Fostering Riverine Diversity: River-Wetland Corridors
Ellen Wohl, PhD
Colorado State University
Fort Collins, CO
We tend to distinguish rivers, which have directional flow, and wetlands, which may have no directional flow within the wetland. This distinction, which can be artificial when wetlands occur within river corridors, has led to different regulations and management for rivers and wetlands. The distinction has also limited our conceptualization of integrated river-wetland corridors as a once-common feature in river networks and a potentially desirable target for restoration. River-wetland corridors can be present from small headwaters to large, lowland floodplain rivers. The wetlands in these corridors can take the form of marshes, carrs, swamps, and ciénagas. I will discuss the diverse conditions under which river-wetland corridors occur and the diverse ecosystem services that they provide. River-wetland corridors can form where a high water table sustains wetlands, even in dry climates and otherwise arid or semiarid landscapes. High riverine water table can result from: geologic drivers such as bedrock structure and stratigraphy; biotic drivers including beaver dams, logjams, and riparian vegetation; and geomorphic processes and landforms such as glacially stepped valleys or tributary fans. River-wetland corridor ecosystem services include flood peak attenuation, groundwater recharge, storage of sediment and soil organic carbon, nitrate uptake, food and habitat supplies, and increased biomass and biodiversity. Restoration of river-wetland corridors relies on enhanced hydrologic connectivity between the channel and floodplain. This can be fostered by: introducing obstructions to the channel; lowering the floodplain surface elevation; restoring peak flows sufficient to inundate the floodplain; restoring processes that recharge alluvial aquifers; or some combination of these changes.
About Ellen Wohl, PhD
Ellen Wohl received a BS in geology from Arizona State University and a PhD in geosciences from the University of Arizona. She is a professor in the Department of Geosciences at Colorado State University and a University Distinguished Professor. Her research focuses on physical processes and forms in river channels and floodplains, and how these interact with biogeochemistry and ecological and human communities. She has conducted field research in diverse environments around the world.
