Mudflat morphodynamics and the impact of sea level rise in South San Francisco Bay

Estuaries and Coasts
By: , and 

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Abstract

Estuarine tidal mudflats form unique habitats and maintain valuable ecosystems. Historic measurements of a mudflat in San Fancsico Bay over the past 150 years suggest the development of a rather stable mudflat profile. This raises questions on its origin and governing processes as well as on the mudflats’ fate under scenarios of sea level rise and decreasing sediment supply. We developed a 1D morphodynamic profile model (Delft3D) that is able to reproduce the 2011 measured mudflat profile. The main, schematised, forcings of the model are a constant tidal cycle and constant wave action. The model shows that wave action suspends sediment that is transported landward during flood. A depositional front moves landward until landward bed levels are high enough to carry an equal amount of sediment back during ebb. This implies that, similar to observations, the critical shear stress for erosion is regularly exceeded during the tidal cycle and that modelled equilibrium conditions include high suspended sediment concentrations at the mudflat. Shear stresses are highest during low water, while shear stresses are lower than critical (and highest at the landward end) along the mudflat during high water. Scenarios of sea level rise and decreasing sediment supply drown the mudflat. In addition, the mudflat becomes more prone to channel incision because landward accumulation is hampered. This research suggests that sea level rise is a serious threat to the presence of many estuarine intertidal mudflats, adjacent salt marshes and their associated ecological values.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Mudflat morphodynamics and the impact of sea level rise in South San Francisco Bay
Series title Estuaries and Coasts
DOI 10.1007/s12237-016-0129-6
Volume 40
Issue 1
Year Published 2017
Language English
Publisher Springer
Contributing office(s) Pacific Coastal and Marine Science Center
Description 13 p.
First page 37
Last page 49
Country United States
State California
Other Geospatial South San Francisco Bay