Field Verification of Two-Dimensional Surface Irrigation Model |
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Authors: | A. J. Clemmens T. S. Strelkoff E. Playán |
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Affiliation: | 1Director, U.S. Water Conservation Laboratory (USWCL), 4331 E. Broadway, Phoenix, AZ?85040. 2Research Hydraulic Engineer, U.S. Water Conservation Laboratory, 4331 E. Broadway, Phoenix, AZ?85040. 3Researcher, Estación Experimental de Aula Dei, CSIC. P.O. Box 202, E-50080, Zaragoza, Spain. Collaborator via a fellowship under the OECD Co-operative Research Programme: Biological Resource Management for Sustainable Agricultural Systems.
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Abstract: | A two-dimensional (2D) model of unsteady shallow-water flow in surface irrigation was developed to evaluate the influence of field-grading precision on surface irrigation performance. This paper presents field data for verification of this 2D model. No attempt was made here to evaluate irrigation performance. Verification of such models relies on independent estimates of parameters for infiltration and roughness. To accomplish this, water surface elevations were measured at 26 points within a 3 ha level basin. A double-bubbler system was used to obtain relative water depths. Field surveys were used to convert these to water surface elevations and field water depths, from which surface water volumes over time were computed. The infiltration function was determined by matching inflow minus surface volume over time with computed subsurface volume. A value of Manning n (0.05) was found for which advance and water depth hydrographs were both well predicted with the 2D model. Differences in advance for a plane versus undulating field surface were minor, except near the end of advance. |
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Keywords: | Surface irrigation Unsteady flow Shallow water Two-dimensional flow Infiltration |
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