RIVER ICE INFLUENCES ON FORT PECK REACH, MISSOURI RIVER
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SURVEY PROGRAM
The survey program first entailed identifying sites where river ice likely
would significantly affect the flow distribution and, thereby, the bathymetry in
the river. A schedule of bathymetric surveys then was coordinated for the sites.
The surveys concentrated especially on determining how ice cover formation,
presence, and breakup might locally alter channel bathymetry and aggravate
riverbank erosion.
Survey personnel
The survey involved a team of personnel from several organizations: the U.S.
Army Corps of Engineers Cold Regions Research and Engineering Laboratory
(CRREL); the Corps' Omaha District (USACE-Omaha); the Iowa Institute of
Hydraulic Research (IIHR); Eisenbraun and Associates Inc., a civil-engineer-
ing company based in Yankton, South Dakota; the U.S. Department of Agricul-
ture, National Resource Conservation Service's (NRCS) Culbertson Office; and
local logistic support from the town of Culbertson. The survey interacted closely
with the Coordinated Resource Management (CRM) Group, an organization of
farmers who live and work along the Fort Peck reach.
Survey sites
As surveys under winter conditions are expensive, an initial issue to be
resolved was the number of survey sites and the extent of measuring and moni-
toring to be conducted at each site. Sites were selected where bank- and channel-
change concerns are most acute and where ice is perceived to be a significant
factor contributing to the concerns. The eventual selection relied mainly on
informal observations made during a visit in October 1998 and on anecdotal
accounts of ice-related changes in channel thalweg alignment, bank erosion, and
pump site sedimentation during prior winters. There was also interest in moni-
toring river ice influences on bank stabilization methods installed at RM 1716
(Pipal site). A further consideration was site accessibility.
Five sites were selected for monitoring:
RM 16201621, a multi-thalweg channel (Culbertson site) (three cross
sections between 1620.35 and 1620.45);
RM 16231624, a complex bend (Tveit-Johnson site) (four cross sections
between 1623.97 and 1624.11);
RM 16321633, a bend (Vournas site) (three cross sections between
1632.55 and 1632.68);
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