7922

• UCREFRP Catalog Number: 7922
• Author: Bovee, K. D.
• Title: A Guide To Stream Habitat Analysis Using The Instream Flow Incremental Methodology, Instream Flow Information Paper No. 12.
• USFW Year: 1982.
• USFW - Doc Type: \
• Copyright Material: NO

PREFACE
The Instream Flow Incremental Methodology (IFIM) draws on a wealth of
approaches that have been developed to assess instream flow problems. Beyond
this history of existing approaches, however, the methodology has undergone a
period of significant expansion, refinement, and evolution. The result is an
approach to the assessment of riverine habitats that has a very wide range of
applications. Perhaps the greatest strength of the IFIM is its flexibility;
the methodology can be applied to virtually any kind of disturbance to a
riverine ecosystem. This flexibility may also be the biggest disadvantage of
the methodology. Although we have provided a fairly comprehensive procedure
for analyzing a variety of problems, a "cookbook" approach is impossible.
Each time a user applies this methodology, he or she essentially builds a
model specific to the problem at hand. It would be very difficult, if not
impossible, for the Instream Flow Group to direct and specify the analysis of
every problem to which this method might be applied. It, therefore, becomes
the responsibility of the user to thoroughly understand the methodological
approach and all of the available options to any analysis.
In this context, this user's guide is designed as a reference for anyone
conducting an instream flow or riverine impact study, regardless of how many
previous studies the user has conducted. This manuscript should be as appro-
priate for the one-hundredth application of this method as it is for the
first. The emphasis of this information paper is on what to do and in what
sequence to do it, rather than on how to do it. The "how to do it" can be
found in the references cited as suggested additional readings at the end of
each chapter.
This manual has been constructed in two parts. Part I consists of
Chapters 1-5 and contains information regarding the preparation, analysis, and
interpretation needed to solve particular types of problems. Chapter 1
explains the overall approach of the IFIM. Chapters 2 and 3 relate to activi-
ties that preceed data collection: determining the scope of the study and
selecting study areas. Chapter 4 shows the sequence of data collection and
analysis that should be followed to address a particular problem. It is at
this stage that the user essentially builds his or her own model to solve a
specific problem. Chapter 5 details the various options for preparing, dis-
playing, and interpreting the output from the IFIM.
Part II contains ancillary information regarding specific parts of the
IFIM. Chapter 6 presents some of the concepts of hydrology and channel
dynamics that must be understood in order to apply the method effectively.
The goal of Chapter 6 is not to make hydrologists or hydraulic engineers out
of everyone using the methodology. Rather, it is intended to provide a back-
ground about how water supplies can be estimated, how reservoirs are operated,
and how channels change in response to watershed or streamflow alterations.
Much of this information is derived from outside sources during most applica-
tions of the methodology, and it is incumbent on the user to understand the
methods used to supply the information, as well as the assumptions and limita-
tions inherent to the estimation technique.
The subject of Chapter 7 is the Physical Habitat Simulation System
(PHABSIM). More specifically, Chapter 7 addresses those aspects of PHABSIM
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