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INVESTIGATING UNCERTAINTY AND SENSITIVITY IN INTEGRATED MULTIMEDIA ENVIRONMENTAL MODELS: TOOLS FOR 3MRA
Citation:
Babendreier, J E. AND K J. Castleton. INVESTIGATING UNCERTAINTY AND SENSITIVITY IN INTEGRATED MULTIMEDIA ENVIRONMENTAL MODELS: TOOLS FOR 3MRA. Presented at International Environmental Modelling and Software Society 2002 Biennial Meeting, Lugano, Switzerland, June 24-27, 2002.
Impact/Purpose:
The current focus is to 1.) develop, distribute, and support the FRAMES-3MRA modeling technology, 2) to apply the FRAMES-3MRA modeling technology for the purposes of executing national and site-specific risk assessments, 3) to complete model application case studies to explore model performance issues, such as, model validation, 5) to collaborate with other Federal Agencies in an effort to leverage expertise and resources associated with common modeling interests, and 6) to monitor ongoing developments at the Office of Solid Waste and within the environmental modeling community in an effort to identify new needs for science modules and locate or develop solutions within the FRAMES 3MRA modeling system.
Description:
Sufficiently elucidating uncertainty and sensitivity structures in environmental models can be a difficult task, even for low-order, single-media constructs driven by a unique set of site-specific data. The ensuing challenge of examining ever more complex, integrated, higher-order models is a formidable one, particularly in regulatory settings applied on national scales that must ensure the continued protection of humans and ecology while preserving the economic viability of industry. Quantitative assessment of integrated, multi-media models that simulate hundreds of sites, spanning multiple geographical and ecological regions, will ultimately require a systematic, comparative approach coupled with sufficient computational power. The Multi-media, Multi-pathway, and Multi-receptor Risk Assessment Model (3MRA) is an important code, being developed by the United States Environmental Protection Agency, for use in risk assessment of hazardous waste management facilities. The model currently entails over 700 variables, 200 of which are explicitly stochastic. 3MRA starts with a chemical concentration in a waste management unit (landfill, waste pile, aerated tank, surface impoundment, or land application unit), estimates the release and transport of the chemical throughout the environment, and predicts associated exposure and risk. 3MRA simulates multi-media (air, water, soil, sediments), fate and transport, multi-pathway exposure routes (food ingestion, water ingestion, soil ingestion, air inhalation, etc.), multi-receptor exposures (resident, gardener, farmer, fisher, ecological habitats and populations; all with various cohort considerations), and resulting risk (human cancer and non-cancer effects, ecological population and community effects). 3MRA collates the output for an overall national risk assessment, offering a probabilistic strategy as a basis for regulatory decisions. Design of SuperMUSE, a 125 GHz PC-based, Windows-based supercomputer for Model Uncertainty and Sensitivity Evaluation is described, along with conceptual layout of an accompanying java-based parallelization software toolset. Initial sensitivity and uncertainty analyses of 3MRA are also presented with plans for conducting additional screening level and global sensitivity analysis techniques.