American Society of Agricultural and Biological Engineers

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Infiltration and Roughness Equations for Surface Irrigation: How Form Influences Estimation

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  012255,  2001 ASAE Annual Meeting. (doi: 10.13031/2013.4126) @2001
Authors:   A. J. Clemmens, D. E. Eisenhauer, B. L. Maheshwari
Keywords:   Surface irrigation, parameter estimation, infiltration, roughness

Some two-dozen methods have been proposed in the literature for estimating an infiltration function from field measurements. These methods vary in their data requirements and analytical rigor, however most assume some functional form of the infiltration equations. Also, the Manning n has also been shown to vary with time during an irrigation as the soil is smoothed by the flowing water. Thus estimates of Manning n based on the advance curve may vary substantially from those based on measured water depths. Inappropriate selection of equations or parameter values for one (infiltration or roughness) can lead to unrealistic parameter values for the other. This leads to a great deal of uncertainty when such parameters are then used in simulation and design software in order to deduce system behavior with the intent of improvement. In this paper, we provide examples that demonstrate the difficulty in the estimation of parameters.

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