Joan L. Florsheim

Bank Erosion as a Desirable Attribute of Rivers

ABSTRACT Bank erosion is integral to the functioning of river ecosystems. It is a geomorphic process that promotes riparian vegetation succession and creates dynamic habitats crucial for aquatic and riparian plants and animals. River managers and policymakers, however, generally regard bank erosion as a process to be halted or minimized in order to create landscape and economic stability. Here, we recognize bank erosion as a desirable attribute of rivers. Recent advances in our understanding of bank erosion processes and of associated ecological functions, as well as of the effects and failure of channel bank infrastructure for erosion control, suggest that alternatives to current management approaches are greatly needed. In this article, we develop a conceptual framework for alternatives that address bank erosion issues. The alternatives conserve riparian linkages at appropriate temporal and spatial scales, consider integral relationships between physical bank processes and ecological functions, and avoid secondary and cumulative effects that lead to the progressive channelization of rivers. By linking geomorphologic processes with ecological functions, we address the significance of channel bank erosion in sustainable river and watershed management.

Fluvial sediment transport in response to moderate storm flows following chaparral wildfire, Ventura County, southern California

Chaparral wildfire has a profound effect on erosion and sedimentation in southern California. The Wheeler Fire in July 1985 burned the entire basin of a tributary (drainage area 2.14 km 2 ) of the north fork of Matilija Creek, near Ventura, California. After the fire, fine gravel was delivered to the channel by the process of dry ravel (dry particle-by-particle sliding of debris under the force of gravity) at a rate of 0.29 m 3 /km 2 /month. The first winter flow (2.1 m 3 /s) following the fire deposited 550 m 3 of fine gravel in the 270-m study reach near the mouth of the tributary. At least 90% of this fine gravel was derived from colluvium delivered by dry ravel processes from hillslopes near the channel. The second winter flow (2.5 m 3 /s) eroded the channel to the pre-fire thalweg. A reduction in particle size and critical shear stress associated with deposition of small gravel following the fire allowed these moderate-magnitude flows to transport large volumes of sediment. Deposits of two debris flows were identified in the tributary basin. Radiocarbon dating of these deposits gives dates of 1045 ± 95 yr B.P. for the older deposit and between 295 ± 35 and 385 ± 84 yr B.P. for the younger deposit. These dates indicate that the recurrence interval of large debris flows in the study basin is at least an order of magnitude greater than the recurrence interval of fire in the area.

The Effects of Longitudinal Differences in Gravel Mobility on the Downstream Fining Pattern in the Cosumnes River, California

Downstream fining in the Cosumnes River is partially controlled by longitudinal variation in sediment mobility linked to changes in cross‐sectional morphology. Strong fining occurs where the channel is self‐formed with section‐averaged bankfull dimensionless shear stress (ndocumentclass{aastex}nusepackage{amsbsy}nusepackage{amsfonts}nusepackage{amssymb}nusepackage{bm}nusepackage{mathrsfs}nusepackage{pifont}nusepackage{stmaryrd}nusepackage{textcomp}nusepackage{portland,xspace}nusepackage{amsmath,amsxtra}nusepackage[OT2,OT1]{fontenc}nnewcommandcyr{nrenewcommandrmdefault{wncyr}nrenewcommandsfdefault{wncyss}nrenewcommandencodingdefault{OT2}nnormalfontnselectfont}nDeclareTextFontCommand{textcyr}{cyr}npagestyle{empty}nDeclareMathSizes{10}{9}{7}{6}nbegin{document}nlandscapen

Channel change, sediment transport, and fish habitat in a coastal stream: Effects of an extreme event

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Promoting Atmospheric-River and Snowmelt-Fueled Biogeomorphic Processes by Restoring River-Floodplain Connectivity in California’s Central Valley

nend{document} ) near the threshold of motion (ca. 0.031), allowing for size‐selective transport. In contrast, fining is minimal in confined reaches where ndocumentclass{aastex}nusepackage{amsbsy}nusepackage{amsfonts}nusepackage{amssymb}nusepackage{bm}nusepackage{mathrsfs}nusepackage{pifont}nusepackage{stmaryrd}nusepackage{textcomp}nusepackage{portland,xspace}nusepackage{amsmath,amsxtra}nusepackage[OT2,OT1]{fontenc}nnewcommandcyr{nrenewcommandrmdefault{wncyr}nrenewcommandsfdefault{wncyss}nrenewcommandencodingdefault{OT2}nnormalfontnselectfont}nDeclareTextFontCommand{textcyr}{cyr}npagestyle{empty}nDeclareMathSizes{10}{9}{7}{6}nbegin{document}nlandscapen

Recovery of the Chaparral Riparian Zone After Wildfire

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