The Alluvial Phase Space Diagram (APSD) and its potential application in the FRAME-RUBRIC model

Colin Thorne*, David Biedenharn, Travis Dahl, Sam Valman, Amanda Cox, Christopher Haring, Charles Little, Philip Soar

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The Alluvial Phase Space Diagram (APSD) was created jointly at the USGS Cascades Volcano Observatory and the University of Nottingham. It provides a template for visualizing, quantifying and evaluating morphological adjustments, and sequences of adjustments, in river form. The APSD is being applied in three elements of the USACE’s FRAME (Future River Analysis & Management Evaluation) project development:
1. testing the performance of FRAME in simulating morphological responses to river management and natural disturbance,
2. training FRAME for application to individual study rivers, based on their past behavior,
3. evaluating the implications of future responses to river management with respect to changes in river form, phase shits, evolutionary trends, and river functions.
In this paper, we introduce the APSD and then illustrate its potential for application in the FRAME model using a case study of the Lower Mississippi River (LMR). The APSD reveals that between 1960 and 2015 the Lower Mississippi between Cairo, IL and Old River, LA adjusted its thalweg elevations and x-section areas in response to long-term trends of net erosion in the fluvially-dominated reach, upstream of Vicksburg, MS and net deposition in the downstream, backwater-influenced reach below St Joseph, LA. Application of the APSD to the 200-mile reach upstream of Vicksburg, MS selected for a pilot application of FRAME provided the opportunity to explore whether the APSD provides the basis for comparing model outcomes for a test run between 2004 and 2013 to the channel changes observed during that period.
Original languageEnglish
Title of host publicationProceedings of the Sedimentation and Hydrologic Modeling (SEDHYD) 2023 Conference
Number of pages15
Publication statusPublished - 12 May 2023
EventSedimentation and Hydrologic Modeling (SEDHYD) 2023 Conference - St Louis, United States
Duration: 8 May 202312 May 2023


ConferenceSedimentation and Hydrologic Modeling (SEDHYD) 2023 Conference
Country/TerritoryUnited States
CitySt Louis

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