EGU21-2430, updated on 03 Mar 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Seasonal variations in the origin of river sediments (Baker River, Chile): A pre-requisite for climate and hydrological reconstructions

Benjamin Amann1, Sebastien Bertrand1, Camila Alvarez Garreton2,3, and Brian Reid4
Benjamin Amann et al.
  • 1Renard Centre of Marine Geology, Ghent University, Belgium (
  • 2Center for Climate and Resilience Research (CR)2, Universidad de Chile, Santiago, Chile
  • 3Department of Civil Engineering, Faculty of Engineering and Sciences, Universidad de La Frontera, Temuco, Chile
  • 4Centro de Investigación en Ecosistemas de la Patagonia (CIEP), Coyhaique, Chile

Fjord sediments are increasingly recognized as high-resolution recorders of past climate and hydrological variability. Using them as such, however, requires a comprehensive understanding of the variables that affect their properties and accumulation rates. Here, we conduct a spatial and temporal study of sediment samples collected at the head of Martínez Channel (Chilean Patagonia, 48°S), to understand how the fjord’s sediments register changes in the hydrodynamics of Baker River, Chile's largest river in terms of mean annual discharge. We apply end-member modeling to particle-size distributions of: (i) river suspended sediments, (ii) surface sediments collected along a proximal-distal transect at the fjord head, and (iii) fjord sediments collected in a sequential sediment trap at 15-day resolution during two consecutive years. Results show that the river suspended sediments and fjord sediments are consistently composed of two grain-size subpopulations. The finest end member (EM1; mode 4.03 μm) reflects the meltwater contribution, which dominates in all but the winter season. The coarser end member (EM2; mode 18.7 μm) dominates in winter, when the meltwater contribution is reduced, and is associated to rainfall events. We propose that log(EM1/EM2) can be used to reconstruct temperature in the lower Baker River watershed (r = 0.81, p < 0.001). We also show that the fluxes of EM1 and EM2 provide quantitative estimates of baseflow (r = 0.82, p < 0.001) and quickflow (r = 0.90, p < 0.001), respectively. These results support the use of fjord sediments for quantitative reconstructions of climate and hydrological changes in glacierized watersheds.

How to cite: Amann, B., Bertrand, S., Alvarez Garreton, C., and Reid, B.: Seasonal variations in the origin of river sediments (Baker River, Chile): A pre-requisite for climate and hydrological reconstructions, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2430,, 2021.


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