Document Type

Capstone Project

Degree Name

Bachelor of Science (B.S.)


Science & Environmental Policy


lean water has become a precious resource, and in response water quality has become a growing concern. The Salinas River Watershed is home to one of the largest agricultural zones in California. Soil loss to the Salinas River due to agricultural runoff is a common and expensive problem. The Salinas River and its tributaries provide habitat and spawning grounds for the steelhead trout and other important species. Steelhead trout are particularly sensitive to fine sediment and sand. Recently, the Central Coast Regional Water Quality Control Board has become responsible for defining and allowable Total Maximum Daily Loads (TMDLs) of sediment for the Salinas River. This report describes the design, building and implementation of a safe, practical, accurate and economical bridge based sediment and discharge sampling system. The final project will include safe use instructions, component descriptions, availability and instructions for possible future replication. A cost benefit analysis will be conducted to assess the differences between building this sediment and discharge monitoring system and purchasing commercially available equipment. To accurately estimate the amount of sediment and water moving through the watershed, sampling teams collect suspended sediment and bed-load sediment as well as take velocity readings with a clear understanding of the limitations of the sampling equipment. A propeller style velocity meter was chosen for the bridge-based sampling system, and an experimental accuracy assessment of this method was performed. This was completed utilizing a known length of a local swimming pool and a stopwatch. Accuracy was assessed by plotting the average velocity of the propeller readings versus the actual velocity calculated from known distance and time. The propeller style velocity meter consisting of a model boat propeller, PVC tee, magnet, and sensor combination that is connected to a bicycle computer has many benefits over USGS style vertical axis velocity meters. In the most basic application of the propeller style meter such as a staff-mounted velocity meter, the propeller style meter is lightweight, durable, accurate, and relatively inexpensive. I believe this style of meter for measuring stream velocity will become widespread in its use and acceptance.


Capstone Project (B.S.) Earth Systems Science & Policy Institute

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