Three-Dimensional Flow Analysis Methodology for Assessing Stream Stability and Channel Migration

Abstract

Increases in the frequency and magnitude of weather events that deviate significantly from average are being observed both globally and in the U.S. Adaptation strategies need to account for and mitigate increased risks to transportation infrastructure that result from more extreme weather. The present study is a part of a project that covers a sensitivity study of the potential impacts of increases in stream flows due to rain events and floods on an active section of the Maple River near Iowa Highway 175 and Danbury, Iowa, which is shown. This study focuses on the use of advanced three-dimensional (3D) computational fluid dynamics (CFD) techniques to enhance the assessment of increased risks to stream stability of a section of the Maple River that may erode into Iowa Highway 175. The methodology developed and presented can be applied to a wide variety of streams and rivers that may face increased risk of migration due to changes in weather patterns and severity of weather events. The Maple River is a laterally active channel flowing through agricultural land that has migrated several hundred feet in recent decades and is currently within approximately 100 feet of the Highway 175 Right-of-Way. In addition to the near-term threat to the highway from the closest river meander, there is also a concern that other river meanders could develop into longer-term threats, especially if increasing intensity or frequency of rain events increase the rate of meander development and channel migration by changing the long-term hydrology of the Maple River.