ABSTRACT
This method consists of injecting into the river of known constant discharge q a tracer solution with the concentration C1 (mother liquid) for a given duration (Figure
8.22). The duration of the injection must be such that the concentration C2 of the tracer at the sampling section remains constant for a certain time duration. Starting from the following assumptions:
• the discharge Q in the river is constant during the measurement period (steady state),
• the discharge q of the tracer at the sampling point is equal to that of the injection (no losses), and is insignificant compared to Q,
• the mixture is homogeneous at the sampling point,
and by applying the assumption of the conservation of mass for the tracer, equation (8.2) is written as follows:
(8.3)
where Q represents the discharge of the river ["/s], C1 is the concentration of the solution injected into the river [g/"], C2 is the concentration of the tracer remaining in the samples collected downstream from the injection point in the river [g/"] and q is the constant flow of the tracer injected into the river ["/s].
