299-4 Tracking Sediment Mixing of Los Angeles Rivers in the San Pedro Littoral Cell

Session: Geochemical Studies of Sediments (Posters)

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Abstract:

In many river and beach ecosystems, sediment transfer has been affected by human modification. The creation of infrastructure continues to create problems, leading to the changing of the natural key processes of the Earth’s ecosystems. Namely the reduction of sediment reaching the coast will negatively impact coastal resilience to rising sea level induced erosion. This research aims to investigate how human infrastructure has impacted the rivers’ capability to transfer sediment in the Los Angeles Basin to coastal regions. This will be accomplished through examining the composition of the coastal deposits before significant human influence to identify key shifts in sediment transport over time. In this work we present initial detrital zircon and apatite U-Pb results from the Los Angeles, San Gabriel, and Santa Ana rivers, as well as the associated beaches these rivers terminate at including Long Beach, Seal Beach, and Newport Beach, respectively. We will integrate geographical information systems to study the watersheds of these river systems and make watershed models of erosion and sediment transport to the coastal regions. These new data will serve as a modern baseline to compare against offshore samples that we expect to record the Los Angeles landscape before significant agriculture, irrigation, and development.  

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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