An exploratory study of fish habitat structures in rivers

Any development in a natural stream such as construction of a hydraulic structure disturbs the flow regime of the stream and possibly changes the water quality. Attempts made to maintain and improve fish habitat in the areas affected by hydraulic structures include the provision of habitat structures. The purpose of these habitat structures is to create a pool behind them with larger depth and smaller velocity to provide a resting, spawning, and feeding area for fish. An exploratory laboratory study was conducted on the hydraulics of habitat structures. Experiments were performed with a single hemispherical structure located centrally in a rectangular flume. Various hemisphere diameters, height to water depth ratios (h/D), and Froude number (F) of flow were used in the experiments. For relatively smaller values of h/D and F, the flow was similar to that of a deeply submerged body. As h/D and F increased, the difference from the deeply submerged wake appeared to increase. Correlations were found for the characteristics of the wake for a range of flow parameters. 5 refs., 6 figs