Southeastern Section - 60th Annual Meeting (23–25 March 2011)

Paper No. 9
Presentation Time: 11:15 AM


PILKEY, Orrin H., Duke University, P.O. Box 90228, Durham, NC 27708,

Applied mathematical modeling of beach processes often trumps field observations and historical evidence. The mathematical models are said to be sophisticated and state- of-the-art and, to the untrained eye of local politicians and jurists, are more impressive than qualitative observational evidence. Coastal science has been damaged in two ways by such modeling. First, actual applications of beach behavior principles (e.g., shoreline response to sea level rise, and environmental impact of measures to combat shoreline retreat due to sea level rise) are largely based on models that clearly don’t work. Among other things, storm activity, generally responsible for most beach changes, is unpredictable. Second, in order to model earth-surface events, processes are routinely represented in simplified fashion. Unfortunately as the science of beaches has evolved, model simplifications have come to be considered reality. Two such model simplifications used in shoreline behavior modeling that have become accepted principles are shoreface closure depth and the shoreface profile of equilibrium. Neither has any basis in reality, and their widespread application has led to errors in interpretation and prediction of shoreline evolution in a rising sea level. There are other examples of carrying model simplifications into the real world to the detriment of understanding shoreline evolution. Best to separate the worlds of modeling and reality.