A SEQUENTIAL UNCERTAINTY DOMAIN INVERSE PROCEDURE FOR ESTIMATING SUBSURFACE FLOW AND TRANSPORT PARAMETERS

A parameter estimation procedure, sequential uncertainty domain parame ter fitting (SUFI), is presented and has the following characteristics . The procedure is sequential in nature, meaning that one more iterati on can always be made before choosing the final estimates. The procedu re has a Bayesian framework, indicating that the method operates withi n uncertainty domains (prior, posterior) associated with each paramete r. The procedure is a fitting procedure, conditioning the unknown para meter estimates on an array of observed values. Finally, the procedure is iterative, requiring a stopping rule which is provided by a critic al value of a goal function. Performance of the SUFI parameter estimat ion procedure is demonstrated using three examples of increasing compl exity: (1) analysis of a solute breakthrough curve measured in the lab oratory during steady state water flow, (2) estimation of the unsatura ted soil hydraulic parameters from a transient drainage experiment car ried out in a 6-m deep lysimeter, and (3) estimation of selected flow and transport parameters from a hypothetical ring infiltrometer experi ment. The procedure was found to be general, stable, and always conver gent.