Hydrological thresholds and basin control over paleoflood records in lakes

Schillereff, DN, Chiverrell, R ORCID: 0000-0002-7307-2756, Macdonald, N ORCID: 0000-0003-0350-7096 and Hooke, J ORCID: 0000-0002-8367-3010
(2016) Hydrological thresholds and basin control over paleoflood records in lakes. Geology, 44 (1). pp. 43-46.

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The scarcity of long-term hydrological data is a barrier to reliably determining the likelihood of floods becoming more frequent and/or intense in a warmer world. Lake sediments preserve characteristic event layers, offering the potential to develop widely distributed and unique chronologies of historical floods. Inferring flood magnitude remains a greater challenge, previously overcome in part by analyzing sharply laminated polar or alpine sequences. Here we demonstrate an approach to obtain flood frequency and magnitude data from an unexploited resource, the largely visually homogeneous, organic sediments that typify most temperate lakes. The geochemical composition and end-member modeling of sediment trap and adjacent short core particle size data for Brotherswater (northwest England) discriminates the signature of infrequent, coarse-grained flood deposits from seasonal and longer-term allogenic (enhanced discharge and sediment supply during winter) and autogenic (summer productivity, thermal mixing) depositional processes. Comparing the paleoflood reconstruction to local river discharges shows that hydrological thresholds censor event signature preservation, with 4 yr recurrence intervals detectable in delta-proximal sediments declining to 9 yr in the lake center. Event threshold (discharge) and process characterization are essential precursors to discerning flood magnitude from sediment archives. Implementation of our approach in globally prevalent temperate lakes offers a vast, unique repository of long-term hydrological data for hydrologists, climate modelers, engineers, and policy makers addressing future flood risks.

Item Type: Article
Subjects: ?? GB ??
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Depositing User: Symplectic Admin
Date Deposited: 21 Jan 2016 09:33
Last Modified: 15 Dec 2022 16:13
DOI: 10.1130/G37261.1
Open Access URL: http://geology.geoscienceworld.org/content/44/1/43
Publisher's Statement : Whether extreme river floods are becoming more frequent and/or severe in a warming world remains under debate, partly because instrumental measurements of river discharge are too restricted in length to detect shifts from natural variability. In this open access article for Geology, Daniel Schillereff and colleagues demonstrate for the first time the recovery in a systematic manner of flood frequency and magnitude data from temperate lakes that accumulate homogeneous (visually similar) sediments. Characterizing contemporary sediment dynamics and material accumulated during recent floods of known-magnitude has established a relationship to river discharge and quantified a threshold of deposit preservation. Lakes of this type are widely distributed globally but largely unexploited for the purposes of paleoflood research; implementation of our approach will yield new sources of paleohydrological information to help model and mitigate future flood risk. FEATURED ARTICLE Hydrological thresholds and basin control over paleoflood records in lakes Daniel N. Schillereff et al., School of Environmental Sciences, Roxby Building, University of Liverpool, L69 7ZT Liverpool, UK. This paper is OPEN ACCESS online at http://geology.gsapubs.org/content/early/2015/11/20/G37261.1.
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URI: https://livrepository.liverpool.ac.uk/id/eprint/2047960