7424

• UCREFRP Catalog Number: 7424
• Author: National Research Council
• Title: Editor
• USFW Year: Series
• USFW - Doc Type: 1987
• Copyright Material: YES

-8-
river channel, observation of the deposition
resulting from debris flows, and the physical
analysis of flow dynamics in rapids are examples of
this good work. Integrating these elements into a
fuller understanding of sedimentary phenomena was
hindered, however, because the modeling study of
the sediment and water flow was conducted
separately. Also, insufficient attention was paid
to sediment source, sinks, and sediment movement to
beaches and riparian zones. These elements are now
realized to be of central importance because they
were the focus of other portions of GCES.
Future work by the Department of the Interior
should seek to
• look for connections between research
disciplines in the planning phases of the study
• initiate studies of tributary processes
because they are the main source of sediment in the
Colorado River mainstem
• include in future hydrologic research
empirical approaches as well as modeling approaches
• link sediment studies to biological and
hydrological monitoring and research
• institute geomorphic studies to supplement the
hydraulic studies of the Colorado River system in
the Grand Canyon
Recreation
The committee was well satisfied that the
relevant questions in the recreation study were
approached given the constraints in the scope of
analysis embedded in the design of the GCES
research program. The change in recreation value
in response to changes in dam operations and in
terms of appropriate monetary units of measure was
evaluated successfully. The study is notable first
for the care that was taken to design a survey
research instrument for each of the relevant
recreation populations and second for the care with
which the statistical inferences were drawn. A