Hydrodynamic Modeling for Climate-Resilient Wastewater Infrastructure: Bridging Flood-Risk Science and Adaptation Policy

Wastewater infrastructure is increasingly exposed to flooding from intense rainfall, high river stages, coastal water levels and rising groundwater. These hazards can impair sewer conveyance, pumping, treatment and effluent discharge, with consequences for public health, receiving waters and municipal service continuity. This narrative review synthesizes peer-reviewed evidence on wastewater flood mechanisms, one-dimensional and two-dimensional hydraulic models, coupled and compound flood simulation, vulnerability assessment and adaptation decision-making, and it classifies 58 studies by the kind of inference each supports. Only five of these studies provide observed or calibrated evidence from wastewater systems; most contribute scenario simulations, transferable flood-modeling methods or decision frameworks. The literature shows that flood extent alone is an insufficient measure of wastewater resilience: model outputs become useful for decisions only when they are translated into asset-specific functional thresholds, service consequences and recovery requirements. Coupled sewer–surface and river–coastal models can represent important interactions, but their value depends on data availability, validation, uncertainty characterization and the choice of performance indicators. No single adaptation measure provides universal protection, and green infrastructure reduces frequent overflows more reliably than it prevents extreme inundation of treatment plants. The review proposes a hazard-to-decision framework that links hydrodynamic modeling to asset risk, adaptive policy pathways and public financing, including the United States Clean Water State Revolving Fund (CWSRF), and it identifies priorities for field validation, compound-hazard research and equitable investment.