PHABSIM/SEFA Application for Minimum Flows and Levels Development in Florida

Abstract

Physical Habitat Simulation System (PHABSIM) or System for Environmental Flow Analysis (SEFA) are typically used to simulate the relationship between river flow and physical habitat of various life stages of a fish species. They are a component of the Instream Flow Incremental Methodology (IFIM) and are widely used across the globe for deductive estimation of biological effects of stream flow alteration. These models have been applied at various spatial and temporal scales corresponding to the objectives of the specific applications. The objectives of this work effort are to review spatial and temporal scales of previous habitat modelling applications and to recommend a best practice approach for the application of physical habitat simulation software. Two leading software packages are considered-PHABSIM and SEFA, both are improvements of IFIM framework. Specifically, this research paper recommends best practices that can be used in environmental flows development. The review was focused on literature related to selecting species, and the time steps for developing and applying Area Weighted Suitability (AWS) vs. discharge curves used for developing environmental flows. The term AWS in SEFA replaces the original weighted usable area (WUA) in PHABSIM because it is a more accurate description of the physical meaning of the variable.