scholarly journals The rate and extent of wind-gap migration regulated by tributary confluences and avulsions

2021 ◽  
Vol 9 (4) ◽  
pp. 687-700
Author(s):  
Eitan Shelef ◽  
Liran Goren
Keyword(s):  
Migration Rate ◽  
Erosion Rate ◽  
Critical Role ◽  
Climatic Changes ◽  
Climatic Conditions ◽  
Sediment Flux ◽  
Drainage Area ◽  
Valley Wind ◽  
Area Distribution ◽  
Natural Landscapes

Abstract. The location of drainage divides sets the distribution of discharge, erosion, and sediment flux between neighboring basins and may shift through time in response to changing tectonic and climatic conditions. Major divides commonly coincide with ridgelines, where the drainage area is small and increases gradually downstream. In such settings, divide migration is attributed to slope imbalance across the divide that induces erosion rate gradients. However, in some tectonically affected regions, low-relief divides, which are also called wind gaps, abound in elongated valleys whose drainage area distribution is set by the topology of large, potentially avulsing side tributaries. In this geometry, distinct dynamics and rates of along-valley wind-gap migration are expected, but this process remains largely unexplored. Inspired by field observations, we investigate along-valley wind-gap migration by simulating the evolution of synthetic and natural landscapes, and we show that confluences with large side tributaries influence migration rate and extent. Such confluences facilitate stable wind-gap locations that deviate from intuitive expectations based on symmetry considerations. Avulsions of side tributaries can perturb stable wind-gap positions, and avulsion frequency governs the velocity of wind-gap migration. Overall, our results suggest that tributaries and their avulsions may play a critical role in setting the rate and extent of wind-gap migration along valleys and thus the timescale of landscape adjustment to tectonic and climatic changes across some of the tectonically most affected regions of Earth, where wind gaps are common.

scholarly journals The rate and extent of windgap migration regulated by tributary confluences and avulsions

2021 ◽  
Author(s):  
Eitan Shelef ◽  
Liran Goren
Keyword(s):  
Migration Rate ◽  
Erosion Rate ◽  
Critical Role ◽  
Climatic Changes ◽  
Climatic Conditions ◽  
Sediment Flux ◽  
Drainage Area ◽  
Field Observations ◽  
Area Distribution ◽  
Natural Landscapes

Abstract. The location of drainage divides sets the distribution of discharge, erosion, and sediment flux between neighboring basins, and may shift through time in response to changing tectonic and climatic conditions. Major divides commonly coincide with ridgelines, where the drainage area is small and increases gradually downstream. In such settings, divide migration is attributed to slope imbalance across the divide that induces erosion rate gradients. However, in tectonically affected region, low-relief divides, windgaps, abound in elongated valleys, whose drainage area distribution is set by the topology of large, potentially avulsing side-tributaries. In this geometry, distinct dynamics and rate of along-valley windgap migration is expected, but this process remains largely unexplored. Inspired by field observations, we investigate along-valley windgap migration by simulating the evolution of synthetic and natural landscapes, and show that confluences with large side tributaries influence migration rate and extent. Such confluences facilitate stable windgap locations that deviate from intuitive expectations based on symmetry considerations. Avulsions of side tributaries can perturb stable windgap positions and avulsion frequency governs the velocity of windgap migration. Overall, our results suggest that tributaries and their avulsions may play a critical role in setting the rate and extent of windgap migration along valleys and thus the time scale of landscape adjustment to tectonic or climatic changes across some of the most tectonically affected regions of Earth, where windgaps are common.

Tree line shifts, changing vegetation assemblages and permafrost dynamics on Galdhøpiggen (Jotunheimen, Norway) over the past ~4400 years

The Holocene ◽  
2021 ◽  
pp. 095968362110665
Author(s):  
Helen Hallang ◽  
Cynthia A Froyd ◽  
John F Hiemstra ◽  
Sietse O Los
Keyword(s):  
Scots Pine ◽  
Late Holocene ◽  
Accumulation Rate ◽  
Climatic Changes ◽  
Climatic Conditions ◽  
Tree Line ◽  
Peat Core ◽  
Modern Pollen ◽  
Modern Analogue ◽  
Downy Birch

An environmental reconstruction based on palynological evidence preserved in peat was carried out to examine late-Holocene alpine tree line dynamics in the context of past climatic changes on Galdhøpiggen (Jotunheimen, southern Norway). We analysed a peat core taken from a mire at the present-day tree line (1000 m a.s.l.), c. 450 m downslope from the lower limit of sporadic permafrost. We adopted a combination of commonly used indicators of species’ local presence to reconstruct past vegetation assemblages, such as the relative pollen abundance (%), pollen accumulation rate (PAR), and presence of indicator species. Additionally, fossil pollen from the peat sequence was compared to modern pollen from a surface moss polster to establish a modern analogue. The results were compared with studies covering the late-Holocene climatic changes in the area. The reconstruction demonstrates that a pine-dominated woodland reached above the present-day tree line at c. 4300 cal. yr BP, suggesting a warmer climate suitable for Scots pine ( Pinus sylvestris) growth at this altitude. Scots pine retreated to lower altitudes between c. 3400 and 1700 cal. yr BP, accompanied by the descent of the low-alpine shrub-dominated belt, in response to cooling climatic conditions. The colder period covered c. 1700–170 cal. yr BP, and an open downy birch ( Betula pubescens) woodland became widespread at 1000 m a.s.l., whilst pine remained sparse at this altitude. From c. 170 cal. yr BP onwards, warming allowed pine to re-establish its local presence alongside downy birch at 1000 m a.s.l.

scholarly journals Climate Change and Conflict

2019 ◽  
Vol 22 (1) ◽  
pp. 343-360 ◽  
Author(s):  
Vally Koubi
Keyword(s):  
Climate Change ◽  
Climatic Changes ◽  
Climatic Conditions ◽  
Future Research ◽  
General Effect ◽  
Substantial Agreement ◽  
Political Factors ◽  
Academic Literature ◽  
The Past ◽  
Level Of Economic Development

The link between climate change and conflict has been discussed intensively in academic literature during the past decade. This review aims to provide a clearer picture of what the research community currently has to say with regard to this nexus. It finds that the literature has not detected a robust and general effect linking climate to conflict onset. Substantial agreement exists that climatic changes contribute to conflict under some conditions and through certain pathways. In particular, the literature shows that climatic conditions breed conflict in fertile grounds: in regions dependent on agriculture and in combination and interaction with other socioeconomic and political factors such as a low level of economic development and political marginalization. Future research should continue to investigate how climatic changes interact with and/or are conditioned by socioeconomic, political, and demographic settings to cause conflict and uncover the causal mechanisms that link these two phenomena.

scholarly journals Geomorphological indicators of large-scale climatic changes in the Eastern Bolivian lowlands

2006 ◽  
Vol 61 (2) ◽  
pp. 120-134 ◽  
Author(s):  
J. May
Keyword(s):  
South America ◽  
Large Scale ◽  
Climate Changes ◽  
Landscape Evolution ◽  
Spatial Scales ◽  
Climatic Changes ◽  
Climatic Conditions ◽  
Fluvial Erosion ◽  
Paleoclimatic Significance ◽  
Bolivian Lowlands

Abstract. This study provides an inventory of geomorphological landforms in Eastern Bolivia at different spatial scales. Landforms and associated processes are interpreted and discussed regarding landscape evolution and paleoclimatic significance. Thereby, preliminary conclusions about past climate changes and the geomorphic evolution in Eastern Bolivia can be provided. Fluvial and aeolian processes are presently restricted to a few locations in the study area. A much more active landscape has been inferred from large-scale Channel shifts and extensive paleodune Systems. Mobilization. transport and deposition of Sediments are thought to be the result of climatic conditions drier than today. However. there are also indications of formerly wetter conditions such as fluvial erosion and paleolake basins. In conclusion, the documentation and interpretation of the manifold landforms has shown to contain a considerable amount of paleoecological information, which might serve as the base for further paleoclimatic research in the central part of tropical South America.

The Influence of Evolution upon the Functional Development of the Lateral Wall of the Nose

1987 ◽  
Vol 1 (1) ◽  
pp. 51-57
Author(s):  
Thomas C. Smersh
Keyword(s):  
Critical Role ◽  
Lateral Wall ◽  
Climatic Changes ◽  
Human Anatomy ◽  
Evolutionary Development ◽  
Anatomy And Physiology ◽  
Functional Development ◽  
Human Anatomy And Physiology ◽  
Nasal Disease ◽  
Insight Into

The nose has played a surprisingly critical role repeatedly in adaptation and survival of the vertebrate family line, in olfaction to detect food and predators, in respiration in adaptation to terrestrial existence, and in preservation of homeostasis in severe climatic changes as in the great ice ages that destroyed the giant reptiles. Most importantly to us, the study of evolutionary development will provide insight into human anatomy and physiology and is an aid in the management of medical and surgical treatment of nasal disease.

Prevention of Soil Erosion and Torrential Floods

2022 ◽  
pp. 92-111
Author(s):  
Bhavya Kavitha Dwarapureddi ◽  
Swathi Dash ◽  
Aman Raj ◽  
Nihanth Soury Garika ◽  
Ankit Kumar ◽  
...  
Keyword(s):  
Public Health ◽  
Climate Change ◽  
Soil Erosion ◽  
Erosion Rate ◽  
Land Use Changes ◽  
Climatic Conditions ◽  
Nutrient Loss ◽  
Erosion Processes ◽  
Over Exploitation ◽  
Flood Waves

Climatic conditions, precise relief features, variations of soil, flora cover, socio-economic conditions together lead to torrential flood waves as a result of current soil erosion processes. Erosion and torrential floods are aggravated due to over exploitation of agricultural and forest land along with urbanization. Effects of soil erosion include nutrient loss, land use changes, reduced productivity, siltation of water bodies, among other effects like affecting livelihood of marginal communities dependent on agriculture globally and public health. Nearly 11 million km2 of soil is impacted by erosion precisely by water. Other factors like intensified agriculture and climate change contribute to and aggravate the erosion rate. Contemporary torrential floods are characterized by their increased destruction and frequency unlike the pre-development periods when their occurrence was rare. The focus of this review is to compile and aid as a data base for understanding methods of preventing erosion of soil and torrential floods as put forth by various researchers.

scholarly journals The Recent Nature of the Siberian Pole of Cold

1961 ◽  
Vol 3 (30) ◽  
pp. 1089-1096
Author(s):  
I. P. Gerasimov
Keyword(s):  
Late Glacial ◽  
Climatic Conditions ◽  
Point Of View ◽  
Natural Conditions ◽  
Dominant Type ◽  
North East ◽  
Natural Landscapes ◽  
Mountain System ◽  
Soil Temperatures ◽  
Extreme North

Abstract The Siberian pole of cold is situated in the extreme north-east of Eurasia (in the region of the Cherskiy mountain system, in the upper parts of the basins of the Yana, Indigirka and Kolyma Rivers). Particularly low air and soil temperatures have been observed in the intermontane areas. Among these localities is the famous Oymyakon, where the lowest minimum temperature in the Northern Hemisphere has been recorded. In the climate of this area extreme aridity, connected with the intracontinental position of the territory, is combined with intense cold. In the two highest massifs (Ulakhan-Chistay and Suntar-Khayata) small centres of recent glacierization (chiefly kars) are developed; there are also distinct traces of a more extensive older mountain glaciation. In the intermontane areas and on the principal level of the dissected hilly peneplain positive indications of a former glaciation are absent. However, the recent cryogenic phenomena represented by fossil ice, permafrost, taryns, as well as thermokarstic, solifluction and congelation features, are very abundant and diverse. The widespread development of all these features gives this territory a periglacial aspect, and also provides the possibility of using the study of many recent phenomena for palaeogeographical purposes. From this point of view, the processes leading to the formation of loess deposits (cryogenic facies) and the formation of structural and thixotropic soils arc of particular interest. The recent natural landscapes in this region are represented by a dominant type of larch tundra–forest associated with comparatively typical taiga bog formations in the depressions and xero-cryophile meadow–steppe landscapes on the steeper and warmer southern slopes. Such a unique landscape combination connected with the specific climatic conditions of this region provide a basis for interpreting the recent natural conditions of the Siberian pole of cold as a survival of the “late glacial.” At present these natural conditions are being intensively developed economically.

scholarly journals The Recent Nature of the Siberian Pole of Cold

1961 ◽  
Vol 3 (30) ◽  
pp. 1089-1096
Author(s):  
I. P. Gerasimov
Keyword(s):  
Late Glacial ◽  
Climatic Conditions ◽  
Point Of View ◽  
Natural Conditions ◽  
Dominant Type ◽  
North East ◽  
Natural Landscapes ◽  
Mountain System ◽  
Soil Temperatures ◽  
Extreme North

AbstractThe Siberian pole of cold is situated in the extreme north-east of Eurasia (in the region of the Cherskiy mountain system, in the upper parts of the basins of the Yana, Indigirka and Kolyma Rivers). Particularly low air and soil temperatures have been observed in the intermontane areas. Among these localities is the famous Oymyakon, where the lowest minimum temperature in the Northern Hemisphere has been recorded. In the climate of this area extreme aridity, connected with the intracontinental position of the territory, is combined with intense cold.In the two highest massifs (Ulakhan-Chistay and Suntar-Khayata) small centres of recent glacierization (chiefly kars) are developed; there are also distinct traces of a more extensive older mountain glaciation. In the intermontane areas and on the principal level of the dissected hilly peneplain positive indications of a former glaciation are absent. However, the recent cryogenic phenomena represented by fossil ice, permafrost, taryns, as well as thermokarstic, solifluction and congelation features, are very abundant and diverse.The widespread development of all these features gives this territory a periglacial aspect, and also provides the possibility of using the study of many recent phenomena for palaeogeographical purposes. From this point of view, the processes leading to the formation of loess deposits (cryogenic facies) and the formation of structural and thixotropic soils arc of particular interest.The recent natural landscapes in this region are represented by a dominant type of larch tundra–forest associated with comparatively typical taiga bog formations in the depressions and xero-cryophile meadow–steppe landscapes on the steeper and warmer southern slopes. Such a unique landscape combination connected with the specific climatic conditions of this region provide a basis for interpreting the recent natural conditions of the Siberian pole of cold as a survival of the “late glacial.” At present these natural conditions are being intensively developed economically.

Along-stream variations in valley flank erosion rates measured using 10Be concentrations in colluvial deposits from Atacama canyons: implications for valley widening

2020 ◽  
Author(s):  
Valeria Zavala ◽  
Sebastien Carretier ◽  
Vincent Regard ◽  
Stephane Bonnet ◽  
Rodrigo Riquelme ◽  
...  
Keyword(s):  
Erosion Rate ◽  
Landscape Evolution ◽  
Sediment Flux ◽  
Lower Probability ◽  
Upward Migration ◽  
Channel Mobility ◽  
Erosion Rates ◽  
Valley Flank ◽  
Lateral Erosion ◽  
Bed Slope

<p>The downstream increase in valley width is an important feature of fluvial landscapes that may be evident to anyone: even if local exceptions exist, wide fluvial valleys in plains are distinctive of narrow upstream mountainous ones. Yet, the processes and rates governing along-stream valley widening over timescales characteristic of landscape development (>1-10 ka) are largely unknown. No suitable law exists in landscape evolution models, thus models imperfectly reproduce the landscape evolution at geological timescales, their rates of erosion and probably their response to tectonics and climate. Here, we study two 1 km-deep canyons in northern Chile with diachronous incision initiation, thus representing two time-stage evolutions of a similar geomorphic system characterized by valley widening following the upward migration of a major knickzone. We use 10Be cosmogenic isotope concentrations measured in colluvial deposits at the foot of hillslopes to quantify along-stream valley flank erosion rates. We observe that valley flank erosion rate increases quasi-linearly with valley-bed slope and decreases non-linearly with valley width. This relation suggests that lateral erosion increases with sediment flux due to higher channel mobility. In turn, valley width exerts a negative feedback on lateral valley flank erosion since channels in wide valleys have a lower probability of eroding the valley sides. This implies a major control of river divagation on valley flank erosion rate and valley widening. Our study provides the first data for understanding the long-term processes and rates governing valley widening in landscapes.</p>

scholarly journals Spatio-temporal variability and controlling factors for postglacial erosion dynamics in the Dora Baltea catchment (western Italian Alps)

2021 ◽  
Author(s):  
Elena Serra ◽  
Pierre Gaston Valla ◽  
Romain Delunel ◽  
Natacha Gribenski ◽  
Marcus Christl ◽  
...  
Keyword(s):  
Drainage System ◽  
Western Alps ◽  
Climatic Conditions ◽  
Sediment Flux ◽  
European Alps ◽  
Italian Alps ◽  
River Sand ◽  
Denudation Rate ◽  
Denudation Rates ◽  
Mont Blanc Massif

Abstract. Disentangling the influence of bedrock erodibility from the respective roles of climate, topography and tectonic forcing on catchment denudation is often challenging in mountainous landscapes due to the diversity of geomorphic processes in action and of spatial/temporal scales involved. The Dora Baltea catchment (western Italian Alps) appears the ideal setting for such investigation, since its large drainage system, extending from the Mont Blanc Massif to the Po Plain, cuts across different major litho-tectonic units of the western Alps, whereas this region has experienced homogeneous climatic conditions and glacial history throughout the Quaternary. We acquired new 10Be-derived catchment-wide denudation rates from 18 river-sand samples collected both along the main Dora Baltea river and at the outlet of its main tributaries. The inferred denudation rate results vary between 0.2 and 0.9 mm/yr, consistent with values obtained across the European Alps by previous studies. Spatial variability in denudation rates was statistically compared with topographic, environmental and geologic metrics. 10Be-derived denudation records do not correlate with the distribution of modern precipitation and rock geodetic uplift. We find, rather, that catchment topography, in turn conditioned by bedrock erodibility (litho-tectonic origin) and glacial overprint, has the main influence on denudation rates. We calculated the highest denudation rate for the Mont Blanc Massif, whose granitoid rocks and long-term tectonic uplift support steep slopes and high relief and thus favour intense glacial/periglacial processes and recurring rock fall events. Finally, our results, in agreement with modern sediment budgets, demonstrate that the high sediment input from the Mont Blanc catchment dominates the Dora Baltea sediment flux, explaining the constant low 10Be concentrations measured along the Dora Baltea course even downstream the multiple junctions with tributary catchments.

Sign in / Sign up

Export Citation Format

Share Document