Submitted to: Proceedings of the World Environmental and Water Resources Congress Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/17/2014
Publication Date: 6/1/2014
Citation: Bautista, E., Warrick, A.W., Schlegel, J.L. 2014. Wetted-perimeter dependent furrow infiltration and its implication for the hydraulic analysis of furrow irrigation systems. Proceedings of the World Environmental and Water Resources Congress Conference. p.1727-1735.
Interpretive Summary: WinSRFR and other furrow irrigation models estimate infiltration process empirically. Modeling furrow infiltration is challenging because it is dependent on flow depth. Empirical infiltration equations can be calibrated from field irrigation measurements and can probably generate reasonable infiltration and irrigation performance estimates if flow depths and opportunity times along the field are relatively uniform, such as with short furrows. However, opportunity times and flow depths tend to vary substantially along the run in long fields. Under those conditions, empirical furrow irrigation modeling can be expected to be increasingly unrealistic. This article discussed an enhancement to a procedure for estimating flow-depth dependent furrow infiltration, based on an approximate solution the two-dimensional Richards equation. The original procedure was developed assuming that the flow depth acting on the infiltrating surface is constant. A modification is proposed to account for the effect of variations in flow depth with time. Tests show that the methodology is reasonably accurate in comparison with infiltration predictions generated with the Richards equation. The method has been tested in conjunction with the WinSRFR surface irrigation simulation software and shown to be computationally efficient in comparison with alternative methods for modeling flow-depth dependent furrow irrigation. This procedure should be of interest to users of surface irrigation software, including researchers, extension agents, consultants, and irrigation engineering students.
Technical Abstract: This article discusses a methodology, derived from the two-dimensional Richards equation, for estimating furrow infiltration. The method was originally derived assuming a constant pressure head at the infiltrating surface. Application of the methodology to cases where the pressure head is variable with time is examined. The procedure was programmed into the WinSRFR surface irrigation software. Initial results show that the method provides a reasonably accurate reproduction of infiltration predicted with the two-dimensional Richards equation.