Comparative tracing of two common dyes in conduits with silt: A case study of the Dingqi underground river

The study area is located in the upstream Dabang river, a branch of the Beipanjiang river in Dingqi town, Zhenning county, Guizhou Province. The strata of this place comprise lower Triassic limestone, dolomite and landform, with landforms of dissolution hills and valleys. It hosts underground rivers A19, A30 and A10, with silt deposits and buried depths less than 30 m. This study focused on the comparison of tracer experiments for two materials of Uranine and Rhodamine B, and discussion on the rationality of the recovery rates by the two methods. The results show that,(1) The recovery rate of Uranine is 53.91%, which is higher than Rhodamine B of 40.72%;(2) Uranine’s recovery intensity for maximum concentration is 2.95 times than that of Rhodamine B; (3) It is relatively easy to notice some complete wave crests in the attenuation section of the Rhodamine B concentration curve. It is concluded that，(1) in the underground rivers with silt deposition, Uranine and Rhodamine B have higher adsorption rates, and there may be some problems in the tracer test technology with higher recovery rates; (2) For the analysis of conduit structure or hydrogeological conditions, Uranine is superior to Rhodamine B; (3) The accuracy of recovery rates depends on fluorimeter calibration, flow monitoring, and closely related to environmental factors, such as water-turbidity and sediments.