Flow measurement using ultra sound Doppler flowmeters. Case of small rural watercourses

Abstract

Measuring flow rates at the outlet of small rural catchments (<3500 Ha) is essential for estimating pollutant fluxes resulting from agricultural activities. Many norms exist for measuring flow rates(28 norms cited in ISO/TR8363: 1997). In this article, we propose a simple method for measuring flow rates in open channels using continuous wave Doppler flowmeters, henceforth rather commonly used. This method has not been registered as a norm, yet, but technical specifications have been drawn (ISO/TS 15769:2000(E)). We here propose a description of the Doppler method principles and limits. Several monitoring stations that we built serve for evaluating the performance of the method. We believe this method can be very appropriately used for flow rates under 10 m³/s and in locations where other classical methods are used in less that satisfactory situations.