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I I I I I I I I I I I I I I I I I I I Fortunately, increased pressure to measure is accompanied by the increased affordability of water measurement for canal companies. Water measurement also has many direct benefits and incentives for canal companies, including: . Improved canal management · Improved on-farm irrigation management · Establishment of a data base and historical patterns of water use · Ability to report for well augmentation plan reporting · Recharge program management & reporting . Billings to secondary supply customers . Securing the water right and decree . Alarm conditions (example: storm inflows) . Accountability There are many types of water measurement structures that can be used to accurately and cost effectively measure water flow. In northern Colorado the Parshall flume is most commonly used, however the long-throated flume (L TF) is increasing in popularity. Long- throated flumes have many advantages over more traditional water measurement structures, including: · Hiaher Accuracv: These flumes are more accurate than most measurement flumes such that rating tables can be calculated with an error less than.!. 2 %. · More Economical: Long-throated flumes are usually the most economical of all structures for accurately measuring flow. · Lower Head Loss: The required head loss over the long-throated flume is small. This head loss requirement may be estimated with sufficient accuracy for any of these structures placed in an arbitrary channel. · Reduced Debris and Sediment: Because of their gradual converging transition, these flumes have few problems with floating debris and sediment. · On-site and Flexible Construction: Long-throated flumes can have nearly any desired cross-sectional shape and can be custom fitted into most canal-site geometries. The throat cross section can be shaped in such a way that the complete range of discharges can be measured accurately. A rating table can also be produced based on post-construction dimensions if flume requirements are met. · Flexible Desian: Long-throated flumes are amenable to selection, design, and calibration by computer techniques. Their design is based on pure hydraulic theory, not empirical calculations. If the Union Ditch finds it necessary to install measurement structures in the future they should consider installing L TFs for the obvious advantages they offer. Figure 9 is a conceptual schematic of a L TF with SCADA (discussed later) and Figure 10 is L TF flume that has recently been built near Greeley. Aqua Engineering, Inc. November 17, 2004 Canal Modernization Study -17-