Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2004
Publication Date: July 2, 2004
Citation: Pachepsky, Y.A., Guber, A.K., Jacques, D., Kouznetsov, M.Y. 2004. Complexity of simulated soil water fluxes. [Abstract].International Workshop "PEDOFRACT 2004", July 2-6, 2004, Barco de Avila, Spain. p. 17.
Technical Abstract:
Complexity of water flow pathways may be easily perceived but is difficult to represent in mathematical terms without making strong simplifying assumptions. This implies that many different model structures could be consistent with available observations. The objective of this work was to find out whether complexity of the simulation results is indicative of differences in model concepts and parameter sources. A Richards equation-based model, and a water budget model were used to simulate one-year of soil water contents and infiltration fluxes in a 1-meter deep soil profile. To compute the complexity measures, time series of fluxes were encoded with a binary alphabet; fluxes greater (less) than the median value were encoded with one (zero). The software SYMDYN has been used to compute Shannon and Rényi entropies, metric entropy, mean information gain, mean mutual information, effective measure complexity, fluctuation complexity, and Rényi complexity. Coordinates 'randomness measure ' complexity measure' were used to compare models. Model outputs showed distinct differences in their relationships between complexity and randomness, including cases when model accuracies appeared to be similar. Model ranking by the output complexity did not match the model ranking by complexity derived from the number of model parameters and/or domain discretization detail. Because the presence of structure in water flux time series may be critical for solute transport, evaluating soil water flow models by the randomness and complexity of their output presents an interesting avenue to explore.
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