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Seasonal variability in turbidity currents in Lake Ohau, New Zealand, and their influence on sedimentation

Citation

Cossu, R and Forrest, AL and Roop, H and Dunbar, G and Vandergoes, M and Levy, R and Stumpner, P and Schladow, G, Seasonal variability in turbidity currents in Lake Ohau, New Zealand, and their influence on sedimentation, Marine and Freshwater Research, 67, (11) pp. 1725-1739. ISSN 1323-1650 (2016) [Refereed Article]

Copyright Statement

Copyright 2015 CSIRO

DOI: doi:10.1071/MF15043

Abstract

Layers of sediment that are deposited on the floor of Lake Ohau, New Zealand offer a means to reconstruct past climate conditions in the Southern Hemisphere at sub-decadal and annual resolution. A robust understanding of the modern physical processes that control the influx and dispersal of sediment in the lake is required to reconstruct climate from these sedimentary archives. In this study, water temperature and velocity measurements collected between 2012/2013 were analyzed to determine the primary physical processes that influence sediment transport in the lake. Sediment input from river inflow occurs throughout the year but exhibits strong seasonal variation. Large inflow events (Q > 500 m3 s-1) that follow strong summer rainstorms trigger high-concentration turbidity currents, which are the main agents for sediment delivery and deposition. During winter, smaller turbidity currents also occur after rain events and contribute to annual sediment accumulation. In addition, large internal waves were observed during the summer and may influence sedimentation. In conclusion, several processes including river inflow, internal waves and convectively driven flows control sediment deposition and accumulation in the Lake Ohau system. We utilize these observations to establish a conceptual model to explain the observed infill stratigraphy in Lake Ohau and guide interpretation of the longer sedimentary record.

Item Details

Item Type:Refereed Article
Keywords:Turbidity currents, Internal waves, sediment transport
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical Oceanography
Objective Division:Environment
Objective Group:Other Environment
Objective Field:Environment not elsewhere classified
Author:Cossu, R (Dr Remo Cossu)
Author:Forrest, AL (Dr Alexander Forrest)
ID Code:102266
Year Published:2016 (online first 2015)
Web of Science® Times Cited:1
Deposited By:NC Maritime Engineering and Hydrodynamics
Deposited On:2015-08-08
Last Modified:2017-10-31
Downloads:0

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