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Effects of antecedent hydrologic conditions, time dependence, and climate cycles on the suspended sediment load of the Salinas River, California
Journal article   Open access   Peer reviewed

Effects of antecedent hydrologic conditions, time dependence, and climate cycles on the suspended sediment load of the Salinas River, California

Andrew B. Gray, Gregory B. Pasternack, Elizabeth B. Watson, Jonathan A. Warrick and Miguel A. Goni
Journal of hydrology (Amsterdam), v 525, pp 632-649
01 Jun 2015
url
https://www.escholarship.org/uc/item/26x146s7View

Abstract

Engineering Engineering, Civil Geology Geosciences, Multidisciplinary Physical Sciences Science & Technology Technology Water Resources
Previous estimations of sediment flux for the Salinas River of central California were based on data collected in the 1970s and assumptions of time invariant suspended sediment-discharge behavior. The goals of this study were to estimate sediment flux from the Salinas River using data from 1967-2011 by incorporating time dependent behavior and reassess the role of El Nino Southern Oscillation patterns in inter-decadal sediment load. This study builds on previous findings that time-dependent suspended sediment behavior in this system is controlled in part by antecedent hydrologic conditions. The condition of temporal dependence was further tested herein through comparison of flux estimates obtained using time-dependent formulations and a multivariate approach incorporating hydrologic factors. Longer sampling records and incorporation of decadal scale behavior or antecedent hydrologic conditions resulted in average annual load estimates of 2.0-2.9 Mt/yr with 95% confidence intervals of +/- 25 to 202%, in comparison to earlier estimates of similar to 3.3 Mt/yr. Previous overestimation of sediment load is due largely to the extrapolation of suspended sediment behavior from a decade of high sediment concentrations to the entire record, and the use of log-linear regression techniques on a non-linear system. The use of LOESS methods lowered Q(ss) estimates and decreased confidence interval size. The inclusion of time-stratified and antecedent flow indices further decreased Q(ss) estimates, but increased confidence interval size. However, temporal dependence of the C-ss-Q relationship violates the assumptions of single base period regression, which suggests that time-stratified rating curves provide more realistic estimates of sediment flux means and uncertainty. The majority of suspended sediment was transported by flows of similar to 25-90 times mean discharge depending on transport constituent (fines or sand) and estimation method. Periods of differential suspended sediment behavior changed the relative importance of rare floods due to changes in the relationship of suspended sediment concentration vs. discharge. El Nino years dominated the sediment budget by producing on average ten times more sediment than non-El Nino years. Sediment load estimates provided further evidence that antecedent hydrologic conditions appear to have caused much of the temporal dependence of suspended sediment behavior. (C) 2015 Elsevier B.V. All rights reserved.

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This publication has contributed to the advancement of the following goals:

#2 Zero Hunger
#14 Life Below Water
#15 Life on Land

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Collaboration types
Domestic collaboration
Web of Science research areas
Engineering, Civil
Geosciences, Multidisciplinary
Water Resources
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