Abstract
Suspended and bedload transport dynamics on rivers draining glacierized basins depend on complex processes of runoff generation together with the degree of sediment connectivity and coupling at the basin scale. This paper presents a recent dataset of sediment transport in the Estero Morales, a 27 km2 glacier-fed basin in Chile where suspended sediment concentration (SSC) and bedload (BL) fluxes have been continuously monitored during two ablation seasons (2014–2015 and 2015–1016). The relationship between discharge and SSC depends on the origin of runoff, which is higher during glacier melting, although the hysteresis index reveals that sediment sources are closer to the outlet during snowmelt. As for suspended sediment transport, bedload availability and yield depend on the origin of runoff. Bedload yield and bedload transport efficiency are higher during the glacier melting period in the first ablations season due to a high coupling to the proglacial area after the snowmelt period. Instead, on the second ablation seasons the peak of bedload yield and bedload transport efficiency occur in the snowmelt period, due to a better coupling of the lower part of the basin caused by a longer permanency of snow. Differences in volumes of transported sediments between the two seasons reveal contrasting mechanisms in the coupling dynamic of the sediment cascade, due to progressive changes of type and location of the main sources of runoff and sediments in this glacierized basin. The paper highlights the importance of studying these trends, as with retreating glaciers basins are likely producing less sediments after the “peak flow”, with long-term consequences on the ecology and geomorphology of rivers downstream.
Highlights
Sediment transport is the main driver of fluvial morphodynamics, which determines river geomorphology and affects riverine ecology
If field measurements are challenging, the prediction of sediment transport is especially difficult in glacierized mountain streams due to the nonlinearities in the processes involved in the production and transfer of sediments and the high variability at different temporal and spatial scales [2,3,4]
The suspended sediment concentration (SSC) peaked at 1727 mg L−1 on 3 January, during the first ablation season, while during the second season, the maximum SSC reached 2160 mg L−1 on 30 December
Summary
Sediment transport is the main driver of fluvial morphodynamics, which determines river geomorphology and affects riverine ecology. If field measurements are challenging, the prediction of sediment transport is especially difficult in glacierized mountain streams due to the nonlinearities in the processes involved in the production and transfer of sediments and the high variability at different temporal and spatial scales [2,3,4]. This natural variability of sediment transport depends on a number of factors and processes [1,5], with the connectivity and coupling of sediment sources one of the most relevant [6].
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