A STUDY ON THE HYDRAULIC JUMP CHARACTERISTICS ON THE ISLAND SURFACE

Abstract

River restoration projects are being implemented in several developed countries and artificial islands are normally constructed as eco-hydraulic components of river ecosystem. Those artificial islands with non cemented material (natural construction) can be damaged and eroded by hydraulic jump. The hydraulic jump with high velocity and high Froude number (Fr>1) can initiate intensive erosion on the island surface. This research is conducted in Theodor Rechbock Laboratory, University of Karlsruhe, Germany and to understand the characteristic of hydraulic jump over an island. The research focuses on the influence of Froude number (Fr) and relative water depth (y/hisland) on the location and type of the hydraulic jumps. The hydraulic jump can arise in the front, behind, above and both sites of island. The research result concludes; that the hydraulic jump occur doe to the direct changing from supercritical to sub critical flow condition over island and the Froude number and relative water depth (Fr and y/hpulau) have significant influence on the type and location of those hydraulic jumps. A diagram expresses the relationship between Fr, (y/hpulau), type and location of hydraulic jump is resulted and can be used to predict the hydraulic jump characteristic over an island in a river by different flow condition and water depth.