Statistical mechanics of wind wave-induced erosion in shallow tidal basins: Inferences from the Venice Lagoon

Abstract

Wind wave-induced erosional effects are among the chief landscape-forming processes in tidal biomorphodynamics. Wave-driven bottom erosion, in fact, controls the equilibrium elevation and dynamics of subtidal and tidal flat surfaces, and the impact of waves against salt marsh margins influences their stability. The relevance of predictive studies projecting wind wave patterns in space and time is thus notable especially in view of the limited insight gained so far. Here we have employed a complete, coupled finite element model accounting for the role of wind waves and tidal currents on the hydrodynamic circulation in shallow basins to analyze the characteristics of combined current- and wave-induced exceedances in bottom shear stress over a given threshold for erosion. The results of our analyses from the Venice Lagoon suggest that wind wave-induced resuspension events can be modeled as a marked Poisson process, thus allowing one to set up a theoretical framework which can be used to model wind wave effects through the use of Monte Carlo realizations. This bears important consequences for quantitative analyses of the long-term biomorphodynamic evolution of tidal landscapes. Key Points Wind wave-induced resuspensions can be modeled as marked Poisson processes Interarrival time, intensity & duration of wind-wave erosion are space dependent Our results bear significant practical implications on tidal morphodynamics ©2013. American Geophysical Union. All Rights Reserved.