title: Ecohydrological model parameter selection for stream health evaluation.
abstract: Variable selection is a critical step in development of empirical stream health prediction models. This study develops a framework for selecting important in-stream variables to predict four measures of biological integrity: total number of Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa, family index of biotic integrity (FIBI), Hilsenhoff biotic integrity (HBI), and fish index of biotic integrity (IBI). Over 200 flow regime and water quality variables were calculated using the Hydrologic Index Tool (HIT) and Soil and Water Assessment Tool (SWAT). Streams of the River Raisin watershed in Michigan were grouped using the Strahler stream classification system (orders 1-3 and orders 4-6), k-means clustering technique (two clusters: C1 and C2), and all streams (one grouping). For each grouping, variable selection was performed using Bayesian variable selection, principal component analysis, and Spearman's rank correlation. Following selection of best variable sets, models were developed to predict the measures of biological integrity using adaptive-neuro fuzzy inference systems (ANFIS), a technique well-suited to complex, nonlinear ecological problems. Multiple unique variable sets were identified, all which differed by selection method and stream grouping. Final best models were mostly built using the Bayesian variable selection method. The most effective stream grouping method varied by health measure, although k-means clustering and grouping by stream order were always superior to models built without grouping. Commonly selected variables were related to streamflow magnitude, rate of change, and seasonal nitrate concentration. Each best model was effective in simulating stream health observations, with EPT taxa validation R2 ranging from 0.67 to 0.92, FIBI ranging from 0.49 to 0.85, HBI from 0.56 to 0.75, and fish IBI at 0.99 for all best models. The comprehensive variable selection and modeling process proposed here is a robust method that extends our understanding of watershed scale stream health beyond sparse monitoring points.
authors.affiliation: Department of Biosystems and Agricultural Engineering, 524 S. Shaw Lane, Room 216, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Sean A
authors.initials: SA
authors.lastname: Woznicki
authors.affiliation: Department of Biosystems and Agricultural Engineering, 524 S. Shaw Lane, Room 216, Michigan State University, East Lansing, MI 48824, USA. Electronic address: pouyan@msu.edu.
authors.forename: A Pouyan
authors.initials: AP
authors.lastname: Nejadhashemi
authors.affiliation: Department of Computer Science and Engineering, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Ross
authors.affiliation: Physical Sciences Division, Department of Statistics, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: International Joint Commission, Great Lakes Office, Windsor, ON N9A 6T3, Canada.
authors.forename: Lizhu
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Computer Science and Engineering, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Abdol-Hossein
authors.initials: AH
authors.lastname: Esfahanian
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D044822:Biodiversity; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D005399:Fishes; D062070:Hydrology; D007313:Insecta; D008824:Michigan; D008962:Models, Theoretical; D045483:Rivers; D014876:Water Pollution / Q000032:analysis / Q000706:statistics & numerical data*
keywords: Biological Integrity; Clustering; Fish; Fuzzy logic; Macroinvertebrate; SWAT