A CONSULTANT'S PERSPECTIVE ON INVERSE METHODS: THIRTY YEARS OF TRIAL AND ERROR

Inverse methods are at the core of many hydrologic analyses; ranging from the estimation of hydraulic conductivity from ground-water level change during an aquifer test to estimation of contaminant release histories from concentration data. This talk will provide my historical perspective on how the use of inverse methods by groundwater consultants working on practical problems has changed during my thirty-year career as a consultant using inverse methods. Much has changed in the use of inverse methods primarily as the result of remarkable changes in computing power, but much has remained the same. Inverse methods are and have been essential tools for the consulting hydrogeologist.

Case studies spanning the past three decades involving the use of automated inverse methods will be used to illustrate my perspective on how the use of inverse methods by consultants has changed. In addition, case studies will be used to illustrate how the use of manual inverse methods has changed. These case studies will describe how inverse methods were used, and in some cases, misused in groundwater analyses and will illustrate what has changed and what has not changed over the past thirty years.