|Strelkoff, Theodor - UNIV OF AZ, TUCSON, AZ|
|Playan, E - CSIC, ZARAGOZA, SPAIN|
Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 17, 2000
Publication Date: June 15, 2003
Citation: Clemmens, A.J., Strelkoff, T.S., Playan, E. Field verification of two-dimensional surface irrigation model. Journal of Irrigation and Drainage Engineering. ASCE 129(6):402-411. 2003 Interpretive Summary: Irrigated agriculture is under pressure from other water users and environmentalists to improve its water management. Many in the irrigation industry assume that improvements in irrigation performance requires conversion to pressurized irrigation systems. However, a variety of modern, highly efficient surface irrigation methods are in use that achieve efficiencies that are competitive with more expensive pressurized systems. Achieving high performance with surface irrigation requires precise grading of the land surface, for example with laser-controlled land grading equipment. Such land grading is never perfect, and deviations from a plane surface can influence the performance of the irrigation system. No rigorous analysis has been made of the influence of these deviations in the ground surface on irrigation performance. Recently, a two-dimensional model of water flow over an irregular ground surface was developed to study these effects under surface irrigation. This paper provides field verification o that model. The paper should be of interest to agriculturalists, consulting engineers, irrigation designers, the Natural Resources Conservation Service, and others. Ultimately more appropriate irrigation methods will conserve water and benefit the environment.
Technical Abstract: A two-dimensional 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 that provides verification of this two-dimensional model. 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 etwo-dimensional model. Differences in advance for a plane versus undulatin field surface were minor, except near the end of advance.