CENTER FOR COMPUTATIONAL MATHEMATICS COLLOQUIUM

                  UNIVERSITY OF COLORADO AT DENVER



TITLE:   Groundwater Transport with Stochastic Retardation


SPEAKER: Patrick O'Leary, University of Wyoming
         

DATE:    Monday, April 20, 1998  


PLACE:   Mathematics Conference Room 626 
         UCD Building, 1250 14th St., Denver


TIME:    noon (Refreshments served at 11:45 am) 



ABSTRACT

Most practical groundwater transport problems involve spatially
heterogeneous porous media.  Also, we rarely have detailed 
knowledge of the aquifer's spatially variable material 
properties, so we must consider them to be random fields with 
some known statistics.  The modeling problem is therefore 
stochastic.

One way to attack the problem is to ask the following question:  
Given statistical knowledge of the coefficients in the partial 
differential equation governing contaminant transport, what can 
we say about the ensemble of contaminant plumes that are 
solutions to the equation?

In this talk, we examine this question for the case when just 
one of the coefficients -- namely the retardation factor 
associated with contaminant adsorption -- is a random field.  
Stochastic analysis shows that the average contaminant plume 
obeys an integrodifferential equation.  This "effective 
equation" has terms that imply both increased effective 
retardation and enhanced contaminant spreading that one cannot 
model using standard Fickian assumptions.  Monte Carlo 
simulations, using suites of computational realizations, 
corroborate both effects.  We discuss some theoretical and 
numerical implications of the new model.