HR: 1340h
AN: H13A-0387    [Abstracts]
TI: The Role of Monitoring in Risk-Informed Assessments Involving Uncertainty
AU: * Meyer, P D
EM: philip.meyer@pnl.gov
AF: Pacific Northwest National Lab, 620 SW Fifth Ave Suite 810, Portland, OR 97204 United States
AU: Nicholson, T J
EM: tjn@nrc.gov
AF: Office of Nuclear Regulatory Research U.S. Nuclear Regulatory Commission, Mail Stop T-9C34, Washington, DC 20555-0001 United States
AB: Research is currently underway to develop a systematic methodology for identifying and assessing uncertainties in ground-water models, focusing on the joint assessment of parameter, conceptual model, and hydrologic scenario uncertainties using a Bayesian model averaging approach. Specially-designed monitoring programs may be useful in this approach in several ways, including (1) developing prior information on parameter and model probabilities, (2) calibration/recalibration of models to provide updated estimates of parameter values/uncertainties and predicted system behavior, including uncertainties, and (3) confirmation/modification of management decisions, including decisions about ongoing monitoring. We outline a framework for making monitoring decisions within the context of a systematic uncertainty assessment. This framework incorporates a number of key concepts. Monitoring needs to support ongoing conceptual model development/refinement, parameter estimation, and hydrologic scenario definition. Since uncertainty is due in part to lack of knowledge of the system's significant features, events, and processes related to flow and transport, monitoring should be focused on improving probabilistic estimates of system performance indicators, such as water and contaminant fluxes. Although monitoring may only directly confirm short-term (e.g., decades) system behavior rather than long-term (e.g., millennia) behavior, insights into long-term prediction uncertainties can be achieved through a Bayesian-based monitoring approach. Furthermore, an ongoing monitoring program focused on identifying and reducing uncertainties can provide information to improve (on a cost or time basis) risk-informed decisions, such as the long-term safety of decommissioning sites or the evaluation of remediation options and closure decisions.
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
DE: 1866 Soil moisture
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting