|Walker, Wynn -|
Submitted to: National Decennial Irrigation Conference
Publication Type: Proceedings
Publication Acceptance Date: December 5, 2010
Publication Date: December 5, 2010
Citation: Bautista, E., Walker, W.R. 2010. Advances in Estimation of Parameters for Surface Irrigation Modeling and Management. National Decennial Irrigation Conference. PAPER NUMBER: IRR10-9643. Interpretive Summary: Surface irrigation is the dominant method of agricultural water application. Since many of those systems exhibit poor performance, opportunites exist for conserving water through improved system design and operation. Models of the irrigation process can be used to predict performance. Key inputs are the infiltration and hydraulic resistance properties of the soil, which are difficult to measure. Models of the irrigation process can also be combined with selected irrigation output measurements to infer field-average values for the infiltration and roughness properties, in a computational process known as estimation. Several estimation methods exist, but few are used in practice because of measurement and computational difficulties and the uncertainty of results. This article reviews advances that have taken place over the last decade on this topic. A basic challenge to estimation is that, depending on the particular conditions, irrigation tests may provide limited information about the properties being measured, but that may not be evident from the measured outputs. Hence, users need significant understanding of the limitaitons of estimation concepts and tools in order to use the available data most effectively. This information should be of interest to professionals working on irrigation system design and management, including staff of the Natural Resources Conservation Service staff, extension agents, and irrigation consultants.
Technical Abstract: Mathematical models of the surface irrigation process are becoming standard tools for analyzing the performance of irrigation systems and developing design and operational recommendations. A continuing challenge to the practical use of these tools is the difficulty in characterizing required model inputs, namely soil and crop hydraulic properties. Numerous procedures have been suggested for estimation of those properties, but few are actually used in practice. Furthermore, users of these procedures often have only a limited understanding of the advantages and limitations of procedures, and the implications of the results. A Task committee of the Irrigation and Drainage Council, Environmental and Water Resources Institue of ASCE examined the state of the science for determination of soil and crop hydraulic properties for surface irrigation modeling and management. This paper summarized some of their findings and other recent advances in this field.