Progressive landscape transformation from a fluvial to a glacial topography

2021 ◽  
Author(s):  
Moritz Liebl ◽  
Jörg Robl ◽  
David Egholm ◽  
Günther Prasicek ◽  
Kurt Stüwe ◽  
...  
Keyword(s):  
Landscape Metrics ◽  
Eastern Alps ◽  
Cold Climate ◽  
Mountain Range ◽  
Equilibrium Line Altitude ◽  
Mountain Ranges ◽  
Model Time Series ◽  
Channel Slope ◽  
Spatial Transition ◽  
Glacial Landforms

<p>Mid-latitude mountain ranges such as the Eastern Alps are characterized by a strong topographic imprint of Pleistocene glaciations. The characteristic geometry of glacial landforms has been quantified in various ways, but studies about the evolution of glacial landscape metrics are lacking. However, such information is needed to interpret the evolutionary state of glacial topography.</p><p>By employing a landscape evolution model for cold climate processes, we trace the fluvial-to-glacial transformation of a synthetic landscape. Our simulations inspired by alpine glaciations of mid-latitude mountain ranges with peaks and ridges towering above the glacier network lead to a general increase in relief. This is expressed as the formation of overdeepened valleys with steepened flanks. Overdeepening starts at the glacier front and progressively extends upstream with ongoing glacial erosion.</p><p>The topographic signature of the progressively transforming landscape is characterized by an increase of mean channel slopes and its variance. However, above the steep flanks, the initial fluvial topography is persisting. Whereas the initial fluvial mountain range is characterized by a monotonic increase of channel slope with elevation, a transition from increasing to decreasing channel slope with elevation emerges above the equilibrium line altitude where (tributary-)headwalls transition to ridges and summits. This turning point and a high slope variance becomes progressively distinctive with ongoing glacial occupation.</p><p>By comparing landscape metrics derived from model time series with those of the Eastern Alps, we found that the temporal transition observed in our numerical experiments occur as spatial transition from the fully glaciated western to a minorly glaciated eastern part of the Alps. Thus, slope-elevation plots serve as a diagnostic tool for interpreting the glacial - fluvial influence in mountain landscapes. However, catchments of the unglaciated part of the Eastern Alps show also turning points in their slope-elevation distributions, but the variance of slope is significantly smaller at all elevation levels, when compared to the glaciated part.</p>

The imprint of glacial and periglacial erosion processes on fluvial landscape metrics

2020 ◽  
Author(s):  
Moritz Liebl ◽  
Jörg Robl ◽  
David Lundbek Egholm ◽  
Kurt Stüwe ◽  
Gerit Gradwohl
Keyword(s):  
Process Model ◽  
Large Scale ◽  
Eastern Alps ◽  
Cold Climate ◽  
Mountain Range ◽  
Mountain Ranges ◽  
Fluvial Processes ◽  
Erosion Processes ◽  
The Impact ◽  
Topographic Pattern

<p>The emerging Pleistocene glaciations have left a distinct topographic footprint in mountain ranges worldwide. However, it is still unclear how the formation of cirques above (including the potential destruction of peak relief) and the excavation of glacial troughs below the long-term snowline altered to the large-scale topographic pattern of mountain ranges originally conditioned by fluvial processes.</p><p>Some mountain ranges such as the Eastern Alps feature a bimodal topographic pattern characterized by a transition from increasing to decreasing slope with elevation. Bimodality might be an expression of glacial reshaping, as glacial troughs with steepened valley flanks have been formed at low elevations and low relief surfaces at high elevations. On the other hand, bimodality might represent the state of fluvial prematurity as expression of ongoing landscape adjustment to an uplift event in the recent past. Despite their completely different evolution, both hypotheses lead to a bimodal landscape with a similar slope-elevation distribution.</p><p>In this study, we explore the impact of cold climate erosional processes on the mountain range scale topographic pattern. For this, we use synthetically generated and natural mountain range landscapes conditioned by fluvial processes and apply a surface process model for cold climate conditions (iSOSIA). In regions with high glacial impact, we explore an upstream migrating glacial signature represented by two frequency maxima in the slope elevation distribution at lower elevations (i.e. below the snowline, where glacial troughs formed). This is accompanied with an increase in slope on average compared to the initial topography. Above the snow line, bimodality vanishes and mean slope is similar to the initial fluvial topography. Interestingly, in the Eastern Alps, we explore a similar pattern where the transition from increasing to decreasing slope with elevation is located at about 1800 m, which is roughly at the position of the last glacial maximum (LGM) snowline of this region.</p>

Microseismicity in the Eastern Alps: Preliminary Results From the Swath-D Network

2021 ◽  
Author(s):  
Rens Hofman ◽  
Joern Kummerow ◽  
Simone Cesca ◽  
Joachim Wassermann ◽  
Thomas Plenefisch ◽  
...  
Keyword(s):  
Large Data ◽  
Eastern Alps ◽  
Detection Methods ◽  
Mountain Range ◽  
Network Methods ◽  
Data Volume ◽  
Geophysical Processes ◽  
The Alps ◽  
Mountain Belts ◽  
Surrounding Areas

<p>The AlpArray seismological experiment is an international and interdisciplinary project to advance our understanding of geophysical processes in the greater Alpine region. The heart of the project consists of a large seismological array that covers the mountain range and its surrounding areas. To understand how the Alps and their neighbouring mountain belts evolved through time, we can only study its current structure and processes. The Eastern Alps are of prime interest since they currently demonstrate the highest crustal deformation rates. A key question is how these surface processes are linked to deeper structures. The Swath-D network is an array of temporary seismological stations complementary to the AlpArray network located in the Eastern Alps. This creates a unique opportunity to investigate high resolution seismicity on a local scale.</p><p>In this study, a combination of waveform-based detection methods was used to find small earthquakes in the large data volume of the Swath-D network. Methods were developed to locate the seismic events using semi-automatic picks, and estimate event magnitudes. We present an overview of the methods and workflow, as well as a preliminary overview of the seismicity in the Eastern Alps.</p>

scholarly journals [Re]covering Jeddah’s Wadis – Building the City’s Resilience through Green Infrastructure

2018 ◽  
Vol 11 (4) ◽  
pp. 228
Author(s):  
Hanaa Motasim
Keyword(s):  
Green Infrastructure ◽  
Rain Water ◽  
Mountain Range ◽  
Water Drainage ◽  
Severe Damage ◽  
Mountain Ranges ◽  
Natural Flow ◽  
The Rich ◽  
The City ◽  
Green Corridors

Jeddah, Saudi Arabia’s largest coastal city, is positioned between two prominent natural features: the mountain range on its eastern side and the Red Sea on its west. The city faces many challenges central to which is storm water drainage. The natural drainage of the city through its pre-existing wadis, bringing down the rain water from the steep mountain ranges through the low inclining coastal plane and into the sea, has been interrupted in the last few decades by massive road infrastructural projects cutting through the city and interrupting the natural flow. The outcome of these interventions has been excessive flooding calamities, of which the ones in 2009 and 2011 were the most extreme, causing severe damage to infrastructure, property and lives.In light of climate change the intensity of flash floods is expected to increase, placing enormous stress on the city. To control the floods the city has pushed forward heavily engineered solutions, canalizing the rich network of wadis, almost 80 in number, into 4 major concrete channels that discharge the rain water accumulated in the mountains directly into the sea. This solution, which has been prohibitive in cost, has robbed the city of any potential of utilizing the precious supply of rain water. This paper explores the potential of recovering Jeddah’s wadis and creating green corridors across the city. As opposed to engineered solutions which address singular problematics, green infrastructures could provide numerous benefits to the city and the region as a whole.

scholarly journals Impact of North Atlantic Oscillation on the Snowpack in Iberian Peninsula Mountains

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 105 ◽  
Author(s):  
Esteban Alonso-González ◽  
Juan I. López-Moreno ◽  
Francisco M. Navarro-Serrano ◽  
Jesús Revuelto
Keyword(s):  
North Atlantic Oscillation ◽  
Iberian Peninsula ◽  
Sierra Nevada ◽  
North Atlantic ◽  
Snow Water Equivalent ◽  
Mountain Range ◽  
Winter Climate ◽  
Mountain Ranges ◽  
Iberian Range ◽  
The Impact

The North Atlantic Oscillation (NAO) is considered to be the main atmospheric factor explaining the winter climate and snow evolution over much of the Northern Hemisphere. However, the absence of long-term snow data in mountain regions has prevented full assessment of the impact of the NAO at the regional scales, where data are limited. In this study, we assessed the relationship between the NAO of the winter months (DJFM-NAO) and the snowpack of the Iberian Peninsula. We simulated temperature, precipitation, and snow data for the period 1979–2014 by dynamic downscaling of ERA-Interim reanalysis data, and correlated this with the DJFM-NAO for the five main mountain ranges of the Iberian Peninsula (Cantabrian Range, Central Range, Iberian Range, the Pyrenees, and the Sierra Nevada). The results confirmed that negative DJFM-NAO values generally occur during wet and mild conditions over most of the Iberian Peninsula. Due to the direction of the wet air masses, the NAO has a large influence on snow duration and the annual peak snow water equivalent (peak SWE) in most of the mountain ranges in the study, mostly on the slopes south of the main axis of the ranges. In contrast, the impact of NAO variability is limited on north-facing slopes. Negative (positive) DJFM-NAO values were associated with longer (shorter) duration and higher (lower) peak SWEs in all mountains analyzed in the study. We found marked variability in correlations of the DJFM-NAO with snow indices within each mountain range, even when only the south-facing slopes were considered. The correlations were stronger for higher elevations in the mountain ranges, but geographical longitude also explained the intra-range variability in the majority of the studied mountains.

Progressive glacial retreat in the Southern Altiplano (Uturuncu volcano, 22°S) between 65 and 14 ka constrained by cosmogenic 3He dating

2014 ◽  
Vol 82 (1) ◽  
pp. 209-221 ◽  
Author(s):  
Pierre-Henri Blard ◽  
Jérôme Lave ◽  
Kenneth A. Farley ◽  
Victor Ramirez ◽  
Nestor Jimenez ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Late Glacial ◽  
Glacial Period ◽  
Tropical Andes ◽  
Equilibrium Line Altitude ◽  
Glacial Retreat ◽  
Late Glacial Period ◽  
Cold Episode ◽  
Glacial Landforms ◽  
Exposure Ages

AbstractThis work presents the first reconstruction of late Pleistocene glacier fluctuations on Uturuncu volcano, in the Southern Tropical Andes. Cosmogenic 3He dating of glacial landforms provides constraints on ancient glacier position between 65 and 14 ka. Despite important scatter in the exposure ages on the oldest moraines, probably resulting from pre-exposure, these 3He data constrain the timing of the moraine deposits and subsequent glacier recessions: the Uturuncu glacier may have reached its maximum extent much before the global LGM, maybe as early as 65 ka, with an equilibrium line altitude (ELA) at 5280 m. Then, the glacier remained close to its maximum position, with a main stillstand identified around 40 ka, and another one between 35 and 17 ka, followed by a limited recession at 17 ka. Then, another glacial stillstand is identified upstream during the late glacial period, probably between 16 and 14 ka, with an ELA standing at 5350 m. This stillstand is synchronous with the paleolake Tauca highstand. This result indicates that this regionally wet and cold episode, during the Heinrich 1 event, also impacted the Southern Altiplano. The ELA rose above 5450 m after 14 ka, synchronously with the Bolling–Allerod.

scholarly journals Glacial limitation of tropical mountain height

2019 ◽  
Vol 7 (1) ◽  
pp. 147-169 ◽  
Author(s):  
Maxwell T. Cunningham ◽  
Colin P. Stark ◽  
Michael R. Kaplan ◽  
Joerg M. Schaefer
Keyword(s):  
Steady State ◽  
Mountain Range ◽  
Equilibrium Line Altitude ◽  
Glacial Erosion ◽  
Tropical Mountains ◽  
Base Level ◽  
Snow Line ◽  
Bedrock River Incision ◽  
High Tropical Mountains ◽  
The Tropics

Abstract. Absent glacial erosion, mountain range height is limited by the rate of bedrock river incision and is thought to asymptote to a steady-state elevation as erosion and rock uplift rates converge. For glaciated mountains, there is evidence that range height is limited by glacial erosion rates, which vary cyclically with glaciations. The strongest evidence for glacial limitation is at midlatitudes, where range-scale hypsometric maxima (modal elevations) lie within the bounds of Late Pleistocene snow line variation. In the tropics, where mountain glaciation is sparse, range elevation is generally considered to be fluvially limited and glacial limitation is discounted. Here we present topographic evidence to the contrary. By applying both old and new methods of hypsometric analysis to high mountains in the tropics, we show that (a) the majority are subject to glacial erosion linked to a perched base level set by the snow line or equilibrium line altitude (ELA) and (b) many truncate through glacial erosion towards the cold-phase ELA. Evaluation of the hypsometric analyses at two field sites where glacial limitation is seemingly marginal reveals how glaciofluvial processes act in tandem to accelerate erosion near the cold-phase ELA during warm phases and to reduce their preservation potential. We conclude that glacial erosion truncates high tropical mountains on a cyclic basis: zones of glacial erosion expand during cold periods and contract during warm periods as fluvially driven escarpments encroach and destroy evidence of glacial action. The inherent disequilibrium of this glaciofluvial limitation complicates the concept of time-averaged erosional steady state, making it meaningful only on long timescales far exceeding the interval between major glaciations.

scholarly journals On the shapes of the isogeotherms under mountain ranges in radio-active districts

1910 ◽  
Vol 83 (563) ◽  
pp. 339-346 ◽  
Keyword(s):  
Physical Condition ◽  
Accurate Solution ◽  
Earth’S Crust ◽  
Mountain Range ◽  
Mountain Ranges ◽  
Earth's Crust

The importance attached by geologists to the distribution of temperature within the earth’s crust as a factor in the production of movements of the crust, and in particular in the formation of mountain ranges, has made it necessary to consider if it is possible to determine the distribution of temperature under and in the neighbourhood of a mountain range, by a method more rigid and accurate than that used by Fisher, and more closely following the physical condition of the problem than that used by Thoma. In what follows it will be shown that an accurate solution can be obtained in certain simple cases, even when the soil is radio-active.

On the Synergistic Climatic Effects of Covarying Major Mountain Range Topographies

2020 ◽  
Author(s):  
Sebastian G. Mutz ◽  
Todd A. Ehlers
Keyword(s):  
General Circulation ◽  
Atmospheric Transport ◽  
Circulation Model ◽  
Careful Consideration ◽  
Mountain Range ◽  
Earth Surface ◽  
Climatic Effects ◽  
Climate Conditions ◽  
Mountain Ranges ◽  
The Impact

<p>The interpretation of Earth surface archives often requires consideration of distant off-site events. One such event is the surface uplift of Earth’s major mountain ranges, which affects climate and the Earth’s surface globally. In this study, the individual and synergistic climatic effects of topographic changes in major mountain ranges are explored with a series of General Circulation Model (GCM) experiments and analyses of atmospheric teleconnections. The GCM experiments are forced with different topographic scenarios for Himalaya-Tibet (TBT) and the Andes (ADS), while environmental boundary conditions are kept constant. The topographic scenarios are constructed by successively lowering modern topography to 0% of its modern height in increments of 25%. This results in a total of 5 topographic scenarios for TBT (tbt100, tbt075, tbt050, tbt025, tbt000) and ADS (ads100, ads075, ads050, ads025, ads000). TBT scenarios are then nested in ADS scenarios, resulting in a total of 25 experiments with unique topographic settings. The climate for each of those 25 scenarios is simulated with the GCM ECHAM5-wiso. We then explore possible synergies and distant impacts of topographic changes by testing the hypothesis that varying ADS has no effect on simulated climate conditions in the TBT region (c_tbt) and vice versa. This can be expressed as the null hypothesis c_tbt(ads100) = c_tbt(ads075) = c_tbt(ads050) = c_tbt(ads025) = c_tbt(ads000) for each of the 5 TBT scenarios, and vice versa. We conduct Kruskal-Wallis tests for a total of 10 treatment sets to address these hypotheses. The results suggest that ADS climate is mostly independent of TBT topography changes, whereas TBT climate is sensitive to ADS topography changes when TBT topography is high, but insensitive when TBT topography is strongly reduced. Analyses of atmospheric pressure fields suggest that TBT height acts as a control on cross-equatorial atmospheric transport and modifies the impact of ADS topography on northern hemisphere climate. These results dictate a more careful consideration of global (off-site) conditions in the interpretation of Earth surface records.</p>

scholarly journals Maximum Covariance Analysis of Typhoon Surface Wind and Rainfall Relationships in Taiwan

2009 ◽  
Vol 48 (5) ◽  
pp. 997-1016 ◽  
Author(s):  
Hsiao-Chung Tsai ◽  
Tim Hau Lee
Keyword(s):  
Surface Wind ◽  
Correlation Coefficients ◽  
Covariance Analysis ◽  
Mountain Range ◽  
Mountain Ranges ◽  
Maximum Covariance Analysis ◽  
Air Temperatures ◽  
Multivariate Relationships ◽  
River Valleys ◽  
Surface Observations

Abstract The multivariate relationships between hourly surface wind and rainfall observations during typhoons affecting Taiwan have been investigated with maximum covariance analysis (MCA). Historical surface observations from 1987 to 2004 are used when typhoon centers were located inside the domain of 19°–28°N, 117°–127°E. The three leading MCA modes explain 70%, 20.6%, and 7.6% of the squared covariance fraction, and the correlation coefficients are 0.59, 0.48, and 0.49, respectively. The wind directions of the three leading positive modes are 1) northwesterly flow perpendicular to the Snow Mountain Range (SMR), 2) southwesterly flow toward the river valleys of the southwestern Central Mountain Range (CMR) and the southern SMR, and 3) easterly flow toward the northeastern SMR and the northern CMR. The rainfall patterns of the three principal modes reveal the contrast between the windward and the leeward sides of the mountain ranges. Based on the MCA singular vectors, historical typhoon surface wind patterns are categorized into major types. The results show that the three major wind types consist of 53% of the data, with 25%, 9%, and 19%, respectively, for these wind types. Furthermore, the analyses of the corresponding surface air temperatures, relative humidities, and air pressures also reveal contrasting patterns between the windward and leeward sides.

Exposure age chronology of the last glaciation in the eastern Pyrenees

2008 ◽  
Vol 69 (2) ◽  
pp. 231-241 ◽  
Author(s):  
Magali Delmas ◽  
Yanni Gunnell ◽  
Régis Braucher ◽  
Marc Calvet ◽  
Didier Bourlès
Keyword(s):  
Ice Cores ◽  
Sampling Strategy ◽  
Large Change ◽  
Equilibrium Line Altitude ◽  
Ice Cap ◽  
Eastern Pyrenees ◽  
Relative Chronology ◽  
Geomorphological Map ◽  
Glacial Landforms

We present a chronology of ice recession in the eastern Pyrenees based onin situ-produced10Be data obtained from the Têt paleoglacier complex. The sampling strategy is based on the relative chronology provided by a detailed geomorphological map of glacial landforms. Results indicate that the last maximum ice advance occurred late (i.e., during Marine Isotope Stage 2) compared to the chronology currently established for the rest of the Pyrenees. Despite debatable evidence for a glacial readvance during the Oldest Dryas stade, ice-cap melt-out was rapid, residual cirque glaciers having disappeared by the Allerød interstade. This is consistent both with North Atlantic excursions established by the Greenland ice cores and paleoenvironmental data for the region. The rapid response of the east-Pyrenean ice cap to temperature variations is primarily linked to its small size compared to larger Pyrenean ice fields, to the dry Mediterranean climate, and to topography-related nonlinearities in which a small vertical rise in equilibrium line altitude generates a large change in ice mass. Possible sources of age uncertainty are discussed in the context of sampling design for single-nuclide (10Be) dating of landform sequences in formerly glaciated landscapes.

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