Estimating Uncertainty in Fish Habitat Modeling Using Two-Dimensional Hydraulics

Sensitivity in the magnitude and functional relationship between Weighted Usable Area (WUA) and discharge are explored for habitat modeling results using two-dimensional hydraulic simulations. Uncertainty in simulated water surface elevations, depths and velocities are examined for a range of expected simulation errors and subsequent magnitude and relationship of predicted WUA. Sensitivity of habitat modeling output is also examined for ranges of expected uncertainty associated with combinations of depth, velocity, and habitat suitability criteria using hydrodynamic simulation results for 18 river systems. Model sensitivity in the magnitude and functional relationships between WUA and discharge were found to be most sensitive to the habitat suitability criteria selected while size of river system and expected ranges in depth and/or velocity uncertainties had little impact on the magnitude or functional relationships in computed habitat. This is attributed to compensatory effects associated with the large number of computational nodes arising from the computational meshes with application of two-dimensional hydraulic simulations