title: Suspended sediment in a high-Arctic river: An appraisal of flux estimation methods.
abstract: Quantifying fluxes of water, sediment and dissolved compounds through Arctic rivers is important for linking the glacial, terrestrial and marine ecosystems and to quantify the impact of a warming climate. The quantification of fluxes is not trivial. This study uses a 8-years data set (2005-2012) of daily measurements from the high-Artic Zackenberg River in Northeast Greenland to estimate annual suspended sediment fluxes based on four commonly used methods: M1) is the discharge weighted mean and uses direct measurements, while M2-M4) are one uncorrected and two bias corrected rating curves extrapolating a continuous concentration trace from measured values. All methods are tested on complete and reduced datasets. The average annual runoff in the period 2005-2012 was 190±25mio·m3y-1. The different estimation methods gave a range of average annual suspended sediment fluxes between 43,000±10,000ty-1and 61,000±16,000ty-1. Extreme events with high discharges had a mean duration of 1day. The average suspended sediment flux during extreme events was 17,000±5000ty-1, which constitutes a year-to-year variation of 20-37% of the total annual flux. The most accurate sampling strategy was bi-daily sampling together with a sampling frequency of 2h during extreme events. The most consistent estimation method was an uncorrected rating curve of bi-daily measurements (M2), combined with a linear interpolation of extreme event fluxes. Sampling can be reduced to every fourth day, with both method-agreements and accuracies <±10%, using 7year averages. The specific annual method-agreements were <±10% for all years and the specific annual accuracies <±20% for 6years out of 7. The rating curves were less sensitive to day-to-day variations in the measured suspended sediment concentrations. The discharge weighted mean was not recommended in the high-Arctic Zackenberg River, unless sampling was done bi-daily, every day and events sampled high-frequently.
authors.affiliation: Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark.
authors.forename: Pernille
authors.initials: P
authors.lastname: Ladegaard-Pedersen
authors.affiliation: Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Sigsgaard
authors.affiliation: Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark.
authors.forename: Aart
authors.initials: A
authors.lastname: Kroon
authors.affiliation: Asiaq, Greenland Survey, Qatserisut 8, GL-3900 Nuuk, Greenland.
authors.forename: Jakob
authors.initials: J
authors.lastname: Abermann
authors.affiliation: Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark; Department of Bioscience, Arctic Research Centre, Aarhus University, Frederiksborgvej 399, DK-4000 Roskilde, Denmark.
authors.forename: Kirstine
authors.initials: K
authors.lastname: Skov
authors.affiliation: Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark. Electronic address: be@ign.ku.dk.
authors.forename: Bo
authors.initials: B
authors.lastname: Elberling
keywords: Annual suspended sediment flux; Arctic river discharge; Estimation methods; Extreme events; Q/h relation