Drainage of the ice-dammed Lake Tinninilik, West Greenland; implication on bedrock uplift

Drainage of ice-dammed lakes is regularly observed along the margin of the Greenland Ice Sheet. However, the speed of the drainage events and implications can vary depending on the size of the lakes and the local settings. Here, we assess the drainage pattern of Lake Tinninilik, dammed by Sarqardliup sermia in West Greenland, using air- and satellite-borne laser- and radar altimetry supplemented with Landsat imagery. We combine the observations with DEMs from aerial imagery to derive lake volume changes which we compare against GPS data used to monitor crustal uplift caused by mass loss close to the site.Our results suggest that the previous pattern of drainage every 10th year has changed to every ~7th year, likely a result of enhanced melting over the last decade in the region. Furthermore, the lake drainage, resulting in a c. 70 m elevation change of the lake level, can occur in less than two months. Preliminary GPS results suggest instantaneous motion of a few centimeters of the solid bedrock in response the rapid drainage of the lake and thus support previous findings derived from radar interferograms that attribute vertical land motion to lake drainage.