Suspended sediment behavior in a coastal dry-summer subtropical catchment: Effects of hydrologic preconditions

Abstract

TitleSuspended sediment behavior in a coastal dry-summer subtropical catchment: Effects of hydrologic preconditions

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

“…Magnitude/frequency analysis clearly shows that moderate to high discharges accounts for most of the sediment transported through the lower Salinas at the interdecadal scale. Furthermore, short elapsed time since the last moderate to high discharge activity has been shown to increase sand concentrations (Gray et al, 2014). Thus, El Niño cycles appear to increase total Q SS and augment sand supply due to closer timing of these high discharge events.…”

“…For in depth reporting on available suspended sediment, water discharge and precipitation data see Gray et al (2014). The USGS collected flow-integrated (depth and width integrated) suspended sediment samples from 8 u n c o r r e c t e d , a c c e p t e d the Salinas at locations corresponding to the S1 and S2 gauges during 1967-2010, while the authors collected near-surface samples during 2008-2011, respectively (USGS NWIS; Gray et al, 2014). Only USGS suspended sediment data that uniquely represent a given discharge event with associated instantaneous Q and particle size data was included in this study.…”

“…The authors previously examined the effects of antecedent hydrologic conditions on suspended sediment behavior in the lower Salinas River at event to interannual (Gray et al, 2014), and decadal timescales (Gray, in press). The one-day change in Q from the day before the day of sampling was described as ∆Q d .…”

Conversion to drip irrigated agriculture may offset historic anthropogenic and wildfire contributions to sediment production

“…However, attributing changes in sediment regimes to a discrete cause is often complicated by the overprinting of many external drivers and internal dynamics that affect watershed scale sediment production and transport, which tend to obscure the effects of individual forcing factors (Walling, 1977;Syvitski et al, 2000). Furthermore, factors affecting watershed-scale sediment production operate over a wide range of time scales, with even seemingly discrete events generating legacy effects that may last for years or decades (Warrick et al, 2012;Warrick et al, 2013;Gray et al, 2014). Semi-arid basins in particular have been found to display persistent dependence on climatically driven antecedent basin conditions, such as storm/flood and wildfire histories (Abraham, 1969;Tanji et al, 1980;Lenzi and Marchi, 2000;Lana-Renault et al, 2007;Warrick and Rubin, 2007;López-Tarazón et al, 2011;Gray et al, 2015a).…”

“…Integrated expressions of external and internal factors in the form of antecedent hydrologic conditions (i.e. discharge and drought history) that are affected by ENSO have also been examined as controls on suspended sediment discharge regimes (Gray et al, 2014;2015a;2015b). One previous study has also addressed the importance of wildfire in controlling the sediment export from a major Salinas tributary (Warrick et al, 2012).…”