BioScapes III: Testing biotic controls on erosion and sediment transport in the Chilean coastal cordillera with cosmogenic 10Be-derived erosion rates and a shear stress-based river incision model.

Investigator Names and Contact Info:

• Dirk Scherler (Geology/Geochemistry). Earth Surface Geochemistry, German Research Centre for GeoSciences (GFZ) Potsdam, Germany
• Eva Paton (Ecohydrology). Institute of Ecology, Technical University of Berlin, Germany

Chilean Collaborators Involved:

• Claudio Meier. Civil Engineering, University of Memphis, USA
• Luca Mao (Fluvial Geomorphology). Pontificia Universidad Catolica de Chile, Santiago, Chile

Testing biotic controls on erosion and sediment transport in the Chilean coastal cordillera with cosmogenic 10Be-derived erosion rates and a shear stress-based river incision model.

PhD-Student:

• Renee van Dongen. GFZ Potsdam, Germany

Supervisor: Prof. Dirk Scherler

The effect of tools with different lithologies on erosion efficiency in bedrock rivers.

MSc-Student:

• Melle Koelewijn. GFZ Potsdam, Germany

Supervisor: Prof. Dirk Scherler

Project Summary:

BioScapes III is part of a series of independent EARTHSHAPE proposals that quantifies biotic, surface process, and paleoclimate interactions at the catchment scale and larger. The topography of the Earth’s surface is shaped by erosion and sediment transport that tend to balance tectonic rock uplift over geological time scales. Although it is widely understood that organisms directly and indirectly affect these processes, their long-term contribution to the evolution of landscapes is not well known. This deficit is rooted in the fact that biotic influences are complex and difficult to disentangle from climatic influences. In this project, we want to examine the influence of biota on erosion and sediment transport in the framework of a threshold-stochastic stream power model of river incision. We shall test the hypothesis that biota, the characteristics of soils, and vegetation, influence river incision primarily by modulating the magnitude-frequency distribution of flood events. To achieve this goal, we will focus on the Earthshape SPP key areas that are distributed across a large climate-and-vegetation gradient in the Coastal Cordillera of Central Chile, and address three key objectives: (1) quantify erosion rates with cosmogenic nuclide concentrations in fluvial sediments; (2) quantify the influence of biota on river discharge by analyzing a large data set of mean daily discharge records, combined with ecohydrological modeling; and (3) model the cosmogenic nuclide-derived erosion rates with a threshold-stochastic stream power model calibrated with discharge distributions and field observations. Our project combines geological/geochemical with ecohydrological/geoecological methods for bridging the different time scales, from the stream response to individual rain events to the long-term effect on landscape development.