Electromagnetic River Flow Gauges: Experience of the Environment Agency of England and Wales

Abstract

The Environment Agency of England and Wales owns and operates over 1,000 river flow gauges of which 35 are electromagnetic (EM) river flow gauges. The Environment Agency became fully operational in 1996 and is a non departmental government body whose principal aim is to protect and improve the environment and in doing so contribute to sustainable development. The EM river flow gauge was first introduced in the early 1980's as a method of continuous river flow measurement. Many have been in service with the Agency and its predecessors for over 15 years. The EM gauge is important because it can provide flow data from difficult sites where other traditional methods have failed. The Theory and Principles of the EM gauge operation is outlined in the paper. The principal components of the gauge are identified along with an outline of the construction process and site applications and limitations. The paper also reviews the calibration process, the performance of EM gauges and the ability to retrospectively reprocess flow data archives when gauge constants are changed through the calibration process.