Exploring real-time control of stormwater systems for mitigating flood risk due to sea level rise

Abstract

Low-lying, low-relief coastal cities have seen increased flooding due to climate change. In these cities, stormwater pipe outlets can be inundated by coastal waters at high tide or from storm surge, making drainage impossible. The objective of this research is to assess the utility of model predictive control (MPC) of stormwater actuators to reduce flooding in a coastal urban setting made worse by sea level rise. The stormwater system and the control scenarios are simulated using the United States Environmental Protection Agency Storm Water Management Model (SWMM5) coupled with a Python library, swmm_mpc. The study area is Norfolk, Virginia, USA, a city which is particularly vulnerable to coastal flooding. A simulated 2-year 12-h design storm and sea level rise scenarios up to 3.5 ft are applied to the model for three control scenarios: 1) a passive system, 2) a passive system with a tide gate (backflow preventer), and 3) a tide gate and three actuators (a pump, a valve, and an inflatable dam) controlled through MPC. Flooding in the passive system reached a tipping point and increased dramatically after a sea level rise of 1.6 ft. The addition of a tide gate greatly mitigated this increase in flooding. MPC further reduced overall flooding with an average effective percent reduction of 32%. The rate of the increase in flooding was significantly smaller with MPC than without. MPC also reduced maximum node flood volume by an average of 52% for sea level increases of 2.0 ft and above. In addition to the installation of a tide gate, our results suggest that the use of actuators controlled by MPC could significantly reduce overall flood volumes and reduce flood severity at individual nodes in coastal cities.