Drivers of Morphodynamic Change and Hypoxic Events in Southern California Lagoons

Extreme weather events can cause flooding in Southern California estuaries, which in turn can close roads, flood neighborhoods, cause other damage to surrounding infrastructure, and cause permanent alterations to the future circulation of the estuary. With the predictions of sea level rise and increased storminess, coastal managers are looking for ways to better predict the response of estuaries in the future, to plan preemptive dredging events, and to adopt coastal resiliency programs to reduce damage. USC Sea Grant funded two studies to assess the impact of extreme storm and wave events and the interaction of waves, currents and sediment movement in different types of Southern California estuaries. The goal is to make predictions about how estuaries will respond to future conditions to assist management efforts.

Key Results:

  • Estuaries that have structures (jetties, groins, etc.) tended to remain open and experience less sediment accretion and less exacerbated high water levels than estuaries without structures (which also tend to have more marsh habitat). 
  • Structures enhanced erosion of the adjacent beaches 
  • Single storm events lasting 1-2 days can result in large-scale sediment changes and alter lagoon circulation for weeks


Project Impacts & Application:

  • Giddings served as a scientific advisor for the Southern California Wetlands Recovery Project and the group intends to use data resulting from this project in a new case study of Los Peñasquitos Lagoon


Principal Investigators:

  • Sarah N Giddings, Ph.D., University of California, San Diego, 
  • Geno Pawlak, Ph.D., University of California, San Diego



NOAA, 2016-2018


Additional Info and Publications:

  • Harvey, M.E., Giddings, S.N., Pawlak, G. et al. Hydrodynamic Variability of an Intermittently Closed Estuary over Interannual, Seasonal, Fortnightly, and Tidal Timescales. Estuaries and Coasts 46, 84–108 (2023).

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