Incorporating sharp-crested weirs into irrigation SCADA systems

Abstract

Real-time flow measurement and monitoring are important components of modern irrigation SCADA systems. Many projects have existing sharp-crested weir structures that have not been incorporated into SCADA systems because they are partially contracted, and thus do not have a simple rating equation relationship. The Kindsvater-Carter procedure for calibrating partially contracted sharp-crested weirs is accurate and straightforward, but also somewhat tedious. Existing computer programs simplify the process but can presently be applied only to individual measurements. This paper presents a Microsoft® Excel spreadsheet model that can compute complete rating tables for sharp-crested weirs with full or partial flow contraction, using the Kindsvater-Carter procedure. Furthermore, through regression analysis, the spreadsheet determines a simplified rating equation that can easily be incorporated into remote terminal units (RTUs) and SCADA systems. The spreadsheet can be applied to fully contracted V-notch weirs with included angles of 25° to 100°, partially or fully contracted 90° V-notch weirs, partially or fully contracted rectangular weirs (including suppressed rectangular weirs), and fully contracted Cipoletti weirs.