habitat suitability index models and instream flow suitability curves

PREFACEThe Habitat Suitability Index (HSI) models presented in this publicationaid in identifying important habitat variables. Facts, ideas, and conceptsobtained from the research literature and expert reviews are synthesized andpresented in a format that can be used for impact assessment. The models arehypotheses of species-habitat relationships, and model users should recognizethat the degree of veracity of the HSI model, S1 graphs, and assumptions willvary according to geographical area and the extent of the data base for individualvariables. After clear study objectives have been set, the HS1 modelbuilding techniques presented in U.S. Fish and Wildlife Service (1981)1 andthe general guidelines for modifying HS1 models and estimating model variablespresented in Terrell et al. (1982)2 may be useful for simplifying and applyingthe models to specific impact assessment problems. Simplified models shouldbe tested with independent data sets, if possible. Statistically-derivedmode 1s that are an alternati ve to using Suitabil i ty I ndi ces to cal cul ate anHS1 are referenced in the text.A brief discussion of the use of selected Suitability Index (S1) curvesfrom HS1 models as a component of the 1nstream Flow Incremental Methodology(1F1M) is provided. Additional S1 curves, developed specifically for analysisof spotted bass habitat with 1F1M, also are presented.Results of a model performance test in a 1imited geographical area aresummarized, but model reliability is likely to vary in different geographicalareas and situations. The U.S. Fish and Wildlife Service encourages modelusers to provide comments, suggestions, and test results that may help usincrease the utility and effectiveness of this habitat-based approach toimpact assessment. Please send comments to:Habitat Evaluation Procedures Group orInstream Flow and Aquatic Systems GroupWestern Energy and Land Use TeamU.S. Fish and Wildlife Service2627 Redwing RoadFort Collins, CO 80526-28991U.S. Fish and Wildlife Service.habitat suitability index models.Ecol. Servo n.p.1981. Standards for the development of103 ESM. U.S. Fish Wildl. Serv., Div.2Terrell. J. W.• T. E. McMahon, P. D. Insk t p, R. F. Raleigh, and K. L.Williamson. 1982. Habitat suitability index models: Appendix A. Guidelinesfor riverine and lacustrine applications of fish HS1 models with the HabitatEvaluation Procedures. U.S. Fish Wildl. Servo FWS/OBS-82/10.A. 54 pp.iii