 Pilkey's research centers on both basic and applied coastal geology, focusing primarily on barrier island coasts and the effects of shoreline stabilization and development, and sea level rise.The PSDS has analyzed the numerical models used by coastal geologists and engineers to predict the movement of beach sand, especially in beach replenishment.In general, Pilkey argues that mathematical models cannot be used to accurately predict the behavior of beaches, although they can be useful if directional or orders-of-magnitude answers are sought.