Measuring Water in Trapezoidal Canals

Abstract

Laboratory experiments were conducted to evaluate the hydraulic characteristics of a simple portable flume. The flume consists of a pipe installed axially inside a trapezoidal channel with side slopes of 1/1. The ratio of the diameter of the pipe to channel bottom width was approximately 90% or more. The presence of the column reduces the cross section of the flow, creating a critical‐flow condition. A gage is installed at the upstream side of the column to measure the depth of the water upstream of the critical‐flow section. The reading on the gage is directly related to the flow rate. Based on the parameters measured in the laboratory, a computer model is developed for calibration of this type of flume. The computer model is tested using data collected from flumes installed in the field. The computer model predicted the measured flow rates with a maximum error of 5.1%. The maximum submergence limit was measured at 81%.