Development of the revised USDA–NRCS intake families for surface irrigation

In the absence of localized field data the US Department of Agriculture–Natural Resources and Conservation Service (USDA–NRCS) intake families have often provided sufficient information for preliminary design, evaluation, or management of surface irrigation systems. However, to more fully utilize advances in procedures for field data collection and analysis as well as the software to automate the hydraulic computations, it has become necessary to revise these intake families. This paper is presented to facilitate the dissemination of these results to the larger international audience as well as provide a more detailed explanation of the protocols used in developing the revised families. A selective comparison is made to illustrate the differences between the original and new curves.