In the conventional tracer method, the flow velocity is determined by the time for the tracer to cover a certain distance, and an arbitrarily chosen empirical correction coefficient.

• 示踪法测量结果需采用经验系数修订才能得到水流速度,而经验系数受多种因素的影响,在不同的条件下如何使用,有较大的随意性。