Paraglacial coasts responses to glacier retreat and associated shifts in river floodplains over decadal timescales (1966-2016), Kongsfjorden, Svalbard

• Published in: Land Degradation & Development
• Main Authors: Bourriquen, Marine, Mercier, Denis, Baltzer, Agnès, Fournier, Jérôme, Costa, Stéphane, Roussel, Erwan
• Other Authors: Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN), Université de Nantes (UN), Sorbonne Université (SU), Espaces, Nature et Culture (ENeC), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN), Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École Pratique des Hautes Études (EPHE), Normandie Université (NU), Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: Arctic; coastal geomorphology; global change; paraglacial; Spitsbergen; [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; [SHS.GEO]Humanities and Social Sciences/Geography; [SDE.MCG]Environmental Sciences/Global Changes; Svalbard; Ny-Ålesund; glacier; Kongsfjord*; Kongsfjorden; Ny Ålesund
• Online Access: https://hal.science/hal-01869431; https://doi.org/10.1002/ldr.3149

International audience The aim of this paper is to quantify and map the impact of the post‐Little Ice Age climatechange on the coastal evolution on three glacier catchments in the Kongsfjordenarea in Svalbard. Climatic data at Ny‐Ålesund indicate an increase in the annual meanair temperature of +4 °C from 1969 to 2016 and an increase in precipitation. On thenorthern coast of the Brøgger Peninsula, the Austre Lovénbreen, Midtre Lovénbreen,and Vestre Lovénbreen glaciers have experienced a net retreat in response to changingmeteorological conditions. Because of this retreat, the glaciers have disclosed alarge area of 7 km2 composed of terrigenous sediments. These sediments aretransported by runoff and created coastal sandur deltas. Channel network behaviorhas been studied using the computation of the active floodplain width by photointerpretation,which decreased in average from 1966 to 2010. This demonstrated a contractionof the active braided belt and a decrease in the number of braided channels.A photointerpretation analysis combined with acquisition of dGPS data during fieldwork shows a mean shoreline progradation of +0.16 m a−1 from 1966 to 2016, witha maximal advance of +82 m seaward. Since 1966, coastal progradation has decreasedin time with higher mean values at the beginning of the studied period and anerosional trend from 1990. The sublittoral area was studied using analog side scansonar in 2009, 2011, 2012, and 2017. Three prodeltas were identified and underwenta huge extension from 2009 to 2017. In the light of this knowledge, our mainconclusion is that, by retreating, glaciers have an impact on the sediment availabilityand on the capacity of the fluvial system to effectively transport sediment to theshoreline. These two factors control the overall coastal evolution by regulating thesediment supply to the coastal area. The coastal zones that were fed with sedimentsby runoff have experienced a coastal progradation, and those that lost this supplyhave undergone a coastal recession. Due to the contraction ...