Coastal resilience investments are accelerating as communities respond to erosion, storm surge and rising sea levels. Inland municipalities face a parallel set of challenges driven by urbanization, aging drainage infrastructure and more frequent high-intensity rainfall. Too often these two systems are planned independently, creating compound flooding scenarios where elevated coastal water levels prevent gravity drainage and trap runoff within inland stormwater systems even when shoreline defenses perform as intended.

This presentation examines how coastal storm defense systems and municipal stormwater infrastructure can be planned and operated as a coordinated hydraulic system. Drawing from recent coastal resilience and urban flood mitigation efforts, the discussion covers how integrated hydrologic and hydraulic modeling can evaluate the interaction between watershed runoff and coastal water levels during major storm events, incorporating NOAA Atlas 14 intensity-duration-frequency data, tidal variability, storm surge and projected sea-level rise.

Infrastructure solutions discussed include tide-controlled outfalls, flap gates, surge-resilient pump stations, upstream storage and distributed green infrastructure. The presentation also addresses coordinated capital planning, updated compound flooding design standards and watershed-scale approaches to urban flood resilience.

Learning Objectives:

• Evaluate compound flooding risks by analyzing the interaction between coastal water levels, storm surge, and inland stormwater runoff using integrated hydrologic and hydraulic modeling approaches.
• Identify resilient infrastructure strategies for mitigating combined coastal and inland flooding impacts.
• Apply coordinated planning principles and updated design standards to develop watershed-scale solutions that improve urban flood resilience.