The study in this thesis concerns Storglaciären, a very well known and studied glacier in northern Sweden. The glacier has been an object for research since the endof the 19th century. During the meltseason of 2012 25 dyetracing experiments were executed. These experiments were conducted to investigate the internal drainage system of Storglaciären in the lower ablation area. Similar studies were done in 1989 by Regine Hock and Roger Leb Hooke (1993). The outcome of the study in 2012 has been compared with their results to see if any changes in the drainage systemhave occurred. The results have also been compared to the results of Seaberg etal. (1988) from their experiments in 1984 and 1985. Studies of glacier behaviour are important since they have a large impact on the local and global environment. Moreover it has been observed that smaller glaciers (such as Storglaciären), that are easier to reach and to work on, have similar behaviour as bigger glaciers, making them good objects for research (Jansson, 1996). The experiments were conducted between the 6th and 24th of august and executed by first injecting dye into moulins on the glacier and then measuring the concentration of dye in the proglacial streams merging out from the front of Storglaciären. Rhodamine WT was used as dye. Storglaciären has three main pro-glacialstreams named Nordjåkk, Centerjåkk and Sydjåkk. Nordjåkk merges from the northside and the other two from the south side of the glacier front. Measurements were in the beginning taken in all of the streams but since no concentration was visible in Nordjåkk the focus was at the end of the fieldperiod only at Centerjåkk and Sydjåkk, which both had detectable dye concentrations. Both manual and automatical measurements were done. Breakthrough curves (concentration vs. time) were plotted for each experimentand for both Centerjåkk and Sydjåkk. From these curves calculations were donefollowing the methods in Willis et al. (2011). The main parameters calculatedwere: transit velocity, dispersivity and dye recovery. Breakthrough curves were also modelled for each experiment using the method in Willis et al. (1990). Overall the drainage system in the lower part of the ablation area of Storglaciärenhas not changed signicantly during the past 20 years. But the drainage systemseems to be divided into dierent parts using both a straight channel system and a distributed system. The distributed system of 2012 seems to be more homogeneous than in 1989 but whether the system is braided or consists of a linked cavity systemis hard to tell. Differences seen this year compared to previous investigations are that the transition from an early to a late season drainage system occurred later in the meltseason. The dominating subglacial stream in 2012 was Centerjåkk and not Sydjåkk as in previous investigations (Nordjåkk dominated north as before). The meltseason lasted only a few weeks in 2012 because of the cold conditions and low precipitation. This may have had a big inuence on the behaviour of the glacier.