Stream Channel Stability and Watershed Resilience of Geomorphic Recovery

Dartmouth College, Hanover NH

Investigators

Abstract

NATIONAL SCIENCE FOUNDATION GEOGRAPHY SPATIAL SCIENCES (GSS) PROGRAM ABSTRACT River systems that have been disturbed by human activities and natural disasters often have severe impacts on watersheds and local communities. This research project will quantify how rivers reestablish equilibrium channel characteristics in response to changes in flow and sediment flux. The investigators will test the assertion that the equilibrium form of a channel cannot be uniquely defined and that channel properties depend on the dominant mode of sediment transport. A clear understanding of river channel equilibrium is vital for river management and restoration. Project findings will provide regional planners, watershed managers, nongovernmental organizations, and others with new methodologies for prioritizing watersheds for restoration and for seeking better ecological and economic advantages from river systems. The project also will contribute to improved education in science, technology, engineering, and mathematics (STEM) fields through special opportunities for the involvement of graduate students and mentoring programs for female scientists. Watershed managers and policy makers currently lack the necessary analytical metrics to gauge the magnitude of river disturbance to determine whether restoration activities are effective in promoting geomorphologically stable rivers that are in equilibrium. In this project, the investigators will identify the various possible geomorphic expressions of watersheds in dynamic equilibrium through the use of sediment tracers, channel transects and flow modeling, and in-channel sediment measurements. They will use sediment bedload information for quantifying the covariant and non-singular pathways that characterize channel recovery from disturbances, and they will employ mathematical models for simulating channel recovery in systems with varying sediment supply along longitudinal profiles of stream channels. The insights developed through this project will be essential for understanding the resiliency of watersheds and for the implementation recovery and restoration efforts of river systems.