7916

• UCREFRP Catalog Number: 7916
• Author: Stalnaker, C. B.
• Title: Methodologies for Preserving Instream Flows, The Incremental Method, ‎(from a syposium by the Upper Mississippi River Basin Commission, Nov. 14, 1978)‎
• USFW Year: 1978
• USFW - Doc Type: Instream Flow Management State of the Art Proceedings
• Copyright Material: YES

C. The probability that fish will choose to live in any
particular hydraulic dimension (such as depth or
velocity) is independent of the probability that they
will choose to live in any other dimension. Thus, the
determination of a weighted usable area for each
life stage of a fish species is made by multiplying
the weighting factors of each hydraulic dimension.
For example, the weighted usable area for
spawning of steel head trout is calculated by
multiplying the normalized probability for depth
with those of velocity and substrate times the total
surface area of the stream.

D. A selected segment of river may be modeled by
using a representative sample reach of that river.
The more homogeneous the river segment, the
more representative the sample reach will be. In
such cases, a single sample reach will be adequate.
In some cases, the user may wish to sample two or
more reaches in order to decrease the risk of
making an error in extrapolation of sample data to
the entire river segment.

E. There is a direct and positive relationship between
the calculated suitability of habitat and the use of
the habitat by selected fish species. Studies will
have to be made to determine the precise nature of
this relationship; however, fishes apparently
choose to live, where possible, under optimum con-
ditions. This assumes that fish species will move
out of stream reaches when the habitat becomes
marginally suitable.

11. Is it difficult to collect data for the IFG incre-
mental methodology?

Data collection for the IFG incremental
methodology is not unusually complex. Most fisheries
or water resource management agencies have used, or
are familiar with the basic survey techniques used in
the methodology for the collection of data. Possible
problems would be where physical access to the
stream is limited or times of the year when high water
prevents sampling. However, these problems are
common to any stream sampling methodology.

12. Can change in stream channel morphology be
factored into the analysis?

The IFG incremental methodology can be used to
evaluate the usability of stream habitat in an altered
stream channel which results from a significant
change in sediment yield to the stream. The extent of
stream aggradation or degradation must first be
predicted and the new channel shape simulated before
calculations of weighted usable area can be made for
similar or changed flow regImes.

REFERENCES:

1. Bovee, Ken D. 1978. Probability-of-use criteria for the
family Salmonidae. Instream Flow Information Paper No.
4. Cooperative Instream Flow Service Group, Fort Collins,
Colorado.

2. Bovee, Ken D. and Tim Cochnauer. 1977. Development
and evaluation of weighted criteria, probability-of-use
curves for instream flow assessments: fisheries. Instream
Flow Information Paper No.3. Cooperative Instream Flow
Service Group, Fort Collins, Colorado.

3. Bovee, Ken D. and Robert T. Mllhous. 1978. Hydraulic
simulation in instream flow studies: theory and
techniques. Instream Flow Information Paper NO.5.
Cooperative Instream Flow Service Group, Fort Collins,
Colorado.

4. Main, Robert B. 1978a. IFG 4 Program, User Manual.
Cooperative Instream Flow Service Group, Fort Collins,
Colorado.

5. Main, Robert B. 1978b. Habitat Program User Manual.
Cooperative Instream Flow Service Group, Fort Collins,
Colorado.

6. Milhous, Robert T. and Ken D. Bovee. 1978. The stochastic
variation of instream values in rivers, Proceedings, 1978
ASCE Hydraulics Division Conference, College Park,
Maryland.

7. Stalnaker, C. B. and J.l. Arnette. 1976. Methodologies for
the determination of stream resource flow requirements:
an assessment. Office of Biological Services, U.S. Fish and
Wildlife Service, Washington, 0, C.

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