MorphoRest: Natural stream restoration design in northern Sweden—analysis of bedload sediment transport
How should we restore the physical features of rivers after channelization in northern Sweden? This project examines bedload transport and channel geometry in semi-alluvial channels in tributaries to large rivers in Sweden.
How do we know what to restore a degraded stream to? Without a basic understanding of physical processes, stream restoration will never truly fulfil its goal of creating a sustainable system benefiting overall ecosystem health. Because few appropriate reference sites for stream restoration exist in northern Sweden (nearly all streams in northern Sweden have been altered by timber-floating), channel design should be based on the fluvial geomorphic processes of sediment and water fluxes.
Headwater streams in northern Sweden have two characteristics that complicate a process-based understanding of sediment transport and channel geometry: (1) streams are typically semi-alluvial, in that they contain coarse glacial legacy sediment that was not transported and deposited by the stream and (2) numerous mainstem lakes buffer sediment and water fluxes. In addition, these models may also need to take into account local biotic factors, such as salmonid redd (nest) building.
In this project I will determine natural channel design of streams in northern Sweden by determining rates of and controls on sediment transport. I will test hypotheses regarding annual bedload (sediment moving along the channel bed) yield, downstream changes in channel geometry interrupted by lakes, and potentially the role of biotic processes (fish nest-building) in transporting sediment. These results will be applied directly to ongoing restoration projects for sustainable restoration of fish habitat and spawning gravel.