Sources of River Corridor Resilience

Abstract

Spatial and temporal variations in water and sediment fluxes moving within the river corridor drive changes in the three-dimensional geometry of channels and floodplains. In forested river corridors, pieces of downed wood and logjams become an integral part of the interactions among water, sediment, and the resulting river corridor form and function. The net effect of the interactions between water, sediment, and wood stored at least temporarily is to increase spatial heterogeneity, or patchiness in a river corridor. Spatially heterogeneous, wide, low-gradient segments within a river network are particularly important for absorbing large disturbance inputs, such as those from wildfire, floods, and landslides, because of their ability to morphologically adjust to abrupt and variable changes. This river corridor resilience, defined as the ability to recover to pre-disturbance conditions, occurs along a continuum dependent on time and space. A river network consists of individual reaches with consistent river corridor morphology and the system of either a river network or an individual river corridor reach includes individual components with different levels of spatial heterogeneity and resilience. Using case studies from the Western US, Japan, and Tennessee, this seminar provides an overview of recent research exploring processes that promote natural resilience in river corridors, resilient response to disturbance, and considers ways in which we can restore resilience to human-altered river corridors.

Biography

Anna Marshall, fluvial geomorphologist and new assistant professor in the Department of Geography & Sustainability, broadly studies how rivers shape the landscape and how humans shape rivers. Anna received her PhD in geosciences from Colorado State University, focusing on river corridor dynamics within the channel(s), floodplain, and underlying hyporheic zone, and the interactions between geomorphic, hydraulic, and ecological processes. She uses fieldwork paired with statistical modeling and remote sensing to answer questions across different spatial and temporal scales. Most recently, she’s been researching ecological and hydraulic interactions between logjams, vegetation, and geomorphic processes; river response to disturbances such as fire and floods; and efforts to restore river function in human modified systems. She also considers how we can translate evolving knowledge of river corridor dynamics into river management through collaboration with communities and resource managers. Her research flows across locations from steep headwater mountain rivers to large, low gradient alluvial rivers and from local projects here in the Appalachians to rivers across the globe.