The animation that you are about to see shows how a 5 kilometer (3 1/4 mile) reach of the Rio Grande in south-central Colorado changed its course between 1875 and 1990 . The animation is a combination of data and interpretation - the data are the surveys, maps, and air photos that show the channel locations at specific times, and the patterns of abandoned channels and meanders on the flood plain that show where the channel was between those times. The interpretation involves estimating how fast the channel migrated, when the channel made distinct jumps (called"avulsions"), and what happened in places where the flood plain patterns are indistinct. Interpretations by other scientists might differ considerably in detail, but would probably be similar with regard to the general pattern of movement.

Location of Rio Grande and the study reach (click image to load higher resolution version)

The idea for this animation came when a colleague (Dr. Jack Deibert) suggested that an animation showing channel changes would be much easier to understand than a still figure. This comment led the authors to use a computer graphics program and a scanner to create same-scale images from which the time-series frames were developed that are the building blocks of the animation.

The vertical and horizontal gridlines define squares (sections) that are approximately one mile on each side. The blue ribbon in each frame is the approximate location of the river at a given time. As the animation progresses and the blue river moves, brown areas are left behind that show where the channel has been since the animation started. The "clock" in the upper right shows approximately how fast time is passing. It stops periodically when the animation pauses, and a year appears. The year represents a time for which a photo, map, or survey shows the exact channel location. At the very end of the animation, the background changes to show the present-day pattern of brown abandoned channels and yellow gravel (point bar) deposits. The total animation is approximately 275 frames, of which about 175 represent channel movement and about 100 represent pauses.
 
Sample frame from animation.

Hints

Before attempting to view the animation, the reader should be aware that the animation files are large (up to 6.5 MB) and that file transfer via modem will take considerable time. The animation is available in AVI, QuickTime, and MPEG digital video formats. There are two ways to view the files: 1) from within your browser using the appropriate "plug-in". 2) by downloading the file to your computer, then using a digital video player to run the animation.

QuickTime and MPEG players are available for all computer platforms -- they can be downloaded, free of charge, from Netscape, Microsoft, or Apple. The Apple site has an easy-to-install QuickTime player for Microsoft Windows. The AVI format is typically only used with the Windows operating system.
 

Download the Digital Video

2.7 MB. 640x480 pixels.

6.5 MB. 640x480 pixels.

2.6 MB. 1566x1174 pixels. Due to the high resolution of this version, the file should be downloaded to your computer then viewed with a Windows AVI player. The option "fit to screen" may need to be selected to see the entire image.

A paper that discusses the channel history of the Rio Grande in more detail is available: Jones, Lawrence S., and Harper, Joel T., 1998, Channel Avulsions and Related Processes, and Large-scale Sedimentation Patterns since 1875, Rio Grande, San Luis Valley, Colorado: Geological Society of America Bulletin, v. 110, no. 3. The first author's dissertation also contains information on the topic and is available on microfilm at many universities: Jones, Lawrence S., 1996, The Evolution of the Modern Rio Grande Floodplain, San Luis Valley, Colorado:Implications for Alluvial Stratigraphy: Dissertation, University of Wyoming, Laramie, Wyoming, 146 p.

 
The authors may be contacted via email.

Lawrence S. Jones: larjones@earthlink.net
Joel T. Harper: joelh@uwyo.edu

Copyright Notice: The figures, text, and animations in this web page are copyright protected and are distributed for public information only. Permission is granted to use for personal or teaching purposes only, so long as Copyright is included. Other presentation or reproduction not covered by the copyright law as Fair Use is prohibited. For permission to use any graphic, or parts thereof, in other presentations, contact: Joel Harper, Dept. of Geology & Geophysics, P.O. Box 3006, University of Wyoming, Laramie, WY 82071.