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Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/25/2016 Publication Date: 12/18/2016 Publication URL: https://handle.nal.usda.gov/10113/5801858 Citation: Bautista, E. 2016. Effect of infiltration modeling approach on operational solutions for furrow irrigation. Journal of Irrigation and Drainage Engineering. 142(12):Article 06016012. Available: http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29IR.1943-4774.0001090 Interpretive Summary: A challenge to the analysis of furrow Irrigation systems is characterizing the infiltration process as a function of flow depth and, thus, wetted perimeter. Porous media flow theory indicates that the final distribution of infiltrated water along a furrow depends on variations in flow depth along the field and in time. However, furrow infiltration studies in the field have not produced consistent relationships between flow depth, wetted perimeter, and infiltration. Thus, when conducting operational or design analyses for furrow systems, solutions need to be developed considering alternative models of the infiltration process. WinSRFR, the surface software package developed by USDA-ARS, currently offers various empirical alternatives for modeling furrow infiltration. An approximate furrow infiltration model based on physical principles has recently been added. A simulation study was conducted to examine the operational solutions that can be developed with different furrow infiltration modeling approaches. The analysis was conducted under the assumption that the true infiltration characteristics of the field are given by the physically-based infiltration model, Results show that operational solutions can be very sensitive to the infiltration modeling approach under some hydraulic conditions, but very insensitive under others. This information should be of interest to users of irrigation modeling software. Technical Abstract: Infiltration in irrigated furrows depends on the variation of depth of flow and, thus, wetted perimeter along the field and in time. However, the magnitude of the wetted perimeter effect has not been clearly established due to soil variability, erosion and deposition, macropore flow, and other processes that affect infiltration. Hence, furrow irrigation models currently offer various alternatives, mostly empirical but some physical, for modeling the infiltration process as a function of wetted perimeter. In principle, the selected a modeling approach can have a significant impact on the predicted performance. This is of particular importance for operation and design analyses, cases in which performance is examined over a wide range of inflow rates and physical configurations. A simulation study was conducted to examine the operational solutions that can be developed with different furrow infiltration modeling approaches. The analysis was based on the infiltration options offered by WinSRFR, the surface software package developed by USDA-ARS. The analysis was conducted under the assumption that the true infiltration characteristics of the example furrow were given by a physically-based infiltration formulation. Performance contours and operational solutions were developed for a free draining and blocked furrow. Results show that operational solutions can be very sensitive to the infiltration modeling approach with the free draining system, but potentially less sensitive with the blocked system. |
