Change characteristics of breakthrough curves with increasing flow rate and prediction

In order to investigate the effect of flow variation on solute transport in the conduit, the tracer experiments were conducted under 9 different flow rates. The experimental results show that the peak concentration increases and the tailing of breakthrough curve (BTC) decreases while the dispersion coefficient is basically unchanged with the increasing flow rate. With the increasing flow rate, the increase of the peak concentration is the fastest for the single pipe and the increase of peak concentration is the slowest for the asymmetrical pool. The symmetrical pool induces appreciable tracer retention (significant tailing of the BTC) due to transient storage in eddies. The asymmetrical pool causes slow penetration of the main tracer cloud (later arrival of the entire BTC) due to flow reversals in the pool and creates the tracer intention (tailing of the BTC) by transient storage in the pool. The relationship between the morphological parameters of BTCs and peak time and the relationship between the parameters and flow rate were developed based on the experimental data obtained under flow rates 2-8. We used two modes to predict the morphological parameters of BTCs under the maximum and minimum discharge: Mode 1, predicting peak time according to the flow rate and then predict other parameters according to peak time; mode 2, predicting all morphological parameters according to the flow rate. It is found that the prediction effect is better in the second mode, but the first mode has the advantages in field conditions.