floodwall

A floodwall is a defensive barrier designed to prevent floodwaters from entering protected areas by forming a continuous, impermeable wall along a riverbank, coastline, or urban floodplain. Unlike earthen embankments, floodwalls are vertical or near-vertical structures that rely on rigid materials and strong foundations to resist water pressure. They are typically constructed from reinforced concrete, precast panels, or steel sheet piles with a concrete or steel facing, and are designed to withstand the hydrostatic and hydrodynamic loads generated by a design flood. Floodwalls are often anchored to buried foundations, piles, or bedrock and may include toe supports or buttresses in high-pressure locations.

Construction options vary by site. Cast-in-place concrete walls, modular precast panel walls, and sheet-pile walls are common configurations. Some floodwalls incorporate movable gates or closures to allow controlled water management or maintenance access, while others are fixed-height barriers with sealants and drainage features to minimize water ingress behind the wall. In urban settings, floodwalls are favored where space is limited or where subsidence or scour makes earthen levees impractical.

Performance and maintenance considerations include ensuring adequate height to meet the design flood, preventing overtopping, and addressing seepage, foundation stability, and scour at the base. Regular inspections and repairs are essential to address deterioration, corrosion, or damage from debris. Floodwalls function as components of broader flood risk management systems that may include levees, pumps, and drainage networks.