Hydraulic Analysis and Modeling of Fish Habitat Structures
Fisheries Bioengineering Symposium: American Fisheries Society Symposium 10
American Fisheries Society
Hydraulic analysis of fish habitat structures has received little attention in engineering research or in practical application. The objective of my work was to calibrate scour and discharge equations for common habitat structures. These equations predict water depths and velocities, which can be used in physical habitat models to predict quantities of habitat created or lost when structures are installed in streams. In addition to habitat estimation, this research can aid in proper placement of structures in streams and in flood-potential analysis. Structures that were physically modeled include log weirs, flow deflectors, digger logs, and a new structure called a digger weir. One existing scour equation slightly underestimated scour at log weir models. The same equation also predicted scour at models of digger weirs. The coefficient of discharge for model log weirs correlated with log diameter. Field conditions of sloped log crests and poorly sealed logs contributed to a wide variation in discharge coefficients at prototype logs. The submerged flow equation predicted backwater depths at model deflectors with less than 15% error. Three deflector scour equations tested were based on sand bed channels and did not accurately predict gravel bed model scour. Model digger logs developed the largest scour hole when the base of the log was level with the channel bed.