29 Jul 2025

Engineering Practice Guide for Floodplain Benching: A Natural Infrastructure Approach for Riverine Systems

Abstract: Floodplain benches are a potential solution for inland river systems where out-of-bank flooding generates unacceptable flood risk and access to riverine floodplains has become restricted over time. Benches are a naturally forming geomorphic feature between the riverbed and a higher floodplain or terrace. In addition to reducing flood risk, benches reduce erosion risk, improve aquatic ecosystems, enhance plant and wildlife diversity, expand recreational opportunities, and may be places of cultural and tribal value. This document informs engineering activities related to site investigation and design of floodplain benches. It is intended to be used by engineers and ecologists to inform the design of floodplain benches in a manner that is consistent with and augments other planning, design, and engineering guidance. A well-designed floodplain bench can improve ecological and biological functions while also reducing flood risk by creating a channel in geomorphic equilibrium with current conditions and resilience to anticipated changes in hydrology and sediment supply rates. This publication is among a series of planned technical reports providing guidance on how to identify, conceptualize, and design natural infrastructure solutions for riverine and coastal systems. It has been produced by the US Army Corps of Engineers (USACE) Engineering With Nature® Program.