Incorporating sharp crested weirs into irrigation SCADA systems
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(r) 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 25deg to 100deg, partially or fully contracted 90deg V notch weirs, partially or fully contracted rectangular weirs (including suppressed rectangular weirs) and fully contracted Cipoletti weirs.