S. Yoon ◽

A. Shirmohammadi ◽

H. Montas ◽

A. Sadeghi

Keyword(s):

Event Mean Concentration ◽

Crop Farming ◽

Mean Concentration

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A new modeling approach for estimating first flush metal mass loading

Water Science & Technology ◽

10.2166/wst.2005.0587 ◽

2005 ◽

Vol 51 (3-4) ◽

pp. 159-167 ◽

Cited By ~ 27

Author(s):

L.-H. Kim ◽

M. Kayhanian ◽

S.-L. Lau ◽

M.K. Stenstrom

Keyword(s):

First Flush ◽

Runoff Coefficient ◽

Mass Loading ◽

Storm Events ◽

Metal Contaminants ◽

Rain Intensity ◽

Dry Period ◽

Variable Parameters ◽

Total Runoff ◽

First Flush Effect

The purpose of this study was to investigate pollutant mass loading from major highways in Southern California, with emphasis on interpretation of event mean concentrations and first flush effects. The results of monitoring eight sites during the 1999–2002 storm seasons found that metal contaminants had higher concentrations at the early stages of storm events compared with other stages of rain storms. A new washoff model was developed to predict the event mean concentrations of metal contaminants taking first flush effect into account. Model variable parameters included average daily traffic, antecedent dry period, rain intensity, total runoff volume, and runoff coefficient. The results obtained using the washoff model were compared with measured values and found to fit well for heavy metals with R2 ranging from 0.8 to 0.95.

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