Jökull - 01.01.2019, Page 4

Terminus lakes on the south side of Vatnajökull
Figure 1. Location map of the outlet glaciers of S-Vatnajökull ice cap from Skeiðarárjökull to Hoffellsjökull
showing the 2018 ice margin. The Little Ice Age maximum extent at the end of the 19th century is shown in
grey in front of the glacier termini, and blue areas show ice-marginal lakes in 2018. – Skriðjöklar í sunnan-
verðum Vatnajökli frá Skeiðarárjökli til Hoffellsjökuls. Jaðar jökulsins er frá 2018. Lega jökulsporða við lok
litlu ísaldar seint á 19. öld er sýnd með grárri skyggingu og blá svæði sýna jökullón árið 2018.
ages, satellite images and digital elevation models
(DEMs). The area development of the lakes is de-
rived by digitizing the shorelines from maps and aerial
photographs collected from the database of the Na-
tional Land Survey of Iceland (NLSI), Landsat im-
ages (Landsat 1–5 and 7–8, image courtesy of the
US Geological Survey), the aerial image database of
the company Loftmyndir ehf. and lidar DEMs of the
Vatnajökull ice cap and its foreland (Jóhannesson and
others, 2013). The oldest maps are from the Danish
General Staff (DGS), based on triangulation surveys
in 1903 and 1904 in SE-Iceland (DGS, 1905a,b,c,d;
DGI 1936a,b, 1944a,b) and the C762 maps of the
US Army Map Service (AMS), based on aerial pho-
tographs taken in 1945 and 1946 (AMS, 1951). Re-
cently, improved DEMs and georectified images of
Öræfajökull have been created based on digital pro-
cessing of the original AMS stereo imagery (Belart,
2018; Belart and others, 2019).
The lidar DEMs of Vatnajökull, surveyed in 2010–
2012 in connection with the International Polar Year
2007–2008 (Jóhannesson and others, 2011, 2013), are
used to georectify aerial and satellite images as well
as to reproject and correct the horizontal positioning
of older maps, and for determining the water level
in the lakes. Information about lake water level was
JÖKULL No. 69, 2019 3