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

Area of Science:

• Environmental Science
• Hydrology
• Water Quality Management

Background:

• Stormwater runoff is a significant source of urban pollution.
• Understanding pollutant characteristics like event mean concentration (EMC) and first flush effect (FFE) is crucial for effective management.
• Different drainage systems and land use areas exhibit varying runoff quality.

Purpose of the Study:

• To investigate the characteristics of EMC and FFE in stormwater outfalls from various drainage systems and functional areas.
• To compare pollutant loads across different urban environments.
• To provide data for improved water quality management strategies.

Main Methods:

• Collected stormwater quality data from five outfalls in Fuzhou City (2011-2012).
• Analyzed samples for key water quality parameters: Chemical Oxygen Demand (COD), Ammonia Nitrogen (NH3-N), Total Phosphorus (TP), and Suspended Solids (SS).
• Evaluated EMC and FFE patterns in relation to drainage system type and land use.

Main Results:

• EMCs followed the order: intercepting combined system > direct emission combined system > separated system.
• The first flush effect (FFE) was observed in most rainfall events across all outfalls.
• FFE strength varied significantly by land use and drainage type, with residential areas of direct emission combined systems showing the strongest FFE.

Conclusions:

• Drainage system design and land use significantly influence stormwater pollutant concentrations and FFE.
• Results offer valuable insights for targeted pollution control measures in urban catchments.
• Effective management requires considering specific characteristics of different drainage systems and functional areas.