L’ incertitude dans la simulation des tendances d’évolution de la qualité des eaux souterraines en écoulement transitoire Las incertidumbres de la simulación de en las tendencias de la calidad del agua subterránea en flujo transitorio Incerteza na simulação de tendências de qualidade de águas subterrâneas em regime variável

Starn, J Jeffrey; Bagtzoglou, Amvrossios C.; Robbins, Gary A.

L’ incertitude dans la simulation des tendances d’évolution de la qualité des eaux souterraines en écoulement transitoire Las incertidumbres de la simulación de en las tendencias de la calidad del agua subterránea en flujo transitorio Incerteza na simulação de tendências de qualidade de águas subterrâneas em regime variável | Uncertainty in simulated groundwater-quality trends in transient flow

2013

Starn, J Jeffrey | Bagtzoglou, Amvrossios C. | Robbins, Gary A.

In numerical modeling of groundwater flow, the result of a given solution method is affected by the way in which transient flow conditions and geologic heterogeneity are simulated. An algorithm is demonstrated that simulates breakthrough curves at a pumping well by convolution-based particle tracking in a transient flow field for several synthetic basin-scale aquifers. In comparison to grid-based (Eulerian) methods, the particle (Lagrangian) method is better able to capture multimodal breakthrough caused by changes in pumping at the well, although the particle method may be apparently nonlinear because of the discrete nature of particle arrival times. Trial-and-error choice of number of particles and release times can perhaps overcome the apparent nonlinearity. Heterogeneous aquifer properties tend to smooth the effects of transient pumping, making it difficult to separate their effects in parameter estimation. Porosity, a new parameter added for advective transport, can be accurately estimated using both grid-based and particle-based methods, but predictions can be highly uncertain, even in the simple, nonreactive case.

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