Is flow control in a space-constrained drainage network effective? A performance assessment for combined sewer...

Area of Science:

• Environmental Engineering
• Water Resource Management
• Urban Drainage Systems

Background:

• Recurring combined sewer overflows (CSOs) significantly impact water body ecology.
• Existing solutions include structural measures and low-impact development.
• Flow control strategies leverage urban drainage networks for temporary storage, but space limitations are a concern.

Purpose of the Study:

• To investigate the efficacy of flow control for space-constrained drainage networks.
• To evaluate a low-cost, heuristic real-time control strategy using flow control devices (FCDs).
• To analyze the impact of FCD location on CSO reduction.

Main Methods:

• Employed a heuristic real-time control strategy with FCDs.
• Conducted over 300 rainfall-event simulations.
• Analyzed the performance and sensitivity to FCD location.

Main Results:

• Flow control is more efficient for smaller rainfall events (10-20 mm/h), reducing CSO for ~80% of events.
• Larger rainfall events show unstable flow control due to water accumulation and pressurized flow.
• Performance is highly sensitive to FCD location, influenced by rainfall intensity and upstream water levels.

Conclusions:

• Flow control strategies can reduce CSOs in space-constrained networks, especially for moderate rainfall.
• Limited sewer space leads to diminished CSO reduction performance and control challenges.
• Optimal FCD placement is critical and depends on available in-sewer storage potential and resistance to water accumulation.