Equipment Review: Using Hydroacoustic Technology to Collect Stream Flow Data
What is Hydroacoustic Technology?
In general, hydroacoustic technology is technology that applies sound to water to collect data and information. When used to quantify discharge/depth relationships and flow velocities, hydroacoustic technology can improve the accuracy of hydraulic modeling. This ability to collect real-time field measurements of discharge and flow velocities is a recent and important advancement in our field, as it allows professionals to take specific, current measurements of ungaged streams and rivers quickly and easily.
FNI’s Purchase: Sontek FlowTracker and Sontek M9
FNI recently acquired and now regularly uses state-of-the-art hydroacoustic technology for data collection on a variety of projects. The firm purchased two hydroacoustic flow meters – an acoustic Doppler velocimeter (ADV) and an acoustic Doppler current profiler (ADCP) – that use advanced acoustic technology to measure flow velocities and calculate instantaneous discharges. ADVs are used to gather discharge and velocity data during times of low to moderate flow conditions, and ADCPs can be used to measure flows ranging from a few cubic feet per second to flood flows in the largest of rivers. FNI’s ADV (Sontek FlowTracker) measures point velocity by emitting and then receiving pulses of sound waves as they reflect off particles suspended in the water. The firm’s ADCP (Sontek M9) has the ability to measure 3-D stream-velocity profile data throughout a measured stream cross section.
How It’s Used
Collecting data over a range of flows is necessary for an accurate analysis of the discharge/depth relationship of a stream or river. The measured range of flows and number of measurements are pre-determined and vary based on a project’s scope of work. Data are best collected during flows of varying magnitude, from base flows to flood flows. FNI’s measurements with this equipment are taken instantaneously by field personnel at any time as required by a given project, such as during and immediately following storm events.
What We’ve Found
The collection of flow measurements is essential in ungaged streams and rivers and particularly those that have undergone urbanization. Actual discharge and velocity measurements allow for accurate hydraulic model calibration of flow, depth and velocity parameters in areas where discharge measurements have not been made in the past or areas that have undergone recent urbanization that impacts stream flow dynamics. Furthermore, measurement of stream discharge and flow velocity enables accurate assessments of stream behavior during flood-flow conditions and prediction of future conditions within the stream channel. Based on recently acquired project data, we give the Sontek FlowTracker and Sontek M9 an enthusiastic two thumbs up!