Mathematical modeling of sewers under surcharge for real time control of combined sewer overflows

Abstract

The efficiency of real time control (RTC) to decrease storm overflows from combined sewers to receiving waters was demonstrated in several case studies. Global predictive control (GPC), an effective strategy to perform real time management of sewers, requires simulation models to anticipate the future state of the system (flow rates and water levels). To compute these predictions, a hydraulic model using an implicit discretization scheme to solve simplified continuity and momentum equations was developed. The performance of the model is evaluated by comparison with the USEPA EXTRAN model results. This comparison shows that the model gives results similar to those of the EXTRAN model, with the advantage of producing faster and more stable results regardless of space and time steps used. Additional validation with the SUPERLINK model is also presented.