Paleohydraulic reconstruction of the largest Glacial Lake Missoula draining(s)

Alho, Petteri; Baker, Victor R.; Smith, Larry N.

doi:10.1016/j.quascirev.2010.07.015

Cited by 63 publications

(49 citation statements)

References 33 publications

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“…Alho et al (2005), Carrivick et al (2004a,b) and Carrivick (2006Carrivick ( , 2007a have quantitatively linked jökulhlaup hydraulics along the Jökulsá á Fjöllum to landforms and sediments matching flood geomorphology to 'hydraulic envelopes'; usually flow depth / flow velocity ratios (Carrivick, 2007b). The same has been done for the Missoula palaeofloods by O'Connor (1993), Benito (1997) and Alho et al (2010), and for modern outburst floods at Mt. Ruapehu, New Zealand, by Carrivick et al (2009bCarrivick et al ( , 2010.…”

Section: Implications Of the Calculation Of A Very Large Peak Dischargementioning

confidence: 94%

Discussion of ‘Field evidence and hydraulic modeling of a large Holocene jökulhlaup at Jökulsá á Fjöllum channel, Iceland’ by Douglas Howard, Sheryl Luzzadder-Beach and Timothy Beach, 2012

Carrivick¹,

Tweed²,

Carling³

et al. 2013

Geomorphology

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This paper discusses Howard et al. (2012) who reconstruct the peak discharge of a glacial outburst flood, or 'jökulhlaup', for part of the Jökulsá á Fjöllum in north-central Iceland. They propose that this flood was the largest on Earth. We consider that the magnitude of the jökulhlaup proposed by Howard et al. (2012) warrants much more robust field evidence and demands more carefully parameterised hydraulic modelling. For these reasons we firstly (i) present their study in the context of previous research (ii) highlight issues with attributing landforms and sediments to jökulhlaups, and (iii) consider uncertainty regarding the timing and magnitude of jökulhlaups along the Jökulsá á Fjöllum. We argue herein that whilst a range of landforms and sediments that are attributable to jökulhlaups can be observed along the Jökulsá á Fjöllum, these are not necessarily diagnostic of jökulhlaups. Secondly, we critically discuss (iv) the major underlying assumptions of their study, and (v) their calculations and subsequent interpretations. These assessments lead us to consider that the proposal by Howard et al. (2012) of the largest flood on Earth is highly unrealistic, especially when due consideration is given to a possible source area and a trigger mechanism.© 2012 Elsevier B.V. All rights reserved. IntroductionHoward et al. (2012) suggested that a glacial outburst flood or 'jökulhlaup' that routed along the Jökulsá á Fjöllum in northern Iceland during the early Holocene was the largest flood to have occurred on Earth. They present field data, most importantly large boulders, that they attribute to deposition by this flood and they use the elevation of these boulders to drive a hydraulic model that they suggest reasonably represents the characteristics of this flood. However, we feel that the field data as presented in their paper is both ambiguous and insufficient. We therefore briefly review the field evidence for, and research into, Jökulsá a Fjöllum jökulhlaups. Given the emphasis placed on the exceptional magnitude of the flood and on the applicability of the work for studies on Mars, we also feel that it is very important to question several assumptions that Howard et al. (2012) relied upon for their calculations. This paper therefore proceeds to discuss these assumptions, namely that: isolated large 'erratic' boulders are the product of jökulhlaup deposition, that the position and location of the boulders are sufficient to parameterise a step-backwater hydraulic model, that a hill named 'Ferjufjall' must have been overtopped, that Manning's n can be treated as a fixed quantity, that modelling a single reach of the Jökulsá á Fjöllum can generate meaningful results, and finally that the volume of water implied by such a large peak discharge could have been sourced from northern Vatnajökull. Discussion of research on Jökulsá á Fjöllum jökulhlaupsAttributing landforms and sediments to jökulhlaups (Table 1), particularly those jökulhlaups that occurred millennia ago, is far from straight forward and has occupied many m...

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Section: Implications Of the Calculation Of A Very Large Peak Dischargementioning

confidence: 94%

Discussion of ‘Field evidence and hydraulic modeling of a large Holocene jökulhlaup at Jökulsá á Fjöllum channel, Iceland’ by Douglas Howard, Sheryl Luzzadder-Beach and Timothy Beach, 2012

Carrivick¹,

Tweed²,

Carling³

et al. 2013

Geomorphology

Self Cite

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“…The area for this lake (Table 2) was estimated using GIS from reconstructed maximum North Sea ice margins and topographic variation around the basin. As the total input of water is relatively small compared to reconstructed glacial outbursts from Lake Agassiz (Teller et al, 2002) or Lake Missoula (Alho et al, 2010) of North America, NS1 assumed a rapid 10 day drainage. This is extremely fast, but not impossible.…”

Section: North Sea Palaeo-lake Drainagementioning

confidence: 99%

Sensitivity of the North Atlantic circulation to break-up of the marine sectors of the NW European ice sheets during the last Glacial: A synthesis of modelling and palaeoceanography

Bigg

Clark

Greenwood

et al. 2012

Global and Planetary Change

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“…Steady-state hydraulic reconstructions using slope-area method [10], one-dimensional step-backwater flow model [41] and cross-section averaged hydraulic modelling [3,7,57] commonly evaluate the flow stage at a given discharge without considering the temporal variations of the hydrograph. In addition to the speed up of the computation, an advantage of the steady-state hypothesis is that no uncertainty is introduced when prescribing the hydrograph shape [23].…”

Section: Two-dimensional Shallow Water Modelling Computational Mesh mentioning

confidence: 99%

“…Two-dimensional hydraulic modelling has become a standard in paleohydrology [2,3,7,[23][24][25]] similar to slope-conveyance, slope-area methods and step-backwater analysis [11,26,27]-perhaps due to recent advances in computational power, the availability of Digital Elevation Models (DEM) and open-source 2D codes, e.g., DassFlow-Shallow [28,29]. Guidelines in the development and application of computational methods to environmental fluid mechanics, including quantification of uncertainty and model testing, can be found in [30].…”

Section: Introductionmentioning

confidence: 99%

Paleohydraulic Reconstruction of Modern Large Floods at Subcritical Speed in a Confined Valley: Proof of Concept

Bohorquez

2016

Water

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Abstract:The present study aims to show the accuracy of paleoflood reconstruction techniques based on two-dimensional (2D) hydraulic modelling of a large flood. Using this reconstruction technique, we determined trends in flood stages over time in a regulated river. A stretch of the Guadalquivir River (Southern Spain) was selected as the study site. High-resolution orthophotos and LiDAR (Light Detection and Ranging) elevations were acquired just after modern floods. They were used for the identification and location of stage indicators. In addition, water gradients were estimated from gauging records, documentary information and paleostage indicators (PSIs) in two situations: (i) pre-vegetation encroachment; and (ii) post-vegetation encroachment due to upstream impoundment. Standard two-dimensional, flow depth-averaged equations over fixed beds were used in the hydraulic modelling. In a first stage, long records of instrumental data at gauging stations and documentary evidence of flood levels served to calibrate the input parameters of the hydraulic model. In a second stage, paleoflood signatures within sedimentary and botanical sequences served to verify the flood stages in the numerical simulations not only at the river reach where instrumental data exist but also in the downstream river reach. Interestingly, the rating curve obtained from the combined use of documentary information and imagery was nearly as accurate as gauging measurements. The thoughtful comparison of 2D modelled hydraulic variables against inferred values from PSIs and instrumental data supports the paleoflood reconstruction method over fixed beds. Vegetation encroachment provoked 10% deeper floods at the water discharge of 2000 m 3 ·s −1 , which implied an increase of Manning's roughness coefficient from 0.04 to 0.055 s·m −1/3 in less than 15 years.

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Paleohydraulic reconstruction of the largest Glacial Lake Missoula draining(s)

Cited by 63 publications

References 33 publications

Discussion of ‘Field evidence and hydraulic modeling of a large Holocene jökulhlaup at Jökulsá á Fjöllum channel, Iceland’ by Douglas Howard, Sheryl Luzzadder-Beach and Timothy Beach, 2012

Discussion of ‘Field evidence and hydraulic modeling of a large Holocene jökulhlaup at Jökulsá á Fjöllum channel, Iceland’ by Douglas Howard, Sheryl Luzzadder-Beach and Timothy Beach, 2012

Sensitivity of the North Atlantic circulation to break-up of the marine sectors of the NW European ice sheets during the last Glacial: A synthesis of modelling and palaeoceanography

Paleohydraulic Reconstruction of Modern Large Floods at Subcritical Speed in a Confined Valley: Proof of Concept

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