HR: 0800h
AN: H51D-0744    [Abstracts]
TI: Suspended Sediment Monitoring Strategies Reduce Model Uncertainties
AU: * Eads, R
EM: rivermetrics@gmail.com
AF: RiverMetrics LLC, PO Box 507, Lafayette, OR 97127-0507, United States
AU: O'Connor, M
EM: matto@oe-i.com
AF: O'Connor Environmental, Inc., PO Box 794, Healdsburg, CA 95448, United States
AB: Regulatory agencies require development and implementation of Total Maximum Daily Loads for watersheds listed under section 303d of the Clean Water Act. For rivers identified as sediment impaired, methods are required to identify sediment sources and to estimate loading capacities, and models, such as sediment budgets, are often employed. Models can be tested and improved when stream monitoring provides accurate estimates of sediment loads. Motivated by proposed vineyard development on forested ridges in a sediment-listed watershed in the Coast Range of northern California, four tributaries to Gualala River ranging in size from 300 to 800 ha2 were monitored over two winter seasons. More than 1850 samples were analyzed for suspended sediment concentration. Inter- annual variability of sediment loads from wet and dry years is compared. Traditional methods for estimating suspended sediment loads often rely on measurements, such as water discharge, that are not well correlated to sediment concentration due to the highly variable routing of sediment to the channel from hillslopes, roads, and landslides. A method, such as Turbidity Threshold Sampling, that employs a parameter well correlated to suspended sediment concentration can improve sampling efficiency by collecting samples that are distributed over a range of rising and falling concentrations. The resulting set of samples can be used to estimate sediment loads by establishing a relationship between concentration and turbidity for any sampled period and applying it to the continuous turbidity record.
UR: http://rivermetrics.com
DE: 1862 Sediment transport (4558)
DE: 1871 Surface water quality
DE: 1874 Ungaged basins
DE: 1895 Instruments and techniques: monitoring
SC: Hydrology [H]
MN: 2007 Fall Meeting