CHARACTERIZING HYDROLOGIC CONNECTIONS AND KARSTIFICATION IN SISTEMA HUAUTLA FROM EXPLORATION AND DYE TRACING (Invited Presentation)

Sierra Mazateca, Mexico is home to deepest cave in the western hemisphere with 1560 meters of depth and 80 kilometers of passage. The integrated Sistema Huautla is comprised of 26 entrances distributed in an intensely karstified terrain with multiple solution dolines, shafts, and sinking streams. A previous study identified the Resurgencia Huautla as the sole spring for the whole system by a series of dye traces, which provides water to the Rio Santo Domingo. During the same period as the study, a nearby phreatic cave called Cueva de La Peña Colorada was explored through a series of sumps in 1984 and presumed to be the old fossil resurgence of Sistema Huautla. Local people observe the cave to have a high discharge during big rain events. This cave can help inform a chronological framework for the karstification process in Sistema Huautla. A dye trace study was performed in April 2018 along with divers from the Huautla Resurgence Team to identify the relationship between Cueva de la Peña Colorada and the Huautla Resurgence. Three pounds of fluorescein dye were injected in Sump VII of Cueva de la Peña Colorada and monitored for three weeks. The area had unusually high rain for the season, which provided insight into the hydrology of the system during high flow. Five springs were monitored along the Rio Santo Domingo near the Huautla Resurgence for three weeks. The dye trace was positive in the sites Agua de Frio and HR Resurgence, which where upstream, with a minor detection in the Huautla Resurgence. Two more visits to the area are scheduled December 2018 and April 2019. Further dye traces, along geochemical sampling, will be done to continue delineating the hydrological basin of the system and understand the hydrological connection between the springs. The results of this study will contribute greatly to understanding of water resources in the region, further exploration of the cave system, potential connections, and geochemical behavior of karst water at depth over seasonal variations in Sistema Huautla.