7424

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

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phenomena (e.g., sediment erosion and deposition)
to terrestrial phenomena (e.g., food of terrestrial
vertebrates from the river) and from a confusing
mixture of science and value judgment. Although it
is often useful to remove references and lengthy
explanations from the body of the report, in this
instance the text became more confusing because
assumptions, values, and facts were not documented,
differentiated, and/or explained. Even so, the
recommendation made by the researchers to continue
the monitoring is significant. Willingness to
adjust the flow pattern in response to resource
changes is the key to managing the system.
The majority of the individual GCES terrestrial
biology research projects were carefully executed.
The results contribute valuable information.
Analysis, however, was limited because some data
were missing, numbers were few, and replication was
minimal. Many of these problems resulted from
unexpected flood conditions during the study
period.
Future work by the Department of the Interior
should seek to
• establish links to river productivity in
future terrestrial studies
• plan for heterogeneity and match methods to
the temporal and spatial scales of the phenomena
• prepare for the unexpected in schedule and
budget preparation; think probabilistically
• document the process by which resource values
are judged
Sediments and Hydrology
The sediment and hydrology research effort has
produced some excellent new understanding of
certain critical components of the complex system
of water and sediment movement through the Grand
Canyon. The information about mechanisms of sand
erosion and deposition in recirculation zones,
observations of changes in sediment storage in the