Use of indicator experiments in ecological and hydrogeological studies of karst waters in Crimea

Introduction. The use of karst groundwater in Crimea is based on the ecological and hydrogeological data obtained in the 60-80s of the last century and requires updating of scientific approaches. Information about in what direction, at what velocity can move and where the pollutant that reached groundwater will appear are the key issues of geo-ecology and water safety of the Republic of Crimea. The aim of this paper is to analyze the current capabilities of the karst water tracing method and to present the results of the latest indicator experiments in the region. Materials and methods. The conditions of more than 30 regional tracing tests performed in Soviet times were analyzed. For the last 5 years, the authors have been using new tracers and approaches to indicator experiments: stable oxygen and hydrogen isotopes, various fluorescent dyes, advanced indicator fixation technologies, and multi-tracer studies of karst waters. In recent multitrace experiments, the detection of fluorescent dyes was performed on a spectrofluorometer Horiba Fluoromax 4. Models for interpreting the results of tracer tests were developed and applied to the experience of such experiments in Crimea. Results and discussion. For tests of the Soviet period, it has been revealed a number of methodological shortcomings and inconsistency of some results with modern data on karst hydrogeology of the tested areas. The results of the latest experiments made it possible to clarify the boundaries of recharge catchments, to identify areas of underground flow bifurcation, to link a number of objects, previously considered isolated, into a single system, to determine the velocities and directions of karst groundwater flows in different hydrological phases. Conclusions. The use of test results from the Soviet period should be treated with great caution. Much more adequate results are provided by modern methods, the algorithm of one of which is presented by the authors. It has been successfully tested at the experimental sites during the last 5 years.