Site Features:

IFIM & PHABSIM

This study is based on the principles of the Instream Flow Incremental Methodology (IFIM). IFIM is a problem solving approach that translates baseline or altered hydrology into descriptions of available or usable habitat for increments of instream flow. Essentially, answering the question of what happens to instream habitat, fish community structure, water quality, etc. when the flow changes? (Stalnaker et al 1995)

The IFIM process involves the following steps:

1. Scoping
2. Selection of Target Species and Habitat Suitability Criteria
3. Habitat Mapping and Selection of Study Reaches
4. Transect Selection and Field Data Collection
5. Hydraulic Modeling
6. Habitat Modeling
7. Interpreting PHABSIM and Completing IFIM Process

Steps 5 - 6 involve the use of PHABSIM software. The Physical Habitat Simulation System (PHABSIM) is an integral component of IFIM (Bovee 1994). PHABSIM is a set of complex modeling tools that develop a prediction of usable habitat for fish, or other biota, as a function of discharge.

Please click on each step to see how this process has been implemented on the North Fork Shenandoah Instream Flow Study!