Influence of history and environment on the sediment dynamics of intertidal flats

• Three intertidal environments were studied with measurement and analysis tools.
• In the lowest energy environment, the critical shear stress prevents net erosion.
• Sediment properties have a strong relationship to morphologic trends and history.

Morphological trends of three distinct intertidal environments in South San Francisco Bay were investigated using a combination of measurement and modeling tools. Because of the inherent relationship between the physical environment and the sediment properties, the sediment properties provide a good indicator of morphologic trends. A significant finding of this study is that surface sediment erodibility increases as the energy level in the environment increases. Conversely subsurface sediment erodibility shows a strong relationship to the long-term history of the site. The combination of the measured sediment properties, the history of deposition and erosion, and simple modeling of the physical environment illustrate the interaction of these properties such that an understanding of intertidal flat behavior is developed.