Reclamation Information Sharing Environment (RISE)

Side channels increase the hydraulic and geomorphic complexity of river systems, which provides aquatic habitat by reducing velocity and increasing shoreline length and cover. Constructed side channels are a common habitat restoration technique to improve ecological value, but design guidance is limited. This study analyzes naturally formed side channels to improve the efficacy of constructed projects. We used historical aerial imagery of the Middle Rio Grande, the Sacramento River, and the Trinity River to better understand how side channels form, how they evolve, and how long they persist. We identified and classified side channels between 1935 and 2012 with a time series of at least five different years for each river. Classification types consider if the side channel was likely created by erosion or deposition through processes such as lateral channel migration or channel avulsion. Evaluating spatial and temporal trends for each river highlights relationships between geomorphic processes and side channel abundance and longevity.