Mean Flow Characteristics in a Rock-Ramp-Type Fish Pass

Detailed mean flow characteristics generated by a staggered arrangement of boulders in a rock-ramp-type naturelike fish pass were investigated experimentally at three different channel slopes (5%, 3%, and 1.5%). The results showed that this type of fish pass can produce adequate water depth and favorable flow velocity suitable for fish passage. Three different characteristic velocity regions were identified, namely, downstream of boulders (wake region), intermediate region, and upstream of boulders. Some general correlations were developed for predicting the flow depth and velocity in a rock-ramp fish pass as a function of normalized discharge. Moreover, a flow-resistance analysis based on basic concepts for wake-interference flow regime in this fish pass has resulted in a general equation for the average velocity. This study improves the understanding of the complex flow characteristics in a rock-ramp fish pass.