Identifying historical flood deposits in a sediment core from an oxbow lake
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Date
2014-06-29
Journal Title
Journal ISSN
Volume Title
Publisher
Australasian Quaternary Association Inc
Abstract
River floods are a risk, not only because of the large volume of water that is mobilized, but also
because of the potentially high level of nutrients and pollutants contained in these waters. There is
limited understanding of flood water quality, which hinders the implementation of appropriate
mitigation strategies. Therefore we must better understand the trends in flood water quality to protect
society and the natural environment from risks associated with poor quality flood waters. Fluvial flood
water quality data could be obtained using sediment cores from floodplains, as sediment cores can
preserve historical flood deposits and can also be used to infer long term trends in the water quality of
aquatic environments.
This presentation aims to identify and separate flood-deposited fluvial sediments from in-situ biogenic
sediments in a sediment core from a floodplain lake, and to then identify the pollutant levels contained
in these flood-deposited sediments. The Yarra River (South-East Australia) and its floodplain lake
(Willsmere Billabong) was used as a case study. Cores taken from Willsmere Billabong were
analysed using the ITRAX micro-X-Ray Fluorescence (XRF) core scanner and the optical and
radiographic images, magnetic susceptibility and elemental composition profiles were used to infer
the sediment type and origins.
Using the data obtained from the core scanner, we found that flooding frequency of the Yarra River
into Willsmere Billabong decreased in the early to mid-20th century. This is most likely due to
increased water extraction with the construction of large reservoirs in the upper river catchment in
1927, 1932 and 1957. Indeed, there is also a decrease in measured flow rates for the Yarra River.
Having identified the flood-deposited sediments within the Willsmere Billabong sediment cores, we
have determined pollutant levels within the flood-deposited sediment layers, to identify water quality
trends in river flood water quality. © 2014, AQUA Biennial Meeting Mildura.
Description
Keywords
Historical aspects, Floods, Deposits, Geologic deposits, Sediments, Lakes, Rivers, Water, Mitigation, Aquatic ecosystems
Citation
Lintern, A., Leahy, P. J., Deletic, A., Gadd, P., Heijnis, H., McCarthy, D. T. (2014). Identifying historical flood deposits in a sediment core from an oxbow lake. Paper presented at the AQUA Biennial Meeting The Grand Hotel, Mildura, 29th June - 4th July, 2014.