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What We Do
Streamflow monitoring
RCD measures stream stage and discharge at several stations on Napa River tributary creeks. Streamflow data are used in a variety of scientific studies, including flood monitoring and modeling, bridge and culvert design, and fish passage and protection.
Sites
Stage-discharge ratings
- RCD monitors stage (water level) in the stream continuously using automated equipment
- In order to convert stage to discharge (flow), which is required for analysis of most water-related issues, it is necessary to develop a stage-discharge rating
- RCD visits the streamgaging sites numerous times during winter storms over several years to physically measure discharge over a wide range of stages
- Stage-discharge pairs are plotted and a curve, known as the rating curve, is fitted to the data. The equation associated with the rating curve is then used to convert the continuous stage record into a continuous record of discharge
Stream gaging methods
- RCD measures streamflow using USGS methods and equipment.
- The cross-sectional area of flow is divided into cells of equal width, and the depth and average water velocity are measured in each cell.The product of the cell width in feet, cell depth in feet, and water velocity in feet per second equals the cell discharge in cubic feet per second (cfs). The sum of the discharges for all cells is the streamflow at the current stage.
- RCD staff collect these measurements by wading across the stream. If the streamflow is high enough to make wading dangerous or impossible, RCD will suspend our streamgaging equipment into the flow from a bridge.
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