The supply of sediment from the landscape to the ocean directly influences the beaches and coastal systems downstream of these sources.
Adequate supply of sediment is necessary for keeping beach "sand-sheds" in balances, thereby reducing the potential for coastal erosion. Jonathan A. Warrick and Leal A.K. Mertes report on the rates and locations of sediment discharge from the Western Transverse Ranges, a major mountain range immediately northwest of Los Angeles, California.
They found that the rates of sediment supply are not only considerably larger than the surrounding southern California region, but that there is considerable variability in the supply rates within the range.
Watersheds with the highest rates of sediment supply were shown to originate in areas with relatively young and highly erodable bedrock and in regions of relatively high tectonic uplift. Land use was also found to significantly affect sediment supply rates.
Thus, the rate of sediment supply to the southern California coast is directly related to the geological setting and land use history of the source watersheds.
This research is published by Jonathan A. Warrick and Leal A.K. Mertes in the July-August 2009 GSA Bulletin.
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