Modeling suspended solids in a Northern Chilean Patagonia glacier-fed fjord: GLOF scenarios under climate change conditions

Suspended solids play an ecologically important role in glacier-fed fjords, given its dominant effect on their primary production arising from the generation of turbid water plumes by retreating glaciers, which increase light attenuation. Glacial-lake outburst floods, GLOFs, are sudden releases of lake-water impounded by a glacier which may affect either locally or regionally depending on the amount of water and suspended solids released. Chilean Patagonia has been characterized by some of the fastest glacial retreats worldwide and by an increase in GLOFs events. In this article we describe the development of a hydrodynamic model to study the distribution of suspended solids in the Baker channel, a glacier-fed fjord located in Northern Chilean Patagonia. We further describe the simulation of three climate change induced GLOF scenarios and discuss their potential effects on fjord's primary production. The model was implemented as a two-level, one-way, nested hierarchy using the MOHID water modeling system. The large extent, oceanic, level corresponded to a one-layer barotropic model, while the smaller extent, fjord, level corresponded to a 3D baroclinic model with 31 Cartesian layers. Velocities, salinity and suspended solids concentrations were calibrated using field measurements. Results show that the most likely scenario is a decrease in light penetration within the inner fjord's area. Only the most catastrophic scenario, equivalent to a large recorded paleo-discharge, would affect outer areas of the Northern Chilean fjords.

► We modeled a Patagonian fjord under three climate change scenarios. ► The state variable was terrigenous suspended solids (glacier flour). ► Results show effects concentrated on inner fjord sector. ► Main ecosystem effect is light limitation of primary production.