Intertidal Area Disappears Under Sea Level Rise

Intertidal Area Disappears Under Sea Level Rise: 250 Years of Morphodynamic Modeling in San Pablo Bay, California

Elmilady, H.M.S.M.A. (TU Delft Coastal Engineering; IHE Delft Institute for Water Education; Deltares)
van der Wegen, M. (IHE Delft Institute for Water Education; Deltares)
Roelvink, D. (TU Delft Coastal Engineering; IHE Delft Institute for Water Education; Deltares)
Jaffe, B. E. (Pacific Coastal and Marine Science Center)

2019

Anticipated sea level rise (SLR) threatens intertidal areas and associated ecosystems in estuaries worldwide. There is a need to develop validated modeling tools to assess the impact of SLR on estuarine morphodynamics. This study explores the morphological impact of SLR on a channel-shoal system in San Pablo Bay, a subembayment of San Francisco Bay, California, using a 3-D, process-based modeling approach (Delft3D) including density currents and wave action. The Bay underwent considerable morphologic development in response to variations in fluvial sediment load and discharge associated with a period of hydraulic mining for gold and later damming in the watershed. The availability of a unique 150-year, 30-year sequenced, bathymetric data set provided a rare opportunity for model validation. We investigate a 250-year period of morphodynamic evolution including a 150-year hindcast and a 100-year forecast with different SLR scenarios. The model shows significant skill in hindcasting volumes and patterns of bathymetric development during both net depositional (1856–1951) and erosional (1951–onward) periods. Forecasts show that SLR alters the Bay's erosional trend to a depositional trend again. Despite increased sediment trapping rates, the intertidal mudflats drown under all modeled SLR scenarios (42, 84, and 167 cm by end of the 21st century). Our work highlights the potential of using process-based models to assess the morphodynamic impact of SLR. The study also suggests that SLR can greatly increase the loss of intertidal area when landward migration is not possible. Sustainable management strategies are required to safeguard these valuable intertidal habitats.

Delft3D
Estuary
Intertidal mudflats
Long-term Morphodynamics
San Francisco Bay
Sea-level rise

http://resolver.tudelft.nl/uuid:d9012741-bceb-472d-8c36-9abb733208e6

https://doi.org/10.1029/2018JF004857

2169-9003

Journal of Geophysical Research: Earth Surface, 124 (1), 38-59

Institutional Repository

journal article

© 2019 H.M.S.M.A. Elmilady, M. van der Wegen, D. Roelvink, B. E. Jaffe