Dye Tracing through Sinks Canyon: Incorporating Advanced Hydrogeology into the University of Missouri's Geology Field Camp

Abstract

The University of Missouri's Branson Geology Field Camp has integrated a series of environmental geology components into its curriculum, including hydrogeology and geophysics. In this paper, we present the results of a dye tracing experiment carried out by undergraduate students as the capstone field experiment of an optional advanced hydrogeology week at the camp. The dye tracing experiment was along the Popo Agie River, which disappears into a karst cave system in Sinks Canyon State Park, Wyoming, and resurfaces about 400 m down the canyon in a large, spring-fed pool, called the “Rise.” At the time of the test, the discharge rate in the river was 4,585 l/s (162 ft3/s). The students used skills developed during the required first week of hydrogeology, including dilution gauging and automated data acquisition, to design and carry out a dye tracing experiment to evaluate flow through the cave system. The leading edge of the Rhodamine WT dye pulse took just over 2 hours and 5 minutes to travel the short distance between the Sinks and the Rise. The peak dye concentration at the Rise was reached 2 hours and 47.5 minutes after the dye addition. The water residence time in the Sinks Canyon cave system was similar to results reported by the U.S. Geological Survey in 1983, indicating that the cave's physical flow system has not changed in the last 23 years. Students participating in the advanced hydrogeology week rated the interest and value levels of the dye tracing test high and several of the students presented their results at the Geological Society of America 2006 annual meeting.