VELOCITY AND WATER DEPTH ANALYSIS ON DIFFERENT TYPES OF BLOCK RAMPS

摘要

Block ramps are used to protect rivers against dangerous bed erosion and to enhance fish migration. To ensure fish passage, hydraulic criteria like maximum flow velocities, minimal water depths and maximum water level differences must be fulfilled. A systematic laboratory study was performed in order to measure these hydraulic criteria fixed for trouts. Statistical and spatial distributions of velocities, water depths as well as the ratios of water depth and velocity head were compared for the different types of block ramps. The results have revealed that uniform block ramps can rarely satisfy the criteria for fish migration. Structured block ramps are more efficient. Nevertheless optimum conditions for fish migration can only be reached for ramp slopes under 6 %.