Comparative Shoreface Evolution along the Laptev Sea Coast

• Main Authors: Are, F.E., Grigoriev, M.N., Hubberten, H.-W., Rachold, V., Razumov, S., Schneider, W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Deutsche Gesellschaft für Polarforschung; Alfred-Wegener-Institu für Polar- und Meeresforschung 2002
• Subjects: Laptev Sea; laptev; lena river; Polarforschung
• Online Access: https://oceanrep.geomar.de/id/eprint/29274/; https://oceanrep.geomar.de/id/eprint/29274/1/Are_et_al-2002-ComparativeShoreface.pdf; http://hdl.handle.net/10013/epic.29866.d001

Field investigations 01' the Laptev Sea shoreface morphology were carried out (1) off erosional shores cornposed 01' unconsolidated sediments, (2) off the modern delta shores 01' the Lena River, and (3) off rocky shores. It was found that profiles off erosional shores had a concave shape. This shape is not weil described by commonly applied power functions, a feature, which is in disagreement with the generally accepted concept 01' the equilibrium shape 01' shoreface profiles. The position 01' the lower shoreface boundary is determined by the elevation 01' the coastal lowland inundated during the last transgrcssion (at -5 to -10m) and may easily be recognized by a sharp, an order 01' magnitude decrease in the mean inclination 01' the sea f1oor. The mean shoreface inclination depends on sediment grain-size and ranges from 0.0022 to 0.033. The concave shape 01' the shoreface did not change substantially during the last 20-30 years, which indicates that shoreline retreat did not slow down and hence suggests continued intensive coastal erosion in the 21" century. The underwater part 01' the Lena River delta extends up to 35 km offshore. Its upper part is fonned by a shallow andup to 18-km wide bench, which reaches deprhs 01' 2-3 m along the outer edge. The evolution 01' the delta was irregular. Whereas some parts 01' the delta are advancing rapidly (58 m/year), other parts are eroding. Comparison 01' measured profiles with older bathymetric data gave an opportunity to evaluate the changes 01' the underwater delta over past decades. Bathymetric surveys 01' the seabed around the delta can thus contribute towards a quantification 01' the scdiment budget 01' the river-sea system. In addition, sorne sections 01' the Laptev Sea coast are composed 01' bedrock that has a comparatively low resistance to wave erosion. These sections may supply a considerable amount 01' sediment, especially if the cliffs are high. This source must therefore also be taken into account when assessing the contribution 01' shore erosion to the ...