Skip to Main Content
GEOREF RECORD

Sources of sediment to the coastal waters of the Southern California Bight

Jonathan A. Warrick and Katherine L. Farnsworth
Sources of sediment to the coastal waters of the Southern California Bight (in Earth science in the urban ocean; the Southern California continental borderland, Homa J. Lee (editor) and William R. Normark (editor))
Special Paper - Geological Society of America (2009) 454: 39-52

Abstract

The sources of sediment to the Southern California Bight were investigated with new calculations and published records of sediment fluxes, both natural and anthropogenic. We find that rivers are by far the largest source of sediment, producing over 10X10 (super 6) t/yr on average, or over 80% of the sediment input to the Bight. This river flux is variable, however, over both space and time. The rivers draining the Transverse Ranges produce sediment at rates approximately an order of magnitude greater than the Peninsular Ranges (600-1500 t/km (super 2) /yr versus <90 t/km (super 2) /yr, respectively). Although the Transverse Range rivers represent only 23% of the total Southern California watershed drainage area, they are responsible for over 75% of the total sediment flux. River sediment flux is ephemeral and highly pulsed due to the semiarid climate and the influence of infrequent large storms. For more than 90% of the tune, negligible amounts of sediment are discharged from the region's rivers, and over half of the post-1900 sediment load has been discharged during events with recurrence intervals greater than 10 yr. These rare, yet important, events are related to the El Nino-Southern Oscillation (ENSO), and the majority of sediment flux occurs during ENSO periods. Temporal trends in sediment discharge due to land-use changes and river damming are also observed. We estimate that there has been a 45% reduction in suspended-sediment flux due to the construction of dams. However, pre-dam sediment loads were likely artificially high due to the massive land-use changes of coastal California to rangeland during the nineteenth century. This increase in sediment production is observed in estuarine deposits throughout coastal California, which reveal that sedimentation rates were two to ten times higher during the nineteenth and twentieth centuries than during pre-European colonization.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 454
Title: Sources of sediment to the coastal waters of the Southern California Bight
Title: Earth science in the urban ocean; the Southern California continental borderland
Author(s): Warrick, Jonathan A.Farnsworth, Katherine L.
Author(s): Lee, Homa J.editor
Author(s): Normark, William R.editor
Affiliation: U. S. Geological Survey, Santa Cruz, CA, United States
Affiliation: U. S. Geological Survey, Menlo Park, CA, United States
Pages: 39-52
Published: 2009
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 60
Accession Number: 2009-074422
Categories: Oceanography
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables, sketch maps
N32°30'00" - N34°30'00", W121°00'00" - W117°00'00"
Secondary Affiliation: Bedford Institute of Oceanography, CAN, Canada
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200940
Program Name: USGSOPNon-USGS publications with USGS authors
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal