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L.A.K. Mertes

Publications and source records attributed to L.A.K. Mertes.

4 recordsLinked to original sources
USGS2010

Estimating suspended sediment concentrations in turbid coastal waters of the Santa Barbara Channel with SeaWiFS

A technique is presented for estimating suspended sediment concentrations of turbid coastal waters with remotely sensed multi-spectral data. The method improves upon many standard techniques, since it incorporates analyses of multiple wavelength bands (four for Sea-viewing Wide Field of view Sensor (SeaWiFS)) and a nonlinear calibration, which produce highly accurate results (expected errors are approximately ±10%). Further, potential errors produced by erroneous atmospheric calibration in excessively turbid waters and influences of dissolved organic materials, chlorophyll pigments and atmospheric aerosols are limited by a dark pixel subtraction and removal of the violet to blue wavelength bands. Results are presented for the Santa Barbara Channel, California where suspended sediment concentrations ranged from 0–200+ mg l −1 (±20 mg l −1 ) immediately after large river runoff events. The largest plumes were observed 10–30 km off the coast and occurred immediately following large El Niño winter floods.

California↗
USGS2009

Sediment yield from the tectonically active semiarid Western Transverse Ranges of California

Sediment yields from the world's rivers are generally highest from steep drainage basins with weak lithology, active tectonics, or severe land-use impacts. Here, we evaluate sediment yields from the Western Transverse Ranges of California in an attempt to explain why they are two- to tenfold greater than the surrounding areas of California. We found that suspended-sediment yields across the gauged basins of the Western Transverse Range during 1969-1999 varied by approximately an order of magnitude (740-5300 t/km 2 /yr). Similarly, fine-sediment concentrations for normalized discharge rates varied by almost two orders of magnitude (e.g., 1.3-110 g/L for the mean annual flood) for 11 previously unmonitored drainages of the Santa Ynez Mountains. Areas with high sediment yields consistently have weakly consolidated bedrock (Quaternary-Pliocene marine formations) and are associated with the highest rates of tectonic uplift of the region (>5 mm/yr). These regions are important to the sediment discharge budgets, because ???50% of the total suspended-sediment discharge from the Western Transverse Range is estimated to be generated within these regions, even though they represent only ???10% of the total watershed area. Previous estimates of suspended-sediment discharge from the Ventura River have likely been underestimated by ???50% because the gauging station is located immediately upstream of a high sediment yield region. We also found a significant and positive correlation between sediment yield and the percentage of a watershed with grassland and agricultural land use. These results suggest that there is adequate variation within the lithology, tectonics, and land use of the broader Western Transverse Range geologic province to induce large variations in sediment yield at the local scale. ?? 2009 Geological Society of America.

Geological Society of America Bulletin↗
USGS2004

A conceptual model for river water and sediment dispersal in the Santa Barbara Channel, California

The ephemeral Santa Clara River delivers large amounts of freshwater and sediment to the eastern Santa Barbara Channel during brief, episodic discharge events. This discharge into the channel was characterized here with shipboard measurements during floods of 1997 and 1998. Within approximately 1-km of the river mouth, the river discharge quickly stratifies into a freshened, turbid surface plume and a bottom nephloid layer. Observations immediately off the Santa Clara River mouth on a peak day of river discharge revealed that sediment rapidly settled from the freshened surface waters, as suspended sediment in the freshened surface plume contained only ???6% of the sediment mass expected if the sediment mixed conservatively. On the two subsequent days the reduction of sediment mass in the surface plume continued at ???50% per day. These observations suggest that river sediment undergoes rapid initial settling within ???1-km of the river mouth, followed by somewhat slower rates of settling. Although we did not measure sedimentation or bottom boundary layer processes, our mass balance results suggest that almost all of the river sediment either escapes along or deposits upon the inner shelf seabed.

Continental Shelf Research↗