Outburst Floods

O’Connor, Jim E.; Clague, John J.; Walder, Joseph S.; Manville, V.; Beebee, Robin A.

doi:10.1016/b978-0-12-818234-5.00007-9

Cited by 10 publications

(10 citation statements)

References 390 publications

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“…Dam type in turn influences the nature of the flood as well as likelihood for repeat events 3,11 . Icedammed lakes are impounded behind a glacier dam, and drainage results from flotation of the ice dam, the opening of subglacial conduits, complete ice-dam failure, or flow over or along the ice margin [13][14][15] . Because subsequent ice flow can effectively repair and reseal the ice dam, icedammed lakes can experience multiple fill and drain cycles.…”

Section: Mainmentioning

confidence: 99%

“…Additionally, some moraine dams remain stable due to low-gradient outlet channels draining the lake, maintaining a stable lake level 1 . Other moraine-dammed lakes may disappear due to sediment infill (as occurred for the seven lakes lost between 1984-2019 18 ), which results in lake displacement and a low likelihood of an outburst flood 15 .…”

Section: The Role Of Dam Type In Drainage Frequencymentioning

confidence: 99%

“…In many instances, LIA moraines are located in large, flat valleys, rather than the steeper settings found in the Himalaya or Tropical Andes. The triggering mechanism for moraine-dammed lake floods are often ice or rock fall into the lake, which initiate from steep adjacent slopes 15 . Few moraine-dammed lakes in Alaska are currently surrounded by these types of steep, triggering slopes, which reduces the likelihood of moraine-dam failure from such a trigger.…”

Section: The Role Of Dam Type In Drainage Frequencymentioning

confidence: 99%

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Decreasing hazards from glacial lakes in Alaska since the 1960s

Rick

McGrath

McCoy

et al. 2022

Preprint

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As ice retreats due to climate change, glacial lakes can form and grow. Rapid lake drainage can produce devastating outburst floods leading many to propose that hazards from glacial lakes are increasing. Outburst flood compilations do show an increase in number of events over time, however, recent studies attribute such trends to observational bias. This leaves large uncertainty about current and future glacial-lake hazards. Here, we focus on ice-dammed lake drainages in Alaska, as a third of documented events globally occurred in this region. Using multitemporal satellite imagery, we documented 1150 drainages from 106 lakes over 1985–2020, with an apparent increase in event frequency. However, accounting for increasing number of satellite images, we find no temporal trend in drainage frequency. Furthermore, we document a loss of >75% of ice-dammed lakes since the 1960s. This suggests a decrease in regional flood hazard and motivates an unbiased look at other regions.

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Section: Mainmentioning

confidence: 99%

Section: The Role Of Dam Type In Drainage Frequencymentioning

confidence: 99%

Section: The Role Of Dam Type In Drainage Frequencymentioning

confidence: 99%

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Decreasing hazards from glacial lakes in Alaska since the 1960s

Rick

McGrath

McCoy

et al. 2022

Preprint

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“…As beaver dams impound water upstream, they also raise the possibility of beaver dam outburst floods. Although such outburst floods are rare, there were cases where such events greatly exceeded discharges of meteorological floods (O'Connor et a l., 2013). Given both ecological benefits and outburst hazard, potential beaver dam locations should thus be known for managing river restoration and flood risk.…”

Section: Beaver Dams In the Tualatin Basin Oregonmentioning

confidence: 99%

A systematic approach and software for the analysis of point patterns on river networks

Schwanghart

Molkenthin

Scherler

2021

Earth Surf Processes Landf

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Many geomorphic phenomena such as bank failures, landslide dams, riffle‐pool sequences and knickpoints can be modelled as spatial point processes. However, as the locations of these phenomena are constrained to lie on or alongside rivers, their analysis must account for the geometry and topology of river networks. Here, we introduce a new numeric class in TopoToolbox called Point Pattern on Stream networks (PPS), which supports exploratory analysis, statistical modelling, simulation and visualization of point processes. We present three case studies that aim at inferring processes and factors that control the spatial density of geomorphic phenomena along river networks: analysis of a synthetic dataset of points on a stream network, the analysis of knickpoints in river profiles, and modelling spatial locations of beaver dams based on topographic metrics. The case studies rely on exploratory analysis and statistical inference using inhomogeneous Poisson point processes. Thereby, statistical and probabilistic procedures implemented in PPS provide a systematic approach for treating and quantifying uncertainties. PPS offers a consistent numeric framework for modelling point processes on river networks with a wide range of applications in fluvial geomorphology, but also other disciplines such as ecology.

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“…Figure 2 serves as an example of the issues that arise from fitting limit lines using Inspection, Selective Regression and application of a data-informed Theoretical Limit. The data sets collectively represent the relationship between measured volumes of released lake water ( V ) and the estimates of the peak discharge ( Q p ) downstream due to catastrophic lake failure (O’Connor et al, 2013). It may be expected that variation in breaching mechanisms, channel geometry and roughness (amongst other controls) will mediate the downstream translation of the flood wave so that different peak discharge values might be obtained for the same initial lake volumes.…”

Section: Examples Of Current Fitting Proceduresmentioning

confidence: 99%

Fitting limit lines (envelope curves) to spreads of geoenvironmental data

Carling

Jonathan

2021

Progress in Physical Geography: Earth and Environment

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Geoscientists frequently are interested in defining the overall trend in x- y data clouds using techniques such as least-squares regression. Yet often the sample data exhibits considerable spread of y-values for given x-values, which is itself of interest. In some cases, the data may exhibit a distinct visual upper (or lower) ‘limit’ to a broad spread of y-values for a given x-value, defined by a marked reduction in concentration of y-values. As a function of x-value, the locus of this ‘limit’ defines a ‘limit line’, with no (or few) points lying above (or below) it. Despite numerous examples of such situations in geoscience, there has been little consideration within the general geoenvironmental literature of methods used to define limit lines (sometimes termed ‘envelope curves’ when they enclose all data of interest). In this work, methods to fit limit lines are reviewed. Many commonly applied methods are ad-hoc and statistically not well founded, often because the data sample available is small and noisy. Other methods are considered which correspond to specific statistical models offering more objective and reproducible estimation. The strengths and weaknesses of methods are considered by application to real geoscience data sets. Wider adoption of statistical models would enhance confidence in the utility of fitted limits and promote statistical developments in limit fitting methodologies which are likely to be transformative in the interpretation of limits. Supplements, a spreadsheet and references to software are provided for ready application by geoscientists.

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Outburst Floods

Cited by 10 publications

References 390 publications

Decreasing hazards from glacial lakes in Alaska since the 1960s

Decreasing hazards from glacial lakes in Alaska since the 1960s

A systematic approach and software for the analysis of point patterns on river networks

Fitting limit lines (envelope curves) to spreads of geoenvironmental data

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