ASCE DU: Establishment of a Standard Performance Indicator for On-Farm Irrigation
The formation of a standard ASCE performance indicator for on-farm irrigation started back in the 1970s with John Merriam and Jack Keller. Their book established a standard method to determine the performance measurement of Distribution Uniformity (DU). This was used in the 1980s as the California Department of Water Resources wanted to kick start an assessment of how water was being used for on-farm irrigation. This was a period that California growers had experienced the worst drought in modern history (1977) and was at the early stages of a massive switch of acreage to modernize the systems with drip irrigation. The simple premise of the new standard was to be able to set up an abbreviated set of measurements that could be replicated by several teams of evaluators. Charles Burt was in the process of forming the Irrigation Training and Research Center and found that there were several researchers and teams that were using their own definitions for DU. ITRC worked with a team of ASCE scientists/engineers to establish a standard definition and methodology for quantifying global DU as well as the various components contributing to it and publish a standard document through the committee process within ASCE (and later through EWRI). ITRC has published the results of teams following the ASCE DU protocol for decades. This has required careful quality control of field technicians and engineers to make sure the protocol was followed. Fast forwarding this outline to 2025. Unfortunately, there persists many evaluation teams that are determined to change the process to shorten the window required for a complete assessment. This lecture will address the challenges of maintaining a standard protocol to highlight the differences between a 0.94 value using the ASCE DU protocol versus some of the other methods being used.
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