ANALYSIS ON FLOWS THROUGH AND OVER A RUBBLE MOUND WEIR AND CLASSIFICATION OF FLOW REGIME

Abstract

 A one-dimensional model was developed in order to clarify hydraulic characteristics of rubble mound weir. Theoretical solutions of water surface profile and discharge rating curve were obtained for every categories of flow regime and they were verified by comparing with a laboratory experiment. The flow structure was classified into three categories of flow regime depending on water level and weir height. They are “Regime-S” in which the weir is submerged and the stream is running completely over the weir, “Regime-P” in which the weir is partially submerged and the stream is buried to the weir body in a middle reach of weir and “Regime-E” in which the weir is emerged and the stream is buried along the whole reach. Each flow regime was divided further into two categories depending on the influence of backwater, which are the flow controlled by backwater and the flow governed by critical depth, respectively. The six categories of flow regime were systematically displayed in a diagram of discharge contour map in which discharge is plotted as a function of the water depths at the cross section of upstream and downstream boundaries.