Closure to "theoretical analysis of wing dike impact on river flood stages" by Fredrik Huthoff, Nicholas Pinter, and Jonathan W. F. Remo

The discussers criticize the analytical approach in the original paper, repeatedly characterizing it as “oversimplified” and “simplistic.” The original paper was designed explicitly as a “simplified theoretical analysis,” and “a first step to better understand the connections between navigation structures and flood levels on the Middle Mississippi River (MMR).” Such calculations were needed in order to test the previous assertion, much repeated but based on presumed theory alone, that flood stage increases linked to wing-dike construction were “counterintuitive, and contrary to established models of hydraulic behavior” [U.S. Government Accountability Office (USGAO) 2011]. The discussers criticize this simplified analytical approach even though new dike structures on the MMR currently are constructed on the basis of small-scale table-top physical models [utilizing scaling factors of ∼1∶10.000, e.g., Davinroy et al. (2011a)] that do not have the ability to estimate their effects on flood flows. The writers believe that theoretical and numerical analyses may fill this gap and add to the understanding of the functioning of these structures. The presented exploratory investigation in the original paper indicates that wing dikes can increase flood levels and underscores the need for more rigorous follow-up studies. The original paper draws very restrained conclusions—that “more accurate estimates would require more detailed (i.e., 3D) hydrodynamic simulation studies that better represent localized boundary and flow conditions” and that “more detailed follow-up studies are required to accurately quantify the impact of wing dikes on flood levels.”