|Guzman-rojo, Daniela - University Of Mexico|
|Gonzalez-trinidad, Julian - University Of Mexico|
Submitted to: Proceedings ASCE North American Water and Environment Congress
Publication Type: Proceedings
Publication Acceptance Date: 3/20/2017
Publication Date: 5/26/2017
Citation: Bautista, E., Guzman-Rojo, D.P., Gonzalez-Trinidad, J. 2017. Variability of furrow infiltration and irrigation performance in a macroporous soil. Proceedings ASCE North American Water and Environment Congress. p.p. 484-494.
Interpretive Summary: A continuing challenge to improving the hydraulic performance of surface irrigation systems is quantifying infiltration and its variability in space and time. This study examines that variability using an infiltration model that accounts for the effect of variable flow depth using porous media flow theory. The model accounts also, empirically, for the flow of water through soil macropores, which cannot be described with porous media flow theory. The study involved 30 irrigation evaluations, conducted over 5 irrigation events. Estimation procedures were used to determine two model parameters, the hydraulic conductivity and the macroporosity term. For the particular field, the measured infiltration varied substantially between furrows and also between irrigation events. This variability can be attributed to a greater degree to variability in the hydraulic conductivity. The proposed infiltration model was found to represent the infiltration process reasonably under the given field conditions. These results should be of interest to irrigation researchers and practitioners, as it illustrates the use of a recently developed approach for modeling furrow infiltration under field conditions.
Technical Abstract: The study of spatial and temporal variations of infiltration in furrows is essential for the design and management of surface irrigation. A key difficulty in quantifying the process is that infiltration is dependent on the depth of flow, which varies along a furrow and with time. An additional difficulty is that under many field conditions, a large fraction of the infiltrated water flows through macropores. This study evaluates a proposed furrow infiltration model that accounts for both effects. Flow depth dependent infiltration is computed based on porous media flow theory. The macropore contribution is modeled as water that infiltrates instantaneously. Parameter estimation techniques were used to determine two of the model parameters, the hydraulic conductivity and the macroporosity term, and the Manning roughness coefficient. The methodology was tested using 30 furrow irrigation data sets collected in 6 furrows over 5 irrigation events. The analysis produced reasonable estimates for hydraulic conductivity relative to values reported in the literature. The estimated macroporosity term exhibited greater variation between irrigation events than between furrows during an event. Irrigation simulations were conducted with the estimated infiltration and roughness parameters. The observed irrigation measurements (advance, recession times, outflow rates, and flow depths) were simulated with reasonable accuracy for all events. Results show that the proposed furrow infiltration model can represent the infiltration process reasonably and that the proposed estimation procedure can yield consistent infiltration and hydraulic resistance parameters. Results also illustrate the large infiltration variability that can be encountered in furrow irrigated fields.