Reservoir and contaminated sediments impacts in high-Andean environments: Morphodynamic interactions with biogeochemical processes

Thursday, 18 December 2014
Cristian R Escauriaza1, María Teresa Contreras1, Daniel Müllendorff1, Pablo Pasten2 and Gonzalo E Pizarro1, (1)Pontifical Catholic University of Chile, Santiago, Chile, (2)CEDEUS, Santiago, Chile
Rapid changes due to anthropic interventions in high-altitude environments, such as the Altiplano region in South America, require new approaches to understand the connections between physical and biogeochemical processes. Alterations of the water quality linked to the river morphology can affect the ecosystems and human development in the long-term.

The future construction of a reservoir in the Lluta river, located in northern Chile, will change the spatial distribution of arsenic-rich sediments, which can have significant effects on the lower parts of the watershed.

In this investigation we develop a coupled numerical model to predict and evaluate the interactions between morphodynamic changes in the Lluta reservoir, and conditions that can potentially desorb arsenic from the sediments. Assuming that contaminants are mobilized under anaerobic conditions, we calculate the oxygen concentration within the sediments to study the interactions of the delta progradation with the potential arsenic release.

This work provides a framework for future studies aimed to analyze the complex connections between morphodynamics and water quality, when contaminant-rich sediments accumulate in a reservoir. The tool can also help to design effective risk management and remediation strategies in these extreme environments.

Research has been supported by Fondecyt grant 1130940 and CONICYT/FONDAP Grant 15110017