Determination of the internal structure of alpine talus deposits using different geophysical methods (Lechtaler Alps, Austria)

Sass, Oliver

doi:10.1016/j.geomorph.2005.09.006

Cited by 99 publications

(82 citation statements)

References 22 publications

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“…Although its depth penetration within standard geological materials is often limited to a few metres, the high-resolution imaging capabilities of GPR have been used to delineate subsurface structures in archeological (e.g., Davis et al, 2000), glaciological (e.g. Moran et al, 2000), and other geological investigations (e.g., Jol and Smith, 1991;Beres et al, 1999;Sass, 2006). We acquired five GPR profiles with various orientations over the talus, meadow, and parts of the bedrock (Fig.…”

Section: Ground-penetrating Radar Profilesmentioning

confidence: 99%

“…Hoffmann and Schrott, 2002;Musil et al, 2002;Sass, 2006). In a typical first-arrival seismic refraction experiment, the subsurface compressional-wave (P-wave) velocity distribution is determined based on the time it takes the energy produced by a seismic source to reach an array of offset receivers.…”

Section: Seismic Refraction Profilementioning

confidence: 99%

“…Other physical properties of slope deposits that can be used to infer hydrological characteristics, including debris volumes and internal structures, have been determined using geophysical methods such as ground-penetrating radar (GPR), electrical resistivity tomography (ERT), and seismic refraction methods (e.g. Sass and Wollny, 2001;Clow et al, 2003;Schrott et al, 2003;Sass, 2006Sass, , 2007.…”

Section: Introductionmentioning

confidence: 99%

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Groundwater flow and storage within an alpine meadow-talus complex

McClymont

Hayashi

Bentley

et al. 2010

Hydrol. Earth Syst. Sci.

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Abstract. The different types of geological deposits and rock formations found in alpine watersheds play key roles in regulating the rate and timing of runoff to mountain rivers. Talus and alpine meadows are dominant features in these areas, but scant data exist for their capacity to store and transmit groundwater. To gain further understanding of these processes, we have undertaken a combined geophysical and hydrological study of a small (2100 m 2 ) alpine meadow and surrounding talus within the Lake O'Hara watershed in the Canadian Rockies. Several intersecting ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) profiles and a seismic refraction profile were acquired to map the thickness of the talus and to image the topography of the bedrock basin that underlies the meadow. From analysis of the GPR and seismic profiles, we estimate that the talus deposits are relatively thin (<6 m). Combined interpretations from the GPR and ERT data show that the fine-grained sediment comprising the meadow basin has a total volume of ca. 3300 m 3 and has a maximum thickness of ca. 4 m. Annual snow surveys and stream gauging reveal that the total input volume of snowmelt and rainfall to the meadow basin is several times larger than its groundwater storage capacity, giving rise to low total-dissolved species concentrations (14-21 mg/L) within the meadow groundwater. Observations from four piezometers established on the meadow show that the water table fluctuates rapidly in response to spring snowmelt and precipitation events but otherwise maintains a relatively stable depth of 0.3-0.4 m below the meadow surface during summer months. A slug test performed on one of the piezometers indicated that the saturated hydraulic conductivity of the shallow meadow sediments is 2.5×10 −7 m/s.Correspondence to: A. F. McClymont (alastairmcclymont@gmail.com) We suggest that a bedrock saddle imaged underneath the southern end of the meadow forms a natural constriction to subsurface flow out of the basin and helps to maintain the stable water-table depth.

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Section: Ground-penetrating Radar Profilesmentioning

confidence: 99%

Section: Seismic Refraction Profilementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Groundwater flow and storage within an alpine meadow-talus complex

McClymont

Hayashi

Bentley

et al. 2010

Hydrol. Earth Syst. Sci.

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“…Several geomorphological and sedimentological studies have focused on their morphology, structure and origin (e.g. Francou, 1988;van Steijn et al, 2002;Sass, 2006), but little research has focused on the permafrost distribution and stratigraphy within talus slopes (e.g. Lütschg et al, 2004;Lambiel and Pieracci, 2008;Phillips et al, 2009) or on the palaeoclimatic significance of their ice content (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Due to the lack of in situ evidence, there is, nevertheless, a paucity of studies focusing on the stratigraphy of periglacial talus slopes (e.g. Berthling et al, 2000;Otto and Sass, 2006;Sass, 2006, Scapozza et al, 2010a.…”

Section: Introductionmentioning

confidence: 99%

Internal structure and permafrost distribution in two alpine periglacial talus slopes, Valais, Swiss Alps

et al. 2011

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In order to determine the spatial extension and the characteristics of permafrost within alpine talus slopes, two sites located in the western part of the Swiss Alps were studied using borehole drilling and electrical resistivity tomography (ERT) profiles. Three boreholes were drilled along an upslope-downslope transect in both talus slopes. In both sites, frozen sediments are present only in the two lowest boreholes, whereas the upper borehole does not present ice. This stratigraphy is confirmed by ground temperatures registered in the boreholes. In each site, three upslope-downslope ERT profiles were crossed with five, respectively four horizontal ERT profiles. All the upslope-downslope profiles show a difference in resistivities between the upper and lower parts of the slope, where a large resistive body with values higher than 35 kΩm is present. In the uppermost part of the profiles, the resistivities are lower than 10-15 kΩm. The borehole data allowed the stratigraphy obtained from the ERT inverted profiles to be validated, with regards to the distribution of frozen sediments as well as the depth of the detected structures. The results confirm that, in the two studied sites, permafrost is present in the lower sections of the talus slopes, whereas it is absent in the upper parts. Finally, the analysis of the talus structure showed that the permafrost stratigraphy, and in particular the ice content, may be an important element of interpretation of the palaeoclimatic significance of an alpine talus slope.

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Postglacial adjustment of steep, low-order drainage basins, Canadian Rocky Mountains

Hoffmann

Müller

Johnson

et al. 2013

J. Geophys. Res. Earth Surf.

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[1] It is generally argued that Pleistocene glaciation results in increased sediment flux in mountain systems. An important, but not well constrained, aspect of Pleistocene glacial erosion is the geomorphic decoupling of cirque basins from main river systems. This study provides a quantitative link between glacier-induced basin morphology, postglacial erosion, and sediment delivery for mountain headwaters (with basin area <10 km 2 ). We analyze the morphology of 57 headwater basins in the Canadian Rockies and establish postglacial sediment budgets for select basins. Notable differences in headwater morphology suggest different degrees of erosion by cirque glaciers, which we classify into headwater basins with either cirque or noncirque morphology. Despite steeper slope gradients in cirque basins, higher-mean postglacial erosion rates in basins with noncirque morphology (0.43-0.6 mm a À1 ) compared to those in cirques (0.19-0.39 mm a À1 ) suggest a more complex relationship between hillslope erosion and slope gradient in calcareous mountain environments than implied by the threshold hillslope concept. Higher values of channel profile concavity and lower channel gradients in cirques imply lower transport capacities and, thus, lower sediment delivery ratios (SDR). These results are supported by (i) postglacial SDR values for cirques and noncirque basins of <15% and >28%, respectively, and (ii) larger fan sizes at outlets of noncirque basins compared to cirques. Although small headwater basins represent the steepest part of mountain environments and erode significant postglacial sediment, the majority of sediment remains in storage under interglacial climatic conditions and does not affect large-scale mountain river systems.

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Determination of the internal structure of alpine talus deposits using different geophysical methods (Lechtaler Alps, Austria)

Cited by 99 publications

References 22 publications

Groundwater flow and storage within an alpine meadow-talus complex

Groundwater flow and storage within an alpine meadow-talus complex

Internal structure and permafrost distribution in two alpine periglacial talus slopes, Valais, Swiss Alps

Postglacial adjustment of steep, low-order drainage basins, Canadian Rocky Mountains

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