Bigelow Watershed Geomorphology

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Projects: sediment terrain wood basin reach

Sediment Sources

These projects address questions such as: where is the sediment coming from? What are the dominant erosion processes? When does most of the erosion occur? Are the sources controllable? Studies to answer these questions involve various components of GIS terrain mapping, fieldwork, and hydrologic and historical analysis. Assessments can range from qualitative reconnaissance to more quantitative sediment budgets covering sediment sources and rates from historic incision and bank erosion in urban environments to mass wasting, post-fire gully erosion, and road surface erosion in steeper forested basins.

Sediment source gallery:

Net bank erosion is a major source of sediment to Arroyo De La Laguna

channel evolution on Arroyo De Laguna over time at the Castlewood Bridge

Idealized channel evolution model for Arroyo De Laguna

6 meters of incision on Arroyo De La Laguna between 1911 and 1971

Sediment budget by process over time on Arroyo De La Laguna

Redcution of nearly half the sediemnt supply to Alameda Creek by reservoir impoundment

Eroding earthflow toe on Pine Creek, mass wasting is a large sediment source to Bolinas Lagoon

Sediment budget by process for Bolinas Lagoon watershed

Gully erosion is a major source of sediment in the Arroyo Mocho watershed

Debris flows are a major source of sediment in the Sinbad Creek watershed, with a debris fan at the bottom of every tributary

Sediment supply on Alameda Creek is highly episodic, where most of the sediment supply and transport occurs during brief extreme events (e.g. El Niño storms)

On upper San Lorenzo Creek, 50% of the suspended load occurred during 14 days (El Niño storms) over the 20 year period

Historic tractor logging created a massive influx of sediment to channels in the 1950s and 1960s, as shown here on historical air photos from SF Wages Creek

Sediment supply by process for SF Wages Creek over four time periods, showing the impact of tractor era logging

Links to sediment source studies:

Bigelow, P., Benda, L., and S. Pearce. 2016. Delineating incised stream sediment sources within a San Francisco Bay tributary basin. Earth Surface Dynamics 4: 531-547.

Bigelow P., L. Benda, S. Pearce, K. Andras, J. Beagle, J. Kass, and L. McKee. 2012. Geospatial terrain analysis of sediment sources within the Arroyo Mocho watershed. Prepared for the Zone 7 Water Agency.

Bigelow P., S. Pearce, L. McKee, and A. Gilbreath. 2008. A sediment budget for two reaches of Alameda Creek (including Arroyo De La Laguna). Prepared for the Alameda County Flood Control District.

Pearce S., Bigelow P., and L. McKee. 2009. Sediment source reconnaissance for Dry Creek watershed. Prepared for the Alameda County Flood Control District.

Bigelow P. and J. Gerstien. 2001. Bolinas Lagoon watershed study input sediment budget (sediment budget sections 3 – 5 only). Prepared by Tetra Tech for the US Army Corps of Engineers.

Projects: sediment terrain wood basin reach

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