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Effect of infiltration modeling approach on operational solutions for furrow irrigation

Bautista, Eduardo
Journal of Irrigation and Drainage Engineering 2016 v.142 no.12 pp. 1-11
Agricultural Research Service, computer software, furrow irrigation, furrows, infiltration (hydrology), macropore flow, models, soil heterogeneity
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 the infiltration process. 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 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, respectively, 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 models. The analysis was based on the modeling options offered by a software package developed by U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS). The analysis was conducted under the assumption that the true infiltration characteristics of the example furrow were given by a semiphysically based infiltration model. 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 a free draining system, but less sensitive with blocked systems.