Richard Huizinga, Hydrologist, Project Chief
Paul Rydlund, Hydrologist
Because of the scouring action of flood waters, bridge piers can be washed out and bridges may collapse causing expensive repairs and possible life-threatening situations. The Bridge Scour project studies the effects of the scouring action of the water by using a fathometer to trace bottom profiles (227679 bytes) of river channels at bridges during flood events. The device is fixed to a weight and slowly pulled back and forth across the river near the bridge. It is nearly impossible to traverse the river at a constant rate, and because of this, the profiles generated by the fathometer have a variety of horizontal scales. This scale problem causes difficulty in interpretation of the data. The Missouri District has devised a way to use the powerful GIS capabilities of "rubber sheeting" to eliminate this problem.
The fathometer trace is digitized into the computer in a "bridge length/water depth" coordinate system. A series of known points (usually located at bridge piers) is then digitized and attributed with the correct horizontal stationing. An AML then creates a link table and adds the links to the original digitized coverage. With the links in place, the original digitized trace can now be stretched/compressed where necessary with the "rubber sheeting" capabilities to fit the correct horizontal stationing.
The final step is to ungenerate the adjusted fathometer trace and bring these coordinates into a graphing package for analysis and comparison with other fathometer traces at different times and river stages.
Contact address:
Joseph M. Richards, Hydrologist
U.S. Geological Survey
1400 Independence Rd, Mail Stop 100
Rolla, MO 65401
PHONE: 573-308-3568
FAX: 573-308-3645
EMAIL: richards@usgs.gov
U.S. Department of the Interior, U.S. Geological Survey
Maintainer: Rita Choate, Webmaster
Updated: September 29, 2003
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URL: http://mo.water.usgs.gov/current_studies/richards/mo_gis/scour.htm
