The Water Assessment Branch, Hydrometric field staff tested several instruments for measuring low stream flows in the filed. An instrument known as the “FlowTracker”, was one of these instruments and the results obtained were very successful.
The FlowTracker uses acoustic Doppler technology to measure 2D or 3D flow in a small sampling volume located a fixed distance (10-cm) from the probe. Sound generated by the transmitter bounces off suspended particles in the water. This reflected sound returns to the receivers, is averaged together by the processor, and results in water velocity measurements that are recorded at a rate of once per second.
The instrument is the only known handheld Acoustic Doppler Velocimeter and it is the most accurate handheld instrument of its type. Alternative acoustic doppler instruments are not handheld and do not measure extremely low flows and other portable types of handheld instruments such as electromagnetic technology is less accurate. The accuracy and the need to be able to measure low flows is important because the data will be used for a variety of purposes including the determination of when water restrictions need to be placed on rivers. This is particularly important during periods of drought, when water availability is limited. This specific instrument is already extensively used across Australia and the World.
Quotation Exemption
The company SonTek through their Australian supplier, Davidson Measurement is the only company that supplies such an instrument to meet the Water Assessment Branches needs and this was confirmed by Industry Network Tasmania (ICNTAS). On this basis, a request was made to the Department of Treasury and Finance for an exemption from the requirement to seek three written quotes under Treasury Instruction 1106 and was subsequently approved.
