The character, shape, and behavior of the world’s rivers reveal their long history of being modified by human activities and actions. Dams, irrigation diversions, erosion control structures, floodplain development, and gravel extraction are just a few of the many interventions that have modified the fluvial landscape and transformed river ecosystems, with both intended and unintended consequences. Recently, river restoration has emerged as a new intervention in fluvial environments that seeks to return some of the more natural forms and biophysical functions that were altered by previous human actions. Restoration activities themselves, however, can leave lasting geomorphic and ecologic imprints on river systems, and represent a new type of fluvial disturbance.
In this talk, I emphasize some of the newer tools in the restoration toolkit – dam removal and gravel augmentation – and consider the geomorphic and ecologic impacts, opportunities and challenges that implementing these activities represent. I draw on recent and dramatic examples from the U.S. Pacific Northwest to explore what the benefits and costs of these strategies might entail. These examples are contrasted with other restoration activities now in common practice in Europe and Japan (i.e., re-meandering, riparian enhancements) to develop a broad international perspective on the scientific and cultural contexts of modern restoration practices. Finally, I offer some observations about how anticipated changes to fluvial systems due to changing climate are likely to affect the manner in which we conduct river restoration worldwide.