The Use of Labyrinth-Weirs for Water Level Control

Abstract

ABSTRACT Labyrinth weirs have particular advantages for water level control in flat land. At low flows intake structures require a certain minimum depth but the maximum depth at high flows must be limited to prevent extensive upstream flooding. Typically this is achieved using a low weir surmounted by a controllable undershot gate that is closed at low flows and opened as the flow increases. A labyrinth weir is an attractive alternative that fulfils the same purpose. In this structure the crest length is made significantly longer than the width of the river; this is achieved by having a planform that consists of repeating geometric cycles, typically trapezoidal in form. The long crest length means that it can pass large flows at low heads. Water levels at low flows are maintained simply by the height of the weir crest. The economic advantages of labyrinth weirs are demonstrated with respect to a weir constructed on the Ciwadas River in Indonesia. This was designed to handle flood flows of 200 m3/s and to ...