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Design and Construction of an Urban Runoff Research Facility
Published on: August 8, 2014
First flush analysis of urban storm runoff
J H Lee1, K W Bang, L H Ketchum
1Department of Environmental Engineering, Chongju National College of Science and Technology, Chungbuk, South Korea. jlee@cjnc.ac.kr
The Science of the Total Environment
|July 12, 2002
Summary
The first flush phenomenon, where initial stormwater runoff has higher pollutant concentrations, varied by pollutant type and was more pronounced in smaller urban watersheds. This initial pollutant surge was not linked to the preceding dry period.
Area of Science:
- Environmental Science
- Urban Hydrology
- Water Quality Management
Background:
- Urbanization significantly alters natural hydrologic processes.
- Stormwater runoff carries pollutants from urban landscapes into receiving waters.
- Understanding pollutant loading dynamics is crucial for effective water quality management.
Purpose of the Study:
- To investigate the occurrence and magnitude of the first flush phenomenon in urban watersheds.
- To analyze how the first flush phenomenon varies across different pollutant types and land uses.
- To determine factors influencing the first flush phenomenon, such as watershed size and antecedent dry period.
Main Methods:
- Monitoring of stormwater runoff from 13 diverse urban watersheds.
- Analysis of 38 storm events to capture initial runoff characteristics.
- Calculation of the first flush phenomenon's magnitude using event mean concentration (EMC).
Main Results:
- The first flush phenomenon was observed, with varying magnitudes depending on pollutant type (e.g., higher for suspended solids in residential areas).
- Pollutant concentrations during the initial runoff phase were significantly higher than later stages.
- Smaller watershed areas exhibited a greater first flush phenomenon; no correlation was found with antecedent dry weather periods.
Conclusions:
- The first flush phenomenon is a significant factor in urban stormwater pollutant export.
- Pollutant characteristics and watershed size are key determinants of the first flush effect.
- Findings inform targeted stormwater management strategies for mitigating urban water pollution.
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