MODELS ON TRIAL: A CASE STUDY

A recent “takings” lawsuit in the state of Florida provides an excellent example of the difficulties faced by those who question the scientific validity and physical reality of models designed to represent complex natural processes. A number of oceanfront property owners filed suit against the Sebastian Inlet Tax District (SITD) in Brevard County, Florida asserting that the inlet and associated jetties have been responsible for substantial downdrift erosion along the entire Brevard County shoreline. Substantial field data covering all aspects of nearshore processes have been collected by SITD scientists over the last 10+ years. These data indicate that the nearshore processes along the Brevard County shoreline are incredibly complex. There is strong geologic control with outcropping Pleistocene Anastasia Formation. This outcropping rock exerts a primary control on wave climate, sediment supply, shoreline position, and all aspects of nearshore processes. Erosion and accretion rates vary considerably alongshore and temporally, definitely not reflecting a simple interruption of longshore sediment as the only cause downdrift shoreline change. In evaluating the substantial data, the author found it impossible to determine how far down the shore the inlet might be impacting shoreline change. What was abundantly clear was that the inlet is far less important in explaining the erosion/accretion pattern than was the control of the outcropping geologic units. Surprisingly, the trial verdict turned on the testimony of two consulting engineers neither of whom collected any of their own data. They used a generalized numerical model and a simple conceptualized sediment budget (an arithmetic, box model) to demonstrate a definite downdrift impact. Neither model considered the offshore geology or any process complexity, yet, it was the models that the judge decided to follow when issuing a judgment, ignoring all other scientific testimony. The models, he decided, were objective. It didn’t matter that they were also irrelevant. The question raised by the experience is this: How can field scientists, provide information in a format that is useful as an alternative to models to a typically non-scientific decision maker? What do we do when our data indicate that a precise answer cannot be determined, but a decision must be made?