Debris flows from failures of neoglacial-age moraine dams in the Three Sisters and Mount Jefferson Wilderness areas, Oregon

172

136

Abstract. In the course of glacier retreat, new glacier lakes can develop. As such lakes can be a source of natural hazards, strategies for predicting future glacier lake formation are important for an early planning of safety measures. In this article, a multi-level strategy for the identification of overdeepened parts of the glacier beds and, hence, sites with potential future lake formation, is presented. At the first two of the four levels of this strategy, glacier bed overdeepenings are estimated qualitatively and over large regions based on a digital elevation model (DEM) and digital glacier outlines. On level 3, more detailed and laborious models are applied for modeling the glacier bed topography over smaller regions; and on level 4, special situations must be investigated in-situ with detailed measurements such as geophysical soundings. The approaches of the strategy are validated using historical data from Trift Glacier, where a lake formed over the past decade. Scenarios of future glacier lakes are shown for the two test regions Aletsch and Bernina in the Swiss Alps. In the Bernina region, potential future lake outbursts are modeled, using a GIS-based hydrological flow routing model. As shown by a corresponding test, the ASTER GDEM and the SRTM DEM are both suitable to be used within the proposed strategy. Application of this strategy in other mountain regions of the world is therefore possible as well.

Section: Modeling Potential Future Lake Outburstsmentioning

confidence: 99%

A multi-level strategy for anticipating future glacier lake formation and associated hazard potentials

Frey

Haeberli

Linsbauer

et al. 2010

172

136

“…by O'Connor et al (2001) and Huggel et al (2002), and used by Allen et al (2009). However, computing lake volume directly from lake area is problematic.…”

Section: Lake Inventory Preparationmentioning

confidence: 99%

Regional-scale analysis of lake outburst hazards in the southwestern Pamir, Tajikistan, based on remote sensing and GIS

Mergili

Schneider

2011

100

Abstract. This paper presents an analysis of the hazards emanating from the sudden drainage of alpine lakes in SouthWestern Tajik Pamir. In the last 40 yr, several new lakes have formed in the front of retreating glacier tongues, and existing lakes have grown. Other lakes are dammed by landslide deposits or older moraines. In 2002, sudden drainage of a glacial lake in the area triggered a catastrophic debris flow. Building on existing approaches, a rating scheme was devised allowing quick, regional-scale identification of potentially hazardous lakes and possible impact areas. This approach relies on GIS, remote sensing and empirical modelling, largely based on medium-resolution international datasets. Out of the 428 lakes mapped in the area, 6 were rated very hazardous and 34 hazardous. This classification was used for the selection of lakes requiring in-depth investigation. Selected cases are presented and discussed in order to understand the potentials and limitations of the approach used. Such an understanding is essential for the appropriate application of the methodology for risk mitigation purposes.

“…These may provide more information on the expected lake breaching mechanism and the resulting flow hydrograph (Walder and O'Connor, 1997), debris flow volume (Iverson et al, 1998;Rickenmann, 1999), sediment entrainment (Zimmermann and Lehmann, 1999;O'Connor et al, 2001), or structures potentially affected (Nakagawa and Takahashi, 1997). Furthermore, 2-D and 3-D debris flow models that are able to yield more detailed information on the flow behaviour have been presented (Hirano et al, 1997;Gamma, 2000).…”

Section: Discussionmentioning

confidence: 99%

Regional-scale GIS-models for assessment of hazards from glacier lake outbursts: evaluation and application in the Swiss Alps

Huggel¹,

Kääb²,

Haeberli³

et al. 2003

178

136

Abstract. Debris flows triggered by glacier lake outbursts have repeatedly caused disasters in various high-mountain regions of the world. Accelerated change of glacial and periglacial environments due to atmospheric warming and increased anthropogenic development in most of these areas raise the need for an adequate hazard assessment and corresponding modelling. The purpose of this paper is to provide a modelling approach which takes into account the current evolution of the glacial environment and satisfies a robust first-order assessment of hazards from glacier-lake outbursts. Two topography-based GIS-models simulating debris flows related to outbursts from glacier lakes are presented and applied for two lake outburst events in the southern Swiss Alps. The models are based on information about glacier lakes derived from remote sensing data, and on digital elevation models (DEM). Hydrological flow routing is used to simulate the debris flow resulting from the lake outburst. Thereby, a multiple-and a single-flow-direction approach are applied. Debris-flow propagation is given in probabilityrelated values indicating the hazard potential of a certain location. The debris flow runout distance is calculated on the basis of empirical data on average slope trajectory. The results show that the multiple-flow-direction approach generally yields a more detailed propagation. The single-flowdirection approach, however, is more robust against DEM artifacts and, hence, more suited for process automation. The model is tested with three differently generated DEMs (including aero-photogrammetry-and satellite image-derived). Potential application of the respective DEMs is discussed with a special focus on satellite-derived DEMs for use in remote high-mountain areas.