Hyperpycnal sediment discharge from semiarid southern California rivers: Implications for coastal sediment budgets
January 1, 2003
Southern California rivers discharge hyperpycnal (river density greater than ocean density) concentrations of suspended sediment (>40 g/L, according to buoyancy theory) during flood events, mostly during El Nin??o-Southern Oscillation (ENSO) conditions. Because hyperpycnal river discharge commonly occurs during brief periods (hours to occasionally days), mean daily flow statistics often do not reveal the magnitude of these events. Hyperpycnal events are particularly important in rivers draining the Transverse Range and account for 75% of the cumulative sediment load discharged by the Santa Clara River over the past 50 yr. These events are highly pulsed, totaling only ??? 30 days (??? 0.15% of the total 50 yr period). Observations of the fate of sediment discharge, although rare, are consistent with hyperpycnal river dynamics and the high likelihood of turbidity currents during these events. We suggest that much of the sediment load initially bypasses the littoral circulation cells and is directly deposited on the adjacent continental shelf, thus potentially representing a loss of immediate beach sand supply. During particularly exceptional events (>100 yr recurrence intervals), flood underflows may extend past the shelf and escape to offshore basins.
Citation Information
Publication Year | 2003 |
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Title | Hyperpycnal sediment discharge from semiarid southern California rivers: Implications for coastal sediment budgets |
DOI | 10.1130/G19671.1 |
Authors | J.A. Warrick, John D. Milliman |
Publication Type | Article |
Publication Subtype | Journal Article |
Series Title | Geology |
Index ID | 70025156 |
Record Source | USGS Publications Warehouse |