Restoring Rivers for Fish and Fishers: There are two forms of water conditions in rivers that fish and aquatic insects interpret and adapt to with remarkable skill. In still water the conditions are primarily shaped by the geometry of the river channel. In flowing water the conditions are particular structures within the flow, for example, the rotational currents formed in meanders or the back-eddies and pools of refuge created next to torrents and rapids.
The flowing forms are also responsible for shaping mobile streams into meanders, pools and riffles. Both water conditions are strategically used by insects and fish for migration, spawning, feeding and resting.
Stream Restoration Science - New Blends of Old Wine: The present uncomplicated hydraulic theory for uniform and rapidly-varied river flow is derived from observations and experiments undertaken in the 18th Century, for example by Daniel Bernoulli (1700-1782) and Antoine Chezy (1718-1798).
Other scientists and engineers have further defined the forms of flow and their occurrence in natural channels; Froude (state of flow), Reynolds (turbulence), Prandtl (separation), Yalin (meanders), and Leopold and Wolman (river geometry) to name a few. Contemporary studies in stream ecology (now coined as eco-hydrology) have followed the advice of Noel Hynes in 1971 to "unite the stream and its valley". This led to the also uncomplicated river continuum model and the use of flow parameters to describe the habitats of insects, fish and aquatic plants.
The early science and contemporary observations are presented and then illustrated in a few examples of restoring fish habitats and migration in channelized and dammed streams. Poster