Uncertainty and Sensitivity of Advective Travel Time

In the May-June edition of Groundwatger, researchers present a method for quantifying uncertainty and sensitivity of advective travel time along a flow path.  The researchers developed a theoretical matrix composed of twenty-seven hydrogeological units (HGUs).  They assigned each unit porosity statistics, including a mean, a coefficient of variation, and a distribution type (normal, log normal or log triangular).  Conductivity values were derived from the mean porosity.  The researchers created three unique scenarios by varying the lengths of the HGUs. Then, they conducted a sensitivity analysis to determine the importance of the individual HGU uncertainty to the overall uncertainty of the travel time. The HGUs with a high mean porosity, a high coefficient of variability, or a long length contributed most to the overall uncertainty.  The work shows that in real world application, practitioners can most efficiently reduce the overall uncertainty be reducing the uncertainty in HGUs that have the identified characteristics.

Zhu, Jianting et al. 2010. Sensitivity of Solute Advective Travel Time to Porosities of Hydrogeologic Units. Groundwater. 48(3). 442-447.