The principle of the tracer dilution method consists to inject a quantity of tracer in the stream. Downstream, at a sufficient distance to obtain a good mix, we measure the concentration of this tracer in the water. The flow value is calculated by integration of this concentration in function of time.
With this method, the flow measurement of a stream can be done by only one person and needs less than one hour, contrary to measurements by current meters which are dull and require at least 2 or 3 hours.
Our flow measurement instrument EasyFlow uses this tracer dilution method with cooking salt as tracer. They are equipped with a probe which measures the water conductivity. The water conductivity is linearly proportional to the concentration of salt dissolved in water.
Cooking salt has the advantage to have a high degree of dilution in water, nonpolluting and very few absorbed by vegetation and materials present in the stream bed. It is an ideal tracer because it is low cost and easy to supply.