ARI Project: 13-01-005 | Funding Round: Round 14 (2012-2013)  | Start Date: 07/01/2012  | Status: Completed

Improving Flow Measurement Accuracy at Farm Delivery Gates in California

ARI Member Campus: California Polytechnic State University, San Luis Obispo
Research Focus Area: Water and Irrigation Technology
Project Personnel: Director: Howes, Daniel, Irrigation Training and Research Center BioResource and Agricultural Engineering Department College of Agriculture, Food and Environmental Sciences Cal Poly State University
Co-Investigator: Burt, Charles, Irrigation Training and Research Center, BRAE Dept., College of Agriculture, Food, and Environmental Sciences, Cal Poly State University
Collaborator: Spiess, Michael, Californa State University, Chico, College of Agriculture
Collaborator: Styles, Stuart, Bioresource & Agricultural Engineering Department, College of Agriculture, Food, and Environmental Sciences, Cal Poly State University
Collaborator: Gaudi, Franklin, Irrigation Training and Research Center, California Polytechnic State University
ARI Allocation: $285,320.00
Match Donors: $287,500.00 - Imperial Irrigation District via Davids Engineering, Inc
Total Funding: $572,820.00

Project Objective: To improve the accuracy of, and confidence in, gate rating equations for the most common types of orifice gates in California: metergates and simple sluice gates. The expected outcomes are three products to help irrigation districts accurately measure farm delivery flow rates: 1. New rating tables for common gates (currently manufactured) installed under standard conditions; 2. Adjustment factors for non-standard conditions within certain acceptable limits; and 3. Specifications on the types of non-standard conditions that are not acceptable for accurate flow measurement (meeting the new +/-12% accuracy standard).

Project Abstract: The recently enacted Senate Bill (SB) X7-7 mandates water conservation and water use efficiency targets for urban and agricultural water suppliers in California. As part of this legislation, large agricultural water suppliers (irrigation districts) are being required to measure water deliveries volumetrically within mandated levels of accuracy. Districts must provide evidence that their existing delivery structures are capable of measuring volumetrically within +/-12% of actual at each delivery, or a new flow measurement device is required (new devices must measure delivery volumes within +/-6%). It is estimated that installation of new flow measurement devices in districts needing to meet the new requirements will cost the districts and the farmers of California $333,000,000. Delivery gate rating tables are one of the most widely used methods of on-farm delivery discharge measurement in California. However, many of these rating tables and constants were developed 60 to 100 years ago based on standard installation design requirements for gates that are no longer manufactured. Because of the vast array of conditions in the field, in many cases, these gates are installed in non-standard conditions. The proposed study aims to develop standard gate discharge rating tables for gates currently manufactured and for gate sizes commonly found in California for standard installation conditions. This will be accomplished by utilizing a combination of field measurements and laboratory investigations. In addition, gate discharges will be examined under non-standard conditions to develop adjustment factors for the new standard rating tables when these conditions exist. Some delivery gate installations are expected to be outside of the range of conditions where accurate flow measurement can be achieved with new standard ratings and adjustment factors. A list of recommendations on how to modify these sites will be developed so that the tables and adjustment factors can be used to meet SB X7-7 requirements. The overall results from this study will provide solutions for irrigation districts to meet SB X7-7 at a fraction of the cost of new flow measurement devices. This project is estimated to save California irrigation districts and farmers $10-20 million.

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