Estimation of Contaminant Concentration in Ground Water Using a Stochastic Flow and Transport Model

Bioplume II, a widely used computer model developed by researchers at Rice University, models the transport of dissolved hydrocarbons in ground water under the influence of oxygen-limited biodegradation. The model is deterministic, and it was of interest to allow the model to reflect uncertainty in its input variables and to quantify the resulting uncertainty in output contamination estimates. A Monte Carlo interface to the model was developed. This interface gives contaminant concentration information in the form of mean and standard deviation maps. An improved method of estimating contaminant concentrations using this stochastic version of Bioplume II is presented. This method allows contaminant concentration estimates to be obtained for arbitrary spatial locations, not limited to locations at the centers of the cells on the grid used by the model. Additionally, the method allows for calculation of the probability that the contaminant exceeds some user-specified threshold for any loc..