Experiences of karstic zones identification using dissolved oxygen as a tracer in the aquifer of Quintana Roo, Mexico

The study of karstic aquifers is a challenge because of their heterogeneous and anisotropic nature; the groundwater flow in these systems often cannot be explained using Darcian theory. Many techniques (direct and indirect) have been used for the characterization of karstic aquifers. Dissolved oxygen alteration method (DOAM) consists in injecting air into wells and tracing the evolution of this parameter over time; this practice offers advantages because it is cheap and harmless. Previous experiences show acceptable results in the identification of fractures and preferential flow in heterogeneous aquifers. The air injection used during the drilling process (rotary perforation with air cleaning) could be used as a tracer. This research monitored the physical parameters in groundwater after drilling wells, especially the dissolved oxygen. Besides, karstic zones have been identified using video surveys in drilling wells. Finally, the results using the DOAM method were contrasted with the physical evidence of karstic zones to compare the technique’s accuracy. Results show that DOAM offers a qualitative approach to the evidence of karstic zones and preferential groundwater flow. DOAM can be considered as a useful choice to study the karstification influence on the aquifer groundwater flow and transport in karstic aquifers. The identification of these zones areis important for the design of supply and wastewater projects; therefore, this approach represents an improvement in the wells’ design process in aquifers with similar conditions.