Arrested geomorphic trajectories and the long-term hidden potential for change

Area of Science:

• Fluvial geomorphology
• River engineering
• Environmental management

Background:

• Geomorphic systems exhibit decadal morphological changes, often arrested by natural or anthropogenic inhibitors.
• Understanding how and where rivers are stabilized is critical to prevent unintended destabilization from modern management projects.

Purpose of the Study:

• To examine two cases of arrested geomorphic trajectories in the lower Yuba and Feather Rivers.
• To analyze how different inhibitors have stabilized these rivers after 150 years of severe human disturbance.

Main Methods:

• Analysis of aerial photographs to study geomorphic changes.
• Examination of historical river modifications and their impact on channel morphology.

Main Results:

• A knickpoint at Shanghai Shoals on the Feather River retreated at 3.67 m/yr from 1963-2013 before breaching.
• Wing dams on the Yuba River, built in the early 19th century, limit floodplain widening and prevent a return to an anastomosing channel planform.

Conclusions:

• Arrested geomorphic trajectories in the Yuba and Feather Rivers demonstrate the impact of inhibitors on river evolution.
• Recognizing fluvial evolution and the role of inhibitors is essential for sustainable river management.