Comparison of stochastic and regression based methods for quantification of predictive uncertainty of model-simulated wellhead protection zones in heterogeneous aquifers

For a synthetic case we computed three types of individual prediction intervals for the location of the aquifer entry point of a particle that moves through a heterogeneous aquifer and ends up in a pumping well. (a) The nonlinear regression-based interval (Cooley, 2004) was found to be nearly accurate and required a few hundred model calls to be computed. (b) The linearized regress ion-based interval (Cooley, 2004) required just over a hundred model calls and also appeared to be nearly correct. (c) The calibration-constrained Monte Carlo interval (Doherty, 2003) was found to be narrower than the regression-based intervals but required about half a million model calls. It is unclear whether or not this type of prediction interval is accurate.