Stream monitoring data provided by the USGS and counties in Arizona can offer insight into the hydrologic conditions across the state. However, the nearest monitoring station may be far from your site, and you may desire more site-specific information. Flow measurements are useful for characterizing streams, understanding stream water quality, and calculating pollutant loadings. Consistently tracking stream flow in your area can help you understand the relationships between local precipitation, stream flow, and overall watershed condition.
Stream flow is measured accurately by hydrologists using a current meter. Cups are spun by the stream current, and the speed of the spinning is calculated by the meter.
Instructions for how to take stream flow measurements using a flow meter are found here.
It is important to note that stream velocity varies based on depth; water at the surface of the stream moves faster than that at the bottom, a concept depicted well in this animation. When stream velocity, or flow, is reported, it is the average velocity of the stream.