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Demonstration Flow Assessment: Judgment and Visual Observation in Instream Flow Studies
Author(s) -
Railsback Steven F.,
Kadvany John
Publication year - 2008
Publication title -
fisheries
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.725
H-Index - 79
eISSN - 1548-8446
pISSN - 0363-2415
DOI - 10.1577/1548-8446-33.5.217
Subject(s) - habitat , computer science , objectivity (philosophy) , flow (mathematics) , environmental resource management , hydrology (agriculture) , data science , environmental science , ecology , geology , geotechnical engineering , mathematics , biology , philosophy , geometry , epistemology
The Demonstration Flow Assessment (DFA) method evaluates instream flow benefits using expert judgment and direct observation of habitat during several flows. Early DFA applications were low‐effort, qualitative, and vulnerable to well‐known biases. We describe a higher‐effort, more quantitative DFA (or expert habitat mapping) approach that uses techniques from the judgment‐based decision analysis literature to increase objectivity and reproducibility. Specific metrics—habitat types to be quantified visually during flow observations—are designed from appropriate conceptual models of how flow affects target resources. During field observations, patches of each habitat type are delineated by consensus and marked on maps for digital analysis. A case study illustrates these procedures applied to instream flows for salmon spawning and rearing.