Seasonal Variations in Fjord Sediment Grain Size: A Pre‐requisite for Hydrological and Climate Reconstructions in Partially Glacierized Watersheds (Baker River, Patagonia)

Fjord sediments are increasingly recognized as high-resolution archives of past hydrological and climate variability. Using them such, however, requires a comprehensive understanding the variables that affect their accumulation rates properties. Here, we conduct spatial temporal study sediment samples collected at head Martínez Channel (Chilean Patagonia, 48°S), to understand how fjord's register changes in hydrology Baker River, Chile's largest river terms mean annual discharge. We apply end-member modeling particle-size distributions of: (a) suspended sediments, (b) surface along proximal-distal transect fjord head, (c) sequential trap 15-day resolution during two consecutive years. then validate use grain-size end members for reconstructions, using core covers last 35 Results show consistently composed subpopulations. The finest member (EM1; mode 4.03 μm) reflects meltwater contribution, which dominates all but winter season. coarser (EM2; 18.7 winter, when contribution is reduced, associated with rainfall. fluxes EM1 EM2 provide quantitative estimates baseflow (r = 0.87, p < 0.001) quickflow 0.86, 0.001), respectively. Additionally, propose log (EM1/EM2) can be used reconstruct production 0.67, temperature 0.81, lower River watershed. These results support reconstructions variability partially glacierized watersheds.