The impact of pro‐glacial lakes on downstream sediment delivery in Norway

• Published in: Earth Surface Processes and Landforms
• Main Authors: Bogen, Jim, Xu, Mengzhen, Kennie, Patricia
• Other Authors: Norwegian Water Resources and Energy Directorate
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2014
• Subjects: Engabreen; Glacial Lake; Norway; glacier
• Online Access: http://dx.doi.org/10.1002/esp.3669; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fesp.3669; https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.3669; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/esp.3669

Abstract Glacier recessions caused by climate change may uncover pro‐glacial lakes that form important sedimentation basins regulating the downstream sediment delivery. The impact of modern pro‐glacial lakes on fluvial sediment transport from three different Norwegian glaciers: Nigardsbreen, Engabreen and Tunsbergdalsbreen, and their long‐term development has been studied. All of these lakes developed in modern times in overdeepened bedrock basins. The recession of Nigardsbreen uncovered a 1.8 km long and on average 15 m deep pro‐glacial lake basin during 1937 to 1968. Since then the glacier front has been situated entirely on land, and the sediment input and output of the lake has been measured. The suspended sediment transport into and out of the lake averaged 11 730 t yr −1 and 2340 t yr −1 respectively. Thus, 20% remained in suspension at the outlet. The measured mean annual bedload supplied to the lake was 11 800 t yr −1 , giving a total transport of 23 530 t yr −1 which corresponds to a specific sediment yield of 561 t km −2 yr −1 . A 1.9 km long and up to 90 m deep pro‐glacial lake basin downstream from Engabreen glacier was uncovered during 1890 to 1944. The average suspended sediment load delivered from the glacier during the years 1970–1981 amounted to 12 375 t yr −1 and the transport out of the lake was 2021 t yr −1 , giving an average of 16% remaining in suspension. The mean annual bedload was 8000 t yr −1 , thus the total transport was 20 375 t yr −1 , giving a specific sediment yield of 566 t km −2 yr −1 . For Tunsbergdalsbreen glacier, measurements in the early 1970s indicated that the suspended sediment transport was on average 44 000 t yr −1 . From 1987 to 1993 the recession of the glacier uncovered a small pro‐glacial lake, 0.3 km long and around 9 m deep. Downstream from this, the suspended sediment load measured in 2009 was 28 000 t yr −1 , indicating that as much as 64% remained in suspension. Flow velocity, grain size of sediment, and morphology of the lake are important factors controlling ...