The Rotating Erosion Testing Apparatus (RETA): A Laboratory Device for Measuring Erosion Rates versus Shear Stresses of Rock and Cohesive Materials

This paper describes an apparatus for testing the erosion rate of erodible rock and stiff clay as a function of water-flow-induced shear stress. The device, referred to as the Rotating Erosion Testing Apparatus, or RETA, is similar in design to other devices but has a number of advantages. The RETA uses a real-time control unit that monitors the shear stress via the torque imparted to the sample and adjusts its rotational speed to maintain a nearly constant shear stress throughout the test. RETA test results have been used to estimate local sediment erosion rates at structures founded in these types of bed materials.