3.2.1 Artifical tracers
Artificial tracers were applied to infer the connection between glacier input from the meltwater stream and the rock glacier spring. Tracer injection was downstream of the cirque glaciers where the glacier melt water infiltrates into the sediments in the vicinity of the rooting zone of the rock glacier (which is already disconnected from the cirque glaciers; Figure 1b). Two tracer experiments were performed with injection points along the creek that infiltrates into the rooting zone of the rock glacier in two different years (Figure 1b; 2015: distance to the gauging station ~980 m; 2017: distance to the gauging station ~910 m) using fluorescein as a conservative dye tracer. In 2015 25 g of tracer were injected, in 2017 a greater amount of 202,5 g was used. Detection of tracer concentrations was done using a field fluorometer GGUN-FL30 (Abilla Co.; Schnegg, 2002) installed at the gauging station. Linear flow velocities were calculated based on the observed peak tracer concentration as well as on the mean tracer residence time using the method of moments (Kreft & Zuber, 1978).