Superfund Research Program
A Holistochastic Approach to Human Exposure Assessment
Project Leader: George Christakos
Grant Number: P42ES005948
Funding Period: 1995 - 2006
The progress on this project during the last year involves the following developments. Scientists have improved and extensively tested numerical codes for space transformation based solutions of fluid flow in heterogeneous porous media. A flowpath approach for solving multiphase flow equations and preliminary numerical implementation of the method were developed. Project researchers continued development of diagrammatic methods for the calculation of stochastic moments and introduced a new variational technique for the evaluation of the effective permeability in heterogeneous media. Researchers have shown that the homogeneous/stationary random field model leads to a decrease in the effective permeability with increasing domain size. In addition, the spatiotemporal analysis of environmental and health processes has been extended by developing new generalized covariance models that permit modeling different types of heterogeneity. The numerical code used for the implementation of spatiotemporal analysis and generation of maps has been expanded and improved in order to improve numerical efficiency and accuracy. Questions related to the interaction of different scales involved in the simulation have been investigated. Finally, the spatiotemporal analysis was used for generating (i) maps of groundwater quality indicators over the Dyle region, as well as (ii) breast cancer incidence in the state of North Carolina, which highlight the dynamic evolution of the spatiotemporal disease patterns due to contamination and other factors. Such maps can be used for estimating environmental risk factors, for exposure-health damage analysis, and also for linking human activity to changes in human health and disease incidence.