Suspended sediment transport characterization along the Biobío River, Chile.

Diego Caamaño, Edwin Behrens, Alba Martinez, Hernán Alcayaga

Wednesday 1 july 2015

8:45 - 9:00h at Mississippi (level 1)

Themes: (T) Sediment management and morphodynamics, (ST) Sediment transport mechanisms and modelling

Parallel session: 8A. Sediment - Transport

The Biobío fluvial system is one of the most important areas for economical developments in the Chile, and it has been recently classified as one of the world’s largest river systems strongly affected by fragmentation and change in flow regime, primarily due to hydropower and irrigation. Remarkable research efforts have been focused on the Biobío, yet little is known about the river sediment transport patterns and its response to natural and/or anthropogenic perturbations. This study utilizes a power-law rating curve to assess the spatial and temporal variability of suspended sediment transport by clustering and characterizing the data collected by the Chilean Ministry of Public Works. Results show highly variable rating coefficients between seasons, and yearly analyses indicate patterns that are in coincidence with dams operations. The different periods are marked and identified before and after the construction/operation of the dams, showing a rapid response in the upper basin station and a minimum change on the lower part of the river. This suggests a strong suspended sediment transport signal coming from the two main tributaries (i.e. Laja and Vergara Rivers). These results help to better understand the river behavior in terms of sediment distribution and transport, and also means an improvement when characterizing the phenomena through empirical expressions that, for example, could be used to feed numerical models.