Sediment Loads on Copeland Creek Alluvial Fan

copeland creek photo by Scott Hesscopeland creek at highwaterstudents measure depth to bank

Project Description: Due to the erosive geology in the headwaters of Copeland Creek, the tiny watershed (only 5.1 square miles) produces an astonishing amount of sediment. How much and what kind of sediment are produced? Where does it come from? How has the amount and type of sediment changed with settlement? This project focuses on Copeland Creeks alluvial fan as a possible source of sediment.

Duration: 2013

Type of Educational Activities: senior thesis

Project Faculty: Jeff Baldwin (Geography)

Partners: Sonoma County Water Agency

Participating Courses:

  • GEOG 490 Geography Senior Seminar (Jeff Baldwin) - 1 student
sites for sediment study

Sampling Locations

  • How much sediment? Sampling location is at SSU campus bridge crossing.
  • Where does it come from? Sampling locations are at 3 sites on Copeland Creek's alluvial fan.


1. How much sediment? This question is addressed with hand or trap sampling and grain size analysis. Measurements taken over time under a variety of flow conditions are used to create a calibration curve that predicts transport rates. This study assessed the feasibilty of installing pit traps immediately downstream of the alluvial fan.

2. Where does it come from? The question is addressed by identifying slumps and slides (using lidar and ground surveys) that intersect the Copeland Creek watercourse. Rates of soil loss over time are then estimated using photomonitoring, cross-sectional surveys, or lidar data if available.

Jeff Baldwin (Geography) worked with students to provide training in the field.

Data: (see data disclaimer)


  • Sediment transport in Copeland Creek. Chase Takajo. 2013. (Advisor: Jeff Baldwin, Geography Department). Senior Thesis. Takajo 2013 (pdf, 2 Mb)




Copeland Creek Restoration Project Monitoring Plan (2001). The report describes method to evaluate the effectiveness of SCWA's habitat restoration for a ~6,000 linear feet of Copeland Creek between Roberts/Pressley Road and Petaluma Hill Road (east of SSU campus). The project objectives were to ( 1) improve aquatic habitat and water quality through decreasing sediment, nutrient loads, and water temperature;( 2) decrease erosion through development of more stable channel banks and channel courses; and (3) increase fish and wildlife diversity and abundance. The plan provides information on how monitoring will be conducted and includes descriptions of stream cross-section profile, stream longitudinal profile, vegetation surveys, stream habitat and fish surveys, reptile and amphibian surveys, bird surveys, small mammal surveys.

Copeland Creek Watershed Assessment (2004).

University District Specific Plan Draft Environmental Impact Report; Chapter 3 Impact Analysis (January 29, 2010) The Draft EIR evaluates the potential effects of the proposed University District development. Section 3.6 includes a description of geology and soils. Other Rohnert Park Specific Plans.

Northern California Geological Society (NCGS) The Geology of Sonoma - Allen et al. 2009. This is a geology field trip guide to Sonoma Mountain with lots of great information. That last few pages are about the Osborn Preserve and there is a detailed analysis of landslide mapping on the Preserve, including the 1986 Valentine’s Day debris flow.

Sediment Analyses in Other Watersheds:

Sediment Source Analysis, Sonoma Creek Watershed, California. Final Report

Napa River Sediment TMDL

Scientific Literature:

Potter, C and S. Hiatt.(2009). Modeling river flows and sediment dynamics for the Laguna de Santa Rosa watershed in Northern California. Journal of Soil and Water Conservation. Vol. 64 (6):383-393.


  • Lidar Data: Bare earth projection (4MB); data location
  • Sonoma County Water Agency (data provided by Mark Bautista). The following amounts of sediment were removed from Copeland Creek between 2008 and 2012 to maintain flood capacity in the lower reaches of the channel:
    • 2008 – 5,120 cu yds
    • 2009 – 240+168 cu yds
    • 2010 – 300 cu yds
    • 2011 – 250+760 cu yd
  • Copeland Creek Watershed Assessment (2004) reports the following information on sediment removal:
    • < 1997 – "In the past, flood control channels were cleared at least once every five years."
    • 1997 – “100 percent of Copeland Creek was cleared in 1997"
    • 1998 – “One of the largest sediment removal activities [of SCWA] was performed in a two and half mile stretch of Copeland Creek three years ago (1998).
    • 2000 – “About 2,000 feet of channel was maintained in 2000. Sediment input from a large runoff area upstream has resulted in significant sediment loads into the creek” (R. Anderson, SCWA, pers comm. 2000)
    • 2001 – “Only 17 percent (2,000 ft) requires cleaning this year (2001).”