Erosional power in the Swiss Alps: characterization of slope failure in the Illgraben
01 Dec 2012-Earth Surface Processes and Landforms (John Wiley & Sons, Ltd)-Vol. 37, Iss: 15, pp 1627-1640
TL;DR: In this article, the authors used digital photogrammetry to produce a multi-temporal record of erosion (1963-2005) of a rock slope at the head of the Illgraben, a very active catchment prone to debris flows in Switzerland.
Abstract: Landslides and rockfalls are key geomorphic processes in mountain basins. Their quantification and characterization are critical for understanding the processes of slope failure and their contributions to erosion and landscape evolution. We used digital photogrammetry to produce a multi-temporal record of erosion (1963–2005) of a rock slope at the head of the Illgraben, a very active catchment prone to debris flows in Switzerland. Slope failures affect 70% of the study slope and erode the slope at an average rate of 0.39 ± 0.03 m yr¯¹. The analysis of individual slope failures yielded an inventory of ~2500 failures ranging over 6 orders of magnitude in volume, despite the small slope area and short study period. The slope failures form a characteristic magnitude–frequency distribution with a rollover and a power-law tail between ~200 m³ and 1.6 × 106 m³ with an exponent of 1.65. Slope failure volume scales with area as a power law with an exponent of 1.1. Both values are low for studies of bedrock landslides and rockfall and result from the highly fractured and weathered state of the quartzitic bedrock. Our data suggest that the magnitude–frequency distribution is the result of two separate slope failure processes. Type (1) failures are frequent, small slides and slumps within the weathered layer of highly fractured rock and loose sediment, and make up the rollover. Type (2) failures are less frequent and larger rockslides and rockfalls within the internal bedded and fractured slope along pre-determined potential failure surfaces, and make up the power-law tail. Rockslides and rockfalls of high magnitude and relatively low frequency make up 99% of the total failure volume and are thus responsible for the high erosion rate. They are also significant in the context of landscape evolution as they occur on slopes above 45° and limit the relief of the slope. Copyright © 2012 John Wiley & Sons, Ltd.
Citations
More filters
01 Jan 2015
TL;DR: In this paper, the basic concepts of SfM photogrammetry are presented, whilst recognising its heritage, and a few examples are employed to illustrate the potential of sfM applications for geomorphological research.
Abstract: Topographic data measurement is a fundamental aspect of many geomorphic research applications, particularly those including landform monitoring and investigation of changes in topography. However, most surveying techniques require relatively expensive technologies or specialized user supervision. Structure from Motion (SfM) photogrammetric technology lightens both these constraints by allowing the use of consumer grade digital cameras and highly automated data processing, which can be free to use. SfM photogrammetry therefore offers the possibility of fast, automated and low-cost acquisition of 3-D data, which has inevitably created great interest amongst the geomorphological community. In this contribution, the basic concepts of SfM photogrammetry are presented, whilst recognising its heritage. A few examples are employed to illustrate the potential of SfM applications for geomorphological research. In particular, SfM photogrammetry offers to geomorphologists a tool for high-resolution characterisation of 3-D forms at a range of scales and for change detection purposes. The high level of automation of SfM data processing creates both opportunities and threats, particularly because user control tends to focus upon the final product visually rather than upon inherent data quality. Accordingly, this contribution seeks to guide potential new users in successfully applying SfM for a range of geomorphic studies.
220 citations
Cites methods from "Erosional power in the Swiss Alps: ..."
...Traditionally, topographic research focused upon constructing digital elevation models (DEMs) using photogrammetric (e.g. Lane et al., 1994; Barker et al., 1997; Chandler, 1999; Lane, 2000; Westaway et al., 2000; Bennett et al., 2012) and differential global positioning system (dGPS) (e....
[...]
...…digital elevation models (DEMs) using photogrammetric (e.g. Lane et al., 1994; Barker et al., 1997; Chandler, 1999; Lane, 2000; Westaway et al., 2000; Bennett et al., 2012) and differential global positioning system (dGPS) (e.g. Fix and Burt, 1995; Brasington et al., 2000; Young, 2012) data....
[...]
Posted Content•
TL;DR: In this article, the authors present the cumulative frequency-size distributions of landslides induced by precipitation in Japan and Bolivia as well as landslides triggered by the 1994 Northridge, California earthquake.
Abstract: Power spectral analyses of soil moisture variability are carried out from scales of 100 m to 10 km on the microwave remotely-sensed data from the Washita experimental watershed during 1992. The power spectrum S(k) has an approximately power-law dependence on wave number k with exponent -1.8. This behavior is consistent with the behavior of a stochastic differential equation for soil moisture at a point. This behavior has important consequences for the frequency-size distribution of landslides. We present the cumulative frequency-size distributions of landslides induced by precipitation in Japan and Bolivia as well as landslides triggered by the 1994 Northridge, California earthquake. Large landslides in these regions, despite being triggered by different mechanisms, have a cumulative frequency-size distribution with a power-law dependence on area with an exponent ranging from -1.5 to -2. We use a soil moisture field with the above statistics in conjunction with a slope stability analysis to model the frequency-size distribution of landslides. In our model landslides occur when a threshold shear stress dependent on cohesion, pore pressure, internal friction and slope angle is exceeded. This implies a threshold dependence on soil moisture and slope angle since these factors are primarily dependent on soil moisture. Abstract continued in paper.
196 citations
TL;DR: A review of the current state of the art in the use of terrestrial radar interferometry for the detection of surface changes related to mass movement can be found in this paper, where different hardware types and acquisition concepts are described, which use either real or synthetic aperture for radar image formation.
Abstract: This paper presents a review of the current state of the art in the use of terrestrial radar interferometry for the detection of surface changes related to mass movement. Different hardware-types and acquisition concepts are described, which use either real or synthetic aperture for radar image formation. We present approaches for data processing procedures, paying special attention to the separation of high resolution displacement information from atmospheric phase variations. Recent case studies are used to illustrate applications in terrestrial radar interferometry for change detection. Applications range from detection and quantification of very slow moving (millimeters to centimeters per year) displacements in rock walls from repeat monitoring, to rapid processes resulting in fast displacements (~50 m/yr) acquired during single measurement campaigns with durations of only a few hours. Fast and episodic acting processes such as rockfall and snow avalanches can be assessed qualitatively in the spatial domain by mapping decorrelation caused by those processes. A concluding guide to best practice outlines the necessary preconditions that have to be fulfilled for successful application of the technique, as well as in areas characterized by rapid decorrelation. Empirical data from a Ku-band sensor show the range of temporal decorrelation of different surfaces after more than two years for rock-surfaces and after a few seconds to minutes in vegetated areas during windy conditions. The examples show that the displacement field can be measured for landslides in dense grassland, ice surfaces on flowing glaciers and snowpack creep. Copyright © 2014 John Wiley & Sons, Ltd.
142 citations
Cites background from "Erosional power in the Swiss Alps: ..."
...…to various triggering factors and has also provided basic information to infer the sediment flux at different spatial and temporal scales, as well as to interpret effects related to coupling relationships between hillslopes and channel networks (Schuerch et al., 2006; Bennett et al., 2012)....
[...]
TL;DR: In this paper, a 125,000 m2 calanchi badland in the Province of Siena (Tuscany) was monitored with an unmanned aerial vehicle (UAV) and terrestrial laser scanning over the period of one year.
105 citations
TL;DR: In this paper, an entrainment model, developed using field data from debris flows at the Illgraben catchment, Switzerland, was incorporated into the existing RAMMS debris-flow model, which solves the 2-D shallow-water equations for granular flows.
Abstract: . This study describes an investigation of channel-bed entrainment of sediment by debris flows. An entrainment model, developed using field data from debris flows at the Illgraben catchment, Switzerland, was incorporated into the existing RAMMS debris-flow model, which solves the 2-D shallow-water equations for granular flows. In the entrainment model, an empirical relationship between maximum shear stress and measured erosion is used to determine the maximum potential erosion depth. Additionally, the average rate of erosion, measured at the same field site, is used to constrain the erosion rate. The model predicts plausible erosion values in comparison with field data from highly erosive debris flow events at the Spreitgraben torrent channel, Switzerland in 2010, without any adjustment to the coefficients in the entrainment model. We find that by including bulking due to entrainment (e.g., by channel erosion) in runout models a more realistic flow pattern is produced than in simulations where entrainment is not included. In detail, simulations without entrainment show more lateral outflow from the channel where it has not been observed in the field. Therefore the entrainment model may be especially useful for practical applications such as hazard analysis and mapping, as well as scientific case studies of erosive debris flows.
101 citations
References
More filters
TL;DR: This work proposes a principled statistical framework for discerning and quantifying power-law behavior in empirical data by combining maximum-likelihood fitting methods with goodness-of-fit tests based on the Kolmogorov-Smirnov (KS) statistic and likelihood ratios.
Abstract: Power-law distributions occur in many situations of scientific interest and have significant consequences for our understanding of natural and man-made phenomena. Unfortunately, the detection and characterization of power laws is complicated by the large fluctuations that occur in the tail of the distribution—the part of the distribution representing large but rare events—and by the difficulty of identifying the range over which power-law behavior holds. Commonly used methods for analyzing power-law data, such as least-squares fitting, can produce substantially inaccurate estimates of parameters for power-law distributions, and even in cases where such methods return accurate answers they are still unsatisfactory because they give no indication of whether the data obey a power law at all. Here we present a principled statistical framework for discerning and quantifying power-law behavior in empirical data. Our approach combines maximum-likelihood fitting methods with goodness-of-fit tests based on the Kolmogorov-Smirnov (KS) statistic and likelihood ratios. We evaluate the effectiveness of the approach with tests on synthetic data and give critical comparisons to previous approaches. We also apply the proposed methods to twenty-four real-world data sets from a range of different disciplines, each of which has been conjectured to follow a power-law distribution. In some cases we find these conjectures to be consistent with the data, while in others the power law is ruled out.
8,753 citations
"Erosional power in the Swiss Alps: ..." refers background or methods in this paper
...A particular benefit of the procedure proposed by Clauset et al. (2009) is the estimation of the minimum magnitude for power law scaling and the fit to the power law tail (p-value), which are difficult to obtain from previous studies that have used PDF or indeed other methods of fitting to the…...
[...]
...Other estimation methods such as the MLE or Hill’s estimator are advisable (Hill, 1975; Clauset et al., 2009)....
[...]
...This bias is real and has been shown numerically (Clauset et al., 2009)....
[...]
...1, meaning that the power law model gives a good fit to the data (Clauset et al., 2009)....
[...]
...…between the logarithmically transformed frequency (f ) and the equivalent logarithmically transformed volumes; (2) maximum likelihood estimation of b and estimation of xmin with fitting to the CCDF following Clauset et al. (2009) (Figure 6 (a), (b)); and (3) robust linear regression on the CCDF....
[...]
TL;DR: In this paper, a simple general approach to inference about the tail behavior of a distribution is proposed, which is not required to assume any global form for the distribution function, but merely the form of behavior in the tail where it is desired to draw inference.
Abstract: A simple general approach to inference about the tail behavior of a distribution is proposed. It is not required to assume any global form for the distribution function, but merely the form of behavior in the tail where it is desired to draw inference. Results are particularly simple for distributions of the Zipf type, i.e., where $G(y) = 1 - Cy^{-\alpha}$ for large $y$. The methods of inference are based upon an evaluation of the conditional likelihood for the parameters describing the tail behavior, given the values of the extreme order statistics, and can be implemented from both Bayesian and frequentist viewpoints.
3,060 citations
"Erosional power in the Swiss Alps: ..." refers methods in this paper
...Other estimation methods such as the MLE or Hill’s estimator are advisable (Hill, 1975; Clauset et al., 2009)....
[...]
2,782 citations
TL;DR: The first edition of this book as mentioned in this paper was published in 1992 and was used for the first year of a physics course at the University of Sheffield. But it was not intended to be a statistics text, nor was it intended to serve as a statistic text, but an introdution to the mathematics required for the analysis of measurements at the level of a first year laboratory course.
Abstract: Students in a science or engineering curriculum ought to be introduced early to the requirement that a meaningful measurement result should always be accompanied by a statement of its uncertainty. This book has been written specifically with this objective in mind. That the first edition has been successful in doing this is attested to by its popularity with both faculty and students, and its translation into six languages. This book is not a statistics text - nor was it intended to be - but an introdution to the mathematics required for the analysis of measurements at the level of a first-year laboratory course. Part 1 begins with uncertainty as a qualitative concept and builds slowly, using many numerical examples and exercises for the student, to develop methods for quantifying uncertainty, and ultimately relating it to the standard deviation of a statistical distribution. Along the way, Taylor develops the rules for expressing and combining (`propagating') uncertainties, and introduces the student to the gaussian (normal) distribution and some of its properties. Part 2 covers, with somewhat more mathematical rigor, specific topics such as data rejection criteria, the binomial and Poisson distributions, covariance and correlation, least-squares fitting, and the chi-squared test. I was not familiar with the first edition, and from a quick scan of the Preface I looked forward to reading this book and learning something about the state of statistical analysis in first-year university texts today. I was disappointed (in part with what the level of the book implies about the sad state of preparation of today's students). Although there are now two ISO publications ( International Vocabulary of Basic and General Terms in Metrology (VIM) and Guide to the Expression of Uncertainty in Measurement (GUM), Geneva, 1993), Taylor makes no mention of either, and never gives a formal definition of `uncertainty' (although he ultimately associates `random uncertainty' with the standard deviation of a gaussian distribution). The book also does not clearly define `error', or the distinction between error and uncertainty. The important point, that the `propagation of uncertainty' is additive in terms of variances is valid for any distributions with finite variance, is not emphasized; instead Taylor restricts the discussion solely to the normal distribution and or those that can be approximated by it. I also find it unfortunate that the book does not clearly distinguish between the variance of a sample , the variance of a distribution , and the sample estimate of the variance of the distribution ( or ). Instead, he accepts the fact that formulas for the variance with either N or N - 1 dividing the sum of the squares of the deviations from the mean exist in the literature and concludes simply: `Nevertheless, you need to be aware of both definitions. In the physics laboratory, using the more conservative... def- inition... is almost always best.' In spite of these shortcomings, the book is a significant contribution to a student laboratory reading list, and it is written at a level that facilitates a self-study program. It has an important message to deliver and it appears to be delivering it well.
2,637 citations
"Erosional power in the Swiss Alps: ..." refers methods in this paper
...…the multi-temporal comparison of the DEMs the combined error in elevation change between two DEMs has a standard deviation, which was calculated as (Taylor, 1997): sdiff ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi s21 þ s22 q (1) with s21 and s 2 2 being the standard deviations of…...
[...]
Book•
01 Jan 1982
TL;DR: Teaching Special Relativity Phys.
Abstract: The need for error analysis is captured in the book's arresting cover shot - of the 1895 Paris train disaster (also available as a wall poster). The early chapters teach elementary techniques of error propagation and statistical analysis to enable students to produce successful lab reports. Later chapters treat a number of more advanced mathematical topics, with many examples from mechanics and optics. End-of-chapter problems include many that call for use of calculators or computers, and numerous figures help readers visualize uncertainties using error bars. "Score a hit! ...the book reveals the exceptional skill of the author as lecturer and teacher...a valuable reference work for any student (or instructor) in the sciences and engineering." The Physics Teacher "This is a well written book with good illustrations, index and general bibliography...The book is well suited for engineering and science courses at universities and as a basic reference text for those engineers and scientists in practice." Strain, Journal of the British Society for Strain Measurement
2,264 citations